source: trunk/kernel/mm/mapper.h @ 612

Last change on this file since 612 was 612, checked in by alain, 3 years ago

Fix several bugs in vfs.c, fatfs.c, and devfs.c to support
the <.> and <..> directory entries.

File size: 15.2 KB
Line 
1/*
2 * mapper.h - Kernel cache for VFS files/directories definition.
3 *
4 * Authors   Mohamed Lamine Karaoui (2015)
5 *           Alain Greiner (2016,2017,2018)
6 *
7 * Copyright (c)  UPMC Sorbonne Universites
8 *
9 * This file is part of ALMOS-MKH.
10 *
11 * ALMOS-MKH is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; version 2.0 of the License.
14 *
15 * ALMOS-MKH is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
22 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
23 */
24
25#ifndef _MAPPER_H_
26#define _MAPPER_H_
27
28#include <hal_kernel_types.h>
29#include <hal_atomic.h>
30#include <xlist.h>
31#include <grdxt.h>
32#include <rwlock.h>
33
34/****  Forward declarations ****/
35
36struct page_s;
37struct vfs_inode_s;
38
39/*******************************************************************************************
40 * The mapper implements the kernel cache for a given VFS file or directory.
41 * There is one mapper per file/dir. It is implemented as a three levels radix tree,
42 * entirely stored in the same cluster as the inode representing the file/dir.
43 * - The fast retrieval key is the page index in the file.
44 *   The ix1_width, ix2_width, ix3_width sub-indexes are configuration parameters.
45 * - The leaves are pointers on physical page descriptors, dynamically allocated
46 *   in the local cluster.
47 * - The mapper is protected by a "remote_rwlock", to support several simultaneous
48 *   "readers", and only one "writer".
49 * - A "reader" thread, calling the mapper_remote_get_page() function to get a page
50 *   descriptor pointer from the page index in file, can be remote (running in any cluster).
51 * - A "writer" thread, calling the mapper_handle_miss() function to handle a page miss
52 *   must be local (running in the mapper cluster).
53 * - The vfs_mapper_move_page() function access the file system to handle a mapper miss,
54 *   or update a dirty page on device.
55 * - The vfs_mapper_load_all() functions is used to load all pages of a directory
56 *   into the mapper (prefetch).
57 * - the mapper_move_user() function is used to move data to or from an user buffer.
58 *   This user space buffer can be physically distributed in several clusters.
59 * - the mapper_move_kernel() function is used to move data to or from a remote kernel
60 *   buffer, that can be physically located in any cluster.
61 * - In the present implementation the cache size for a given file increases on demand,
62 *   and the  allocated memory is only released when the mapper/inode is destroyed.
63 *
64 * TODO : the mapper being only used to implement the VFS cache(s), the mapper.c
65 *        and mapper.h file should beerro trandfered to the vfs directory.
66 ******************************************************************************************/
67
68
69/*******************************************************************************************
70 * This structure defines the mapper descriptor.
71 ******************************************************************************************/
72
73typedef struct mapper_s
74{
75        struct vfs_inode_s * inode;           /*! owner inode                                     */
76    uint32_t             type;        /*! file system type                                */
77        grdxt_t              rt;              /*! embedded pages cache descriptor (radix tree)    */
78        remote_rwlock_t      lock;        /*! several readers / only one writer               */
79        uint32_t                 refcount;    /*! several vsegs can refer the same file           */
80        xlist_entry_t        vsegs_root;  /*! root of list of vsegs refering this mapper      */
81        xlist_entry_t        wait_root;   /*! root of list of threads waiting on mapper       */
82    list_entry_t         dirty_root;  /*! root of list of dirty pages                     */
83}
84mapper_t;
85
86/*******************************************************************************************
87 * This structure defines a "fragment". It is used to move data between the kernel mapper,
88 * and an user buffer, that can be split in several distributed physical pages located
89 * in different clusters. A fragment is a set of contiguous bytes in the file.
90 * - It can be stored in one single physical page in the user buffer.
91 * - It can spread two successive physical pages in the kernel mapper.
