Changeset 657 for trunk/kernel/fs/fatfs.c

Timestamp:

Mar 18, 2020, 11:16:59 PM (5 years ago)

Author:

alain

Message:

Introduce remote_buf.c/.h & socket.c/.h files.
Update dev_nic.c/.h files.

File:

• trunk/kernel/fs/fatfs.c (modified) (65 diffs)

trunk/kernel/fs/fatfs.c

@@ -2 +2 @@
  * fatfs.c - FATFS file system API implementation.
  *
- * Author    Alain Greiner (2016,2017,2018,2019)
+ * Author    Alain Greiner (2016,2017,2018,2019,2020)
  *
  * Copyright (c) UPMC Sorbonne Universites
@@ -122 +122 @@
         for( i = nbytes ; i > 0 ; i-- )
         {
-            res = (res<<8) | hal_remote_lb( buffer_xp+offset+i-1 );
+            res = (res<<8) | hal_remote_lb( buffer_xp + offset + i-1 );
         }
     }
@@ -129 +129 @@
         for( i = 0 ; i < nbytes ; i++ )
         {
-            res = (res<<8) | hal_remote_lb( buffer_xp+offset+i );
+            res = (res<<8) | hal_remote_lb( buffer_xp + offset + i );
         }
     }
@@ -135 +135 @@
 
 }  // end fatfs_get_remote_record()
+
+/*
 
 //////////////////////////////////////////////////////////////////////////////////////////
@@ -164 +166 @@
 }  // end fatfs_set_record()
 
+*/
+
 //////////////////////////////////////////////////////////////////////////////////////////
 // This function writes one, two, or four bytes from a 32 bits integer to a remote
@@ -185 +189 @@
         for( i = nbytes ; i > 0 ; i-- )
         {
-            hal_remote_sb( (buffer_xp+offset+i-1) , (uint8_t)(value>>((i-1)<<3)) );
+            hal_remote_sb( (buffer_xp + offset + i-1 ) , (uint8_t)(value>>((i-1)<<3)) );
         }
     }
@@ -192 +196 @@
         for( i = 0 ; i < nbytes ; i++ )
         {
-            hal_remote_sb( (buffer_xp+offset+i) , (uint8_t)(value>>((nbytes-1-i)<<3)) );
+            hal_remote_sb( (buffer_xp + offset + i) , (uint8_t)(value>>((nbytes-1-i)<<3)) );
         }
     }
@@ -470 +474 @@
     cxy_t         fat_cxy;         // FAT cluster identifier
     fatfs_ctx_t * fatfs_ctx;       // local pointer on FATFS context in FAT cluster
-    xptr_t        fat_mapper_xp;   // extended pointer on FAT mapper
     mapper_t    * fat_mapper_ptr;  // local pointer on FAT mapper
     uint32_t      page_id;         // current page index in FAT mapper
@@ -482 +485 @@
     fatfs_ctx = GET_PTR( fatfs_ctx_xp );
  
-    // get FAT mapper pointers from FATFS context 
-    fat_mapper_xp  = hal_remote_l64( XPTR( fat_cxy , &fatfs_ctx->fat_mapper_xp ) );
-    fat_mapper_ptr = GET_PTR( fat_mapper_xp );
-
-// check FAT cluster
-assert( (fat_cxy == GET_CXY( fat_mapper_xp )) , "unconsistent FAT cluster" );
+    // get FAT mapper pointer from FATFS context 
+    fat_mapper_ptr  = hal_remote_lpt( XPTR( fat_cxy , &fatfs_ctx->fat_mapper ) );
 
     // build extended pointer on FAT mapper radix tree
@@ -575 +574 @@
     
     // update the FS_INFO sector on IOC device
-    return dev_ioc_move_data( IOC_SYNC_WRITE , fs_info_buffer_xp , fs_info_lba , 1 );
+    return dev_ioc_sync_write( fs_info_buffer_xp , fs_info_lba , 1 );
  
 }  // end fatfs_update_ioc_fsinfo()
@@ -581 +580 @@
 //////////////////////////////////////////////////////////////////////////////////////////
 // This static function decrements the  "free_clusters" variable, and updates the 
-// "free_cluster_hint" variable in the FATFS context in FAT cluster, identified 
-// by the <fat_ctx_xp> argument, when a new <cluster> has been allocated from FAT.
+// "free_cluster_hint" variable in the FATFS context in FAT cluster,  when a new 
+// <cluster_id> has been allocated from the FAT.
+// It synchronously updates the FS_INFO sector on the IOC device. 
+// The FATFS context in FAT cluster is identified by the <fat_ctx_xp> argument.
+// It can be called by a thead running in any cluster. 
 // It scan all slots in the FAT mapper seen as an array of 32 bits words, looking for the
-// first free slot larger than the <cluster> argument, to update "free_cluster_hint".
-// It synchronously updates the FS_INFO sector on the IOC device. 
-// It can be called by a thead running in any cluster. 
+// first free slot larger than the <cluster_id>.
 // The lock protecting exclusive access to the FAT must be taken by the calling function. 
 //////////////////////////////////////////////////////////////////////////////////////////
 // @ fatfs_ctx_xp  : extended pointer on FATFS context in FAT cluster. 
-// @ cluster       : recently allocated cluster index in FAT.
+// @ cluster_id    : recently allocated cluster index in FAT.
 // @ return 0 if success, return -1 if the FS_INFO sector cannot be updated.
 //////////////////////////////////////////////////////////////////////////////////////////
 static error_t fatfs_free_clusters_decrement( xptr_t    fatfs_ctx_xp,
-                                              uint32_t  cluster )
+                                              uint32_t  cluster_id )
 {
     error_t       error;
-    cxy_t         fat_cxy;        // FAT cluster identifier
-    fatfs_ctx_t * fat_ctx_ptr;    // local pointer on fatfs context in FAT cluster
-    xptr_t        fat_mapper_xp;  // extended pointer on FAT mapper
-    xptr_t        hint_xp;        // extended pointer on "free_cluster_hint" shared variable
-    xptr_t        numb_xp;        // extended pointer on "free_clusters" shared variable 
-    uint32_t      numb;           // "free_clusters" variable current value
-    uint32_t      hint;           // "free_cluster_hint" variable current value
-    uint32_t      page_id;        // page index in FAT mapper
-    uint32_t      slot_id;        // slot index in one page of FAT (1024 slots per page)
-    uint32_t      page_max;       // max number of pages in FAT mapper
-    xptr_t        page_xp;        // extended pointer on current page in FAT mapper
-    xptr_t        base_xp;        // extended pointer on current page base
-    xptr_t        slot_xp;        // extended pointer on current slot in FAT mapper
+    cxy_t         fat_cxy;         // FAT cluster identifier
+    fatfs_ctx_t * fat_ctx_ptr;     // local pointer on fatfs context in FAT cluster
+    mapper_t    * fat_mapper_ptr;  // local pointer on FAT mapper
+    xptr_t        fat_mapper_xp;   // extended pointer on FAT mapper
+    xptr_t        hint_xp;         // extended pointer on "free_cluster_hint" shared variable
+    xptr_t        numb_xp;         // extended pointer on "free_clusters" shared variable 
+    uint32_t      page_id;         // page index in FAT mapper
+    uint32_t      slot_id;         // slot index in one page of FAT (1024 slots per page)
+    uint32_t      page_max;        // max number of pages in FAT mapper
+    xptr_t        page_xp;         // extended pointer on current page in FAT mapper
+    xptr_t        base_xp;         // extended pointer on current page base
+    xptr_t        slot_xp;         // extended pointer on current slot in FAT mapper
+    uint32_t      found;           // free slot found when non zero
 
 #if DEBUG_FATFS_FREE_CLUSTERS
@@ -615 +615 @@
 thread_t * this  = CURRENT_THREAD;
 if( DEBUG_FATFS_FREE_CLUSTERS < cycle )
-printk("\n[%s] thread[%x,%x] enter for allocated cluster %x / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, cluster , cycle );
+printk("\n[%s] thread[%x,%x] enter for allocated cluster_id %x / cycle %d\n",
+__FUNCTION__, this->process->pid, this->trdid, cluster_id , cycle );
 #endif
 
@@ -627 +627 @@
     numb_xp = XPTR( fat_cxy , &fat_ctx_ptr->free_clusters );
 
-    // update "free_clusters" value
-    numb = hal_remote_l32( numb_xp ) - 1;
-    hal_remote_s32( numb_xp , numb );
-
-    // get extended pointer on FAT mapper
-    fat_mapper_xp = hal_remote_l64( XPTR( fat_cxy , &fat_ctx_ptr->fat_mapper_xp ) );
-
-    // initialise variables to scan the FAT mapper
-    // and find the first free slot > cluster
-    page_id  = (cluster + 1) >> 10;
-    slot_id  = (cluster + 1) & 0x3FF;
+    // get pointers on FAT mapper from FATFS context
+    fat_mapper_ptr = hal_remote_lpt( XPTR( fat_cxy , &fat_ctx_ptr->fat_mapper ) );
+    fat_mapper_xp  = XPTR( fat_cxy , fat_mapper_ptr );
+
+    // initialise the loop variables to scan the FAT mapper
+    page_id  = (cluster_id + 1) >> 10;
+    slot_id  = (cluster_id + 1) & 0x3FF;
     page_max = hal_remote_l32( XPTR( fat_cxy, &fat_ctx_ptr->fat_sectors_count ) ) >> 3;
-
-    // scan FAT mapper / loop on pages
-    while ( page_id < page_max )            
+    found    = 0;
+
+    // scan FAT mapper : first loop on pages
+    while ( (page_id < page_max) && (found == 0) )            
     {
         // get current page from mapper
-        page_xp = mapper_remote_get_page( fat_mapper_xp , page_id );
+        page_xp = mapper_get_fat_page( fat_mapper_xp , page_id );
 
         if( page_xp == XPTR_NULL )
@@ -655 +652 @@
         base_xp = ppm_page2base( page_xp );
 
-        // scan FAT mapper / loop on slots
-        while ( slot_id < 1024 )
+        // scan the FAT mapper : second loop on slots
+        while ( (slot_id < 1024) && (found == 0) )
         {
             // get extended pointer on current slot
@@ -664 +661 @@
             if ( hal_remote_l32( slot_xp ) == FREE_CLUSTER )
             {
-                // update "free_cluster_hint" value
-                hint = (page_id << 10) + slot_id - 1;
-                hal_remote_s32( hint_xp , hint );
-
-                // update FS_INFO sector on IOC device
-                error = fatfs_update_ioc_fat( fatfs_ctx_xp,
-                                              page_id,
-                                              page_id );
-
-                if( error ) 
-                {
-                    printk("\n[ERROR] in %s : cannot update FS_INFO on IOC\n", __FUNCTION__ );
-                    return -1;
-                }
+                // exit both loops
+                found = 1;
+            }
+            else
+            {
+                // update slot_id if not found
+                slot_id++;
+            }
+        }  // end loop on slots
+
+        // update page_id & slot_id variables if not found
+        if( found == 0 )
+        {
+            page_id++;
+            slot_id = 0;
+        }
+    }  // end loop on pages
+
+    if( found )  // free cluster found
+    {
+        // update "free_clusters" and "free_cluster_hint" value in FATFS context
+        hal_remote_atomic_add( numb_xp , -1 );
+        hal_remote_s32( hint_xp , (page_id << 10) + slot_id - 1 );
+
+        // update FS_INFO sector on IOC device
+        error = fatfs_update_ioc_fsinfo( fatfs_ctx_xp );
+
+        if( error ) 
+        {
+            printk("\n[ERROR] in %s : cannot update FS_INFO on IOC\n", __FUNCTION__ );
+            return -1;
+        }
 
 #if DEBUG_FATFS_FREE_CLUSTERS 
-cycle = (uint32_t)hal_get_cycles();
-if( DEBUG_FATFS_FREE_CLUSTERS < (uint32_t)hal_get_cycles() )
-printk("\n[%s] thread[%x,%x] exit / hint %x / free %x / cycle %d\n",
+if( DEBUG_FATFS_FREE_CLUSTERS < cycle )
+printk("\n[%s] thread[%x,%x] exit / hint %x / free %x\n",
 __FUNCTION__, this->process->pid, this->trdid, 
-hal_remote_l32(hint_xp), hal_remote_l32(numb_xp), cycle );
-#endif
-                return 0;
-            }
-
-            // update slot_id
-            slot_id = 0;
-
-        }  // end loop on slots
-
-        // update page_id & slot_id variables
-        page_id++;
-        slot_id = 0;
-
-    }  // end loop on pages
-
-    // return error if no free cluster found 
-    printk("\n[ERROR] in %s : No free cluster found\n", __FUNCTION__ );
-    return -1;
+hal_remote_l32(hint_xp), hal_remote_l32(numb_xp) );
+#endif
+        return 0;
+    }
+    else  // free cluster not found
+    {
+        printk("\n[ERROR] in %s : No free cluster_id found\n", __FUNCTION__ );
+        return -1;
+    }
     
 }  // end fatfs_free_clusters_decrement()
@@ -709 +713 @@
 // This static function increments the "free_clusters" variable, and updates the
 // "free_cluster_hint" variables in the FATFS context in FAT cluster, identified 
-// by the <fat_ctx_xp> argument, when a FATFS cluster is released.
+// by the <fat_ctx_xp> argument, when a FATFS <cluster_id> has been released.
 // If the released cluster index is smaller than the current (hint) value, 
 // it set "free_cluster_hint" <= cluster.
-// It does NOT update the  FS_INFO sector on the IOC device.
+// It does NOT update the  FS_INFO sector on the IOC device, as this is done by the
+// calling fatfs_release_inode() function.
 // It can be called by a thead running in any cluster. 
 // The lock protecting exclusive access to the FAT must be taken by the calling function. 
 //////////////////////////////////////////////////////////////////////////////////////////
 // @ fatfs_ctx_xp  : extended pointer on FATFS context in FAT cluster. 
-// @ cluster       : recently released cluster index in FAT.
+// @ cluster_id    : recently released cluster index in FAT.
 // @ return 0 if success, return -1 if the FS_INFO sector cannot be updated.
 //////////////////////////////////////////////////////////////////////////////////////////
 static error_t fatfs_free_clusters_increment( xptr_t   fatfs_ctx_xp,
-                                              uint32_t cluster )
-{
-    error_t       error;
+                                              uint32_t cluster_id )
+{
     cxy_t         fat_cxy;      // FAT cluster identifier
     fatfs_ctx_t * fat_ctx_ptr;  // local pointer on fatfs context in FAT cluster
@@ -735 +739 @@
 thread_t * this  = CURRENT_THREAD;
 if( DEBUG_FATFS_FREE_CLUSTERS < cycle )
-printk("\n[%s] thread[%x,%x] enter for released cluster %x / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, cluster , cycle );
+printk("\n[%s] thread[%x,%x] enter for released cluster_id %x / cycle %d\n",
+__FUNCTION__, this->process->pid, this->trdid, cluster_id , cycle );
 #endif
 
@@ -753 +757 @@
     // update "numb" and "hint" variables as required
     numb++;
-    if ( (cluster - 1) < hint ) hint = cluster - 1;
+    if ( (cluster_id - 1) < hint ) hint = cluster_id - 1;
 
     // update free_clusters
@@ -759 +763 @@
     hal_remote_s32( hint_xp , hint );
 
-    // update FS_INFO sector on IOC device
-    error = fatfs_update_ioc_fsinfo( fatfs_ctx_xp );
-
-    if( error ) 
-    {
-        printk("\n[ERROR] in %s : cannot update FS_INFO on IOC\n", __FUNCTION__ );
-        return -1;
-    }
-
 #if DEBUG_FATFS_FREE_CLUSTERS 
-cycle = (uint32_t)hal_get_cycles();
-if( DEBUG_FATFS_FREE_CLUSTERS < (uint32_t)hal_get_cycles() )
-printk("\n[%s] thread[%x,%x] exit / hint %x / free %x / cycle %d\n",
+if( DEBUG_FATFS_FREE_CLUSTERS < cycle )
+printk("\n[%s] thread[%x,%x] exit / hint %x / free %x\n",
 __FUNCTION__, this->process->pid, this->trdid,
-hal_remote_l32( hint_xp ), hal_remote_l32( numb_xp ), cycle );
+hal_remote_l32( hint_xp ), hal_remote_l32( numb_xp ) );
 #endif
 
