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 (2016,2017,2018) |
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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_kernel_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/dir. 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 mapper_get_page() function that return a page descriptor pointer from a page |
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52 | * index in file is in charge of handling the miss on the mapper cache. |
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53 | * - The vfs_mapper_move_page() function access the file system to handle a mapper miss, |
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54 | * or update a dirty page on device. |
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55 | * - The vfs_mapper_load_all() functions is used to load all pages of a given file |
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56 | * or directory into the mapper. |
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57 | * - the mapper_move_user() function is used to move data to or from an user buffer. |
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58 | * This user space buffer can be physically distributed in several clusters. |
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59 | * - the mapper_move_kernel() function is used to move data to or from a remote kernel |
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60 | * buffer, that can be physically located in any cluster. |
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61 | * - In the present implementation the cache size for a given file increases on demand, |
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62 | * and the allocated memory is only released when the mapper/inode is destroyed. |
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63 | ******************************************************************************************/ |
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64 | |
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65 | |
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66 | /******************************************************************************************* |
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67 | * This structure defines the mapper descriptor. |
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68 | ******************************************************************************************/ |
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69 | |
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70 | typedef struct mapper_s |
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71 | { |
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72 | struct vfs_inode_s * inode; /*! owner inode */ |
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73 | uint32_t type; /*! file system type */ |
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74 | grdxt_t radix; /*! pages cache implemented as a radix tree */ |
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75 | rwlock_t lock; /*! several readers / only one writer */ |
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76 | uint32_t refcount; /*! several vsegs can refer the same file */ |
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77 | xlist_entry_t vsegs_root; /*! root of list of vsegs refering this mapper */ |
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78 | xlist_entry_t wait_root; /*! root of list of threads waiting on mapper */ |
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79 | list_entry_t dirty_root; /*! root of list of dirty pages */ |
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80 | } |
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81 | mapper_t; |
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82 | |
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83 | /******************************************************************************************* |
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84 | * This structure defines a "fragment". It is used to move data between the kernel mapper, |
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85 | * and an user buffer, that can be split in several distributed physical pages located |
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86 | * in different clusters. A fragment is a set of contiguous bytes in the file. |
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87 | * - It can be stored in one single physical page in the user buffer. |
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88 | * - It can spread two successive physical pages in the kernel mapper. |
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89 | ******************************************************************************************/ |
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90 | |
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91 | typedef struct fragment_s |
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92 | { |
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93 | uint32_t file_offset; /*! offset of fragment in file (i.e. in mapper) */ |
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94 | uint32_t size; /*! number of bytes in fragment */ |
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95 | cxy_t buf_cxy; /*! user buffer cluster identifier */ |
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96 | void * buf_ptr; /*! local pointer on first byte in user buffer */ |
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97 | } |
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98 | fragment_t; |
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99 | |
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100 | /******************************************************************************************* |
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101 | * This function allocates physical memory for a mapper descriptor, and initializes it |
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102 | * (refcount <= 0) / inode <= NULL). |
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103 | * It must be executed by a thread running in the cluster containing the mapper. |
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104 | ******************************************************************************************* |
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105 | * @ return pointer on created mapper if success / return NULL if no memory |
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106 | ******************************************************************************************/ |
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107 | mapper_t * mapper_create( void ); |
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108 | |
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109 | /******************************************************************************************* |
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110 | * This function releases all physical pages allocated for the mapper. |
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111 | * It synchronizes all dirty pages (i.e. update the file on disk) if required. |
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112 | * The mapper descriptor and the radix tree themselves are released. |
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113 | * It must be executed by a thread running in the cluster containing the mapper. |
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114 | ******************************************************************************************* |
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115 | * @ mapper : target mapper. |
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116 | * @ return 0 if success / return EIO if a dirty page cannot be updated on device. |
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117 | ******************************************************************************************/ |
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118 | error_t mapper_destroy( mapper_t * mapper ); |
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119 | |
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120 | /******************************************************************************************* |
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121 | * This function move data between a mapper and a - possibly distributed - user buffer. |