92 ******************************************************************************************/
93
94typedef struct fragment_s
95{
96    uint32_t    file_offset;         /*! offset of fragment in file (i.e. in mapper)      */
97    uint32_t    size;                /*! number of bytes in fragment                      */
98    cxy_t       buf_cxy;             /*! user buffer cluster identifier                   */
99    void      * buf_ptr;             /*! local pointer on first byte in user buffer       */
100}
101fragment_t;
102
103/*******************************************************************************************
104 * This function allocates physical memory for a mapper descriptor, and initializes it
105 * (refcount <= 0) / inode <= NULL).
106 * It must be executed by a thread running in the cluster containing the mapper.
107 *******************************************************************************************
108 * @ type   : type of the mapper to create.
109 * @ return : pointer on created mapper if success / return NULL if no memory
110 ******************************************************************************************/
111mapper_t * mapper_create( vfs_fs_type_t type );
112
113/*******************************************************************************************
114 * This function releases all physical memory allocated for a mapper.
115 * Both the mapper descriptor and the radix tree are released.
116 * It does NOT synchronize dirty pages. Use the vfs_sync_inode() function if required.
117 * It must be executed by a thread running in the cluster containing the mapper.
118 *******************************************************************************************
119 * @ mapper      : target mapper.
120 ******************************************************************************************/
121void mapper_destroy( mapper_t * mapper );
122
123/*******************************************************************************************
124 * This function load from device a missing page identified by the <page_id> argument
125 * into the mapper identified by the <mapper> local pointer.
126 * It allocates a physical page from the local cluster, initialise by accessing device,
127 * and register the page in the mapper radix tree.
128 * It must be executed by a thread running in the cluster containing the mapper.
129 * WARNING : the calling function mapper_remote_get_page() is supposed to take and release
130 * the lock protecting the mapper in WRITE_MODE.
131 *******************************************************************************************
132 * @ mapper      : [in]  target mapper.
133 * @ page_id : [in]  missing page index in file.
134 * @ page_xp : [out] buffer for extended pointer on missing page descriptor.
135 * @ return 0 if success / return -1 if a dirty page cannot be updated on device.
136 ******************************************************************************************/
137error_t mapper_handle_miss( mapper_t * mapper,
138                            uint32_t   page_id,
139                            xptr_t   * page_xp );
140
141/*******************************************************************************************
142 * This function move data between a remote mapper, dentified by the <mapper_xp> argument,
143 * and a distributed user buffer. It can be called by a thread running in any cluster.
144 * It is called by the vfs_user_move() to implement sys_read() and sys_write() syscalls.
145 * If required, the data transfer is split in "fragments", where one fragment contains
146 * contiguous bytes in the same mapper page.
147 * It uses "hal_uspace" accesses to move a fragment to/from the user buffer.
148 * In case of write, the dirty bit is set for all pages written in the mapper.
149 * The mapper being an extendable cache, it is automatically extended when required.
150 * The "offset" field in the file descriptor, and the "size" field in inode descriptor
151 * are not modified by this function.
152 *******************************************************************************************
153 * @ mapper_xp    : extended pointer on mapper.
154 * @ to_buffer    : mapper -> buffer if true / buffer -> mapper if false.
155 * @ file_offset  : first byte to move in file.
156 * @ u_buf        : user space pointer on user buffer.
157 * @ size         : number of bytes to move.
158 * returns O if success / returns -1 if error.
159 ******************************************************************************************/
160error_t mapper_move_user( xptr_t     mappe_xp,
161                          bool_t     to_buffer,
162                          uint32_t   file_offset,
163                          void     * u_buf,
164                          uint32_t   size );
165
166/********************************************************************************************
167 * This function move data between a remote mapper and a remote kernel buffer.
168 * It can be called by a thread running any cluster.
169 * If required, the data transfer is split in "fragments", where one fragment contains
170 * contiguous bytes in the same mapper page.
171 * It uses a "remote_memcpy" to move a fragment to/from the kernel buffer.
172 * In case of write, the dirty bit is set for all pages written in the mapper.
173 *******************************************************************************************
174 * @ mapper_xp    : extended pointer on mapper.
175 * @ to_buffer    : mapper -> buffer if true / buffer -> mapper if false.
176 * @ file_offset  : first byte to move in file.
177 * @ buffer_xp    : extended pointer on kernel buffer.
178 * @ size         : number of bytes to move.
179 * returns O if success / returns -1 if error.