@@ -853 +847 @@
 
 //////////////////////////////////////////////////////////////////////////////////////////
+// This static function access the FAT mapper to allocate a new cluster in the FATFS,
+// and returns in <searched_cluster_id> the FATFS cluster index of a free cluster.
+// It updates the FAT mapper (handling miss from IOC device if required) :
+// - if the <last_cluster_id> is zero, the new cluster is the first allocated cluster,
+//   and the <searched_cluster_id> FAT slot is set to END_OF_CHAIN_CLUSTER.
+// - if the <last_cluster_id> argument is not zero, the new cluster is not the first,
+//   the <last_cluster_id> FAT slot is set to <searched_cluster_id>, 
+//   the <searched_cluster_id> FAT slot is set to END_OF_CHAIN_CLUSTER.
+// This function also updates the  two "free_cluster_hint" and "free_clusters" variables
+// stored in the FATFS context. It takes the rwlock stored in the FATFS context in the
+// FAT cluster to get exclusive access to the FAT.
+// This function synchronously updates the FAT region on IOC device. 
+// It can be called by a thread running in any cluster as it uses remote accesses.
+//////////////////////////////////////////////////////////////////////////////////////////
+// @ last_cluster_id      : [in]  previous last cluster index. 
+// @ searched_cluster_id  : [out] allocated cluster index.
+// @ return 0 if success / return -1 if no more free clusters on IOC device.
+//////////////////////////////////////////////////////////////////////////////////////////
+static error_t fatfs_cluster_alloc( uint32_t   last_cluster_id,
+                                    uint32_t * searched_cluster_id )
+{
+    error_t       error;
+    uint32_t      free_clusters;   // total number of free clusters
+    uint32_t      hint;            // hint + 1 is the first free cluster
+    uint32_t      new_cluster_id;  // allocated cluster index in FAT
+    uint32_t      new_page_id;     // allocated cluster page index in FAT mapper
+    uint32_t      new_slot_id;     // allocated cluster slot index in page (1024 slots per page)
+    xptr_t        new_page_xp;     // extended pointer on FAT page for allocated cluster
+    xptr_t        new_slot_xp;     // extended pointer on allocated cluster slot in FAT 
+    uint32_t      last_page_id;    // last cluster page index in FAT mapper
+    uint32_t      last_slot_id;    // last cluster slot index in page (1024 slots per page)
+    xptr_t        last_slot_xp;    // extended pointer on last cluster slot in FAT 
+    xptr_t        last_page_xp;    // extended pointer on FAT page for last cluster
+    vfs_ctx_t   * vfs_ctx;         // local pointer on VFS context (same in all clusters)
+    fatfs_ctx_t * loc_fatfs_ctx;   // local pointer on local FATFS context
+    fatfs_ctx_t * fat_fatfs_ctx;   // local pointer on FATFS context in FAT cluster
+    mapper_t    * fat_mapper_ptr;  // local pointer on FAT mapper
+    xptr_t        fat_mapper_xp;   // extended pointer on FAT mapper
+    cxy_t         fat_cxy;         // FAT mapper cluster identifier
+    xptr_t        lock_xp;         // extended pointer on lock protecting free clusters info
+    xptr_t        hint_xp;         // extended pointer on free_cluster_hint in FAT cluster
+    xptr_t        free_xp;         // extended pointer on free_clusters_number in FAT cluster
+    
+#if DEBUG_FATFS_CLUSTER_ALLOC
+uint32_t   cycle = (uint32_t)hal_get_cycles();
+thread_t * this  = CURRENT_THREAD;
+if( DEBUG_FATFS_CLUSTER_ALLOC < cycle )
+printk("\n[%s] thread[%x,%x] enter / lats_cluster_id %x / cycle = %d\n",
+__FUNCTION__, this->process->pid, this->trdid, last_cluster_id, cycle );
+#endif
+
+    // get local pointer on VFS context (same in all clusters)
+    vfs_ctx = &fs_context[FS_TYPE_FATFS];
+
+    // get local pointer on local FATFS context
+    loc_fatfs_ctx = vfs_ctx->extend;
+
+    // get FAT cluster
+    fat_cxy = CONFIG_VFS_ROOT_CXY;
+
+    // get pointers on FAT mapper
+    fat_mapper_ptr = loc_fatfs_ctx->fat_mapper;
+    fat_mapper_xp  = XPTR( fat_cxy , fat_mapper_ptr );
+
+    // get local pointer on FATFS context in FAT cluster 
+    fat_fatfs_ctx = hal_remote_lpt( XPTR( fat_cxy , &vfs_ctx->extend ) );
+
+    // build relevant extended pointers on free clusters info in FAT cluster 
+    lock_xp = XPTR( fat_cxy , &fat_fatfs_ctx->lock );
+    hint_xp = XPTR( fat_cxy , &fat_fatfs_ctx->free_cluster_hint );
+    free_xp = XPTR( fat_cxy , &fat_fatfs_ctx->free_clusters );
+
+    // take the FAT lock in write mode
+    remote_rwlock_wr_acquire( lock_xp );
+
+    // get hint and free_clusters values from FATFS context in FAT cluster
+    hint          = hal_remote_l32( hint_xp );
+    free_clusters = hal_remote_l32( free_xp );
+        
+#if (DEBUG_FATFS_CLUSTER_ALLOC & 1)
+if( DEBUG_FATFS_CLUSTER_ALLOC < cycle )
+printk("\n[%s] thread[%x,%x] get free info : hint %x / free_clusters %x\n",
+__FUNCTION__, this->process->pid, this->trdid, hint, free_clusters );
+#endif
+
+    // check "free_clusters"
+    if ( free_clusters == 0 )
+    {
+        printk("\n[ERROR] in %s : no more free FATFS clusters\n", __FUNCTION__ );
+        remote_rwlock_wr_release( lock_xp );
+        return -1;
+    }
+    else if ( free_clusters < CONFIG_VFS_FREE_CLUSTERS_MIN )
+    {
+        printk("\n[WARNING] in %s : only %d free FATFS clusters\n", 
+        __FUNCTION__, CONFIG_VFS_FREE_CLUSTERS_MIN );
+    }
+
+    // get new cluster, page & slot indexes in FAT
+    new_cluster_id = hint + 1; 
+    new_page_id    = new_cluster_id >> 10;
+    new_slot_id    = new_cluster_id & 0x3FF;
+
+    // get relevant FAT page descriptor from FAT mapper
+    new_page_xp = mapper_get_fat_page( fat_mapper_xp , new_page_id );
+
+    if( new_page_xp == XPTR_NULL )
+    {
+        printk("\n[ERROR] in %s : cannot acces FAT mapper\n", __FUNCTION__ );
+        remote_rwlock_wr_release( lock_xp );
+        return -1;
+    }
+
+    // build extended pointer on new cluster slot in FAT mapper
+    new_slot_xp = ppm_page2base( new_page_xp ) + (new_slot_id << 2);
+         
+    // check selected cluster actually free
+    if( hal_remote_l32( new_slot_xp ) != FREE_CLUSTER )
+    { 
+        printk("\n[ERROR] in %s : selected cluster_id %x not free\n",
+        __FUNCTION__, new_cluster_id );
+        remote_rwlock_wr_release( lock_xp );
+        return -1;
+    }
+
+    // update new_cluster slot in FAT mapper
+    hal_remote_s32( new_slot_xp  , END_OF_CHAIN_CLUSTER_MIN );
+
+    // handle last_cluster_id argument if non zero
+    if( last_cluster_id )
+    {
+        // get last cluster page & slot indexes in FAT
+        last_page_id    = last_cluster_id >> 10;
+        last_slot_id    = last_cluster_id & 0x3FF;
+
+        // get relevant FAT page descriptor from FAT mapper
+        last_page_xp = mapper_get_fat_page( fat_mapper_xp , last_page_id );
+
+        if( last_page_xp == XPTR_NULL )
+        {
+            printk("\n[ERROR] in %s : cannot acces FAT mapper\n", __FUNCTION__ );
+            remote_rwlock_wr_release( lock_xp );
+            return -1;
+        }
+
+        // build extended pointer on new cluster slot in FAT mapper
+        last_slot_xp = ppm_page2base( last_page_xp ) + (last_slot_id << 2);
+         
+        // check last cluster actually end of chain
+        if( hal_remote_l32( last_slot_xp ) != END_OF_CHAIN_CLUSTER_MIN )
+        { 
+            printk("\n[ERROR] in %s : last_cluster_id %x not END_OF_CHAIN\n",
+            __FUNCTION__, last_cluster_id );
+            remote_rwlock_wr_release( lock_xp );
+            return -1;
+        }
+
+        // update last_cluster slot in FAT mapper
+        hal_remote_s32( last_slot_xp , new_cluster_id );
+    }
+    else
+    {
+        last_page_xp = XPTR_NULL;
+    }
+
+    // update the FAT new_page on device
+    error = fatfs_move_page( new_page_xp , IOC_SYNC_WRITE );
+
+    if( error )
+    { 
+        printk("\n[ERROR] in %s : cannot update FAT on IOC device\n", __FUNCTION__ );
+        remote_rwlock_wr_release( lock_xp );
+        return -1;
+    }
+
+    // update the FAT last_page on device when required
+    if( (last_page_xp != XPTR_NULL) && (last_page_xp != new_page_xp) )
+    {
+        error = fatfs_move_page( last_page_xp , IOC_SYNC_WRITE );
+
+        if( error )
+        { 
+            printk("\n[ERROR] in %s : cannot update FAT on IOC device\n", __FUNCTION__ );
+            remote_rwlock_wr_release( lock_xp );
+            return -1;
+        }
+    }
+
+    // update free cluster info in FATFS context and in FS_INFO sector
+    error = fatfs_free_clusters_decrement( XPTR( fat_cxy , fat_fatfs_ctx ) , new_cluster_id );
+
+    if( error )
+    { 
+        printk("\n[ERROR] in %s : cannot update free cluster info\n", __FUNCTION__ );
+        remote_rwlock_wr_release( lock_xp );
+        return -1;
+    }
+
+    // release FAT lock
+    remote_rwlock_wr_release( lock_xp );
+
+#if DEBUG_FATFS_CLUSTER_ALLOC 
+cycle = (uint32_t)hal_get_cycles();
+if( DEBUG_FATFS_CLUSTER_ALLOC < cycle )
+printk("\n[%s] thread[%x,%x] exit / allocated cluster_id %x in FAT / cycle %d\n",
+__FUNCTION__, this->process->pid, this->trdid, new_cluster_id, cycle );
+#endif
+
+    *searched_cluster_id = new_cluster_id;
+    return 0;
+
+}  // end fatfs_cluster_alloc()
+
+
+//////////////////////////////////////////////////////////////////////////////////////////
 // This static function access the FAT (File Allocation Table), stored in the FAT mapper,
 // and returns in <searched_cluster_id> the FATFS cluster_id for a given page of a given 
-// inode, identified by the <searched_page_id> argument, that is the page index in file
+// inode, identified by the <searched_page_id> argument that is the page index in file
 // (i.e. the page index in file mapper). The entry point in the FAT is defined by the
 // <first_cluster_id> argument, that is the cluster_id of an already allocated cluster.
@@ -861 +1070 @@
 // fatfs_inode extension), or any page of the file whose <first_page_id> argument
 // is smaller than the searched <first_page_id> argument. 
-// This function can be called by a thread running in any cluster, as it uses remote
-// access primitives when the FAT mapper is remote.
+// This function can be called by a thread running in any cluster.
 // The FAT mapper being a WRITE-THROUGH cache, this function updates the FAT mapper 
 // from informations stored on IOC device in case of miss when scanning the FAT mapper.
@@ -885 +1093 @@
     uint32_t   current_cluster_id;     // index of cluster in FATFS
     xptr_t     lock_xp;                // extended pointer on FAT lock
+    xptr_t     fat_mapper_xp;          // extended pointer on FAT mapper
+    mapper_t * fat_mapper_ptr;         // local pointer on FAT mapper
+    cxy_t      fat_cxy;                // FAT cluster
+    error_t    error;
 
 assert( (searched_page_id > first_page_id) ,
@@ -893 +1105 @@
 thread_t * this  = CURRENT_THREAD;
 if( DEBUG_FATFS_GET_CLUSTER < cycle )
-printk("\n[%s] thread[%x,%x] enter / first_cluster_id %x / searched_page_id %d / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, first_cluster_id, searched_page_id, cycle );
+printk("\n[%s] thread[%x,%x] enter / frst_pid %x / frst_cid %x / srch_pid %d / cycle %d\n",
+__FUNCTION__, this->process->pid, this->trdid,
+first_page_id, first_cluster_id, searched_page_id, cycle );
 #endif
 
@@ -903 +1116 @@
     fatfs_ctx_t * loc_fatfs_ctx = vfs_ctx->extend;
 
-    // get extended pointer and cluster on FAT mapper
-    xptr_t fat_mapper_xp  = loc_fatfs_ctx->fat_mapper_xp;
-    cxy_t  fat_cxy        = GET_CXY( fat_mapper_xp );
+    // get FAT cluster
+    fat_cxy = CONFIG_VFS_ROOT_CXY;
+    
+    // get pointers on FAT mapper
+    fat_mapper_ptr = loc_fatfs_ctx->fat_mapper;
+    fat_mapper_xp  = XPTR( fat_cxy , fat_mapper_ptr );
 
     // get local pointer on FATFS context in FAT cluster 
@@ -931 +1147 @@
 
         // get pointer on current page descriptor in FAT mapper
-        xptr_t current_page_xp = mapper_remote_get_page( fat_mapper_xp , fat_page_index );
+        xptr_t current_page_xp = mapper_get_fat_page( fat_mapper_xp , fat_page_index );
 
         if( current_page_xp == XPTR_NULL )
@@ -942 +1158 @@
 
         // get pointer on buffer containing the FAT mapper page
-        xptr_t base_xp = ppm_page2base( current_page_xp );
-        uint32_t * buffer = (uint32_t *)GET_PTR( base_xp );
+        xptr_t     base_xp = ppm_page2base( current_page_xp );
+        uint32_t * buffer  = (uint32_t *)GET_PTR( base_xp );
 
         // get next_cluster_id from FAT slot  
         uint32_t next_cluster_id = hal_remote_l32( XPTR( fat_cxy, &buffer[fat_slot_index] ) );
 
-        // allocate a new FAT cluster when there is no cluster
-        // allocated on device for the current page
+        // allocate a new FAT cluster when END_OF_CHAIN found
         if( next_cluster_id >= END_OF_CHAIN_CLUSTER_MIN ) 
         {
@@ -956 +1171 @@
 
             // allocate a new cluster_id (and update both FAT mapper and FAT on device).
-            error_t error = fatfs_cluster_alloc( &next_cluster_id );
-
+            error = fatfs_cluster_alloc( current_cluster_id,
+                                         &next_cluster_id );
             if( error )
             {
@@ -968 +1183 @@
 #if (DEBUG_FATFS_GET_CLUSTER & 1)
 if( DEBUG_FATFS_GET_CLUSTER < cycle )
-printk("\n[%s] allocated a new cluster_id %d in FATFS\n",
+printk("\n[%s] allocated a new cluster_id %x in FATFS\n",
 __FUNCTION__, next_cluster_id );
 #endif
@@ -977 +1192 @@
 #if (DEBUG_FATFS_GET_CLUSTER & 1)
 if( DEBUG_FATFS_GET_CLUSTER < cycle )
-printk("\n[%s] traverse FAT / fat_page_index %d / fat_slot_index %d / next_cluster_id %x\n",
-__FUNCTION__, fat_page_index, fat_slot_index , next_cluster_id );
+printk("\n[%s] traverse FAT / current_cluster_id %x / next_cluster_id %x\n",
+__FUNCTION__, current_cluster_id , next_cluster_id );
 #endif
 
@@ -991 +1206 @@
 #if DEBUG_FATFS_GET_CLUSTER
 if( DEBUG_FATFS_GET_CLUSTER < cycle )
-printk("\n[%s] thread[%x,%x] exit / searched_cluster_id = %d\n",
-__FUNCTION__, this->process->pid, this->trdid, current_cluster_id );
+printk("\n[%s] thread[%x,%x] exit / frst_pid %d / frst_cid %x / srch_pid %d / srch_cid %x\n",
+__FUNCTION__, this->process->pid, this->trdid,
+first_page_id, first_cluster_id, searched_page_id, current_cluster_id );
 #endif
 
@@ -1000 +1216 @@
 }  // end fatfs_get_cluster()
 
