fs/9p/cache.c

   1 /*
   2  * V9FS cache definitions.
   3  *
   4  *  Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License version 2
   8  *  as published by the Free Software Foundation.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to:
  17  *  Free Software Foundation
  18  *  51 Franklin Street, Fifth Floor
  19  *  Boston, MA  02111-1301  USA
  20  *
  21  */
  22
  23 #include <linux/jiffies.h>
  24 #include <linux/file.h>
  25 #include <linux/slab.h>
  26 #include <linux/stat.h>
  27 #include <linux/sched.h>
  28 #include <linux/fs.h>
  29 #include <net/9p/9p.h>
  30
  31 #include "v9fs.h"
  32 #include "cache.h"
  33
  34 #define CACHETAG_LEN  11
  35
  36 struct fscache_netfs v9fs_cache_netfs = {
  37         .name           = "9p",
  38         .version        = 0,
  39 };
  40
  41 /**
  42  * v9fs_random_cachetag - Generate a random tag to be associated
  43  *                        with a new cache session.
  44  *
  45  * The value of jiffies is used for a fairly randomly cache tag.
  46  */
  47
  48 static
  49 int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
  50 {
  51         v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
  52         if (!v9ses->cachetag)
  53                 return -ENOMEM;
  54
  55         return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
  56 }
  57
  58 static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,
  59                                            void *buffer, uint16_t bufmax)
  60 {
  61         struct v9fs_session_info *v9ses;
  62         uint16_t klen = 0;
  63
  64         v9ses = (struct v9fs_session_info *)cookie_netfs_data;
  65         p9_debug(P9_DEBUG_FSC, "session %p buf %p size %u\n",
  66                  v9ses, buffer, bufmax);
  67
  68         if (v9ses->cachetag)
  69                 klen = strlen(v9ses->cachetag);
  70
  71         if (klen > bufmax)
  72                 return 0;
  73
  74         memcpy(buffer, v9ses->cachetag, klen);
  75         p9_debug(P9_DEBUG_FSC, "cache session tag %s\n", v9ses->cachetag);
  76         return klen;
  77 }
  78
  79 const struct fscache_cookie_def v9fs_cache_session_index_def = {
  80         .name           = "9P.session",
  81         .type           = FSCACHE_COOKIE_TYPE_INDEX,
  82         .get_key        = v9fs_cache_session_get_key,
  83 };
  84
  85 void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
  86 {
  87         /* If no cache session tag was specified, we generate a random one. */
  88         if (!v9ses->cachetag)
  89                 v9fs_random_cachetag(v9ses);
  90
  91         v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
  92                                                 &v9fs_cache_session_index_def,
  93                                                 v9ses, true);
  94         p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
  95                  v9ses, v9ses->fscache);
  96 }
  97
  98 void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
  99 {
 100         p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
 101                  v9ses, v9ses->fscache);
 102         fscache_relinquish_cookie(v9ses->fscache, 0);
 103         v9ses->fscache = NULL;
 104 }
 105
 106
 107 static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,
 108                                          void *buffer, uint16_t bufmax)
 109 {
 110         const struct v9fs_inode *v9inode = cookie_netfs_data;
 111         memcpy(buffer, &v9inode->qid.path, sizeof(v9inode->qid.path));
 112         p9_debug(P9_DEBUG_FSC, "inode %p get key %llu\n",
 113                  &v9inode->vfs_inode, v9inode->qid.path);
 114         return sizeof(v9inode->qid.path);
 115 }
 116
 117 static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,
 118                                       uint64_t *size)
 119 {
 120         const struct v9fs_inode *v9inode = cookie_netfs_data;
 121         *size = i_size_read(&v9inode->vfs_inode);
 122
 123         p9_debug(P9_DEBUG_FSC, "inode %p get attr %llu\n",
 124                  &v9inode->vfs_inode, *size);
 125 }
 126
 127 static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,
 128                                          void *buffer, uint16_t buflen)
 129 {
 130         const struct v9fs_inode *v9inode = cookie_netfs_data;
 131         memcpy(buffer, &v9inode->qid.version, sizeof(v9inode->qid.version));
 132         p9_debug(P9_DEBUG_FSC, "inode %p get aux %u\n",
 133                  &v9inode->vfs_inode, v9inode->qid.version);
 134         return sizeof(v9inode->qid.version);
 135 }
 136
 137 static enum
 138 fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
 139                                             const void *buffer,
 140                                             uint16_t buflen)
 141 {
 142         const struct v9fs_inode *v9inode = cookie_netfs_data;
 143
 144         if (buflen != sizeof(v9inode->qid.version))
