1 | /* |
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2 | * mapper.h - Map memory, file or device in process virtual address space. |
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3 | * |
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4 | * Authors Mohamed Lamine Karaoui (2015) |
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5 | * Alain Greiner (2016) |
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6 | * |
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7 | * Copyright (c) UPMC Sorbonne Universites |
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8 | * |
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9 | * This file is part of ALMOS-MKH. |
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10 | * |
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11 | * ALMOS-MKH is free software; you can redistribute it and/or modify it |
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12 | * under the terms of the GNU General Public License as published by |
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13 | * the Free Software Foundation; version 2.0 of the License. |
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14 | * |
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15 | * ALMOS-MKH is distributed in the hope that it will be useful, but |
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16 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
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17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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18 | * General Public License for more details. |
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19 | * |
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20 | * You should have received a copy of the GNU General Public License |
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21 | * along with ALMOS-MKH; if not, write to the Free Software Foundation, |
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22 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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23 | */ |
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24 | |
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25 | #ifndef _MAPPER_H_ |
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26 | #define _MAPPER_H_ |
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27 | |
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28 | #include <hal_types.h> |
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29 | #include <hal_atomic.h> |
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30 | #include <xlist.h> |
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31 | #include <grdxt.h> |
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32 | #include <rwlock.h> |
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33 | |
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34 | /**** Forward declarations ****/ |
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35 | |
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36 | struct page_s; |
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37 | struct vfs_inode_s; |
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38 | |
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39 | /******************************************************************************************* |
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40 | * The mapper implements the kernel cache for a given file or directory. |
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41 | * There is one mapper per file. It is implemented as a three levels radix tree, |
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42 | * entirely stored in the same cluster as the inode representing the file/dir. |
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43 | * - The fast retrieval key is the page index in the file. |
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44 | * The ix1_width, ix2_width, ix3_width sub-indexes are configuration parameters. |
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45 | * - The leaves are pointers on physical page descriptors, dynamically allocated |
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46 | * in the local cluster. |
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47 | * - In a given cluster, a mapper is a "private" structure: a thread accessing the mapper |
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48 | * must be running in the cluster containing it (can be a local thread or a RPC thread). |
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49 | * - The mapper is protected by a blocking "rwlock", to support several simultaneous |
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50 | * readers, and only one writer. This lock implement a busy waiting policy. |
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51 | * - The two functions mapper_sync_page() and mapper_updt_page() define the generic API |
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52 | * used to move pages to or from the relevant file system on IOC device. |
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53 | * - the mapper_move fragments() function is used to move data to or from a distributed |
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54 | * user buffer. |
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55 | * - The mapper_get_page() function that return a page descriptor pointer from a page |
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56 | * index in file is in charge of handling the miss on the mapper cache. |
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57 | * - In the present implementation the cache size increases on demand, and the |
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58 | * allocated memory is only released when the mapper is destroyed. |
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59 | ******************************************************************************************/ |
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60 | |
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61 | |
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62 | /******************************************************************************************* |
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63 | * This structure defines the mapper descriptor. |
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64 | ******************************************************************************************/ |
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65 | |
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66 | typedef struct mapper_s |
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67 | { |
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68 | struct vfs_inode_s * inode; /*! owner file inode */ |
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69 | grdxt_t radix; /*! pages cache implemented as a radix tree */ |
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70 | rwlock_t lock; /*! several readers / only one writer */ |
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71 | uint32_t refcount; /*! several vsegs can refer the same file */ |
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72 | xlist_entry_t vsegs_root; /*! root of list of vsegs refering this mapper */ |
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73 | xlist_entry_t wait_root; /*! root of list of threads waiting on mapper */ |
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74 | list_entry_t dirty_root; /*! root of list of dirty pages */ |
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75 | } |
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76 | mapper_t; |
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77 | |
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78 | /******************************************************************************************* |
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79 | * This structure defines a "fragment". It is used to move data between the kernel mapper, |
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80 | * and an user buffer, that can be split in several distributed physical pages located |
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81 | * in different clusters. A fragment is a set of contiguous bytes in the file. |
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82 | * - It can be stored in one single physical page in the user buffer. |
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83 | * - It can spread two successive physical pages in the kernel mapper. |
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84 | ******************************************************************************************/ |
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85 | |
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86 | typedef struct fragment_s |
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87 | { |
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88 | uint32_t file_offset; /*! offset of fragment in file (i.e. in mapper) */ |
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89 | uint32_t size; /*! number of bytes in fragment */ |
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90 | cxy_t buf_cxy; /*! user buffer cluster identifier */ |
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91 | uint8_t * buf_ptr; /*! local pointer on first byte in user buffer */ |
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92 | } |
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93 | fragment_t; |
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94 | |
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95 | /******************************************************************************************* |
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96 | * This function allocates physical memory for a mapper descriptor, and initializes it |
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97 | * (refcount <= 0) / inode <= NULL). |
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98 | * It must be executed by a thread running in the cluster containing the mapper. |
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99 | ******************************************************************************************* |
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100 | * @ return pointer on created mapper if success / return NULL if no memory |
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101 | ******************************************************************************************/ |
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102 | mapper_t * mapper_create(); |
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103 | |
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104 | /******************************************************************************************* |
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105 | * This function releases all physical pages allocated for the mapper. |
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106 | * It synchronizes all dirty pages (i.e. update the file on disk) if required. |