-
-
-
-
-//////////////////////////////////////////////////////////////////////////////////////////
-//              FATFS specific extern functions 
-//////////////////////////////////////////////////////////////////////////////////////////
-
-///////////////////////////////////
-void fatfs_display_ctx( cxy_t cxy )
-{
-    // get pointer on local FATFS context
-    vfs_ctx_t   * vfs_ctx = &fs_context[FS_TYPE_FATFS];
-        fatfs_ctx_t * ctx     = hal_remote_lpt( XPTR( cxy , &vfs_ctx->extend ) );
-
-    uint32_t fat_sectors       = hal_remote_l32( XPTR( cxy , &ctx->fat_sectors_count ) );
-    uint32_t sector_size       = hal_remote_l32( XPTR( cxy , &ctx->bytes_per_sector ) );
-    uint32_t sec_per_clus      = hal_remote_l32( XPTR( cxy , &ctx->sectors_per_cluster ) );
-    uint32_t fat_lba           = hal_remote_l32( XPTR( cxy , &ctx->fat_begin_lba ) );
-    uint32_t data_lba          = hal_remote_l32( XPTR( cxy , &ctx->cluster_begin_lba ) );
-    uint32_t fsinfo_lba        = hal_remote_l32( XPTR( cxy , &ctx->fs_info_lba ) );
-    uint32_t root_dir_clus     = hal_remote_l32( XPTR( cxy , &ctx->root_dir_cluster ) );
-    uint32_t free_clusters     = hal_remote_l32( XPTR( cxy , &ctx->free_clusters ) );
-    uint32_t free_cluster_hint = hal_remote_l32( XPTR( cxy , &ctx->free_cluster_hint ) );
-    xptr_t   mapper_xp         = hal_remote_l64( XPTR( cxy , &ctx->fat_mapper_xp ) );
-    void   * fs_info_buffer    = hal_remote_lpt( XPTR( cxy , &ctx->fs_info_buffer ) );
-
-    printk("\n*** FAT context in cluster %x\n" 
-           "- fat_sectors       = %d\n"
-           "- sector size       = %d\n"
-           "- cluster size      = %d\n"
-           "- fat_lba           = %x\n"
-           "- data_lba          = %x\n"
-           "- fsinfo_lba        = %x\n"
-           "- root_dir_cluster  = %x\n"
-           "- free_clusters     = %x\n"
-           "- free_cluster_hint = %x\n"
-           "- fat_mapper_ptr    = %x\n"
-           "- fs_info_buffer    = %x\n",
-           cxy,
-           fat_sectors,
-           sector_size,
-           sector_size * sec_per_clus,
-           fat_lba,
-           data_lba,
-           fsinfo_lba,
-           root_dir_clus,
-           free_clusters,
-           free_cluster_hint,
-           GET_PTR( mapper_xp ),
-           fs_info_buffer );
-
-}  // end fatfs_ctx_display()
-
-//////////////////////////////////////////
-void fatfs_display_fat( uint32_t  page_id,
-                        uint32_t  min_slot,
-                        uint32_t  nb_slots )
-{
-    uint32_t line;
-
-    // compute number of lines to display
-    uint32_t min_line = min_slot >> 3;
-    uint32_t max_line = (min_slot + nb_slots - 1) >> 3;
-
-    // get pointer on local FATFS context
-    vfs_ctx_t   * vfs_ctx       = &fs_context[FS_TYPE_FATFS];
-    fatfs_ctx_t * loc_fatfs_ctx = (fatfs_ctx_t *)vfs_ctx->extend;
-
-    // get pointers on FAT mapper (in FAT cluster)
-    xptr_t     mapper_xp  = loc_fatfs_ctx->fat_mapper_xp;
-    cxy_t      mapper_cxy = GET_CXY( mapper_xp );
-
-    // get pointer on FATFS context in FAT cluster
-    fatfs_ctx_t * fat_fatfs_ctx = hal_remote_lpt( XPTR( mapper_cxy , &vfs_ctx->extend ) );
- 
-    // get current value of hint and free_clusters
-    uint32_t hint = hal_remote_l32( XPTR( mapper_cxy , &fat_fatfs_ctx->free_cluster_hint ) );
-    uint32_t free = hal_remote_l32( XPTR( mapper_cxy , &fat_fatfs_ctx->free_clusters ) );
-
-    // get extended pointer on requested page descriptor in FAT mapper 
-    xptr_t page_xp = mapper_remote_get_page( mapper_xp , page_id );
-
-    // get pointers on requested page base
-    xptr_t     base_xp  = ppm_page2base( page_xp );
-    void     * base     = GET_PTR( base_xp );
-
-    printk("\n***** FAT mapper / cxy %x / page_id %d / base %x / free_clusters %x / hint %x\n",
-    mapper_cxy, page_id, base, free, hint );
-
-    for( line = min_line ; line <= max_line ; line++ )
-    {
-        printk("%d : %X | %X | %X | %X | %X | %X | %X | %X\n", (line<<3),
-        hal_remote_l32( base_xp + ((line<<5)      ) ),
-        hal_remote_l32( base_xp + ((line<<5) + 4  ) ),
-        hal_remote_l32( base_xp + ((line<<5) + 8  ) ),
-        hal_remote_l32( base_xp + ((line<<5) + 12 ) ),
-        hal_remote_l32( base_xp + ((line<<5) + 16 ) ),
-        hal_remote_l32( base_xp + ((line<<5) + 20 ) ),
-        hal_remote_l32( base_xp + ((line<<5) + 24 ) ),
-        hal_remote_l32( base_xp + ((line<<5) + 28 ) ) );
-    }
-
-}  // end fatfs_display_fat()
-
-
-
-///////////////////////////////////////////////////////////////////////////////////////
-// Generic API : the following functions are called by the kernel VFS
-//               and must be defined by all supported file systems.
-///////////////////////////////////////////////////////////////////////////////////////
-
-/////////////////////////////////////
-fatfs_ctx_t * fatfs_ctx_alloc( void )
-{
-    kmem_req_t    req;
-        req.type    = KMEM_KCM;
-        req.order   = bits_log2( sizeof(fatfs_ctx_t) );
-    req.flags   = AF_KERNEL | AF_ZERO;
-
-        return kmem_alloc( &req );
-}
-
-//////////////////////////////////////////////
-void fatfs_ctx_init( fatfs_ctx_t * fatfs_ctx )
-{
-    error_t       error;
-    kmem_req_t    req;
-    uint8_t     * buffer;
-    xptr_t        buffer_xp;
-
-#if DEBUG_FATFS_CTX_INIT
-uint32_t   cycle = (uint32_t)hal_get_cycles();
-thread_t * this  = CURRENT_THREAD;
-if( DEBUG_FATFS_CTX_INIT < cycle )
-printk("\n[%s] thread[%x,%x] enter for fatfs_ctx = %x / cycle %d\n",
-__FUNCTION__ , this->process->pid, this->trdid, fatfs_ctx , cycle );
-#endif
-
-// check argument
-assert( (fatfs_ctx != NULL) , "pointer on FATFS context is NULL" );
-
-// check only cluster 0 does FATFS initialization
-assert( (local_cxy == 0) , "only cluster 0 can initialize FATFS");
-
-    // allocate a permanent 512 bytes buffer to store
-    // - temporarily the BOOT sector
-    // - permanently the FS_INFO sector
-        req.type    = KMEM_KCM;
-    req.order   = 9;                    // 512 bytes
-    req.flags   = AF_KERNEL | AF_ZERO;
-        buffer      = kmem_alloc( &req );
-
-    if( buffer == NULL ) 
-    {
-        printk("\n[PANIC] in %s : cannot allocate buffer\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-     
-    buffer_xp   = XPTR( local_cxy , buffer );
-
-    // load the BOOT record from device
-    error = dev_ioc_move_data( IOC_SYNC_READ , buffer_xp , 0 , 1 );
-
-    if ( error )
-    {
-        printk("\n[PANIC] in %s : cannot access boot record\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-
-#if (DEBUG_FATFS_CTX_INIT & 0x1)
-if( DEBUG_FATFS_CTX_INIT < cycle )
-putb( "boot record", buffer , 256 );
-#endif
-
-    // get sector size from boot record
-    uint32_t sector_size = fatfs_get_record( BPB_BYTSPERSEC , buffer );
-    if ( sector_size != 512 )
-    {
-        printk("\n[PANIC] in %s : sector size must be 512 bytes\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-
-    // get cluster size from boot record
-    uint32_t nb_sectors = fatfs_get_record( BPB_SECPERCLUS , buffer );
-    if ( nb_sectors != 8 )
-    {
-        printk("\n[PANIC] in %s : cluster size must be 8 sectors\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-
-    // get number of FAT copies from boot record
-    uint32_t nb_fats = fatfs_get_record( BPB_NUMFATS , buffer );
-    if ( nb_fats != 1 )
-    {
-        printk("\n[PANIC] in %s : number of FAT copies must be 1\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-
-    // get number of sectors in FAT from boot record
-    uint32_t fat_sectors = fatfs_get_record( BPB_FAT32_FATSZ32 , buffer );
-    if ( (fat_sectors & 0xF) != 0 )
-    {
-        printk("\n[PANIC] in %s : FAT size not multiple of 16 sectors\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-
-    // get root cluster from boot record
-    uint32_t root_cluster = fatfs_get_record( BPB_FAT32_ROOTCLUS , buffer );
-    if ( root_cluster != 2 ) 
-    {
-        printk("\n[PANIC] in %s : root cluster index must be 2\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-
-    // get FAT lba from boot record
-    uint32_t fat_lba = fatfs_get_record( BPB_RSVDSECCNT , buffer );
-
-    // get FS_INFO sector lba from boot record
-    uint32_t fs_info_lba = fatfs_get_record( BPB_FAT32_FSINFO , buffer );
-
-    // load the FS_INFO record from device
-    error = dev_ioc_move_data( IOC_SYNC_READ , buffer_xp , fs_info_lba , 1 );
-
-    if ( error )
-    {
-        printk("\n[PANIC] in %s : cannot access FS_INFO record\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-
-    // get free_clusters number from FS_INFO record
-    uint32_t free_clusters = fatfs_get_record( FS_FREE_CLUSTERS , buffer );
-    if ( free_clusters >= fat_sectors << 7 )
-    {
-        printk("\n[PANIC] in %s : unconsistent free_clusters\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-
-    // get free_cluster_hint from FS_INFO record
-    uint32_t free_cluster_hint = fatfs_get_record( FS_FREE_CLUSTER_HINT , buffer );
-
-    if ( free_cluster_hint >= fat_sectors << 7 )
-    {
-        printk("\n[PANIC] in %s : unconsistent free_cluster_hint\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-
-    // allocate a mapper for the FAT itself
-    mapper_t * fat_mapper = mapper_create( FS_TYPE_FATFS );
-    if ( fat_mapper == NULL )
-    {
-        printk("\n[PANIC] in %s : no memory for FAT mapper\n", __FUNCTION__ );
-        hal_core_sleep();
-    }
-
-    // the inode field is NULL for the FAT mapper
-    fat_mapper->inode = NULL;
-
-    // initialize the FATFS context
-    fatfs_ctx->fat_begin_lba         = fat_lba;
-    fatfs_ctx->fat_sectors_count     = fat_sectors; 
-    fatfs_ctx->bytes_per_sector      = sector_size;
-    fatfs_ctx->sectors_per_cluster   = nb_sectors;
-    fatfs_ctx->cluster_begin_lba     = fat_lba + fat_sectors;
-    fatfs_ctx->root_dir_cluster      = 2;
-    fatfs_ctx->fat_mapper_xp         = XPTR( local_cxy , fat_mapper );
-    fatfs_ctx->fs_info_lba           = fs_info_lba;
-    fatfs_ctx->free_clusters         = free_clusters;
-    fatfs_ctx->free_cluster_hint     = free_cluster_hint;
-    fatfs_ctx->fs_info_buffer        = buffer;
-
-    remote_rwlock_init( XPTR( local_cxy , &fatfs_ctx->lock ) , LOCK_FATFS_FAT );
-
-#if (DEBUG_FATFS_CTX_INIT & 0x1)
-if( DEBUG_FATFS_CTX_INIT < cycle )
-fatfs_ctx_display( fatfs_ctx );
-#endif
-
-#if DEBUG_FATFS_CTX_INIT
-cycle = (uint32_t)hal_get_cycles();
-if( DEBUG_FATFS_CTX_INIT < cycle )
-printk("\n[%s]  thread[%x,%x] exit for fatfs_ctx = %x / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, fatfs_ctx, cycle );
-#endif
-
-}  // end fatfs_ctx_init()
-
-/////////////////////////////////////////////////
-void fatfs_ctx_destroy( fatfs_ctx_t * fatfs_ctx )
-{
-    kmem_req_t    req;
-    req.type = KMEM_KCM;
-    req.ptr  = fatfs_ctx;
-    kmem_free( &req );
-}
-
-///////////////////////////////////////////////
-error_t fatfs_add_dentry( vfs_inode_t  * inode,
-                          vfs_dentry_t * dentry )
-{
-    error_t       error;
-    uint32_t      length;        // dentry name length
-    uint32_t      nb_lfn;        // number or required LFN
-    char          sfn[11];       // buffer for SFN name
-    uint8_t       checksum;      // name checksum 
-    mapper_t    * mapper;        // loal pointer on parent inode mapper
-    xptr_t        mapper_xp;     // extended pointer on parent inode mapper
-    xptr_t        child_xp;      // extended pointer on child inode 
-    cxy_t         child_cxy;     // child inode cluster
-    vfs_inode_t * child_ptr;     // child inode local pointer
-    uint32_t      size;          // child inode size
-    uint32_t      type;          // child inode type
-    uint32_t      cluster;       // child inode cluster index
-
-#if DEBUG_FATFS_ADD_DENTRY
-char       dir_name[CONFIG_VFS_MAX_NAME_LENGTH];
-uint32_t   cycle = (uint32_t)hal_get_cycles();
-thread_t * this  = CURRENT_THREAD;
-vfs_inode_get_name( XPTR( local_cxy , inode ) , dir_name );
-if( DEBUG_FATFS_ADD_DENTRY < cycle )
-printk("\n[%s]  thread[%x,%x] enter / parent <%s> / child <%s> / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, dir_name, dentry->name, cycle );
-#endif
-
-// check arguments
-assert( (inode != NULL) , "inode pointer is NULL\n" );
-assert( (dentry != NULL) , "dentry pointer is NULL\n" );
-assert( (inode->mapper != NULL ) , "mapper pointer is NULL\n" );
-  
-    // get pointers on directory mapper
-    mapper    = inode->mapper;
-    mapper_xp = XPTR( local_cxy , mapper );
-
-    // get extended pointers on remote child inode
-    child_xp  = dentry->child_xp;
-    child_cxy = GET_CXY( child_xp );
-    child_ptr = GET_PTR( child_xp );
-
-    // get relevant infos from child inode
-    type    =                     hal_remote_l32( XPTR( child_cxy , &child_ptr->type ) );
-    size    =                     hal_remote_l32( XPTR( child_cxy , &child_ptr->size ) );
-    cluster = (uint32_t)(intptr_t)hal_remote_lpt( XPTR( child_cxy , &child_ptr->extend ) );
-
-    // analyse dentry name
-    error = fatfs_name_format( dentry->name,
-                               &length,
-                               &nb_lfn,
-                               sfn,
-                               &checksum );
-    if ( error )
-    {
-        printk("\n[ERROR] in %s : dentry name > 31 bytes\n", __FUNCTION__ );
-        return -1;
-    }
-                               
-    // Search end of directory with two embedded loops:
-    // - scan the pages in the mapper
-    // - scan the entries in each page to find NO_MORE_ENTRY
-
-    xptr_t     page_xp;                 // extended pointer on page descriptor
-    xptr_t     base_xp;                 // extended pointer on page base
-    uint8_t  * base;                    // local pointer on page base (array of bytes)
-    uint32_t   page_id = 0;             // page index in mapper
-    uint32_t   offset  = 0;             // position in page
-    uint32_t   found   = 0;             // NO_MORE_ENTRY found
-
-    // loop on pages in mapper
-    while ( found == 0 )
-    {
-        // get extended pointer on page descriptor in mapper 
-        page_xp  = mapper_remote_get_page( mapper_xp , page_id );
-
-        if ( page_xp == XPTR_NULL )
-        {
-            printk("\n[ERROR] in %s : cannot extend directory mapper\n", __FUNCTION__ );
-            return -1;
-        }
-        
-        // get pointer on page base
-        base_xp = ppm_page2base( page_xp );
-        base = GET_PTR( base_xp );
-
-        // loop on directory entries in this page
-        while ( (offset < 4096) && (found == 0) )
-        {
-            if ( fatfs_get_record( LDIR_ORD, (base + offset) ) == NO_MORE_ENTRY )
-            {
-                found = 1;
-            }  
-            else
-            {
-                offset = offset + 32;
-            }
-        }  // end loop on entries
-
-        if ( found == 0 )
-        {
-            page_id++;
-            offset = 0;
-        }
-    }  // end loop on pages
-
-    // Modify the directory mapper: depending on the name length,
-    // the new child requires to write (3, 4, or 5) directory entries.
-    // To actually register the new child, we use a 5 steps FSM
-    // (one state per entry to be written), that is traversed as:
-    // LFN3 -> LFN2 -> LFN1 -> NORMAL -> NOMORE 
-    // At most two pages are modified:
-    // - the page containing the NO_MORE_ENTRY is always modified
-    // - the following page can be modified if the name spread on to pages.
-
-    char * name = dentry->name;
-
-    uint32_t step;          // FSM state
-
-    if      ( nb_lfn == 1 ) step = 3;
-    else if ( nb_lfn == 2 ) step = 4;
-    else if ( nb_lfn == 3 ) step = 5;
-    
-    uint8_t  * entry;       // pointer on directory entry to be written
-    uint32_t   i;           // byte index in one 32 bytes directory
-    uint32_t   c;           // character index in name
-
-    while ( step )   
-    {
-        // when the new child is split on two pages,
-        // we need to access a new page in mapper
-        if ( offset >= 4096 )
-        {
-            // copy the modified page to IOC device
-            fatfs_move_page( page_xp , IOC_SYNC_WRITE );   
-
-            // get the next page in FAT mapper
-            page_xp  = mapper_remote_get_page( mapper_xp , page_id + 1 );
-
-            if ( page_xp == XPTR_NULL )
-            {
-                printk("\n[ERROR] in %s : cannot extend directory mapper\n", __FUNCTION__ );
-                return -1;
-            }
-        
-            // get pointer on page base
-            base_xp = ppm_page2base( page_xp );
-            base = GET_PTR( base_xp );
-            
-            // update offset
-            offset = 0;
-        }
-
-        // compute directory entry address
-        entry = base + offset;
-
-#if (DEBUG_FATFS_ADD_DENTRY & 1)
-cycle = (uint32_t)hal_get_cycles();
-if( DEBUG_FATFS_ADD_DENTRY < cycle )
-printk("\n[%s] FSM step = %d / offset = %x / nb_lfn = %d / cycle %d\n",
-__FUNCTION__, step, offset, nb_lfn, cycle );
-#endif
-
-        // write 32 bytes (one directory entry) per iteration
-        switch ( step )
-        {
-            case 5:   // write LFN3 entry
-            {
-                c = 26;
-                // scan the 32 bytes in dir_entry
-                for ( i = 0 ; i < 32 ; i++ )
-                {
-                    if (i == 0)
-                    {
-                        if ( nb_lfn == 3) entry[i] = 0x43;
-                        else              entry[i] = 0x03;
-                    }
-                    else if ( ( ((i >= 1 ) && (i<=10) && ((i&1)==1))   ||
-                                ((i >= 14) && (i<=25) && ((i&1)==0))   ||
-                                ((i >= 28) && (i<=31) && ((i&1)==0)) ) &&
-                              ( c < length ) )
-                    {
-                                          entry[i] = name[c];
-                                          c++;
-                    }
-                    else if (i == 11)     entry[i] = 0x0F;
-                    else if (i == 13)     entry[i] = checksum;
-                    else                  entry[i] = 0x00;
-                }
-                step--;
-                break;
-            }
-            case 4:   // write LFN2 entry  
-            {
-                c = 13;
-                // scan the 32 bytes in dir_entry
-                for ( i = 0 ; i < 32 ; i++ )
-                {
-                    if (i == 0)
-                    {
-                        if ( nb_lfn == 2) entry[i] = 0x42;
-                        else              entry[i] = 0x02;
-                    }
-                    else if ( ( ((i >= 1 ) && (i<=10) && ((i&1)==1))   ||
-                                ((i >= 14) && (i<=25) && ((i&1)==0))   ||
-                                ((i >= 28) && (i<=31) && ((i&1)==0)) ) &&
-                              ( c < length ) )
-                    {
-                                          entry[i] = name[c];
-                                          c++;
-                    }
-                    else if (i == 11)     entry[i] = 0x0F;
-                    else if (i == 13)     entry[i] = checksum;
-                    else                  entry[i] = 0x00;
-                }
-                step--;
-                break;
-            }
-            case 3:   // Write LFN1 entry   
-            {
-                c = 0;
-                // scan the 32 bytes in dir_entry
-                for ( i = 0 ; i < 32 ; i++ )
-                {
-                    if (i == 0)
-                    {
-                        if ( nb_lfn == 1) entry[i] = 0x41;
-                        else              entry[i] = 0x01;
-                    }
-                    else if ( ( ((i >= 1 ) && (i<=10) && ((i&1)==1))   ||
-                                ((i >= 14) && (i<=25) && ((i&1)==0))   ||
-                                ((i >= 28) && (i<=31) && ((i&1)==0)) ) &&
-                              ( c < length ) )
-                    {
-                                          entry[i] = name[c];
-                                          c++;
-                    }
-                    else if (i == 11)     entry[i] = 0x0F;
-                    else if (i == 13)     entry[i] = checksum;
-                    else                  entry[i] = 0x00;
-                }
-                step--;
-                break;
-            }
-            case 2:   // write NORMAL entry     
-            {
-                // scan the 32 bytes in dir_entry
-                for ( i = 0 ; i < 32 ; i++ )
-                {
-                    if      ( i < 11 )                              // 8.3 SFN
-                    {
-                                          entry[i] = sfn[i];
-                    }
-                    else if (i == 11)                               // ATTR
-                    {
-                        if (type == INODE_TYPE_DIR)  entry[i] = 0x10;
-                        else                         entry[i] = 0x20;
-                    }
-                    else if (i == 20)     entry[i] = cluster>>16;   // cluster.B2
-                    else if (i == 21)     entry[i] = cluster>>24;   // cluster.B3
-                    else if (i == 26)     entry[i] = cluster>>0;    // cluster.B0
-                    else if (i == 27)     entry[i] = cluster>>8;    // cluster.B1
-                    else if (i == 28)     entry[i] = size>>0;       // size.B0
-                    else if (i == 29)     entry[i] = size>>8;       // size.B1
-                    else if (i == 30)     entry[i] = size>>16;      // size.B2
-                    else if (i == 31)     entry[i] = size>>24;      // size.B3
-                    else                  entry[i] = 0x00;
-                }
-
-                // update the "extend" field in dentry descriptor
-                dentry->extend = (void*)(intptr_t)(((page_id<<12) + offset)>>5);
-
-                step--;
-                break;
-            }
-            case 1:   // write NOMORE entry  
-            {
-                entry [0] = 0x00;
-                step--;
-                break;
-            }
-        } // end switch step
-
-        offset += 32;
-
-    } // exit while     
-
-#if (DEBUG_FATFS_ADD_DENTRY & 1)
-cycle = (uint32_t)hal_get_cycles();
-if( DEBUG_FATFS_ADD_DENTRY < cycle )
-printk("\n[%s]  thread[%x,%x] before IOC access / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, cycle );
-#endif
-
-    // copy the modified page to the IOC device
-    fatfs_move_page( page_xp , IOC_SYNC_WRITE );   
-
-#if DEBUG_FATFS_ADD_DENTRY
-cycle = (uint32_t)hal_get_cycles();
-if( DEBUG_FATFS_ADD_DENTRY < cycle )
-printk("\n[%s]  thread[%x,%x] exit / parent <%s> / child <%s> / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, dir_name, dentry->name, cycle );
-#endif
-
-    return 0;
-
-}  // end fatfs_add_dentry()
-
-//////////////////////////////////////////////////
-error_t fatfs_remove_dentry( vfs_inode_t  * inode,
-                             vfs_dentry_t * dentry )
-{
-    xptr_t     mapper_xp;  // extended pointer on mapper
-    mapper_t * mapper;     // local pointer on mapper
-    xptr_t     page_xp;    // extended pointer on mapper page descriptor
-    xptr_t     base_xp;    // extended pointer on mapper page base
-    uint8_t  * base;       // local pointer on mapper page base
-
-#if DEBUG_FATFS_REMOVE_DENTRY
-char       dir_name[CONFIG_VFS_MAX_NAME_LENGTH];
-uint32_t   cycle = (uint32_t)hal_get_cycles();
-thread_t * this  = CURRENT_THREAD;
-vfs_inode_get_name( XPTR( local_cxy , inode ) , dir_name );
-if( DEBUG_FATFS_REMOVE_DENTRY < cycle )
-printk("\n[%s] thread[%x,%x] enter / parent <%s> / child <%s> / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, dir_name, dentry->name, cycle );
-#endif
-
-// check arguments
-assert( (inode != NULL) , "inode pointer is NULL\n" );
-assert( (dentry != NULL) , "dentry pointer is NULL\n" );
-assert( (inode->type == INODE_TYPE_DIR) , "inode is not a directory\n" );
-assert( (inode->mapper != NULL ) , "mapper pointer is NULL\n" );
-
-    // get pointers on directory mapper
-    mapper    = inode->mapper;
-    mapper_xp = XPTR( local_cxy , mapper );
-
-    // compute number of LFN entries
-    uint32_t nb_lfn;
-    uint32_t name_length = strlen( dentry->name );
-
-    if      ( name_length <= 13 ) nb_lfn  = 1;
-    else if ( name_length <= 26 ) nb_lfn  = 2;
-    else                          nb_lfn  = 3;
-
-    // we must invalidate (2, 3 or 4) 32 bytes entries:
-    // the NORMAL entry (registered in dentry->extend) and all preceding LFN entries
-    // At most two pages are modified:
-    // - the page containing the NORMAL entry is always modified.
-    // - the preceding page is modified when the name spread on two pages. 
-
-    // get 32 bytes directory entry index from dentry->extend 
-    uint32_t  dentry_id  = (uint32_t)(intptr_t)dentry->extend; 
-
-    // get page index and offset in parent directory mapper
-    uint32_t  page_id    = dentry_id >> 7;
-    uint32_t  offset     = (dentry_id & 0x7F)<<5;
-
-#if DEBUG_FATFS_REMOVE_DENTRY & 1
-if( DEBUG_FATFS_REMOVE_DENTRY < cycle )
-printk("\n[%s] dentry_id %x / page_id %x / offset %x\n",
-__FUNCTION__, dentry_id, page_id, offset );
-#endif
-
-    // get extended pointer on page descriptor from parent directory mapper
-    page_xp  = mapper_remote_get_page( mapper_xp , page_id );
-
-    if ( page_xp == XPTR_NULL )
-    {
-        printk("\n[ERROR] in %s : cannot extend directory mapper\n", __FUNCTION__ );
-        return -1;
-    }
-        
-    // get pointers on page base
-    base_xp = ppm_page2base( page_xp );
-    base    = GET_PTR( base_xp );
-
-    // invalidate NORMAL entry in directory cache
-    base[offset] = 0xE5;
-
-    // invalidate LFN entries
-    while ( nb_lfn )
-    {
-        if (offset == 0)  // we must load page (page_id - 1)
-        {
-
-// check page_id 
-assert( (page_id > 0), "page_id and offset cannot be both 0\n" );
-
-            // copy the modified page to the IOC device
-            fatfs_move_page( page_xp , IOC_SYNC_WRITE );   
-
-            // get extended pointer on page descriptor from parent directory mapper
-            page_xp  = mapper_remote_get_page( mapper_xp , page_id );
-
-            if ( page_xp == XPTR_NULL )
-            {
-                printk("\n[ERROR] in %s : cannot access directory mapper\n", __FUNCTION__ );
-                return -1;
-            }
-        
-            // get pointers on page base
-            base_xp = ppm_page2base( page_xp );
-            base    = GET_PTR( base_xp );
-
-            // update offset
-            offset = 4096;
-        }
-
-        offset = offset - 32;
-
-// check for LFN entry
-assert( (fatfs_get_record( DIR_ATTR, base + offset ) == ATTR_LONG_NAME_MASK ),
-"this directory entry must be a LFN\n");
-
-        // invalidate LFN entry
-        base[offset] = 0xE5;
-
-        nb_lfn--;
-    }     
-
-    // copy the modified page to the IOC device
-    fatfs_move_page( page_xp , IOC_SYNC_WRITE );   
-    
-
-#if DEBUG_FATFS_REMOVE_DENTRY
-cycle = (uint32_t)hal_get_cycles();
-if( DEBUG_FATFS_REMOVE_DENTRY < cycle )
-printk("\n[%s] thread[%x,%x] exit / parent %s / child %s / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, dir_name, dentry->name, cycle );
-#endif
-
-    return 0;
-
-}  // end fatfs_remove_dentry
-
-
 //////////////////////////////////////////////////////////////////////////////////////////////
-// This static function scan the pages of a mapper containing a FAT32 directory, identified 
-// by the <mapper> argument, to find the directory entry identified by the <name> argument,
-// and return a pointer on the directory entry, described as and array of 32 bytes, and the
-// index of this entry in the FAT32 mapper, seen as an array of 32 bytes entries.
-// It is called by the fatfs_new_dentry() and fatfs_update_dentry() functions.
-// It must be called by a thread running in the cluster containing the mapper.
+// This static function scan the pages of a directory mapper, identified by the <mapper_xp> 
+// argument, to find the directory entry identified by the <name> argument, and returns
+// a pointer on the directory entry, described as an array of 32 bytes, and the index of 
+// this entry in the FAT32 mapper, seen as an array of 32 bytes entries. 
+// It makes a local copy of each directory entry to reduce the number of remote accesses.
+// It is called by the fatfs_new_dentry_from_mapper() function.
+// It can be called by a thread running in any cluster.
 //////////////////////////////////////////////////////////////////////////////////////////////
-// @ mapper    : [in]  local pointer on directory mapper.
+// @ mapper_xp : [in]  extended pointer on directory mapper.
 // @ name      : [in]  searched directory entry name.
 // @ entry     : [out] buffer for the pointer on the 32 bytes directory entry (when found).
@@ -1748 +1231 @@
 // @ return 0 if found / return 1 if not found / return -1 if mapper access error. 
 //////////////////////////////////////////////////////////////////////////////////////////////
-static error_t fatfs_scan_directory( mapper_t *  mapper,
+static error_t fatfs_scan_directory( xptr_t      mapper_xp,
                                      char     *  name,
                                      uint8_t  ** entry,
                                      uint32_t *  index )
 {
-    // Two embedded loops to scan the directory mapper:
-    // - scan the parent directory mapper pages 
-    // - scan the directory entries in each 4 Kbytes page
-
-// check parent_inode and child_inode
-assert( (mapper != NULL) , "mapper pointer is NULL\n" );
-assert( (name   != NULL ), "child name is undefined\n" );
-assert( (entry  != NULL ), "entry buffer undefined\n" );
+    uint8_t  buf[32];   // local buffer for one FAT32 directory entry
+
+// check arguments
+assert( (mapper_xp != XPTR_NULL) , "mapper pointer is NULL\n" );
+assert( (name      != NULL     ) , "child name is undefined\n" );
 