 145                 return FSCACHE_CHECKAUX_OBSOLETE;
 146
 147         if (memcmp(buffer, &v9inode->qid.version,
 148                    sizeof(v9inode->qid.version)))
 149                 return FSCACHE_CHECKAUX_OBSOLETE;
 150
 151         return FSCACHE_CHECKAUX_OKAY;
 152 }
 153
 154 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
 155         .name           = "9p.inode",
 156         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 157         .get_key        = v9fs_cache_inode_get_key,
 158         .get_attr       = v9fs_cache_inode_get_attr,
 159         .get_aux        = v9fs_cache_inode_get_aux,
 160         .check_aux      = v9fs_cache_inode_check_aux,
 161 };
 162
 163 void v9fs_cache_inode_get_cookie(struct inode *inode)
 164 {
 165         struct v9fs_inode *v9inode;
 166         struct v9fs_session_info *v9ses;
 167
 168         if (!S_ISREG(inode->i_mode))
 169                 return;
 170
 171         v9inode = V9FS_I(inode);
 172         if (v9inode->fscache)
 173                 return;
 174
 175         v9ses = v9fs_inode2v9ses(inode);
 176         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 177                                                   &v9fs_cache_inode_index_def,
 178                                                   v9inode, true);
 179
 180         p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
 181                  inode, v9inode->fscache);
 182 }
 183
 184 void v9fs_cache_inode_put_cookie(struct inode *inode)
 185 {
 186         struct v9fs_inode *v9inode = V9FS_I(inode);
 187
 188         if (!v9inode->fscache)
 189                 return;
 190         p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
 191                  inode, v9inode->fscache);
 192
 193         fscache_relinquish_cookie(v9inode->fscache, 0);
 194         v9inode->fscache = NULL;
 195 }
 196
 197 void v9fs_cache_inode_flush_cookie(struct inode *inode)
 198 {
 199         struct v9fs_inode *v9inode = V9FS_I(inode);
 200
 201         if (!v9inode->fscache)
 202                 return;
 203         p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
 204                  inode, v9inode->fscache);
 205
 206         fscache_relinquish_cookie(v9inode->fscache, 1);
 207         v9inode->fscache = NULL;
 208 }
 209
 210 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
 211 {
 212         struct v9fs_inode *v9inode = V9FS_I(inode);
 213
 214         if (!v9inode->fscache)
 215                 return;
 216
 217         mutex_lock(&v9inode->fscache_lock);
 218
 219         if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 220                 v9fs_cache_inode_flush_cookie(inode);
 221         else
 222                 v9fs_cache_inode_get_cookie(inode);
 223
 224         mutex_unlock(&v9inode->fscache_lock);
 225 }
 226
 227 void v9fs_cache_inode_reset_cookie(struct inode *inode)
 228 {
 229         struct v9fs_inode *v9inode = V9FS_I(inode);
 230         struct v9fs_session_info *v9ses;
 231         struct fscache_cookie *old;
 232
 233         if (!v9inode->fscache)
 234                 return;
 235
 236         old = v9inode->fscache;
 237
 238         mutex_lock(&v9inode->fscache_lock);
 239         fscache_relinquish_cookie(v9inode->fscache, 1);
 240
 241         v9ses = v9fs_inode2v9ses(inode);
 242         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 243                                                   &v9fs_cache_inode_index_def,
 244                                                   v9inode, true);
 245         p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
 246                  inode, old, v9inode->fscache);
 247
 248         mutex_unlock(&v9inode->fscache_lock);
 249 }
 250
 251 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
 252 {
 253         struct inode *inode = page->mapping->host;
 254         struct v9fs_inode *v9inode = V9FS_I(inode);
 255
 256         BUG_ON(!v9inode->fscache);
 257
 258         return fscache_maybe_release_page(v9inode->fscache, page, gfp);
 259 }
 260
 261 void __v9fs_fscache_invalidate_page(struct page *page)
 262 {
 263         struct inode *inode = page->mapping->host;
 264         struct v9fs_inode *v9inode = V9FS_I(inode);
 265
 266         BUG_ON(!v9inode->fscache);
 267
 268         if (PageFsCache(page)) {
 269                 fscache_wait_on_page_write(v9inode->fscache, page);
 270                 BUG_ON(!PageLocked(page));
 271                 fscache_uncache_page(v9inode->fscache, page);
 272         }
 273 }
 274
 275 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
 276                                        int error)
 277 {
 278         if (!error)
 279                 SetPageUptodate(page);
 280
 281         unlock_page(page);
 282 }
 283
 284 /**
 285  * __v9fs_readpage_from_fscache - read a page from cache
 286  *
 287  * Returns 0 if the pages are in cache and a BIO is submitted,
 288  * 1 if the pages are not in cache and -error otherwise.
