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 static void v9fs_cache_inode_now_uncached(void *cookie_netfs_data)
 155 {
 156         struct v9fs_inode *v9inode = cookie_netfs_data;
 157         struct pagevec pvec;
 158         pgoff_t first;
 159         int loop, nr_pages;
 160
 161         pagevec_init(&pvec, 0);
 162         first = 0;
 163
 164         for (;;) {
 165                 nr_pages = pagevec_lookup(&pvec, v9inode->vfs_inode.i_mapping,
 166                                           first,
 167                                           PAGEVEC_SIZE - pagevec_count(&pvec));
 168                 if (!nr_pages)
 169                         break;
 170
 171                 for (loop = 0; loop < nr_pages; loop++)
 172                         ClearPageFsCache(pvec.pages[loop]);
 173
 174                 first = pvec.pages[nr_pages - 1]->index + 1;
 175
 176                 pvec.nr = nr_pages;
 177                 pagevec_release(&pvec);
 178                 cond_resched();
 179         }
 180 }
 181
 182 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
 183         .name           = "9p.inode",
 184         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 185         .get_key        = v9fs_cache_inode_get_key,
 186         .get_attr       = v9fs_cache_inode_get_attr,
 187         .get_aux        = v9fs_cache_inode_get_aux,
 188         .check_aux      = v9fs_cache_inode_check_aux,
 189         .now_uncached   = v9fs_cache_inode_now_uncached,
 190 };
 191
 192 void v9fs_cache_inode_get_cookie(struct inode *inode)
 193 {
 194         struct v9fs_inode *v9inode;
 195         struct v9fs_session_info *v9ses;
 196
 197         if (!S_ISREG(inode->i_mode))
 198                 return;
 199
 200         v9inode = V9FS_I(inode);
 201         if (v9inode->fscache)
 202                 return;
 203
 204         v9ses = v9fs_inode2v9ses(inode);
 205         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 206                                                   &v9fs_cache_inode_index_def,
 207                                                   v9inode, true);
 208
 209         p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
 210                  inode, v9inode->fscache);
 211 }
 212
 213 void v9fs_cache_inode_put_cookie(struct inode *inode)
 214 {
 215         struct v9fs_inode *v9inode = V9FS_I(inode);
 216
 217         if (!v9inode->fscache)
 218                 return;
 219         p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
 220                  inode, v9inode->fscache);
 221
 222         fscache_relinquish_cookie(v9inode->fscache, 0);
 223         v9inode->fscache = NULL;
 224 }
 225
 226 void v9fs_cache_inode_flush_cookie(struct inode *inode)
 227 {
 228         struct v9fs_inode *v9inode = V9FS_I(inode);
 229
 230         if (!v9inode->fscache)
 231                 return;
 232         p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
 233                  inode, v9inode->fscache);
 234
 235         fscache_relinquish_cookie(v9inode->fscache, 1);
 236         v9inode->fscache = NULL;
 237 }
 238
 239 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
 240 {
 241         struct v9fs_inode *v9inode = V9FS_I(inode);
 242
 243         if (!v9inode->fscache)
 244                 return;
 245
 246         mutex_lock(&v9inode->fscache_lock);
 247
 248         if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 249                 v9fs_cache_inode_flush_cookie(inode);
 250         else
 251                 v9fs_cache_inode_get_cookie(inode);
 252
 253         mutex_unlock(&v9inode->fscache_lock);
 254 }
 255
 256 void v9fs_cache_inode_reset_cookie(struct inode *inode)
 257 {
 258         struct v9fs_inode *v9inode = V9FS_I(inode);
 259         struct v9fs_session_info *v9ses;
 260         struct fscache_cookie *old;
 261
 262         if (!v9inode->fscache)
 263                 return;
 264
 265         old = v9inode->fscache;
 266
 267         mutex_lock(&v9inode->fscache_lock);
 268         fscache_relinquish_cookie(v9inode->fscache, 1);
 269
 270         v9ses = v9fs_inode2v9ses(inode);
 271         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 272                                                   &v9fs_cache_inode_index_def,
 273                                                   v9inode, true);
 274         p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
 275                  inode, old, v9inode->fscache);
 276
 277         mutex_unlock(&v9inode->fscache_lock);
 278 }
 279
 280 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
 281 {
 282         struct inode *inode = page->mapping->host;
 283         struct v9fs_inode *v9inode = V9FS_I(inode);
 284