 #if DEBUG_FATFS_SCAN_DIRECTORY
-char       parent_name[CONFIG_VFS_MAX_NAME_LENGTH];
-uint32_t   cycle = (uint32_t)hal_get_cycles();
-thread_t * this  = CURRENT_THREAD;
-vfs_inode_get_name( XPTR( local_cxy , mapper->inode ) , parent_name );
+char          parent_name[CONFIG_VFS_MAX_NAME_LENGTH];
+uint32_t      cycle      = (uint32_t)hal_get_cycles();
+thread_t    * this       = CURRENT_THREAD;
+mapper_t    * mapper_ptr = GET_PTR( mapper_xp );
+cxy_t         mapper_cxy = GET_CXY( mapper_xp );
+vfs_inode_t * inode_ptr  = hal_remote_lpt( XPTR( mapper_cxy , &mapper_ptr->inode ) );
+vfs_inode_get_name( XPTR( mapper_cxy , inode_ptr ) , parent_name );
 if( DEBUG_FATFS_SCAN_DIRECTORY < cycle )
 printk("\n[%s]  thread[%x,%x] enter to search child <%s> in parent <%s> / cycle %d\n",
@@ -1777 +1260 @@
     char       lfn2[16];         // buffer for one partial cname
     char       lfn3[16];         // buffer for one partial cname
-    xptr_t     mapper_xp;        // extended pointer on mapper descriptor
-    xptr_t     page_xp;          // extended pointer on page descriptor
-    xptr_t     base_xp;          // extended pointer on page base
-    uint8_t  * base;             // local pointer on page base
+    xptr_t     page_xp;          // extended pointer on one page descriptor
+    xptr_t     base_xp;          // extended pointer on one page base
     uint8_t    attr;             // directory entry ATTR field
     uint8_t    ord;              // directory entry ORD field
@@ -1789 +1270 @@
     uint32_t   offset    = 0;    // byte offset in page
 
-    mapper_xp = XPTR( local_cxy , mapper );
+    // Two embedded loops to scan the directory mapper:
+    // - scan the parent directory mapper pages 
+    // - scan the directory entries in each 4 Kbytes page
 
     // scan the mapper pages
@@ -1795 +1278 @@
     {
         // get one page
-        page_xp = mapper_remote_get_page( mapper_xp , page_id );
+        page_xp = mapper_get_page( mapper_xp , page_id );
 
         if( page_xp == XPTR_NULL)
@@ -1804 +1287 @@
         // get page base
         base_xp = ppm_page2base( page_xp );
-        base    = (uint8_t *)GET_PTR( base_xp );
-
-#if (DEBUG_FATFS_SCAN_DIRECTORY & 0x1)
+
+#if (DEBUG_FATFS_SCAN_DIRECTORY & 1)
 if( DEBUG_FATFS_SCAN_DIRECTORY < cycle )
 mapper_display_page( mapper_xp , page_xp , 256 );
@@ -1813 +1295 @@
         while( (offset < 4096) && (found == 0) )
         {
-            attr = fatfs_get_record( DIR_ATTR , base + offset );   
-            ord  = fatfs_get_record( LDIR_ORD , base + offset );   
+            // makes a local copy of current directory entry  (32 bytes)
+            hal_remote_memcpy( XPTR( local_cxy , buf ) , base_xp + offset , 32 );
+
+            // get attr and ord from local buffer
+            attr = fatfs_get_record( DIR_ATTR , buf );   
+            ord  = fatfs_get_record( LDIR_ORD , buf );   
 
             if (ord == NO_MORE_ENTRY)                 // no more entry => break
@@ -1832 +1318 @@
                 seq = ord & 0x3;
                 lfn = (seq > lfn) ? seq : lfn;   
-                if      ( seq == 1 ) fatfs_get_name_from_long( base + offset, lfn1 );
-                else if ( seq == 2 ) fatfs_get_name_from_long( base + offset, lfn2 );
-                else if ( seq == 3 ) fatfs_get_name_from_long( base + offset, lfn3 );
+                if      ( seq == 1 ) fatfs_get_name_from_long( buf , lfn1 );
+                else if ( seq == 2 ) fatfs_get_name_from_long( buf , lfn2 );
+                else if ( seq == 3 ) fatfs_get_name_from_long( buf , lfn3 );
                 offset = offset + 32;
             }
@@ -1842 +1328 @@
                 if      ( lfn == 0 )
                 {
-                    fatfs_get_name_from_short( base + offset , cname );
+                    fatfs_get_name_from_short( buf , cname );
                 }
                 else if ( lfn == 1 )
@@ -1863 +1349 @@
                 if ( strcmp( name , cname ) == 0 )
                 {
+                    uint8_t * base = GET_PTR( base_xp );
                     *entry = base + offset;
-                    *index = ((page_id<<12) + offset)>>5; 
-                    found     = 1;
+                    *index = ( (page_id << 12) + offset ) >> 5; 
+                    found  = 1;
                 }
                 offset = offset + 32;
                 lfn    = 0;
             }
+
         }  // end loop on directory entries in page
 
@@ -1881 +1369 @@
 
 #if DEBUG_FATFS_SCAN_DIRECTORY
-cycle = (uint32_t)hal_get_cycles();
 if( DEBUG_FATFS_SCAN_DIRECTORY < cycle )
 printk("\n[%s]  thread[%x,%x] exit / found child <%s> in <%s>\n",
@@ -1892 +1379 @@
 
 #if DEBUG_FATFS_SCAN_DIRECTORY
-cycle = (uint32_t)hal_get_cycles();
 if( DEBUG_FATFS_SCAN_DIRECTORY < cycle )
 printk("\n[%s]  thread[%x,%x] exit / child <%s> in <%s> not found\n",
@@ -1909 +1395 @@
 