 289  */
 290
 291 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
 292 {
 293         int ret;
 294         const struct v9fs_inode *v9inode = V9FS_I(inode);
 295
 296         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 297         if (!v9inode->fscache)
 298                 return -ENOBUFS;
 299
 300         ret = fscache_read_or_alloc_page(v9inode->fscache,
 301                                          page,
 302                                          v9fs_vfs_readpage_complete,
 303                                          NULL,
 304                                          GFP_KERNEL);
 305         switch (ret) {
 306         case -ENOBUFS:
 307         case -ENODATA:
 308                 p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
 309                 return 1;
 310         case 0:
 311                 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
 312                 return ret;
 313         default:
 314                 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
 315                 return ret;
 316         }
 317 }
 318
 319 /**
 320  * __v9fs_readpages_from_fscache - read multiple pages from cache
 321  *
 322  * Returns 0 if the pages are in cache and a BIO is submitted,
 323  * 1 if the pages are not in cache and -error otherwise.
 324  */
 325
 326 int __v9fs_readpages_from_fscache(struct inode *inode,
 327                                   struct address_space *mapping,
 328                                   struct list_head *pages,
 329                                   unsigned *nr_pages)
 330 {
 331         int ret;
 332         const struct v9fs_inode *v9inode = V9FS_I(inode);
 333
 334         p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
 335         if (!v9inode->fscache)
 336                 return -ENOBUFS;
 337
 338         ret = fscache_read_or_alloc_pages(v9inode->fscache,
 339                                           mapping, pages, nr_pages,
 340                                           v9fs_vfs_readpage_complete,
 341                                           NULL,
 342                                           mapping_gfp_mask(mapping));
 343         switch (ret) {
 344         case -ENOBUFS:
 345         case -ENODATA:
 346                 p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
 347                 return 1;
 348         case 0:
 349                 BUG_ON(!list_empty(pages));
 350                 BUG_ON(*nr_pages != 0);
 351                 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
 352                 return ret;
 353         default:
 354                 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
 355                 return ret;
 356         }
 357 }
 358
 359 /**
 360  * __v9fs_readpage_to_fscache - write a page to the cache
 361  *
 362  */
 363
 364 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
 365 {
 366         int ret;
 367         const struct v9fs_inode *v9inode = V9FS_I(inode);
 368
 369         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 370         ret = fscache_write_page(v9inode->fscache, page, GFP_KERNEL);
 371         p9_debug(P9_DEBUG_FSC, "ret =  %d\n", ret);
 372         if (ret != 0)
 373                 v9fs_uncache_page(inode, page);
 374 }
 375
 376 /*
 377  * wait for a page to complete writing to the cache
 378  */
 379 void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
 380 {
 381         const struct v9fs_inode *v9inode = V9FS_I(inode);
 382         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 383         if (PageFsCache(page))
 384                 fscache_wait_on_page_write(v9inode->fscache, page);
 385 }