180 ******************************************************************************************/
181error_t mapper_move_kernel( xptr_t     mapper_xp,
182                            bool_t     to_buffer,
183                            uint32_t   file_offset,
184                            xptr_t     buffer_xp,
185                            uint32_t   size );
186
187/*******************************************************************************************
188 * This function removes a physical page from the mapper, and releases
189 * the page to the local PPM. It is called by the mapper_destroy() function.
190 * It must be executed by a thread running in the cluster containing the mapper.
191 * It takes the mapper lock in WRITE_MODE to update the mapper.
192 *******************************************************************************************
193 * @ mapper     : local pointer on the mapper.
194 * @ page       : pointer on page to remove.
195 ******************************************************************************************/
196void mapper_release_page( mapper_t      * mapper,
197                          struct page_s * page );
198
199/*******************************************************************************************
200 * This function returns an extended pointer on a page descriptor.
201 * The - possibly remote - mapper is identified by the <mapper_xp> argument.
202 * The page is identified by <page_id> argument (page index in the file).
203 * It can be executed by a thread running in any cluster, as it uses remote
204 * access primitives to scan the mapper.
205 * In case of miss, this function takes the mapper lock in WRITE_MODE, and call the
206 * mapper_handle_miss() to load the missing page from device to mapper, using an RPC
207 * when the mapper is remote.
208 *******************************************************************************************
209 * @ mapper_xp  : extended pointer on the mapper.
210 * @ page_id    : page index in file
211 * @ returns extended pointer on page descriptor if success / return XPTR_NULL if error.
212 ******************************************************************************************/
213xptr_t mapper_remote_get_page( xptr_t    mapper_xp,
214                               uint32_t  page_id );
215
216/*******************************************************************************************
217 * This function allows to read a single word in a mapper seen as and array of uint32_t.
218 * It has bee designed to support remote access to the FAT mapper of the FATFS.
219 * It can be called by any thread running in any cluster.
220 * In case of miss, it takes the mapper lock in WRITE_MODE, load the missing
221 * page from device to mapper, and release the mapper lock.
222 *******************************************************************************************
223 * @ mapper_xp  : [in]  extended pointer on the mapper.
224 * @ word_id    : [in]  32 bits word index in file.
225 * @ p_value    : [out] local pointer on destination buffer.
226 * @ returns 0 if success / return -1 if error.
227 ******************************************************************************************/
228error_t mapper_remote_get_32( xptr_t     mapper_xp,
229                              uint32_t   word_id,
230                              uint32_t * p_value );
231
232/*******************************************************************************************
233 * This function allows to write a single word to a mapper seen as and array of uint32_t.
234 * It has bee designed to support remote access tho the FAT mapper of the FATFS.
235 * It can be called by any thread running in any cluster.
236 * In case of miss, it takes the mapper lock in WRITE_MODE, load the missing
237 * page from device to mapper, and release the mapper lock.
238 *******************************************************************************************
239 * @ mapper_xp  : [in]  extended pointer on the mapper.
240 * @ word_id    : [in]  32 bits word index in file.
241 * @ value      : [in]  value to be written.
242 * @ returns 0 if success / return -1 if error.
243 ******************************************************************************************/
244error_t mapper_remote_set_32( xptr_t     mapper_xp,
245                              uint32_t   word_id,
246                              uint32_t   value );
247
248/*******************************************************************************************
249 * This debug function displays the content of a given page of a given mapper.
250 * - the mapper is identified by the <mapper_xp> argument.
251 * - the page is identified by the <page_id> argument.
252 * - the number of bytes to display in page is defined by the <nbytes> argument.
253 * The format is eigth (32 bits) words per line in hexadecimal.
254 * It can be called by any thread running in any cluster.
255 * In case of miss in mapper, it load the missing page from device to mapper.
256 *******************************************************************************************
257 * @ mapper_xp  : [in]  extended pointer on the mapper.
258 * @ page_id    : [in]  page index in file.
259 * @ nbytes     : [in]  value to be written.
260 * @ string     : [in]  string printed in header.
261 * @ returns 0 if success / return -1 if error.
262 ******************************************************************************************/
263error_t mapper_display_page( xptr_t     mapper_xp,
264                             uint32_t   page_id,
265                             uint32_t   nbytes,
266                             char     * string );
267
268
269#endif /* _MAPPER_H_ */
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