 
-
-/////////////////////////////////////////////////////
-error_t fatfs_new_dentry( vfs_inode_t * parent_inode,
-                          char        * name,
-                          xptr_t        child_inode_xp )
-{
-    uint8_t      * entry;            // pointer on FAT32 directory entry (array of 32 bytes)
-    uint32_t       index;            // index of FAT32 directory entry in mapper
-    mapper_t     * mapper;           // pointer on directory mapper
-    uint32_t       cluster;          // directory entry cluster
-    uint32_t       size;             // directory entry size
-    bool_t         is_dir;           // directory entry type (file/dir)
-    xptr_t         root_xp;          // extended pointer on root of parent dentries
-    xptr_t         iter_xp;          // iterator for this list
-    cxy_t          child_inode_cxy;  // child inode cluster  
-    vfs_inode_t  * child_inode_ptr;  // child inode local pointer
-    xptr_t         dentry_xp;        // extended pointer on searched dentry descriptor
-    cxy_t          dentry_cxy;       // cluster identifier of dentry (must be local_cxy)
-    vfs_dentry_t * dentry_ptr;       // local pointer 
-    error_t        error;
-
-    char           parent_name[CONFIG_VFS_MAX_NAME_LENGTH];
-
-// check arguments
-assert( (parent_inode   != NULL)       , "parent_inode is NULL\n" );
-assert( (name           != NULL)       , "name is NULL\n" );
-assert( (child_inode_xp != XPTR_NULL ) , "child_inode is NULL\n" );
-
-    // get child inode cluster and local pointer
-    child_inode_cxy = GET_CXY( child_inode_xp );
-    child_inode_ptr = GET_PTR( child_inode_xp );
-
-    // build extended pointer on root of list of parent dentries
-    root_xp = XPTR( child_inode_cxy , &child_inode_ptr->parents );
-
-// check child inode has at least one parent
-assert( (xlist_is_empty( root_xp ) == false ), "child inode must have one parent\n");
-
-#if DEBUG_FATFS_NEW_DENTRY
+//////////////////////////////////////////////////////////////////////////////////////////
+//              FATFS debug functions 
+//////////////////////////////////////////////////////////////////////////////////////////
+
+///////////////////////////////////
+void fatfs_display_ctx( cxy_t cxy )
+{
+    // get pointer on local FATFS context
+    vfs_ctx_t   * vfs_ctx = &fs_context[FS_TYPE_FATFS];
+        fatfs_ctx_t * ctx     = hal_remote_lpt( XPTR( cxy , &vfs_ctx->extend ) );
+
+    uint32_t fat_sectors       = hal_remote_l32( XPTR( cxy , &ctx->fat_sectors_count ) );
+    uint32_t sector_size       = hal_remote_l32( XPTR( cxy , &ctx->bytes_per_sector ) );
+    uint32_t sec_per_clus      = hal_remote_l32( XPTR( cxy , &ctx->sectors_per_cluster ) );
+    uint32_t fat_lba           = hal_remote_l32( XPTR( cxy , &ctx->fat_begin_lba ) );
+    uint32_t data_lba          = hal_remote_l32( XPTR( cxy , &ctx->cluster_begin_lba ) );
+    uint32_t fsinfo_lba        = hal_remote_l32( XPTR( cxy , &ctx->fs_info_lba ) );
+    uint32_t root_dir_clus     = hal_remote_l32( XPTR( cxy , &ctx->root_dir_cluster ) );
+    uint32_t free_clusters     = hal_remote_l32( XPTR( cxy , &ctx->free_clusters ) );
+    uint32_t free_cluster_hint = hal_remote_l32( XPTR( cxy , &ctx->free_cluster_hint ) );
+    void   * fat_mapper        = hal_remote_lpt( XPTR( cxy , &ctx->fat_mapper ) );
+    void   * fs_info_buffer    = hal_remote_lpt( XPTR( cxy , &ctx->fs_info_buffer ) );
+
+    printk("\n*** FAT context in cluster %x\n" 
+           "- fat_sectors       = %d\n"
+           "- sector size       = %d\n"
+           "- cluster size      = %d\n"
+           "- fat_lba           = %x\n"
+           "- data_lba          = %x\n"
+           "- fsinfo_lba        = %x\n"
+           "- root_dir_cluster  = %x\n"
+           "- free_clusters     = %x\n"
+           "- free_cluster_hint = %x\n"
+           "- fat_mapper        = %x\n"
+           "- fs_info_buffer    = %x\n",
+           cxy,
+           fat_sectors,
+           sector_size,
+           sector_size * sec_per_clus,
+           fat_lba,
+           data_lba,
+           fsinfo_lba,
+           root_dir_clus,
+           free_clusters,
+           free_cluster_hint,
+           fat_mapper,
+           fs_info_buffer );
+
+}  // end fatfs_display_ctx()
+
+//////////////////////////////////////////
+void fatfs_display_fat( uint32_t  min_slot,
+                        uint32_t  nb_slots )
+{
+    // one FAT mapper page contains 1024 slots = 128 lines of 8 slots
+
+    uint32_t   page_id;
+    uint32_t   line;
+    cxy_t      fat_cxy;         // FAT cluster
+    mapper_t * mapper;          // local pointer on FAT mapper
+    xptr_t     mapper_xp;       // extended pointer on fat_mapper
+    uint32_t   min_cluster_id;  // index of min slot to be displayed
+    uint32_t   min_page_id;     // index of min page to be displayed
+    uint32_t   min_line_id;     // index of min line in min page ( < 128 )
+    uint32_t   max_cluster_id;  // index of max slot to be displayed
+    uint32_t   max_page_id;     // index of max page to be displayed
+    uint32_t   max_line_id;     // index of max line in max page ( < 128 )
+
+    // compute min values
+    min_cluster_id = min_slot & 0xFFFFFFF8;
+    min_line_id    = (min_cluster_id & 0x3FF) >> 3;
+    min_page_id    = min_cluster_id >> 10;
+
+    // compute max values
+    max_cluster_id = min_slot + nb_slots - 1;
+    max_line_id    = (max_cluster_id & 0x3FF) >> 3;
+    max_page_id    = max_cluster_id >> 10;
+
+    // get pointer on local FATFS context
+    vfs_ctx_t   * vfs_ctx       = &fs_context[FS_TYPE_FATFS];
+    fatfs_ctx_t * loc_fatfs_ctx = (fatfs_ctx_t *)vfs_ctx->extend;
+
+    // get FAT cluster
+    fat_cxy = CONFIG_VFS_ROOT_CXY;
+
+    // get pointers on FAT mapper (in FAT cluster)
+    mapper    = loc_fatfs_ctx->fat_mapper;
+    mapper_xp = XPTR( fat_cxy , mapper );
+
+    // get pointer on FATFS context in FAT cluster
+    fatfs_ctx_t * fat_fatfs_ctx = hal_remote_lpt( XPTR( fat_cxy , &vfs_ctx->extend ) );
+ 
+    // get current value of hint and free_clusters
+    uint32_t hint = hal_remote_l32( XPTR( fat_cxy , &fat_fatfs_ctx->free_cluster_hint ) );
+    uint32_t free = hal_remote_l32( XPTR( fat_cxy , &fat_fatfs_ctx->free_clusters ) );
+
+    printk("\n***** FAT mapper / cxy %x / free_clusters %x / hint %x\n", fat_cxy, free, hint );
+
+    // scan all pages as required by min_page_id and max_page_id
+    for( page_id = min_page_id ; page_id <= max_page_id ; page_id++ )
+    {
+        // get extended pointer on requested page descriptor in FAT mapper 
+        xptr_t page_xp = mapper_get_fat_page( mapper_xp , page_id );
+
+        // get extended pointer on requested page base
+        xptr_t     base_xp  = ppm_page2base( page_xp );
+
+        // compute min_line & max_line in current page
+        uint32_t min_line = (page_id == min_page_id) ? min_line_id : 0;
+        uint32_t max_line = (page_id == max_page_id) ? max_line_id : 127;
+
+        // loop on lines in current page
+        for( line = min_line ; line <= max_line ; line++ )
+        {
+            printk("%x : %X | %X | %X | %X | %X | %X | %X | %X\n",
+            (page_id << 10) + (line <<3 ),
+            hal_remote_l32( base_xp + ((line<<5)      ) ),
+            hal_remote_l32( base_xp + ((line<<5) + 4  ) ),
+            hal_remote_l32( base_xp + ((line<<5) + 8  ) ),
+            hal_remote_l32( base_xp + ((line<<5) + 12 ) ),
+            hal_remote_l32( base_xp + ((line<<5) + 16 ) ),
+            hal_remote_l32( base_xp + ((line<<5) + 20 ) ),
+            hal_remote_l32( base_xp + ((line<<5) + 24 ) ),
+            hal_remote_l32( base_xp + ((line<<5) + 28 ) ) );
+        }
+    }
+}  // end fatfs_display_fat()
+
+/////////////////////////////////////
+error_t fatfs_check_free_info( void )
+{
+    error_t       error;
+    fatfs_ctx_t * fatfs_ctx_ptr;              // local pointer on fatfs context in cluster 0
+    uint32_t      ctx_free_clusters;          // number of free clusters from fatfs context
+    uint32_t      ctx_free_cluster_hint;      // free cluster hint from fatfs context
+    uint32_t      ioc_free_clusters;          // number of free clusters from fatfs context
+    uint32_t      ioc_free_cluster_hint;      // free cluster hint from fatfs context
+    uint32_t      fs_info_lba;                // lba of FS_INFO sector on IOC device
+    uint8_t     * fs_info_buffer;             // local pointer on FS_INFO buffer in cluster 0
+    xptr_t        fs_info_buffer_xp;          // extended pointer on FS_INFO buffer in cluster 0
+    uint8_t       tmp_buf[512];               // 512 bytes temporary buffer 
+    xptr_t        tmp_buf_xp;                 // extended pointer on temporary buffer
+
+#if DEBUG_FATFS_SYNC_FSINFO
 uint32_t   cycle = (uint32_t)hal_get_cycles();
 thread_t * this  = CURRENT_THREAD;
-vfs_inode_get_name( XPTR( local_cxy , parent_inode ) , parent_name );
-if( DEBUG_FATFS_NEW_DENTRY < cycle )
+if( DEBUG_FATFS_SYNC_FSINFO < cycle )
+printk("\n[%s] thread[%x,%x] enter / cycle %d\n",
+__FUNCTION__ , this->process->pid, this->trdid, cycle );
+#endif
+
+    // get pointer on fatfs context in cluster 0
+    fatfs_ctx_ptr = hal_remote_lpt( XPTR( 0 , &fs_context[FS_TYPE_FATFS].extend ) );
+
+    // get "free_clusters" and "free_cluster_hint" from fatfs context in cluster 0
+    ctx_free_clusters     = hal_remote_l32( XPTR( 0 , &fatfs_ctx_ptr->free_clusters ) );
+    ctx_free_cluster_hint = hal_remote_l32( XPTR( 0 , &fatfs_ctx_ptr->free_cluster_hint ) );
+
+    // get fs_info_lba 
+    fs_info_lba = hal_remote_l32( XPTR( 0 , &fatfs_ctx_ptr->fs_info_lba ) );
+
+    // build extended pointer on temporary buffer
+    tmp_buf_xp = XPTR( local_cxy , tmp_buf );
+
+    // copy FS_INFO sector from IOC to local buffer
+    error = dev_ioc_sync_read( tmp_buf_xp , fs_info_lba , 1 );
+
+    if ( error )
+    {
+        printk("\n[ERROR] in %s : cannot access FS_INFO on IOC device\n", __FUNCTION__ );
+        return -1;
+    }
+
+    // get current values of "free_clusters" and "free_cluster_hint" from FS_INFO on IOC
+    ioc_free_clusters     = fatfs_get_remote_record( FS_FREE_CLUSTERS     , tmp_buf_xp );
+    ioc_free_cluster_hint = fatfs_get_remote_record( FS_FREE_CLUSTER_HINT , tmp_buf_xp );
+
+#if DEBUG_FATFS_SYNC_FSINFO
+if( DEBUG_FATFS_SYNC_FSINFO < cycle )
+printk("\n[%s] thread[%x,%x] / ctx_free %x / ioc_free %x / ctx_hint %x / ioc_hint %x\n",
+__FUNCTION__ , this->process->pid, this->trdid, 
+ctx_free_clusters, ioc_free_clusters, ctx_free_cluster_hint, ioc_free_cluster_hint );
+#endif
+
+    // check values
+    if( (ioc_free_clusters     != ctx_free_clusters) || 
+        (ioc_free_cluster_hint != ctx_free_cluster_hint) )
+    {
+        printk("\n[WARNING] in %s : unconsistent free clusters info\n"
+        " ioc_free %x / ctx_free %x / ioc_hint %x / ctx_hint %x\n",
+        __FUNCTION__, ioc_free_clusters, ctx_free_clusters,
+        ioc_free_cluster_hint, ctx_free_cluster_hint );
+
+        // get pointers on FS_INFO buffer in cluster 0
+        fs_info_buffer    = hal_remote_lpt( XPTR( 0 , &fatfs_ctx_ptr->fs_info_buffer ) );
+        fs_info_buffer_xp = XPTR( 0 , fs_info_buffer );
+
+        // update FS_INFO buffer in cluster 0 
+        fatfs_set_remote_record(FS_FREE_CLUSTERS    ,fs_info_buffer_xp,ctx_free_clusters );
+        fatfs_set_remote_record(FS_FREE_CLUSTER_HINT,fs_info_buffer_xp,ctx_free_cluster_hint);
+
+        // update the FS_INFO sector on IOC device
+        error = dev_ioc_sync_write( fs_info_buffer_xp , fs_info_lba , 1 );
+
+        if ( error )
+        {
+            printk("\n[ERROR] in %s : cannot update FS_INFO on IOC device\n", __FUNCTION__ );
+            return -1;
+        }
+    }
+
+#if DEBUG_FATFS_SYNC_FSINFO
+cycle = (uint32_t)hal_get_cycles();
+if( DEBUG_FATFS_SYNC_FSINFO < cycle )
+printk("\n[%s] thread[%x,%x] exit / cycle %d\n",
+__FUNCTION__ , this->process->pid, this->trdid, cycle );
+#endif
+
+    return 0;
+
+}  // end fatfs_check_free_info()
+
+
+
+
+
+///////////////////////////////////////////////////////////////////////////////////////
+// Generic API : the following functions are called by the kernel VFS
+//               and must be defined by all supported file systems.
+///////////////////////////////////////////////////////////////////////////////////////
+
+
+/////////////////////////////////////
+xptr_t  fatfs_ctx_alloc( cxy_t  cxy )
+{
+    kmem_req_t    req;
+
+    // allocate memory from remote cluster
+        req.type     = KMEM_KCM;
+        req.order    = bits_log2( sizeof(fatfs_ctx_t) );
+    req.flags    = AF_KERNEL | AF_ZERO;
+ 
+    return XPTR( cxy , kmem_remote_alloc( cxy , &req ) );
+
+}  //end faffs_ctx_alloc()
+
+///////////////////////////////////////////////
+error_t  fatfs_ctx_init( xptr_t  fatfs_ctx_xp )
+{
+    error_t       error;
+    kmem_req_t    req;
+    cxy_t         cxy;             // FATFS context cluster identifier
+    fatfs_ctx_t * fatfs_ctx_ptr;   // local pointer on FATFS context
+    uint8_t     * buffer;          // local pointer on 512 bytes buffer
+    xptr_t        buffer_xp;       // extended pointer on 512 bytes buffer
+    xptr_t        fat_mapper_xp;   // extended pointer on FAT mapper
+    mapper_t    * fat_mapper;      // local pointer on FAT mapper
+
+    // get FATFS context cluster and local pointer
+    cxy           = GET_CXY( fatfs_ctx_xp );        
+    fatfs_ctx_ptr = GET_PTR( fatfs_ctx_xp );
+    
+#if DEBUG_FATFS_CTX_INIT
+uint32_t   cycle = (uint32_t)hal_get_cycles();
+thread_t * this  = CURRENT_THREAD;
+if( DEBUG_FATFS_CTX_INIT < cycle )
+printk("\n[%s] thread[%x,%x] enter for fatfs_ctx (%x,%x) / cycle %d\n",
+__FUNCTION__ , this->process->pid, this->trdid, cxy, fatfs_ctx_ptr , cycle );
+#endif
+
+    // allocate a 512 bytes buffer in remote cluster, used to store
+    // temporarily the BOOT sector, and permanently the FS_INFO sector
+        req.type    = KMEM_KCM;
+    req.order   = 9;                    // 512 bytes
+    req.flags   = AF_KERNEL | AF_ZERO;
+        buffer      = kmem_remote_alloc( cxy , &req );
+
+    if( buffer == NULL ) 
+    {
+        printk("\n[PANIC] in %s : cannot allocate buffer in cluster %x\n",
+        __FUNCTION__ , cxy );
+        return -1;
+    }
+     
+    // build extended pointer on buffer
+    buffer_xp = XPTR( cxy , buffer );
+
+    // load the BOOT record from device
+    error = dev_ioc_sync_read( buffer_xp , 0 , 1 );
+
+    if ( error )
+    {
+        printk("\n[PANIC] in %s : cannot access boot record\n", __FUNCTION__ );
+        return -1;
+    }
+
+#if (DEBUG_FATFS_CTX_INIT & 0x1)
+uint8_t bs[256];
+hal_remote_memcpy( XPTR( local_cxy , bs ) , buffer_xp , 256 );
+if( DEBUG_FATFS_CTX_INIT < cycle )
+putb( "boot record", bs , 256 );
+#endif
+
+    // get sector size from boot record
+    uint32_t sector_size = fatfs_get_remote_record( BPB_BYTSPERSEC , buffer_xp );
+
+    if ( sector_size != 512 )
+    {
+        printk("\n[PANIC] in %s : sector size must be 512 bytes\n", __FUNCTION__ );
+        return -1;
+    }
+
+    // get cluster size from boot record
+    uint32_t nb_sectors = fatfs_get_remote_record( BPB_SECPERCLUS , buffer_xp );
+
+    if ( nb_sectors != 8 )
+    {
+        printk("\n[PANIC] in %s : cluster size must be 8 sectors\n", __FUNCTION__ );
+        return -1;
+    }
+
+    // get number of FAT copies from boot record
+    uint32_t nb_fats = fatfs_get_remote_record( BPB_NUMFATS , buffer_xp );
+
+    if ( nb_fats != 1 )
+    {
+        printk("\n[PANIC] in %s : number of FAT copies must be 1\n", __FUNCTION__ );
+        return -1;
+    }
+
+    // get number of sectors in FAT from boot record
+    uint32_t fat_sectors = fatfs_get_remote_record( BPB_FAT32_FATSZ32 , buffer_xp );
+
+    if ( (fat_sectors & 0xF) != 0 )
+    {
+        printk("\n[PANIC] in %s : FAT size not multiple of 16 sectors\n", __FUNCTION__ );
+        return -1;
+    }
+
+    // get root cluster from boot record
+    uint32_t root_cluster = fatfs_get_remote_record( BPB_FAT32_ROOTCLUS , buffer_xp );
+
+    if ( root_cluster != 2 ) 
+    {
+        printk("\n[PANIC] in %s : root cluster index must be 2\n", __FUNCTION__ );
+        return -1;
+    }
+
+    // get FAT lba from boot record
+    uint32_t fat_lba = fatfs_get_remote_record( BPB_RSVDSECCNT , buffer_xp );
+
+    // get FS_INFO sector lba from boot record
+    uint32_t fs_info_lba = fatfs_get_remote_record( BPB_FAT32_FSINFO , buffer_xp );
+
+    // load the FS_INFO record from device
+    error = dev_ioc_sync_read( buffer_xp , fs_info_lba , 1 );
+
+    if ( error )
+    {
+        printk("\n[PANIC] in %s : cannot access FS_INFO record\n", __FUNCTION__ );
+        return -1;
+    }
+
+    // get free_clusters number from FS_INFO record
+    uint32_t free_clusters = fatfs_get_remote_record( FS_FREE_CLUSTERS , buffer_xp );
+
+    if ( free_clusters >= fat_sectors << 7 )
+    {
+        printk("\n[PANIC] in %s : unconsistent free_clusters\n", __FUNCTION__ );
+        return -1;
+    }
+
+    // get free_cluster_hint from FS_INFO record
+    uint32_t free_hint = fatfs_get_remote_record( FS_FREE_CLUSTER_HINT , buffer_xp );
+
+    if ( free_hint >= fat_sectors << 7 )
+    {
+        printk("\n[PANIC] in %s : unconsistent free_cluster_hint\n", __FUNCTION__ );
+        return -1;
+    }
+
+    // allocate a mapper for the FAT in remote cluster
+    fat_mapper_xp  = mapper_create( cxy , FS_TYPE_FATFS );
+
+    // get local pointer on FAT mapper
+    fat_mapper = GET_PTR( fat_mapper_xp );
+
+    if ( fat_mapper == NULL )
+    {
+        printk("\n[PANIC] in %s : no memory for FAT mapper in cluster %x\n",
+        __FUNCTION__ , cxy );
+        return -1;
+    }
+
+#if (DEBUG_FATFS_CTX_INIT & 0x1)
+if( DEBUG_FATFS_CTX_INIT < cycle )
+printk("\n[%s] sector_size %d / nb_sectors %d / fat_sectors %x / hint %x\n",
+__FUNCTION__, sector_size, nb_sectors, fat_sectors, free_hint );
+#endif
+
+    // the inode field is NULL for the FAT mapper
+    hal_remote_spt( XPTR( cxy , &fat_mapper->inode ) , NULL );
+
+    // initialize the FATFS context
+    hal_remote_s32( XPTR( cxy , &fatfs_ctx_ptr->fat_begin_lba       ), fat_lba );
+    hal_remote_s32( XPTR( cxy , &fatfs_ctx_ptr->fat_sectors_count   ), fat_sectors );
+    hal_remote_s32( XPTR( cxy , &fatfs_ctx_ptr->bytes_per_sector    ), sector_size );
+    hal_remote_s32( XPTR( cxy , &fatfs_ctx_ptr->sectors_per_cluster ), nb_sectors );
+    hal_remote_s32( XPTR( cxy , &fatfs_ctx_ptr->cluster_begin_lba   ), fat_lba + fat_sectors );
+    hal_remote_s32( XPTR( cxy , &fatfs_ctx_ptr->root_dir_cluster    ), 2 );
+    hal_remote_spt( XPTR( cxy , &fatfs_ctx_ptr->fat_mapper          ), fat_mapper );
+    hal_remote_s32( XPTR( cxy , &fatfs_ctx_ptr->fs_info_lba         ), fs_info_lba );
+    hal_remote_s32( XPTR( cxy , &fatfs_ctx_ptr->free_clusters       ), free_clusters );
+    hal_remote_s32( XPTR( cxy , &fatfs_ctx_ptr->free_cluster_hint   ), free_hint );
+    hal_remote_spt( XPTR( cxy , &fatfs_ctx_ptr->fs_info_buffer      ), buffer );
+
+    // initialize FATFS lock
+    remote_rwlock_init( XPTR( cxy , &fatfs_ctx_ptr->lock ) , LOCK_FATFS_FAT );
+
+#if DEBUG_FATFS_CTX_INIT
+if( DEBUG_FATFS_CTX_INIT < cycle )
+printk("\n[%s]  thread[%x,%x] exit for fatfs_ctx (%x,%x)\n",
+__FUNCTION__, this->process->pid, this->trdid, cxy, fatfs_ctx_ptr );
+#endif
+
+        return 0;
+
+}  // end fatfs_ctx_init()
+
+//////////////////////////////////////////////
+void fatfs_ctx_destroy( xptr_t  fatfs_ctx_xp )
+{
+    kmem_req_t   req;
+    mapper_t   * fat_mapper;
+    uint8_t    * fs_info_buffer;
+
+    // get FATFS context cluster and local pointer
+    fatfs_ctx_t * fatfs_ctx_ptr = GET_PTR( fatfs_ctx_xp );
+    cxy_t         fatfs_ctx_cxy = GET_CXY( fatfs_ctx_xp );
+
+    // get pointer on FAT mapper
+    fat_mapper = hal_remote_lpt( XPTR( fatfs_ctx_cxy , &fatfs_ctx_ptr->fat_mapper ) );
+
+    // release FAT mapper
+    mapper_destroy( XPTR( fatfs_ctx_cxy , fat_mapper ) );
+
+    // get pointer on FS_INFO buffer
+    fs_info_buffer = hal_remote_lpt( XPTR( fatfs_ctx_cxy , &fatfs_ctx_ptr->fs_info_buffer ) );
+
+    // release FS_INFO buffer
+    req.type = KMEM_KCM;
+    req.ptr  = fs_info_buffer;
+    kmem_remote_free( fatfs_ctx_cxy , &req );
+
+    // release FATFS context descriptor
+    req.type = KMEM_KCM;
+    req.ptr  = fatfs_ctx_ptr;
+    kmem_remote_free( fatfs_ctx_cxy , &req );
+
+}  // end fatfs_ctx_destroy()
+
+/////////////////////////////////////////////////////////
+error_t fatfs_add_dentry( xptr_t         parent_inode_xp,
+                          vfs_dentry_t * dentry_ptr )
+{
+    error_t       error;
+    vfs_inode_t * parent_inode_ptr;   // parent inode local pointer
+    cxy_t         parent_cxy;         // pparent inode cluster
+    xptr_t        child_inode_xp;     // extended pointer on child inode 
+    cxy_t         child_cxy;          // child inode cluster
+    vfs_inode_t * child_inode_ptr;    // child inode local pointer
+    uint32_t      length;             // dentry name length
+    uint32_t      nb_lfn;             // number or required LFN
+    char          sfn[11];            // buffer for SFN name
+    uint8_t       checksum;           // name checksum 
+    mapper_t    * mapper_ptr;         // local pointer on parent directory mapper
+    xptr_t        mapper_xp;          // extended pointer on parent directory mapper
+    uint32_t      size;               // child inode size
+    uint32_t      type;               // child inode type
+    void        * extend;             // child inode extension
+    uint32_t      cluster_id;         // child inode first cluster_id in FATFS 
+
+    char          child_name[CONFIG_VFS_MAX_NAME_LENGTH];
+
+    uint8_t       buf[32];            // local buffer for one FAT32 directory entry
+ 
+// check arguments
+assert( (parent_inode_xp != XPTR_NULL) , "parent_inode_xp argument is NULL\n" );
+assert( (dentry_ptr      != NULL)      , "dentry_ptr argument is NULL\n" );
+
+    // get directory inode cluster and local pointer 
+    parent_cxy       = GET_CXY( parent_inode_xp );
+    parent_inode_ptr = GET_PTR( parent_inode_xp );
+
+    // get extended pointers on child inode
+    child_inode_xp  = hal_remote_l64( XPTR( parent_cxy , &dentry_ptr->child_xp ) );
+    child_cxy       = GET_CXY( child_inode_xp );
+    child_inode_ptr = GET_PTR( child_inode_xp );
+
+    // get a local copy of the child name
+    vfs_inode_get_name( child_inode_xp  , child_name );
+
+#if DEBUG_FATFS_ADD_DENTRY
+uint32_t   cycle = (uint32_t)hal_get_cycles();
+thread_t * this  = CURRENT_THREAD;
+char       parent_name[CONFIG_VFS_MAX_NAME_LENGTH];
+vfs_inode_get_name( parent_inode_xp , parent_name );
+if( DEBUG_FATFS_ADD_DENTRY < cycle )
+printk("\n[%s]  thread[%x,%x] enter for <%s> in <%s> directory / cycle %d\n",
+__FUNCTION__, this->process->pid, this->trdid, child_name, parent_name, cycle );
+#endif
+
+    // get pointers on parent directory mapper
+    mapper_ptr = hal_remote_lpt( XPTR( parent_cxy , &parent_inode_ptr->mapper ) );
+    mapper_xp  = XPTR( parent_cxy , mapper_ptr );
+
+#if (DEBUG_FATFS_ADD_DENTRY & 1)
+mapper_display_page( mapper_xp , 0 , 512 );
+#endif
+
+    // get relevant infos from child inode
+    type       = hal_remote_l32( XPTR( child_cxy , &child_inode_ptr->type ) );
+    size       = hal_remote_l32( XPTR( child_cxy , &child_inode_ptr->size ) );
+    extend     = hal_remote_lpt( XPTR( child_cxy , &child_inode_ptr->extend ) );
+    cluster_id = (uint32_t)(intptr_t)extend;
+
+    // analyse child name
+    error = fatfs_name_format( child_name,
+                               &length,
+                               &nb_lfn,
+                               sfn,
+                               &checksum );
+    if ( error )
+    {
+        printk("\n[ERROR] in %s : dentry name > 31 bytes\n", __FUNCTION__ );
+        return -1;
+    }
+                               
+    // Search end of directory with two embedded loops:
+    // - scan the pages in the mapper
+    // - scan the entries in each page to find NO_MORE_ENTRY
+
+    xptr_t     page_xp;                 // extended pointer on page descriptor
+    xptr_t     base_xp;                 // extended pointer on page base
+
+    // initialise loop variables
+    uint32_t   page_id = 0;             // page index in mapper
+    uint32_t   offset  = 0;             // position in page
+    uint32_t   found   = 0;             // NO_MORE_ENTRY found
+
+    // loop on pages in mapper
+    while ( found == 0 )
+    {
+        // get extended pointer on page descriptor in mapper 
+        page_xp  = mapper_get_page( mapper_xp , page_id );
+
+        if ( page_xp == XPTR_NULL )
+        {
+            printk("\n[ERROR] in %s : cannot extend directory mapper\n",
+            __FUNCTION__ );
+            return -1;
+        }
+        
+        // get pointer on page base
+        base_xp = ppm_page2base( page_xp );
+
+        // loop on directory entries in this page
+        while ( (offset < 4096) && (found == 0) )
+        {
+            if ( fatfs_get_remote_record( LDIR_ORD, (base_xp + offset) ) == NO_MORE_ENTRY )
+            {
+                found = 1;
+            }  
+            else
+            {
+                offset = offset + 32;
+            }
+        }  // end loop on entries
+
+        if ( found == 0 )
+        {
+            page_id++;
+            offset = 0;
+        }
+    }  // end loop on pages
+
+#if (DEBUG_FATFS_ADD_DENTRY & 1)
+if( DEBUG_FATFS_ADD_DENTRY < cycle )
+printk("\n[%s]  thread[%x,%x] found NO_MORE_ENTRY : page_id %d / offset %d\n",
+__FUNCTION__, this->process->pid, this->trdid, page_id, offset );
+#endif
+
+    // Modify the directory mapper: depending on the name length,
+    // the new child requires to write (3, 4, or 5) directory entries.
+    // We build one complete directory entry in a local buffer
+    // before copying it the remote mapper. We use use a 5 steps FSM 
+    // (one state per entry to be written), that is traversed as :
+    // LFN3 -> LFN2 -> LFN1 -> NORMAL -> NOMORE 
+    // At most two pages are modified:
+    // - the page containing the NO_MORE_ENTRY is always modified
+    // - the following page can be modified if the name spread on two pages.
+
+    uint32_t step;          // FSM state
+
+    if      ( nb_lfn == 1 ) step = 3;
+    else if ( nb_lfn == 2 ) step = 4;
+    else if ( nb_lfn == 3 ) step = 5;
+    
+    uint32_t   i;           // byte index in one 32 bytes directory
+    uint32_t   c;           // character index in name
+
+    while ( step )   
+    {
+        // this block is only executed when the new name spread 
+        // on two pages, and we need to access a new page in mapper
+        if ( offset >= 4096 )
+        {
+            // copy the modified page to IOC device
+            error = fatfs_move_page( page_xp , IOC_SYNC_WRITE );   
+
+            if ( error )
+            {
+                printk("\n[ERROR] in %s : cannot update directory on device\n",
+                __FUNCTION__ );
+                return -1;
+            }
+
+            // get the next page in directory mapper
+            page_xp  = mapper_get_page( mapper_xp , page_id + 1 );
+
+            if ( page_xp == XPTR_NULL )
+            {
+                printk("\n[ERROR] in %s : cannot extend directory mapper\n",
+                __FUNCTION__ );
+                return -1;
+            }
+        
+            // get pointer on page base
+            base_xp = ppm_page2base( page_xp );
+            
+            // update offset
+            offset = 0;
+        }
+
+#if (DEBUG_FATFS_ADD_DENTRY & 1)
+cycle = (uint32_t)hal_get_cycles();
+if( DEBUG_FATFS_ADD_DENTRY < cycle )
+printk("\n[%s] FSM step = %d / offset = %x / nb_lfn = %d / cycle %d\n",
+__FUNCTION__, step, offset, nb_lfn, cycle );
+#endif
+
+        // write one FATFS directory entry (32 bytes) per iteration
+        switch ( step )
+        {
+            case 5:   // write LFN3 entry
+            {
+                c = 26;
+
+                // write 32 bytes in local buf
+                for ( i = 0 ; i < 32 ; i++ )
+                {
+                    if (i == 0)
+                    {
+                        if ( nb_lfn == 3) buf[i] = 0x43;
+                        else              buf[i] = 0x03;
+                    }
+                    else if ( ( ((i >= 1 ) && (i<=10) && ((i&1)==1))   ||
+                                ((i >= 14) && (i<=25) && ((i&1)==0))   ||
+                                ((i >= 28) && (i<=31) && ((i&1)==0)) ) &&
+                              ( c < length ) )
+                    {
+                                          buf[i] = child_name[c];
+                                          c++;
+                    }
+                    else if (i == 11)     buf[i] = 0x0F;
+                    else if (i == 13)     buf[i] = checksum;
+                    else                  buf[i] = 0x00;
+                }
+
+                // copy 32 bytes from local buffer to remote mapper
+                hal_remote_memcpy( base_xp + offset , XPTR( local_cxy  , buf ) , 32 );
+
+                step--;
+                break;
+            }
+            case 4:   // write LFN2 entry  
+            {
+                c = 13;
+
+                // write 32 bytes in local buf
+                for ( i = 0 ; i < 32 ; i++ )
+                {
+                    if (i == 0)
+                    {
+                        if ( nb_lfn == 2) buf[i] = 0x42;
+                        else              buf[i] = 0x02;
+                    }
+                    else if ( ( ((i >= 1 ) && (i<=10) && ((i&1)==1))   ||
+                                ((i >= 14) && (i<=25) && ((i&1)==0))   ||
+                                ((i >= 28) && (i<=31) && ((i&1)==0)) ) &&
+                              ( c < length ) )
+                    {
+                                          buf[i] = child_name[c];
+                                          c++;
+                    }
+                    else if (i == 11)     buf[i] = 0x0F;
+                    else if (i == 13)     buf[i] = checksum;
+                    else                  buf[i] = 0x00;
+                }
+
+                // copy 32 bytes from local buffer to remote mapper
+                hal_remote_memcpy( base_xp + offset , XPTR( local_cxy  , buf ) , 32 );
+
+                step--;
+                break;
+            }
+            case 3:   // Write LFN1 entry   
+            {
+                c = 0;
+
+                // write 32 bytes in local buf
+                for ( i = 0 ; i < 32 ; i++ )
+                {
+                    if (i == 0)
+                    {
+                        if ( nb_lfn == 1) buf[i] = 0x41;
+                        else              buf[i] = 0x01;
+                    }
+                    else if ( ( ((i >= 1 ) && (i<=10) && ((i&1)==1))   ||
+                                ((i >= 14) && (i<=25) && ((i&1)==0))   ||
+                                ((i >= 28) && (i<=31) && ((i&1)==0)) ) &&
+                              ( c < length ) )
+                    {
+                                          buf[i] = child_name[c];
+                                          c++;
+                    }
+                    else if (i == 11)     buf[i] = 0x0F;
+                    else if (i == 13)     buf[i] = checksum;
+                    else                  buf[i] = 0x00;
+                }
+
+                // copy 32 bytes from local buffer to remote mapper
+                hal_remote_memcpy( base_xp + offset , XPTR( local_cxy  , buf ) , 32 );
+
+                step--;
+                break;
+            }
+            case 2:   // write NORMAL entry     
+            {
+                // write 32 bytes in local buf
+                for ( i = 0 ; i < 32 ; i++ )
+                {
+                    if      ( i < 11 )                               // 8.3 SFN
+                    {
+                                          buf[i] = sfn[i];
+                    }
+                    else if (i == 11)                                // ATTR
+                    {
+                        if (type == INODE_TYPE_DIR)  buf[i] = 0x10;
+                        else                         buf[i] = 0x20;
+                    }
+                    else if (i == 20)     buf[i] = cluster_id>>16;   // cluster.B2
+                    else if (i == 21)     buf[i] = cluster_id>>24;   // cluster.B3
+                    else if (i == 26)     buf[i] = cluster_id>>0;    // cluster.B0
+                    else if (i == 27)     buf[i] = cluster_id>>8;    // cluster.B1
+                    else if (i == 28)     buf[i] = size>>0;          // size.B0
+                    else if (i == 29)     buf[i] = size>>8;          // size.B1
+                    else if (i == 30)     buf[i] = size>>16;         // size.B2
+                    else if (i == 31)     buf[i] = size>>24;         // size.B3
+                    else                  buf[i] = 0x00;
+                }
+
+                // copy 32 bytes from local buffer to remote mapper
+                hal_remote_memcpy( base_xp + offset , XPTR( local_cxy  , buf ) , 32 );
+
+                // set the dentry "extend" field 
+                hal_remote_spt( XPTR( parent_cxy , &dentry_ptr->extend ),
+                                (void *)(intptr_t)(((page_id << 12) + offset) >> 5 ) );
+                step--;
+                break;
+            }
+            case 1:   // write NOMORE entry  
+            {
+                hal_remote_s32( base_xp + offset , 0 );
+
+                step--;
+                break;
+            }
+
+        } // end switch step
+
+        offset += 32;
+
+    } // end while     
+
+    // copy the modified page to the IOC device
+    error = fatfs_move_page( page_xp , IOC_SYNC_WRITE );   
+
+    if ( error )
+    {
+        printk("\n[ERROR] in %s : cannot update directory on device\n",
+        __FUNCTION__ );
+        return -1;
+    }
+
+#if DEBUG_FATFS_ADD_DENTRY
+cycle = (uint32_t)hal_get_cycles();
+if( DEBUG_FATFS_ADD_DENTRY < cycle )
+printk("\n[%s]  thread[%x,%x] exit for <%s> in <%s> directory\n",
+__FUNCTION__, this->process->pid, this->trdid, child_name, parent_name );
+#endif
+
+#if (DEBUG_FATFS_ADD_DENTRY & 1)
+mapper_display_page( mapper_xp , 0 , 512 );
+#endif
+
+    return 0;
+
+}  // end fatfs_add_dentry()
+
+////////////////////////////////////////////////////////////
+error_t fatfs_remove_dentry( xptr_t         parent_inode_xp,
+                             vfs_dentry_t * dentry_ptr )
+{
+    error_t       error;
+    vfs_inode_t * parent_inode_ptr;   // parent inode local pointer
+    cxy_t         parent_cxy;         // pparent inode cluster
+    xptr_t        child_inode_xp;     // extended pointer on child inode 
+    cxy_t         child_cxy;          // child inode cluster
+    vfs_inode_t * child_inode_ptr;    // child inode local pointer
+    xptr_t        mapper_xp;          // extended pointer on mapper
+    mapper_t    * mapper_ptr;         // local pointer on mapper
+    xptr_t        page_xp;            // extended pointer on mapper page descriptor
+    xptr_t        base_xp;            // extended pointer on mapper page base
+    uint32_t      dentry_id;          // FAT32 directory entry index
+    uint32_t      page_id;            // page index in directory mapper
+    uint32_t      offset;             // offset in this mapper page
+
+    char          child_name[CONFIG_VFS_MAX_NAME_LENGTH];
+
+// check arguments
+assert( (parent_inode_xp != XPTR_NULL) , "parent_inode_xp argument is NULL\n" );
+assert( (dentry_ptr      != NULL)      , "dentry_ptr argument is NULL\n" );
+
+    // get directory inode cluster and local pointer 
+    parent_cxy       = GET_CXY( parent_inode_xp );
+    parent_inode_ptr = GET_PTR( parent_inode_xp );
+
+    // get extended pointers on child inode
+    child_inode_xp  = hal_remote_l64( XPTR( parent_cxy , &dentry_ptr->child_xp ) );
+    child_cxy       = GET_CXY( child_inode_xp );
+    child_inode_ptr = GET_PTR( child_inode_xp );
+
+    // get a local copy of the child name
+    vfs_inode_get_name( child_inode_xp  , child_name );
+
+#if DEBUG_FATFS_REMOVE_DENTRY
+uint32_t   cycle = (uint32_t)hal_get_cycles();
+thread_t * this  = CURRENT_THREAD;
+char       parent_name[CONFIG_VFS_MAX_NAME_LENGTH];
+vfs_inode_get_name( parent_inode_xp , parent_name );
+if( DEBUG_FATFS_REMOVE_DENTRY < cycle )
+printk("\n[%s]  thread[%x,%x] enter for <%s> in <%s> directory / cycle %d\n",
+__FUNCTION__, this->process->pid, this->trdid, child_name, parent_name, cycle );
+#endif
+
+    // get pointers on directory mapper
+    mapper_ptr = hal_remote_lpt( XPTR( parent_cxy , &parent_inode_ptr->mapper ) );
+    mapper_xp  = XPTR( parent_cxy , mapper_ptr );
+
+    // compute number of LFN entries
+    uint32_t nb_lfn;
+    uint32_t name_length = strlen( child_name );
+
+    if      ( name_length <= 13 ) nb_lfn  = 1;
+    else if ( name_length <= 26 ) nb_lfn  = 2;
+    else                          nb_lfn  = 3;
+
+    // We must invalidate (2,3,4) 32 bytes entries:
+    // - the NORMAL entry, registered in dentry->extend.
+    // - the (1,2,3) preceding LFN entries.
+    // At most two pages are modified:
+    // - the page containing the NORMAL entry is always modified.
+    // - the preceding page is modified when the name spread on two pages. 
+
+    // get NORMAL entry index from dentry extension 
+    dentry_id  = (uint32_t)(intptr_t)hal_remote_lpt( XPTR( parent_cxy , &dentry_ptr->extend ) ); 
+
+    // get page index and offset in parent directory mapper
+    page_id  = dentry_id >> 7;
+    offset   = (dentry_id & 0x7F)<<5;
+
+#if DEBUG_FATFS_REMOVE_DENTRY & 1
+if( DEBUG_FATFS_REMOVE_DENTRY < cycle )
+printk("\n[%s] dentry_id %x / page_id %x / offset %x\n",
+__FUNCTION__, dentry_id, page_id, offset );
+#endif
+
+    // get extended pointer on page descriptor 
+    page_xp  = mapper_get_page( mapper_xp , page_id );
+
+    if ( page_xp == XPTR_NULL )
+    {
+        printk("\n[ERROR] in %s : cannot access directory mapper\n", __FUNCTION__ );
+        return -1;
+    }
+        
+    // get extended pointer on page base
+    base_xp = ppm_page2base( page_xp );
+
+    // invalidate NORMAL entry in directory cache
+    hal_remote_sb( base_xp + offset , 0xE5 );
+
+    // invalidate LFN entries
+    while ( nb_lfn )
+    {
+        // this block is only executed when the removed name
+        // spread on two mapper pages
+        if (offset == 0)  // we must load page (page_id - 1)
+        {
+            // copy the modified page to the IOC device
+            error = fatfs_move_page( page_xp , IOC_SYNC_WRITE );   
+
+            if ( error )
+            {
+                printk("\n[ERROR] in %s : cannot update directory on device\n",
+                __FUNCTION__ );
+                return -1;
+            }
+
+            // get extended pointer on page descriptor 
+            page_xp  = mapper_get_page( mapper_xp , page_id );
+
+            if ( page_xp == XPTR_NULL )
+            {
+                printk("\n[ERROR] in %s : cannot access directory mapper\n", __FUNCTION__ );
+                return -1;
+            }
+        
+            // get extended pointer on page base
+            base_xp = ppm_page2base( page_xp );
+
+            // update offset
+            offset = 4096;
+        }
+
+        offset = offset - 32;
+
+// check for LFN entry
+assert( (fatfs_get_remote_record( DIR_ATTR, base_xp + offset ) == ATTR_LONG_NAME_MASK ),
+"this directory entry must be a LFN\n");
+
+        // invalidate LFN entry
+        hal_remote_sb( base_xp + offset , 0xE5 );
+
+        nb_lfn--;
+    }     
+
+    // copy the modified page to the IOC device
+    error = fatfs_move_page( page_xp , IOC_SYNC_WRITE );   
+    
+    if ( error )
+    {
+        printk("\n[ERROR] in %s : cannot update directory on device\n",
+        __FUNCTION__ );
+        return -1;
+    }
+
+#if DEBUG_FATFS_REMOVE_DENTRY
+cycle = (uint32_t)hal_get_cycles();
+if( DEBUG_FATFS_REMOVE_DENTRY < cycle )
+printk("\n[%s] thread[%x,%x] exit for <%s> in <%s> directory\n",
+__FUNCTION__, this->process->pid, this->trdid, child_name, parent_name );
+#endif
+
+    return 0;
+
+}  // end fatfs_remove_dentry
+
+/////////////////////////////////////////////////////////////////////
+error_t fatfs_new_dentry_from_mapper( xptr_t         parent_inode_xp,
+                                      vfs_dentry_t * dentry_ptr )
+{
+    uint32_t       cluster_id;        // directory entry first FATFS cluster
+    uint32_t       size;              // directory entry size
+    bool_t         is_dir;            // directory entry type (file/dir)
+    cxy_t          parent_cxy;        // parent inode cluster  
+    vfs_inode_t  * parent_inode_ptr;  // parent inode local pointer
+    mapper_t     * parent_mapper;     // pointer on parent directory mapper
+    xptr_t         child_inode_xp;    // extended pointer on child inode
+    cxy_t          child_cxy;         // child inode cluster  
+    vfs_inode_t  * child_inode_ptr;   // child inode local pointer
+    error_t        error;
+
+    uint8_t        buf[32];           // FAT32 directory entry local copy
+
+    char           parent_name[CONFIG_VFS_MAX_NAME_LENGTH];     // local parent name copy
+    char           child_name[CONFIG_VFS_MAX_NAME_LENGTH];      // local child name copy
+
+// check arguments
+assert( (parent_inode_xp != XPTR_NULL)  , "parent_inode_xp is NULL\n" );
+assert( (dentry_ptr      != NULL ) , "dentry_ptr is NULL\n" );
+
+    // get parent inode cluster and local pointer
+    parent_cxy       = GET_CXY( parent_inode_xp );
+    parent_inode_ptr = GET_PTR( parent_inode_xp );
+
+    // get child inode cluster and pointers
+    child_inode_xp  = hal_remote_l64( XPTR( parent_cxy , &dentry_ptr->child_xp ) );
+    child_cxy       = GET_CXY( child_inode_xp );
+    child_inode_ptr = GET_PTR( child_inode_xp );
+
+    // get child and parent names
+    vfs_inode_get_name( parent_inode_xp , parent_name );
+    vfs_inode_get_name( child_inode_xp  , child_name );
+
+#if DEBUG_FATFS_NEW_DENTRY_FROM
+uint32_t   cycle = (uint32_t)hal_get_cycles();
+thread_t * this  = CURRENT_THREAD;
+if( DEBUG_FATFS_NEW_DENTRY_FROM < cycle )
 printk("\n[%s]  thread[%x,%x] enter for child <%s> in parent <%s> / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, name , parent_name , cycle );
+__FUNCTION__, this->process->pid, this->trdid, child_name , parent_name , cycle );
 #endif
 