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107 | * The mapper descriptor and the radix tree themselves are released. |
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108 | * It must be executed by a thread running in the cluster containing the mapper. |
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109 | ******************************************************************************************* |
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110 | * @ mapper : target mapper. |
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111 | * @ return 0 if success / return EIO if a dirty page cannot be updated on device. |
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112 | ******************************************************************************************/ |
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113 | error_t mapper_destroy( mapper_t * mapper ); |
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114 | |
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115 | /******************************************************************************************* |
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116 | * This function moves all fragments covering a distributed user buffer between |
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117 | * a mapper (associated to a local inode), and the user buffer. |
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118 | * [See the fragment definition in the mapper.h file] |
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119 | * It must be executed by a thread running in the cluster containing the mapper. |
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120 | * The lock protecting the mapper must have been taken in WRITE_MODE or READ_MODE |
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121 | * by the caller thread, depending on the transfer direction. |
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122 | * In case of write, the dirty bit is set for all pages written in the mapper. |
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123 | * The offset in the file descriptor is not modified by this function. |
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124 | * Implementation note: |
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125 | * For each fragment, this function makes ONE hal_remote_memcpy() when the fragment is |
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126 | * fully contained in one single page of the mapper. It makes TWO hal_remote_memcpy() |
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127 | * if the fragment spread on two contiguous pages in the mapper. |
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128 | ******************************************************************************************* |
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129 | * @ mapper : local pointer on the local mapper. |
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130 | * @ to_buffer : mapper to buffer if true / buffer to mapper if false. |
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131 | * @ nb_frags : number of fragments covering the user buffer (one per page). |
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132 | * @ frags_xp : extended pointer on array of fragments. |
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133 | FAT * returns O if success / returns EINVAL if error. |
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134 | ******************************************************************************************/ |
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135 | error_t mapper_move_fragments( mapper_t * mapper, |
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136 | bool_t to_buffer, |
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137 | uint32_t nb_frags, |
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138 | xptr_t frags_xp ); |
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139 | |
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140 | |
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141 | /******************************************************************************************* |
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142 | * This function removes a physical page from the mapper, update the FS if the page |
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143 | * is dirty, and releases the page to PPM. It is called by the mapper_destroy() function. |
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144 | * It must be executed by a thread running in the cluster containing the mapper. |
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145 | * It takes both the page lock and the mapper lock in WRITE_MODE to release the page. |
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146 | ******************************************************************************************* |
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147 | * @ mapper : local pointer on the mapper. |
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148 | * @ index : page index in file |
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149 | * @ page : pointer on page to remove. |
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150 | * @ return 0 if success / return EIO if a dirty page cannot be copied to FS. |
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151 | ******************************************************************************************/ |
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152 | error_t mapper_release_page( mapper_t * mapper, |
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153 | uint32_t index, |
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154 | struct page_s * page ); |
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155 | |
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156 | /******************************************************************************************* |
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157 | * This function searches a physical page descriptor from its index in mapper. |
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158 | * It must be executed by a thread running in the cluster containing the mapper. |
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159 | * In case of miss, it takes the mapper lock in WRITE_MODE, load the missing |
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160 | * page from device to the mapper, and release the mapper lock. |
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161 | ******************************************************************************************* |
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162 | * @ mapper : local pointer on the mapper. |
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163 | * @ index : page index in file |
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164 | * @ returns pointer on page descriptor if success / return NULL if error. |
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165 | ******************************************************************************************/ |
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166 | struct page_s * mapper_get_page( mapper_t * mapper, |
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167 | uint32_t index ); |
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168 | |
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169 | /******************************************************************************************* |
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170 | * This function makes an I/O operation to move one page from FS to mapper. |
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171 | * Depending on the file system type, it calls the proper, FS specific function. |
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172 | * It must be executed by a thread running in the cluster containing the mapper. |
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173 | ******************************************************************************************* |
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174 | * @ mapper : local pointer on the mapper. |
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175 | * @ index : page index in file. |
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176 | * @ page : local pointer on the page descriptor in mapper. |
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177 | * @ returns 0 if success / return EINVAL if it cannot access the device. |
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178 | ******************************************************************************************/ |
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179 | error_t mapper_updt_page( mapper_t * mapper, |
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180 | uint32_t index, |
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181 | struct page_s * page ); |
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182 | |
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183 | /******************************************************************************************* |
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184 | * This function makes an I/0 operation to move one page from mapper to FS. |
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185 | * Depending on the file system type, it calls the proper, FS specific function. |
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186 | * It must be executed by a thread running in the cluster containing the mapper. |
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187 | * It does nothing if the page is not dirty. If the page is dirty, it takes |
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188 | * the page lock before launching the IO operation, clear the page dirty bit, |
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189 | * and remove the page from the PPM dirty list. It does nothing if the page is not dirty. |
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190 | ******************************************************************************************* |
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191 | * @ mapper : local pointer on the mapper. |
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192 | * @ index : page index in file. |
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193 | * @ page : local pointer on the page descriptor in mapper. |
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194 | * @ returns 0 if success / return EINVAL if it cannot access the device. |
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195 | ******************************************************************************************/ |
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196 | error_t mapper_sync_page( mapper_t * mapper, |
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197 | uint32_t index, |
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198 | struct page_s * page ); |
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199 | |
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200 | #endif /* _MAPPER_H_ */ |
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