 285         BUG_ON(!v9inode->fscache);
 286
 287         return fscache_maybe_release_page(v9inode->fscache, page, gfp);
 288 }
 289
 290 void __v9fs_fscache_invalidate_page(struct page *page)
 291 {
 292         struct inode *inode = page->mapping->host;
 293         struct v9fs_inode *v9inode = V9FS_I(inode);
 294
 295         BUG_ON(!v9inode->fscache);
 296
 297         if (PageFsCache(page)) {
 298                 fscache_wait_on_page_write(v9inode->fscache, page);
 299                 BUG_ON(!PageLocked(page));
 300                 fscache_uncache_page(v9inode->fscache, page);
 301         }
 302 }
 303
 304 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
 305                                        int error)
 306 {
 307         if (!error)
 308                 SetPageUptodate(page);
 309
 310         unlock_page(page);
 311 }
 312
 313 /**
 314  * __v9fs_readpage_from_fscache - read a page from cache
 315  *
 316  * Returns 0 if the pages are in cache and a BIO is submitted,
 317  * 1 if the pages are not in cache and -error otherwise.
 318  */
 319
 320 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
 321 {
 322         int ret;
 323         const struct v9fs_inode *v9inode = V9FS_I(inode);
 324
 325         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 326         if (!v9inode->fscache)
 327                 return -ENOBUFS;
 328
 329         ret = fscache_read_or_alloc_page(v9inode->fscache,
 330                                          page,
 331                                          v9fs_vfs_readpage_complete,
 332                                          NULL,
 333                                          GFP_KERNEL);
 334         switch (ret) {
 335         case -ENOBUFS:
 336         case -ENODATA:
 337                 p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
 338                 return 1;
 339         case 0:
 340                 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
 341                 return ret;
 342         default:
 343                 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
 344                 return ret;
 345         }
 346 }
 347
 348 /**
 349  * __v9fs_readpages_from_fscache - read multiple pages from cache
 350  *
 351  * Returns 0 if the pages are in cache and a BIO is submitted,
 352  * 1 if the pages are not in cache and -error otherwise.
 353  */
 354
 355 int __v9fs_readpages_from_fscache(struct inode *inode,
 356                                   struct address_space *mapping,
 357                                   struct list_head *pages,
 358                                   unsigned *nr_pages)
 359 {
 360         int ret;
 361         const struct v9fs_inode *v9inode = V9FS_I(inode);
 362
 363         p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
 364         if (!v9inode->fscache)
 365                 return -ENOBUFS;
 366
 367         ret = fscache_read_or_alloc_pages(v9inode->fscache,
 368                                           mapping, pages, nr_pages,
 369                                           v9fs_vfs_readpage_complete,
 370                                           NULL,
 371                                           mapping_gfp_mask(mapping));
 372         switch (ret) {
 373         case -ENOBUFS:
 374         case -ENODATA:
 375                 p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
 376                 return 1;
 377         case 0:
 378                 BUG_ON(!list_empty(pages));
 379                 BUG_ON(*nr_pages != 0);
 380                 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
 381                 return ret;
 382         default:
 383                 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
 384                 return ret;
 385         }
 386 }
 387
 388 /**
 389  * __v9fs_readpage_to_fscache - write a page to the cache
 390  *
 391  */
 392
 393 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
 394 {
 395         int ret;
 396         const struct v9fs_inode *v9inode = V9FS_I(inode);
 397
 398         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 399         ret = fscache_write_page(v9inode->fscache, page, GFP_KERNEL);
 400         p9_debug(P9_DEBUG_FSC, "ret =  %d\n", ret);
 401         if (ret != 0)
 402                 v9fs_uncache_page(inode, page);
 403 }
 404
 405 /*
 406  * wait for a page to complete writing to the cache
 407  */
 408 void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
 409 {
 410         const struct v9fs_inode *v9inode = V9FS_I(inode);
 411         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 412         if (PageFsCache(page))
 413                 fscache_wait_on_page_write(v9inode->fscache, page);
 414 }