     // get local pointer on parent mapper
-    mapper = parent_inode->mapper;
-
-    // get pointer and index in mapper for searched directory entry 
-    error  = fatfs_scan_directory( mapper, name , &entry , &index );
-
-    // return non fatal error if not found
-    if( error )
-    {
-        vfs_inode_get_name( XPTR( local_cxy , parent_inode ) , parent_name );
-        printk("\n[ERROR] in %s : cannot find <%s> entry in <%s> directory mapper\n",
-        __FUNCTION__, name , parent_name, name );
-        return -1;
-    }
-  
-
-    // get relevant infos from FAT32 directory entry
-    cluster = (fatfs_get_record( DIR_FST_CLUS_HI , entry ) << 16) |
-              (fatfs_get_record( DIR_FST_CLUS_LO , entry )      ) ;
-    is_dir  = (fatfs_get_record( DIR_ATTR        , entry ) & ATTR_DIRECTORY);
-    size    =  fatfs_get_record( DIR_FILE_SIZE   , entry );
-
-    // scan list of parent dentries to search the parent_inode
-    bool_t found = false;
-    XLIST_FOREACH( root_xp , iter_xp )
-    {
-        // get pointers on dentry
-        dentry_xp  = XLIST_ELEMENT( iter_xp , vfs_dentry_t , parents );
-        dentry_cxy = GET_CXY( dentry_xp );
-        dentry_ptr = GET_PTR( dentry_xp );
-
-        // get local pointer on current parent directory inode
-        vfs_inode_t * current = hal_remote_lpt( XPTR( dentry_cxy , &dentry_ptr->parent ) );
-
-        // check if current parent is the searched parent
-        if( XPTR( dentry_cxy , current ) == XPTR( local_cxy , parent_inode ) )
-        {
-            found = true;
-            break;
-        }
-    }
-
-    if( found == false )
-    { 
-        vfs_inode_get_name( XPTR( local_cxy , parent_inode ) , parent_name );
-        printk("\n[ERROR] in %s : cannot find <%s> directory in list of parents for <%s>\n",
-        __FUNCTION__, parent_name, name );
-        return -1;
-    }
+    parent_mapper = hal_remote_lpt( XPTR( parent_cxy , &parent_inode_ptr->mapper ) );
+
+    // try to get pointer and index of directory entry in mapper 
+    uint8_t      * entry = NULL;
+    uint32_t       index = 0;
+
+    error  = fatfs_scan_directory( XPTR( parent_cxy , parent_mapper ),
+                                   child_name, 
+                                   &entry,
+                                   &index );
+    
+    // an error can be non fatal, for a new (created) entry
+    if( error )  return -1;
+
+    // get local copy of found directory entry
+    hal_remote_memcpy( XPTR( local_cxy  , buf ),
+                       XPTR( parent_cxy , entry ), 32 );
+
+    // get relevant infos from directory entry
+    cluster_id = (fatfs_get_record( DIR_FST_CLUS_HI , buf ) << 16) |
+                 (fatfs_get_record( DIR_FST_CLUS_LO , buf )      ) ;
+    is_dir     = (fatfs_get_record( DIR_ATTR        , buf ) & ATTR_DIRECTORY );
+    size       =  fatfs_get_record( DIR_FILE_SIZE   , buf );
 
     // update the child inode "type", "size", and "extend" fields
     vfs_inode_type_t type = (is_dir) ? INODE_TYPE_DIR : INODE_TYPE_FILE;
 
-    hal_remote_s32( XPTR( child_inode_cxy , &child_inode_ptr->type   ) , type );
-    hal_remote_s32( XPTR( child_inode_cxy , &child_inode_ptr->size   ) , size );
-    hal_remote_s32( XPTR( child_inode_cxy , &child_inode_ptr->extend ) , cluster );
+    hal_remote_s32( XPTR( child_cxy , &child_inode_ptr->type   ) , type );
+    hal_remote_s32( XPTR( child_cxy , &child_inode_ptr->size   ) , size );
+    hal_remote_s32( XPTR( child_cxy , &child_inode_ptr->extend ) , cluster_id );
 
     // update the dentry "extend" field
-    dentry_ptr->extend = (void *)(intptr_t)index;
-
-#if DEBUG_FATFS_NEW_DENTRY
+    hal_remote_spt( XPTR( parent_cxy , &dentry_ptr->extend ) , (void *)(intptr_t)index );
+
+#if DEBUG_FATFS_NEW_DENTRY_FROM
 cycle = (uint32_t)hal_get_cycles();
-if( DEBUG_FATFS_NEW_DENTRY < cycle )
-printk("\n[%s]  thread[%x,%x] exit for <%s> in <%s> / cluster_id %x / size %d  / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, name, parent_name, cluster, size,  cycle );
-#endif
-
-
-#if (DEBUG_FATFS_NEW_DENTRY & 1)
-if( DEBUG_FATFS_NEW_DENTRY < cycle )
-{
-    fatfs_display_fat( 0 , 0 , 64 );
-    fatfs_display_fat( cluster >> 10 ,  (cluster & 0x3FF) , 32 );
-}
+if( DEBUG_FATFS_NEW_DENTRY_FROM < cycle )
+printk("\n[%s]  thread[%x,%x] exit for <%s> in <%s> / cluster_id %x / size %d\n",
+__FUNCTION__, this->process->pid, this->trdid, child_name, parent_name, cluster_id, size );
+#endif
+
+#if (DEBUG_FATFS_NEW_DENTRY_FROM & 1)
+if( DEBUG_FATFS_NEW_DENTRY_FROM < cycle )
+fatfs_display_fat( cluster_id , 32 );
 #endif
 
     return 0;
 
-}  // end fatfs_new_dentry()
-
-//////////////////////////////////////////////////
-error_t fatfs_update_dentry( vfs_inode_t  * inode,
-                             vfs_dentry_t * dentry,
-                             uint32_t       size )
-{
-    uint8_t  * entry;    // pointer on FAT32 directory entry (array of 32 bytes)
-    uint32_t   index;    // index of FAT32 directory entry in mapper 
-    mapper_t * mapper;   // pointer on directory mapper
-    error_t    error;
-
-    char       dir_name[CONFIG_VFS_MAX_NAME_LENGTH];
+}  // end fatfs_new_dentry_from_mapper()
+
+///////////////////////////////////////////////////////////////////
+error_t fatfs_new_dentry_to_mapper( xptr_t         parent_inode_xp,
+                                    vfs_dentry_t * dentry_ptr )
+{
+    uint32_t       cluster_id;        // directory entry cluster
+    cxy_t          parent_cxy;        // parent inode cluster identifier  
+    vfs_inode_t  * parent_inode_ptr;  // child inode local pointer
+    xptr_t         child_inode_xp;    // extended pointer on child inode
+    cxy_t          child_cxy;         // child inode cluster identifier  
+    vfs_inode_t  * child_inode_ptr;   // child inode local pointer
+    error_t        error;
+
+    char           parent_name[CONFIG_VFS_MAX_NAME_LENGTH];
+    char           child_name[CONFIG_VFS_MAX_NAME_LENGTH];
 
