Changeset 627 for trunk/kernel/fs/fatfs.h

Timestamp:

May 1, 2019, 5:13:47 PM (5 years ago)

Author:

alain

Message:

Replace the queuelock protectingthe FAT by a rwlock in the FATFS.

File:

• trunk/kernel/fs/fatfs.h (modified) (3 diffs)

trunk/kernel/fs/fatfs.h

@@ -32 +32 @@
 
 
-///////////////////////////////////////////////////////////////////////////////////////////
-// The FATFS File System implements a FAT32 read/write file system.
-//
-// The FATFS specific extensions to the generic VFS are the following:
-//
-// 1) The vfs_ctx_t "extend" field is a void* pointing on the fatfs_ctx_t structure.
-//    This structure contains various general informations such as the total
-//    number of sectors in FAT region, the number of bytes per sector, the number 
-//    of sectors per cluster, the lba of FAT region, the lba of data region, or the
-//    cluster index for the root directory. It contains also an extended pointer
-//    on the FAT mapper.
-//
-// 2) The vfs_inode_t "extend" contains, for each inode,
-//    the first FAT cluster index (after cast to intptr).
-//
-// 3) The vfs_dentry_t "extend" field contains, for each dentry, the entry index
-//    in the FATFS directory (32 bytes per FATFS entry). 
+/**************************************************************************************
+ * The FATFS File System implements a FAT32 read/write file system.
+ *
+ * The FATFS specific extensions to the generic VFS are the following:
+ * 1) The vfs_ctx_t "extend" field is a void* pointing on the fatfs_ctx_t structure.
+ *    This structure contains various general informations such as the total
+ *    number of sectors in FAT region, the number of bytes per sector, the number 
+ *    of sectors per cluster, the lba of FAT region, the lba of data region, or the
+ *    cluster index for the root directory. It contains also an extended pointer
+ *    on the FAT mapper.
+ * 2) The vfs_inode_t "extend" contains, for each inode,
+ *    the first FAT cluster index (after cast to intptr).
+ * 3) The vfs_dentry_t "extend" field contains, for each dentry, the entry index
+ *    in the FATFS directory (32 bytes per FATFS entry).
+ *************************************************************************************/
+ 
 ///////////////////////////////////////////////////////////////////////////////////////////
 
@@ -175 +174 @@
  * This fatfs context is replicated in all clusters.
  *
- * WARNING : Almost all fields are constant values, but the <free_cluster_hint>, 
- * <free_clusters> and <free_lock> are shared variables. Moreover, the <fs_info_buffer>,
- * only allocated in cluster 0, contains a copy of the FS_INFO sector. It is used by all
+ * WARNING 1 : All access to the FAT are protected by a remote_rwlock. 
+ * - it is taken in READ mode by the fatfs_get_cluster() function to scan the
+ *   linked list associated to a given inode. 
+ * - it is taken in WRITE mode by the fatfs_cluster_alloc() and fatfs_release_inode()
+ *   functions to modify the FAT in both the FAT mapper and on IOC device.
+ *
+ * WARNING é : Almost all fields are constant values, but the <free_cluster_hint>, 
+ * <free_clusters> and <lock> are shared variables. The <fs_info_buffer>, only
+ * allocated in cluster 0, contains a copy of the FS_INFO sector. It is used by all
  * kernel instances to synchronously update the free clusters info on IOC device.
  * For these four variables, all kernel instances must use the values in cluster 0, 
- * and take the <free_lock> stored in this cluster for exclusive access to FAT.
+ * containing the FAT mapper.
  ****************************************************************************************/
 
@@ -198 +203 @@
     uint32_t            free_cluster_hint;     /*! cluster[hint+1] is the first free    */
     uint32_t            free_clusters;         /*! free clusters number                 */
-    remote_queuelock_t  free_lock;             /*! exclusive access to FAT              */
+    remote_rwlock_t     lock;                  /*! exclusive access to FAT              */
     uint8_t           * fs_info_buffer;        /*! local pointer on FS_INFO buffer      */
 }