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122 | * It must be called by a thread running in the cluster containing the mapper. |
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123 | * It is called by the vfs_user_move() function to implement sys_read() and sys_write(). |
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124 | * If required, the data transfer is split in "fragments", where one fragment contains |
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125 | * contiguous bytes in the same mapper page. |
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126 | * It uses "hal_uspace" accesses to move a fragment to/from the user buffer. |
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127 | * In case of write, the dirty bit is set for all pages written in the mapper. |
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128 | * The offset in the file descriptor is not modified by this function. |
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129 | ******************************************************************************************* |
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130 | * @ mapper : local pointer on mapper. |
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131 | * @ to_buffer : mapper -> buffer if true / buffer -> mapper if false. |
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132 | * @ file_offset : first byte to move in file. |
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133 | * @ u_buf : user space pointer on user buffer. |
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134 | * @ size : number of bytes to move. |
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135 | * returns O if success / returns EINVAL if error. |
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136 | ******************************************************************************************/ |
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137 | error_t mapper_move_user( mapper_t * mapper, |
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138 | bool_t to_buffer, |
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139 | uint32_t file_offset, |
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140 | void * u_buf, |
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141 | uint32_t size ); |
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142 | |
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143 | /******************************************************************************************* |
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144 | * This function move data between a mapper and a remote kernel buffer. |
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145 | * It must be called by a thread running in the cluster containing the mapper. |
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146 | * If required, the data transfer is split in "fragments", where one fragment contains |
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147 | * contiguous bytes in the same mapper page. |
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148 | * It uses a "remote_memcpy" to move a fragment to/from the kernel buffer. |
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149 | * In case of write, the dirty bit is set for all pages written in the mapper. |
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150 | * The offset in the file descriptor is not modified by this function. |
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151 | ******************************************************************************************* |
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152 | * @ mapper : local pointer on mapper. |
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153 | * @ to_buffer : mapper -> buffer if true / buffer -> mapper if false. |
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154 | * @ file_offset : first byte to move in file. |
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155 | * @ buffer_xp : extended pointer on kernel buffer. |
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156 | * @ size : number of bytes to move. |
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157 | * returns O if success / returns EINVAL if error. |
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158 | ******************************************************************************************/ |
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159 | error_t mapper_move_kernel( mapper_t * mapper, |
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160 | bool_t to_buffer, |
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161 | uint32_t file_offset, |
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162 | xptr_t buffer_xp, |
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163 | uint32_t size ); |
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164 | |
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165 | |
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166 | /******************************************************************************************* |
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167 | * This function removes a physical page from the mapper, update the FS if the page |
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168 | * is dirty, and releases the page to PPM. It is called by the mapper_destroy() function. |
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169 | * It must be executed by a thread running in the cluster containing the mapper. |
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170 | * It takes both the page lock and the mapper lock in WRITE_MODE to release the page. |
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171 | ******************************************************************************************* |
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172 | * @ mapper : local pointer on the mapper. |
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173 | * @ page : pointer on page to remove. |
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174 | * @ return 0 if success / return EIO if a dirty page cannot be copied to FS. |
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175 | ******************************************************************************************/ |
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176 | error_t mapper_release_page( mapper_t * mapper, |
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177 | struct page_s * page ); |
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178 | |
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179 | /******************************************************************************************* |
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180 | * This function searches a physical page descriptor from its index in mapper. |
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181 | * It must be executed by a thread running in the cluster containing the mapper. |
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182 | * In case of miss, it takes the mapper lock in WRITE_MODE, load the missing |
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183 | * page from device to the mapper, and release the mapper lock. |
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184 | ******************************************************************************************* |
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185 | * @ mapper : local pointer on the mapper. |
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186 | * @ index : page index in file |
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187 | * @ returns pointer on page descriptor if success / return NULL if error. |
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188 | ******************************************************************************************/ |
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189 | struct page_s * mapper_get_page( mapper_t * mapper, |
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190 | uint32_t index ); |
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191 | |
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192 | |
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193 | |
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194 | #endif /* _MAPPER_H_ */ |
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