 // check arguments
-assert( (inode  != NULL) , "inode is NULL\n" );
-assert( (dentry != NULL) , "dentry is NULL\n" );
+assert( (parent_inode_xp != XPTR_NULL) , "parent_inode_xp argument is NULL\n" );
+assert( (dentry_ptr      != NULL)      , "dentry_ptr argument NULL\n" );
+
+    // get child inode cluster and local pointer
+    parent_cxy       = GET_CXY( parent_inode_xp );
+    parent_inode_ptr = GET_PTR( parent_inode_xp );
+
+    // get child inode cluster and pointers
+    child_inode_xp  = hal_remote_l64( XPTR( parent_cxy , &dentry_ptr->child_xp ) );
+    child_cxy       = GET_CXY( child_inode_xp );
+    child_inode_ptr = GET_PTR( child_inode_xp );
+
+    // get child and parent names
+    vfs_inode_get_name( parent_inode_xp , parent_name );
+    vfs_inode_get_name( child_inode_xp  , child_name );
+
+#if DEBUG_FATFS_NEW_DENTRY_TO_MAP
+uint32_t   cycle = (uint32_t)hal_get_cycles();
+thread_t * this  = CURRENT_THREAD;
+if( DEBUG_FATFS_NEW_DENTRY_TO_MAP < cycle )
+printk("\n[%s]  thread[%x,%x] enter for child <%s> in parent <%s> / cycle %d\n",
+__FUNCTION__, this->process->pid, this->trdid, child_name , parent_name , cycle );
+#endif
+
+    // 1. allocate one FATFS cluster (update FAT and FSINFO) 
+    error = fatfs_cluster_alloc( 0 , &cluster_id );
+
+    if( error )
+    {
+        printk("\n[ERROR] in %s : cannot find a free cluster_id\n",
+        __FUNCTION__ );
+        return -1;
+    }
+       
+    // 2. register cluster_id in inode descriptor
+    hal_remote_spt( XPTR( child_cxy , &child_inode_ptr->extend ),
+                    (void*)(intptr_t)cluster_id );
+    
+    // 3. introduce dentry in the directory mapper
+    error = fatfs_add_dentry( parent_inode_xp , dentry_ptr );
+        
+    if( error )
+    {
+        printk("\n[ERROR] in %s : cannot update parent directory mapper\n",
+        __FUNCTION__ );
+        // TODO release cluster_id [AG]
+        return -1;
+    }
+
+#if DEBUG_FATFS_NEW_DENTRY_TO_MAP
+if( DEBUG_FATFS_NEW_DENTRY_TO_MAP < cycle )
+printk("\n[%s]  thread[%x,%x] exit for <%s> in <%s> / cluster_id %x\n",
+__FUNCTION__, this->process->pid, this->trdid, child_name, parent_name, cluster_id );
+#endif
+
+    return 0;
+
+}  // end fatfs_new_dentry_to mapper()
+
+
+////////////////////////////////////////////////////////////
+error_t fatfs_update_dentry( xptr_t         parent_inode_xp,
+                             vfs_dentry_t * dentry_ptr )
+{
+    cxy_t         parent_cxy;        // parent directory cluster identifier
+    vfs_inode_t * parent_inode_ptr;  // extended pointer on parent directory inode
+    mapper_t    * parent_mapper_ptr; // local pointer on parent directory mapper
+    xptr_t        parent_mapper_xp;  // extended pointer on parent directory mapper
+    xptr_t        child_inode_xp;    // extended pointer on child inode
+    cxy_t         child_cxy;         // child inode cluster identifier
+    vfs_inode_t * child_inode_ptr;   // extended pointer on child inode
+
+    uint32_t      current_size;      // current size in directory mapper 
+    uint32_t      new_size;          // new size (from child inode) 
+    
+    uint32_t      entry_id;          // directory entry index in parent directory mapper
+    uint32_t      page_id;           // page_index in parent directory mapper
+    uint32_t      offset;            // directory entry offset in page
+    xptr_t        page_xp;           // extended pointer on page descriptor
+    xptr_t        base_xp;           // extended pointer on page base 
+    xptr_t        entry_xp;          // extended pointer on directory entry
+
+    error_t       error;
+
+    char       parent_name[CONFIG_VFS_MAX_NAME_LENGTH];
+    char       child_name[CONFIG_VFS_MAX_NAME_LENGTH];
+
+// check arguments
+assert( (parent_inode_xp  != XPTR_NULL) , "parent_inode_xp argument is NULL\n" );
+assert( (dentry_ptr       != NULL)      , "dentry_ptr argument is NULL\n" );
+
+    // get parent directory cluster ans local pointer
+    parent_inode_ptr = GET_PTR( parent_inode_xp );
+    parent_cxy       = GET_CXY( parent_inode_xp );
+
+    // get extended pointer on child inode
+    child_inode_xp  = hal_remote_l64( XPTR( parent_cxy , &dentry_ptr->child_xp ) );
+
+    // get child and parent names
+    vfs_inode_get_name( parent_inode_xp , parent_name );
+    vfs_inode_get_name( child_inode_xp  , child_name );
 
 #if DEBUG_FATFS_UPDATE_DENTRY
 uint32_t   cycle = (uint32_t)hal_get_cycles();
 thread_t * this  = CURRENT_THREAD;
-vfs_inode_get_name( XPTR( local_cxy , inode ) , dir_name );
 if( DEBUG_FATFS_UPDATE_DENTRY < cycle )
-printk("\n[%s]  thread[%x,%x] enter for <%s/%s> / size %d / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, dir_name, dentry->name, size, cycle );
-#endif
-
-    // get local pointer on mapper
-    mapper = inode->mapper;
-
-    // get pointer and index in mapper for searched directory entry
-    error  = fatfs_scan_directory( mapper, dentry->name , &entry , &index );
-
-    if( error )
-    { 
-        vfs_inode_get_name( XPTR( local_cxy , inode ) , dir_name );
-        printk("\n[ERROR] in %s : cannot find <%s> in parent mapper <%s>\n",
-        __FUNCTION__, dentry->name, dir_name );
-        return -1;
-    }
-
-    // get current size value
-    uint32_t current_size = fatfs_get_record( DIR_FILE_SIZE , entry );
+printk("\n[%s]  thread[%x,%x] enter for <%s> in <%s> / new_size %d / cycle %d\n",
+__FUNCTION__, this->process->pid, this->trdid, child_name, parent_name, new_size, cycle );
+#endif
+
+    // get child inode cluster and local pointer
+    child_cxy       = GET_CXY( child_inode_xp );
+    child_inode_ptr = GET_PTR( child_inode_xp );
+ 
+    // get size from child inode
+    new_size = hal_remote_l32( XPTR( child_cxy , &child_inode_ptr->size ) );
+ 
+    // get local and extended pointers on parent directory mapper
+    parent_mapper_ptr = hal_remote_lpt( XPTR( parent_cxy , &parent_inode_ptr->mapper ) );
+    parent_mapper_xp  = XPTR( parent_cxy , parent_mapper_ptr );
+
+    // get directory entry index from dentry extension
+    entry_id = (intptr_t)hal_remote_lpt( XPTR( parent_cxy , &dentry_ptr->extend ) );
+
+    // get page index and offset in parent directory mapper
+    page_id  = entry_id >> 7;
+    offset   = (entry_id & 0x7F) << 5;
+
+    // get extended pointers on page descriptor and page base
+    page_xp = mapper_get_page( parent_mapper_xp , page_id );     
+    base_xp = ppm_page2base( page_xp ); 
+
+    // build extended pointer on directory entry
+    entry_xp = base_xp + offset;
+
+    // get current size from directory mapper
+    current_size = fatfs_get_remote_record( DIR_FILE_SIZE , entry_xp );
 
     // update dentry in mapper & device only if required
-    if( size != current_size )
+    if( new_size != current_size )
     {
         // set size field in FAT32 directory entry
-        fatfs_set_record( DIR_FILE_SIZE , entry , size );
-
-        // get pointer on modified page base
-        void * base = (void *)((intptr_t)entry & (~CONFIG_PPM_PAGE_MASK)); 
-
-        // get extended pointer on modified page descriptor
-        xptr_t page_xp = ppm_base2page( XPTR( local_cxy , base ) );
-
-        // synchronously update the modified page on device
+        fatfs_set_remote_record( DIR_FILE_SIZE , entry_xp , new_size );
+
+        // synchronously update the modified mapper page on device
         error = fatfs_move_page( page_xp , IOC_SYNC_WRITE );
 
         if( error )
         { 
-            vfs_inode_get_name( XPTR( local_cxy , inode ) , dir_name );
             printk("\n[ERROR] in %s : cannot update parent directory <%s> on device\n",
-            __FUNCTION__, dir_name );
+            __FUNCTION__, parent_name );
             return -1;
         }
@@ -2105 +2644 @@
 cycle = (uint32_t)hal_get_cycles();
 if( DEBUG_FATFS_UPDATE_DENTRY < cycle )
-printk("\n[%s]  thread[%x,%x] exit / updated size for <%s/%s> / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, dir_name, dentry->name, cycle );
+printk("\n[%s]  thread[%x,%x] exit for <%s> in <%s> directory / size %d / cycle %d\n",
+__FUNCTION__, this->process->pid, this->trdid, parent_name, child->name, new_size, cycle );
 #endif
 
@@ -2168 +2707 @@
     {
         // get one page from mapper
-        page_xp = mapper_remote_get_page( mapper_xp , page_id );
+        page_xp = mapper_get_page( mapper_xp , page_id );
 
         if( page_xp == XPTR_NULL) return -1;
@@ -2273 +2812 @@
 }  // end fatfs_get_user_dir()
 
-///////////////////////////////////////////////
-error_t fatfs_sync_inode( vfs_inode_t * inode )
-{
+///////////////////////////////////////////
+error_t fatfs_sync_inode( xptr_t inode_xp )
+{
+    cxy_t         inode_cxy;      // remote inode cluster
+    vfs_inode_t * inode_ptr;      // remote inode local pointer
+    mapper_t    * mapper;         // remote inode mapper local pointer
+    uint32_t      size;           // remote inode size in bytes
+    uint32_t      type;           // remote inode type
+    xptr_t        rt_xp;          // extended pointer on mapper radix tree
+    uint32_t      npages;         // number of pages in mapper
+    uint32_t      page_id;        // current page index in mapper
+    xptr_t        page_xp;        // extended pointer on current page
+    page_t      * page_ptr;       // local pointer on current page
+    uint32_t      flags;          // current page flags
+    error_t       error;
 
 // check inode pointer and cluster index
-assert( (inode != NULL)                  , "inode pointer undefined\n" );
-assert( (inode->mapper != NULL )         , "mapper pointer undefined\n" );
-assert( (inode->type == INODE_TYPE_FILE) , "inode must be a file\n" );     
+assert( (inode_xp != XPTR_NULL)          , "inode pointer undefined\n" );
 
 #if DEBUG_FATFS_SYNC_INODE
@@ -2286 +2835 @@
 uint32_t   cycle = (uint32_t)hal_get_cycles();
 thread_t * this  = CURRENT_THREAD;
-vfs_inode_get_name( XPTR( local_cxy , inode ) , name );
+vfs_inode_get_name( inode_xp , name );
 if( DEBUG_FATFS_SYNC_INODE < cycle )
 printk("\n[%s] thread[%x,%x] enter for <%s> / cycle %d\n",
@@ -2292 +2841 @@
 #endif
 
-    error_t    error;
-    mapper_t * mapper;
-    page_t   * page;
-    uint32_t   page_id;
-
-    // get mapper from inode 
-    mapper = inode->mapper;
-
-    // compute max number of pages in mapper from file size
-    uint32_t size  = inode->size;
-    uint32_t pages = size >> CONFIG_PPM_PAGE_SHIFT;
-    if( size & CONFIG_PPM_PAGE_MASK ) pages++; 
+    // get inode cluster and local pointer
+    inode_cxy = GET_CXY( inode_xp );
+    inode_ptr = GET_PTR( inode_xp );
+
+    //get inode mapper pointer
+    mapper    = hal_remote_lpt( XPTR( inode_cxy , &inode_ptr->mapper ) );
+
+assert( (mapper != NULL) , "mapper pointer is NULL\n" );     
+
+    // get inode type and size
+    size = hal_remote_l32( XPTR( inode_cxy , &inode_ptr->size ) );
+    type = hal_remote_l32( XPTR( inode_cxy , &inode_ptr->type ) );
+
+assert( (type == INODE_TYPE_FILE) , "inode is not a file\n" );     
+
+    // compute number of pages
+    npages = size >> CONFIG_PPM_PAGE_SHIFT;
+    if( size & CONFIG_PPM_PAGE_MASK ) npages++; 
          
-    // get pointer on mapper radix tree
-    grdxt_t * rt = &mapper->rt;
+    // build pointers on mapper radix tree
+    rt_xp = XPTR( inode_cxy , &mapper->rt );
 
     // scan all pages
-    for( page_id = 0 ; page_id < pages ; page_id++ )
+    for( page_id = 0 ; page_id < npages ; page_id++ )
     {
         // get page descriptor from mapper
-        page = grdxt_lookup( rt , page_id );
+        page_xp = grdxt_remote_lookup( rt_xp , page_id );
 
         // check all existing pages
-        if ( page != NULL )
-        {
-            if ( page->flags & PG_DIRTY )
+        if ( page_xp != XPTR_NULL )
+        {
+            // get page cluster and local pointer
+            page_ptr = GET_PTR( page_xp );
+
+            // get page flags
+            flags = hal_remote_l32( XPTR( inode_cxy , &page_ptr->flags ) );
+   
+            if ( flags & PG_DIRTY )
             {
 
 #if (DEBUG_FATFS_SYNC_INODE & 1)
 if( DEBUG_FATFS_SYNC_INODE < cycle )
-printk("\n[%s] thread[%x,%x] synchronizes page %d from <%s> mapper to IOC device\n",
+printk("\n[%s] thread[%x,%x] synchronizes page %d of <%s> mapper to IOC device\n",
 __FUNCTION__, page_id, name );
 #endif
-                // build extended pointer on page descriptor
-                xptr_t page_xp = XPTR( local_cxy , page );
-
                 // move page from mapper to device
                 error = fatfs_move_page( page_xp , IOC_WRITE );
@@ -2342 +2900 @@
 cycle = (uint32_t)hal_get_cycles();
 if( DEBUG_FATFS_SYNC_INODE < cycle )
-printk("\n[%s] thread[%x,%x] exit for <%s> / cycle %d\n",
-__FUNCTION__ , this->process->pid, this->trdid, name, cycle );
+printk("\n[%s] thread[%x,%x] exit for <%s>\n",
+__FUNCTION__ , this->process->pid, this->trdid, name );
 #endif
 
@@ -2349 +2907 @@
 
 }  // end fatfs_sync_inode()
-
-
-
-
-
 
 //////////////////////////////
 error_t fatfs_sync_fat( void )
 {
+
+    fatfs_ctx_t * fatfs_ctx; 
+    cxy_t         fat_cxy;
+    mapper_t    * mapper_ptr;
+    xptr_t        mapper_xp;
+    uint32_t      start_page_id;
+    uint32_t      found_page_id;
+    page_t      * page_ptr;
+    xptr_t        page_xp;
+    uint32_t      flags;
+    error_t       error;
 
 #if DEBUG_FATFS_SYNC_FAT
@@ -2366 +2930 @@
 __FUNCTION__ , this->process->pid, this->trdid, cycle );
 #endif
-
-    uint32_t   page_id;
-    error_t    error;
-
-    // get FAT mapper pointers an cluster 
-    fatfs_ctx_t * fatfs_ctx  = fs_context[FS_TYPE_FATFS].extend;
-    xptr_t        mapper_xp  = fatfs_ctx->fat_mapper_xp;
-    cxy_t         mapper_cxy = GET_CXY( mapper_xp );
-    mapper_t    * mapper_ptr = GET_PTR( mapper_xp );
-
-    // compute max number of 4 Kbytes pages in FAT mapper 
-    // TODO : this could be improved (see fatfs.h) [AG]
-    uint32_t   pages = fatfs_ctx->fat_sectors_count >> 3;
-         
+    
+    // get FAT cluster
+    fat_cxy = CONFIG_VFS_ROOT_CXY;
+    
+    // get FAT mapper pointers  
+    fatfs_ctx  = fs_context[FS_TYPE_FATFS].extend;
+    mapper_ptr = fatfs_ctx->fat_mapper;
+    mapper_xp  = XPTR( fat_cxy , mapper_ptr );
+
     // get pointers on remote FAT mapper radix tree
     grdxt_t  * rt_ptr = &mapper_ptr->rt;
-    xptr_t     rt_xp  = XPTR( mapper_cxy , rt_ptr );
-
-    // scan all pages
-    for( page_id = 0 ; page_id < pages ; page_id++ )
-    {
-        // get extended pointer on page descriptor from FAT mapper
-        xptr_t page_xp = grdxt_remote_lookup( rt_xp , page_id );
-
-        // check all existing pages
-        if ( page_xp != XPTR_NULL )
-        {
-            page_t * page_ptr = GET_PTR( page_xp );
-            uint32_t flags    = hal_remote_l32( XPTR( mapper_cxy , &page_ptr->flags ) );
-
-            if ( flags & PG_DIRTY )
-            {
+    xptr_t     rt_xp  = XPTR( fat_cxy , rt_ptr );
+
+    // initialise page_id
+    start_page_id = 0;
+
+    // scan FAT mapper
+    while( 1 )
+    {
+        // get one page
+        page_xp = grdxt_remote_get_first( rt_xp , start_page_id , &found_page_id );
+
+        // exit loop when no more page found 
+        if ( page_xp != XPTR_NULL ) break;
+
+        // get page flags
+        page_ptr = GET_PTR( page_xp );
+        flags    = hal_remote_l32( XPTR( fat_cxy , &page_ptr->flags ) );
+
+        if ( flags & PG_DIRTY )
+        {
 
 #if (DEBUG_FATFS_SYNC_FAT & 1)
@@ -2404 +2967 @@
 __FUNCTION__, page_id );
 #endif
-                // move page from mapper to device
-                error = fatfs_move_page( page_xp , IOC_SYNC_WRITE );
-
-                if ( error )  return -1;
-
-                // reset page dirty flag
-                ppm_page_undo_dirty( page_xp );
-            }
-        }
+            // move page from mapper to device
+            error = fatfs_move_page( page_xp , IOC_SYNC_WRITE );
+
+            if ( error )  return -1;
+
+            // reset page dirty flag
+            ppm_page_undo_dirty( page_xp );
+        }
+
+        // update loop variable
+        start_page_id = found_page_id + 1;
+
     }  // end loop on pages
 
@@ -2418 +2984 @@
 cycle = (uint32_t)hal_get_cycles();
 if( DEBUG_FATFS_SYNC_FAT < cycle )
-printk("\n[%s] thread[%x,%x] exit / cycle %d\n",
-__FUNCTION__ , this->process->pid, this->trdid, cycle );
+printk("\n[%s] thread[%x,%x] exit\n",
+__FUNCTION__ , this->process->pid, this->trdid );
 #endif
 
@@ -2425 +2991 @@
 
 }  // end fatfs_sync_fat()
-
-////////////////////////////////////
-error_t fatfs_sync_free_info( void )
-{
-    error_t       error;
-    fatfs_ctx_t * fatfs_ctx_ptr;              // local pointer on fatfs context in cluster 0
-    uint32_t      ctx_free_clusters;          // number of free clusters from fatfs context
-    uint32_t      ctx_free_cluster_hint;      // free cluster hint from fatfs context
-    uint32_t      ioc_free_clusters;          // number of free clusters from fatfs context
-    uint32_t      ioc_free_cluster_hint;      // free cluster hint from fatfs context
-    uint32_t      fs_info_lba;                // lba of FS_INFO sector on IOC device
-    uint8_t     * fs_info_buffer;             // local pointer on FS_INFO buffer in cluster 0
-    xptr_t        fs_info_buffer_xp;          // extended pointer on FS_INFO buffer in cluster 0
-    uint8_t       tmp_buf[512];               // 512 bytes temporary buffer 
-    xptr_t        tmp_buf_xp;                 // extended pointer on temporary buffer
-
-#if DEBUG_FATFS_SYNC_FSINFO
-uint32_t   cycle = (uint32_t)hal_get_cycles();
-thread_t * this  = CURRENT_THREAD;
-if( DEBUG_FATFS_SYNC_FSINFO < cycle )
-printk("\n[%s] thread[%x,%x] enter / cycle %d\n",
-__FUNCTION__ , this->process->pid, this->trdid, cycle );
-#endif
-
-    // get pointer on fatfs context in cluster 0
-    fatfs_ctx_ptr = hal_remote_lpt( XPTR( 0 , &fs_context[FS_TYPE_FATFS].extend ) );
-
-    // get "free_clusters" and "free_cluster_hint" from fatfs context in cluster 0
-    ctx_free_clusters     = hal_remote_l32( XPTR( 0 , &fatfs_ctx_ptr->free_clusters ) );
-    ctx_free_cluster_hint = hal_remote_l32( XPTR( 0 , &fatfs_ctx_ptr->free_cluster_hint ) );
-
-    // get fs_info_lba 
-    fs_info_lba = hal_remote_l32( XPTR( 0 , &fatfs_ctx_ptr->fs_info_lba ) );
-
-    // build extended pointer on temporary buffer
-    tmp_buf_xp = XPTR( local_cxy , tmp_buf );
-
-    // copy FS_INFO sector from IOC to local buffer
-    error = dev_ioc_move_data( IOC_SYNC_READ , tmp_buf_xp , fs_info_lba , 1 );
-
-    if ( error )
-    {
-        printk("\n[ERROR] in %s : cannot access FS_INFO on IOC device\n", __FUNCTION__ );
-        return -1;
-    }
-
-    // get current values of "free_clusters" and "free_cluster_hint" from FS_INFO on IOC
-    ioc_free_clusters     = fatfs_get_remote_record( FS_FREE_CLUSTERS     , tmp_buf_xp );
-    ioc_free_cluster_hint = fatfs_get_remote_record( FS_FREE_CLUSTER_HINT , tmp_buf_xp );
-
-#if DEBUG_FATFS_SYNC_FSINFO
-if( DEBUG_FATFS_SYNC_FSINFO < cycle )
-printk("\n[%s] thread[%x,%x] / ctx_free %x / ioc_free %x / ctx_hint %x / ioc_hint %x\n",
-__FUNCTION__ , this->process->pid, this->trdid, 
-ctx_free_clusters, ioc_free_clusters, ctx_free_cluster_hint, ioc_free_cluster_hint );
-#endif
-
-    // check values
-    if( (ioc_free_clusters     != ctx_free_clusters) || 
-        (ioc_free_cluster_hint != ctx_free_cluster_hint) )
-    {
-        printk("\n[WARNING] in %s : unconsistent free clusters info\n"
-        " ioc_free %x / ctx_free %x / ioc_hint %x / ctx_hint %x\n",
-        __FUNCTION__, ioc_free_clusters, ctx_free_clusters,
-        ioc_free_cluster_hint, ctx_free_cluster_hint );
-
-        // get pointers on FS_INFO buffer in cluster 0
-        fs_info_buffer    = hal_remote_lpt( XPTR( 0 , &fatfs_ctx_ptr->fs_info_buffer ) );
-        fs_info_buffer_xp = XPTR( 0 , fs_info_buffer );
-
-        // update FS_INFO buffer in cluster 0 
-        fatfs_set_remote_record(FS_FREE_CLUSTERS    ,fs_info_buffer_xp,ctx_free_clusters );
-        fatfs_set_remote_record(FS_FREE_CLUSTER_HINT,fs_info_buffer_xp,ctx_free_cluster_hint);
-
-        // update the FS_INFO sector on IOC device
-        error = dev_ioc_move_data( IOC_SYNC_WRITE , fs_info_buffer_xp , fs_info_lba , 1 );
-
-        if ( error )
-        {
-            printk("\n[ERROR] in %s : cannot update FS_INFO on IOC device\n", __FUNCTION__ );
-            return -1;
-        }
-    }
-
-#if DEBUG_FATFS_SYNC_FSINFO
-cycle = (uint32_t)hal_get_cycles();
-if( DEBUG_FATFS_SYNC_FSINFO < cycle )
-printk("\n[%s] thread[%x,%x] exit / cycle %d\n",
-__FUNCTION__ , this->process->pid, this->trdid, cycle );
-#endif
-
-    return 0;
-
-}  // end fatfs_sync_free_info()
-
-//////////////////////////////////////////////////////////
-error_t fatfs_cluster_alloc( uint32_t * searched_cluster )
-{
-    error_t       error;
-    uint32_t      page_id;        // page index in FAT mapper
-    uint32_t      slot_id;        // slot index in page (1024 slots per page)
-    uint32_t      cluster;        // first free cluster index in FAT
-    uint32_t      free_clusters;  // total number of free clusters
-    vfs_ctx_t   * vfs_ctx;        // local pointer on VFS context (same in all clusters)
-    fatfs_ctx_t * loc_fatfs_ctx;  // local pointer on local FATFS context
-    fatfs_ctx_t * fat_fatfs_ctx;  // local pointer on FATFS context in FAT cluster
-    xptr_t        fat_mapper_xp;  // extended pointer on FAT mapper
-    cxy_t         fat_cxy;        // Fat mapper cluster identifier
-    xptr_t        page_xp;        // extended pointer on current page descriptor in mapper
-    xptr_t        slot_xp;        // extended pointer on FAT slot defined by hint
-    xptr_t        lock_xp;        // extended pointer on lock protecting free clusters info
-    xptr_t        hint_xp;        // extended pointer on free_cluster_hint in FAT cluster
-    xptr_t        free_xp;        // extended pointer on free_clusters_number in FAT cluster
-
-#if DEBUG_FATFS_CLUSTER_ALLOC
-uint32_t   cycle = (uint32_t)hal_get_cycles();
-thread_t * this  = CURRENT_THREAD;
-if( DEBUG_FATFS_CLUSTER_ALLOC < cycle )
-printk("\n[%s] thread[%x,%x] enter / cycle = %d\n",
-__FUNCTION__, this->process->pid, this->trdid, cycle );
-#endif
-
-    // get local pointer on VFS context (same in all clusters)
-    vfs_ctx = &fs_context[FS_TYPE_FATFS];
-
-    // get local pointer on local FATFS context
-    loc_fatfs_ctx = vfs_ctx->extend;
-
-    // get extended pointer on FAT mapper
-    fat_mapper_xp  = loc_fatfs_ctx->fat_mapper_xp;
-
-    // get FAT cluster
-    fat_cxy = GET_CXY( fat_mapper_xp );
-    
-    // get local pointer on FATFS context in FAT cluster 
-    fat_fatfs_ctx = hal_remote_lpt( XPTR( fat_cxy , &vfs_ctx->extend ) );
-
-    // build relevant extended pointers on free clusters info in mapper cluster 
-    lock_xp = XPTR( fat_cxy , &fat_fatfs_ctx->lock );
-    hint_xp = XPTR( fat_cxy , &fat_fatfs_ctx->free_cluster_hint );
-    free_xp = XPTR( fat_cxy , &fat_fatfs_ctx->free_clusters );
-
-    // take the FAT lock in write mode
-    remote_rwlock_wr_acquire( lock_xp );
-
-    // get hint and free_clusters values from FATFS context in FAT cluster
-    cluster       = hal_remote_l32( hint_xp ) + 1;
-    free_clusters = hal_remote_l32( free_xp );
-        
-#if (DEBUG_FATFS_CLUSTER_ALLOC & 1)
-if( DEBUG_FATFS_CLUSTER_ALLOC < cycle )
-printk("\n[%s] thread[%x,%x] get free info : hint %x / free_clusters %x\n",
-__FUNCTION__, this->process->pid, this->trdid, (cluster - 1), free_clusters );
-#endif
-
-    // check "free_clusters"
-    if ( free_clusters == 0 )
-    {
-        printk("\n[ERROR] in %s : no more free FATFS clusters\n", __FUNCTION__ );
-        remote_rwlock_wr_release( lock_xp );
-        return -1;
-    }
-    else if ( free_clusters < CONFIG_VFS_FREE_CLUSTERS_MIN )
-    {
-        printk("\n[WARNING] in %s : only %n free FATFS clusters\n", 
-        __FUNCTION__, CONFIG_VFS_FREE_CLUSTERS_MIN );
-    }
-
-    // get page index & slot index for selected cluster 
-    page_id  = cluster >> 10;
-    slot_id  = cluster & 0x3FF;
-
-    // get relevant page descriptor from FAT mapper
-    page_xp = mapper_remote_get_page( fat_mapper_xp , page_id );
-
-    if( page_xp == XPTR_NULL )
-    {
-        printk("\n[ERROR] in %s : cannot acces FAT mapper\n", __FUNCTION__ );
-        remote_rwlock_wr_release( lock_xp );
-        return -1;
-    }
-
-    // build extended pointer on selected cluster slot in FAT mapper
-    slot_xp = ppm_page2base( page_xp ) + (slot_id << 2);
-         
-    // check selected cluster actually free
-    if( hal_remote_l32( slot_xp ) != FREE_CLUSTER )
-    { 
-        printk("\n[ERROR] in %s : selected cluster %x not free\n", __FUNCTION__, cluster );
-        remote_rwlock_wr_release( lock_xp );
-        return -1;
-    }
-
-    // update free cluster info in FATFS context and in FS_INFO sector
-    error = fatfs_free_clusters_decrement( XPTR( fat_cxy , fat_fatfs_ctx ) , cluster );
-
-    if( error )
-    { 
-        printk("\n[ERROR] in %s : cannot update free cluster info\n", __FUNCTION__ );
-        remote_rwlock_wr_release( lock_xp );
-        return -1;
-    }
-
-    // update FAT mapper
-    hal_remote_s32( slot_xp , END_OF_CHAIN_CLUSTER_MAX );
-
-    // we don't mark the FAT mapper page as dirty,
-    // because we synchronously update FAT on IOC device
-    error = fatfs_move_page( page_xp , IOC_SYNC_WRITE );
-
-    if( error )
-    { 
-        printk("\n[ERROR] in %s : cannot update FAT on IOC device\n", __FUNCTION__ );
-        remote_rwlock_wr_release( lock_xp );
-        return -1;
-    }
-
-    // release FAT lock
-    remote_rwlock_wr_release( lock_xp );
-
-#if DEBUG_FATFS_CLUSTER_ALLOC 
-cycle = (uint32_t)hal_get_cycles();
-if( DEBUG_FATFS_CLUSTER_ALLOC < cycle )
-printk("\n[%s] thread[%x,%x] exit / allocated cluster %x in FAT / cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, cluster, cycle );
-#endif
-
-    *searched_cluster = cluster;
-    return 0;
-
-}  // end fatfs_cluster_alloc()
 
 //////////////////////////////////////////////
 error_t fatfs_release_inode( xptr_t inode_xp )
 {
-    vfs_ctx_t   * vfs_ctx;        // local pointer on VFS context (same in all clusters).
-    fatfs_ctx_t * loc_fatfs_ctx;  // local pointer on local FATFS context
-    cxy_t         fat_cxy;        // FAT cluster identifier
-    xptr_t        fatfs_ctx_xp;   // extended pointer on FATFS context in FAT cluster
-    fatfs_ctx_t * fatfs_ctx_ptr;  // local pointer on FATFS context in FAT cluster
-    xptr_t        fat_mapper_xp;  // extended pointer on FAT mapper
-    xptr_t        lock_xp;        // extended pointer on lock protecting FAT.
-    xptr_t        first_xp;       // extended pointer on inode extension
-    uint32_t      first_cluster;  // first cluster index for released inode
-    vfs_inode_t * inode_ptr;      // local pointer on target inode
-    cxy_t         inode_cxy;      // target inode cluster identifier
+    vfs_ctx_t   * vfs_ctx;           // local pointer on VFS context (same in all clusters)
+    cxy_t         fat_cxy;           // FAT cluster identifier
+    fatfs_ctx_t * fatfs_ctx_ptr;     // local pointer on FATFS context in FAT cluster
+    xptr_t        fatfs_ctx_xp;      // extended pointer on FATFS-context in FAT cluster
+    mapper_t    * fat_mapper_ptr;    // local pointer on FAT mapper
+    xptr_t        fat_mapper_xp;     // extended pointer on FAT mapper
+    xptr_t        lock_xp;           // extended pointer on lock protecting FAT.
+    xptr_t        first_xp;          // extended pointer on inode extension
+    uint32_t      first_cluster_id;  // first cluster index for released inode
+    vfs_inode_t * inode_ptr;         // local pointer on target inode
+    cxy_t         inode_cxy;         // target inode cluster identifier
     error_t       error;
 
@@ -2680 +3015 @@
     inode_cxy     = GET_CXY( inode_xp );
 
-    // get first_cluster from inode extension
-    first_xp      = XPTR( inode_cxy , &inode_ptr->extend );
-    first_cluster = (uint32_t)(intptr_t)hal_remote_lpt( first_xp );
+    // get first_cluster_id from inode extension
+    first_xp         = XPTR( inode_cxy , &inode_ptr->extend );
+    first_cluster_id = (uint32_t)(intptr_t)hal_remote_lpt( first_xp );
 
 // check first cluster index
-assert( (first_cluster != 0) , "inode extend is NULL\n" );
+assert( (first_cluster_id != 0) , "inode extend is NULL\n" );
 
 #if DEBUG_FATFS_RELEASE_INODE
@@ -2693 +3028 @@
 vfs_inode_get_name( inode_xp , name );
 if( DEBUG_FATFS_RELEASE_INODE < cycle )
-printk("\n[%s] thread[%x,%x] enter for <%s> / first_cluster %x / cycle %d\n",
-__FUNCTION__ , this->process->pid, this->trdid, name, first_cluster, cycle );
+printk("\n[%s] thread[%x,%x] enter for <%s> / first_cluster_id %x / cycle %d\n",
+__FUNCTION__ , this->process->pid, this->trdid, name, first_cluster_id, cycle );
 #endif
 
@@ -2700 +3035 @@
     vfs_ctx = &fs_context[FS_TYPE_FATFS];
 
-    // get local pointer on local FATFS context
-    loc_fatfs_ctx = vfs_ctx->extend;
-
-    // get FAT mapper cluster
-    fat_mapper_xp  = loc_fatfs_ctx->fat_mapper_xp;
-    fat_cxy        = GET_CXY( fat_mapper_xp );
+    // get FAT cluster
+    fat_cxy = CONFIG_VFS_ROOT_CXY;
+
+    // get pointers on FATFS context in FAT cluster 
+    fatfs_ctx_ptr = hal_remote_lpt( XPTR( fat_cxy , &vfs_ctx->extend ) );
+    fatfs_ctx_xp  = XPTR( fat_cxy , fatfs_ctx_ptr ); 
+
+    // get FAT mapper pointers
+    fat_mapper_ptr = hal_remote_lpt( XPTR( fat_cxy , &fatfs_ctx_ptr->fat_mapper ) );
+        fat_mapper_xp  = XPTR( fat_cxy , fat_mapper_ptr );
     
-    // get pointers on FATFS context in FAT cluster 
-    fatfs_ctx_ptr  = hal_remote_lpt( XPTR( fat_cxy , &vfs_ctx->extend ) );
-    fatfs_ctx_xp   = XPTR( fat_cxy , fatfs_ctx_ptr );
-
-    // get extended pointer on FAT lock in FAT cluster
+    // build extended pointer on FAT lock in FAT cluster
     lock_xp = XPTR( fat_cxy , &fatfs_ctx_ptr->lock );
 
@@ -2727 +3062 @@
     if ( fatfs_recursive_release( fat_mapper_xp,
                                   fatfs_ctx_xp,
-                                  first_cluster,
+                                  first_cluster_id,
                                   &dirty_page_min,
                                   &dirty_page_max ) )
@@ -2791 +3126 @@
 }  // end fatfs_release_inode()
 
-////////////////////////////////////////////
-error_t fatfs_move_page( xptr_t     page_xp,
-                         cmd_type_t cmd_type )
-{
-    error_t       error;
+/////////////////////////////////////////////////
+error_t fatfs_move_page( xptr_t          page_xp,
+                         ioc_cmd_type_t  cmd_type )
+{
+    error_t       error = 0;
+
     vfs_inode_t * inode_ptr;
     mapper_t    * mapper_ptr;      
@@ -2829 +3165 @@
 #if DEBUG_FATFS_MOVE_PAGE
 if( DEBUG_FATFS_MOVE_PAGE < cycle )
-printk("\n[%s] thread[%x,%x] enters for %s /  page %d in FAT mapper / cycle %d\n",
+printk("\n[%s] thread[%x,%x] enters %s for  page %d in FAT mapper / cycle %d\n",
 __FUNCTION__, this->process->pid, this->trdid, dev_ioc_cmd_str(cmd_type), page_id, cycle );
 #endif
@@ -2836 +3172 @@
  
         // access IOC device
-        error = dev_ioc_move_data( cmd_type , buffer_xp , lba , 8 );
+        if     (cmd_type == IOC_SYNC_WRITE) error = dev_ioc_sync_write( buffer_xp, lba, 8 );
+        else if(cmd_type == IOC_SYNC_READ ) error = dev_ioc_sync_read( buffer_xp, lba, 8 );
+        else
+        {
+            printk("\n[ERROR] in %s : illegal asynchronous FAT access\n", __FUNCTION__ );
+        }
 
         if( error )
         {
-            printk("\n[ERROR] in %s : cannot access device\n", __FUNCTION__ );
+            printk("\n[ERROR] in %s : cannot access IOC device\n", __FUNCTION__ );
             return -1;
         }
@@ -2846 +3187 @@
 #if DEBUG_FATFS_MOVE_PAGE
 if( DEBUG_FATFS_MOVE_PAGE < cycle )
-printk("\n[%s] thread[%x,%x] exit / page %d in FAT mapper\n",
-__FUNCTION__, this->process->pid, this->trdid, page_id, cycle );
+printk("\n[%s] thread[%x,%x] exit %s for page %d in FAT mapper\n",
+__FUNCTION__, this->process->pid, this->trdid, dev_ioc_cmd_str(cmd_type), page_id );
 #endif
 
@@ -2856 +3197 @@
 
 #if DEBUG_FATFS_MOVE_PAGE
-vfs_inode_get_name( XPTR( page_cxy , inode_ptr ) , name );
 if( DEBUG_FATFS_MOVE_PAGE < cycle )
-printk("\n[%s] thread[%x,%x] enters for %s / page %d in <%s> mapper/ cycle %d\n",
-__FUNCTION__, this->process->pid, this->trdid, 
-dev_ioc_cmd_str( cmd_type ), page_id, name, cycle );
+{
+    vfs_inode_get_name( XPTR( page_cxy , inode_ptr ) , name );
+    printk("\n[%s] thread[%x,%x] enters %s for page %d in <%s> mapper / cycle %d\n",
+    __FUNCTION__, this->process->pid, this->trdid, 
+    dev_ioc_cmd_str( cmd_type ), page_id, name, cycle );
+}
 #endif
 
@@ -2893 +3236 @@
         uint32_t lba = fatfs_lba_from_cluster( fatfs_ctx , searched_cluster_id );
 
-        // access IOC device to move 8 blocks
-        error = dev_ioc_move_data( cmd_type , buffer_xp , lba , 8 );
+        // access IOC device
+        if     (cmd_type == IOC_WRITE     ) error = dev_ioc_write( buffer_xp, lba, 8 );
+        else if(cmd_type == IOC_READ      ) error = dev_ioc_read( buffer_xp, lba, 8 );
+        else if(cmd_type == IOC_SYNC_READ ) error = dev_ioc_sync_read( buffer_xp, lba, 8 );
+        else if(cmd_type == IOC_SYNC_WRITE) error = dev_ioc_sync_write( buffer_xp, lba, 8 );
+        else
+        {
+            printk("\n[ERROR] in %s : illegal cmd_type\n", __FUNCTION__ );
+        }
 
         if( error )
@@ -2904 +3254 @@
 #if DEBUG_FATFS_MOVE_PAGE
 if( DEBUG_FATFS_MOVE_PAGE < cycle )
-vfs_inode_get_name( XPTR( page_cxy, inode_ptr ) , name );
-printk("\n[%s] thread[%x,%x] exit / page %d in <%s> mapper / cluster_id %x\n",
-__FUNCTION__, this->process->pid, this->trdid, page_id, name, searched_cluster_id );
+{
+    printk("\n[%s] thread[%x,%x] exit %s for page %d in <%s> mapper / cluster_id %x\n",
+    __FUNCTION__, this->process->pid, this->trdid, 
+    dev_ioc_cmd_str( cmd_type ), page_id, name, searched_cluster_id );
+}
+#endif
+
+#if (DEBUG_FATFS_MOVE_PAGE & 1)
+if( DEBUG_FATFS_MOVE_PAGE < cycle )
+fatfs_display_fat( searched_cluster_id , 64 );
 #endif