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 const struct fscache_cookie_def v9fs_cache_session_index_def = {
  59         .name           = "9P.session",
  60         .type           = FSCACHE_COOKIE_TYPE_INDEX,
  61 };
  62
  63 void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
  64 {
  65         /* If no cache session tag was specified, we generate a random one. */
  66         if (!v9ses->cachetag) {
  67                 if (v9fs_random_cachetag(v9ses) < 0) {
  68                         v9ses->fscache = NULL;
  69                         return;
  70                 }
  71         }
  72
  73         v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
  74                                                 &v9fs_cache_session_index_def,
  75                                                 v9ses->cachetag,
  76                                                 strlen(v9ses->cachetag),
  77                                                 NULL, 0,
  78                                                 v9ses, 0, true);
  79         p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
  80                  v9ses, v9ses->fscache);
  81 }
  82
  83 void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
  84 {
  85         p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
  86                  v9ses, v9ses->fscache);
  87         fscache_relinquish_cookie(v9ses->fscache, NULL, false);
  88         v9ses->fscache = NULL;
  89 }
  90
  91 static enum
  92 fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
  93                                             const void *buffer,
  94                                             uint16_t buflen,
  95                                             loff_t object_size)
  96 {
  97         const struct v9fs_inode *v9inode = cookie_netfs_data;
  98
  99         if (buflen != sizeof(v9inode->qid.version))
 100                 return FSCACHE_CHECKAUX_OBSOLETE;
 101
 102         if (memcmp(buffer, &v9inode->qid.version,
 103                    sizeof(v9inode->qid.version)))
 104                 return FSCACHE_CHECKAUX_OBSOLETE;
 105
 106         return FSCACHE_CHECKAUX_OKAY;
 107 }
 108
 109 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
 110         .name           = "9p.inode",
 111         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 112         .check_aux      = v9fs_cache_inode_check_aux,
 113 };
 114
 115 void v9fs_cache_inode_get_cookie(struct inode *inode)
 116 {
 117         struct v9fs_inode *v9inode;
 118         struct v9fs_session_info *v9ses;
 119
 120         if (!S_ISREG(inode->i_mode))
 121                 return;
 122
 123         v9inode = V9FS_I(inode);
 124         if (v9inode->fscache)
 125                 return;
 126
 127         v9ses = v9fs_inode2v9ses(inode);
 128         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 129                                                   &v9fs_cache_inode_index_def,
 130                                                   &v9inode->qid.path,
 131                                                   sizeof(v9inode->qid.path),
 132                                                   &v9inode->qid.version,
 133                                                   sizeof(v9inode->qid.version),
 134                                                   v9inode,
 135                                                   i_size_read(&v9inode->vfs_inode),
 136                                                   true);
 137
 138         p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
 139                  inode, v9inode->fscache);
 140 }
 141
 142 void v9fs_cache_inode_put_cookie(struct inode *inode)
 143 {
 144         struct v9fs_inode *v9inode = V9FS_I(inode);
 145
 146         if (!v9inode->fscache)
 147                 return;
 148         p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
 149                  inode, v9inode->fscache);
 150
 151         fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,
 152                                   false);
 153         v9inode->fscache = NULL;
 154 }
 155
 156 void v9fs_cache_inode_flush_cookie(struct inode *inode)
 157 {
 158         struct v9fs_inode *v9inode = V9FS_I(inode);
 159
 160         if (!v9inode->fscache)
 161                 return;
 162         p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
 163                  inode, v9inode->fscache);
 164
 165         fscache_relinquish_cookie(v9inode->fscache, NULL, true);
 166         v9inode->fscache = NULL;
 167 }
 168
 169 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
 170 {
 171         struct v9fs_inode *v9inode = V9FS_I(inode);
 172
 173         if (!v9inode->fscache)
 174                 return;
 175
 176         mutex_lock(&v9inode->fscache_lock);
 177
 178         if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 179                 v9fs_cache_inode_flush_cookie(inode);
 180         else
 181                 v9fs_cache_inode_get_cookie(inode);
 182
 183         mutex_unlock(&v9inode->fscache_lock);
 184 }
 185
 186 void v9fs_cache_inode_reset_cookie(struct inode *inode)
 187 {
 188         struct v9fs_inode *v9inode = V9FS_I(inode);
 189         struct v9fs_session_info *v9ses;
 190         struct fscache_cookie *old;
 191
 192         if (!v9inode->fscache)
 193                 return;
 194
 195         old = v9inode->fscache;
 196
 197         mutex_lock(&v9inode->fscache_lock);
 198         fscache_relinquish_cookie(v9inode->fscache, NULL, true);
 199
 200         v9ses = v9fs_inode2v9ses(inode);
 201         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 202                                                   &v9fs_cache_inode_index_def,
 203                                                   &v9inode->qid.path,
 204                                                   sizeof(v9inode->qid.path),
 205                                                   &v9inode->qid.version,
 206                                                   sizeof(v9inode->qid.version),
 207                                                   v9inode,
 208                                                   i_size_read(&v9inode->vfs_inode),
 209                                                   true);
 210         p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
 211                  inode, old, v9inode->fscache);
 212
 213         mutex_unlock(&v9inode->fscache_lock);
 214 }
 215
 216 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
 217 {
 218         struct inode *inode = page->mapping->host;
 219         struct v9fs_inode *v9inode = V9FS_I(inode);
 220
 221         BUG_ON(!v9inode->fscache);
 222
 223         return fscache_maybe_release_page(v9inode->fscache, page, gfp);
 224 }
 225
 226 void __v9fs_fscache_invalidate_page(struct page *page)
 227 {
 228         struct inode *inode = page->mapping->host;
 229         struct v9fs_inode *v9inode = V9FS_I(inode);
 230
 231         BUG_ON(!v9inode->fscache);
 232
 233         if (PageFsCache(page)) {
 234                 fscache_wait_on_page_write(v9inode->fscache, page);
 235                 BUG_ON(!PageLocked(page));
 236                 fscache_uncache_page(v9inode->fscache, page);
 237         }
 238 }
 239
 240 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
 241                                        int error)
 242 {
 243         if (!error)
 244                 SetPageUptodate(page);
 245
 246         unlock_page(page);
 247 }
 248
 249 /**
 250  * __v9fs_readpage_from_fscache - read a page from cache
 251  *
 252  * Returns 0 if the pages are in cache and a BIO is submitted,
 253  * 1 if the pages are not in cache and -error otherwise.
 254  */
 255
 256 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
 257 {
 258         int ret;
 259         const struct v9fs_inode *v9inode = V9FS_I(inode);
 260
 261         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 262         if (!v9inode->fscache)
 263                 return -ENOBUFS;
 264
 265         ret = fscache_read_or_alloc_page(v9inode->fscache,
 266                                          page,
 267                                          v9fs_vfs_readpage_complete,
 268                                          NULL,
 269                                          GFP_KERNEL);
 270         switch (ret) {
 271         case -ENOBUFS:
 272         case -ENODATA:
 273                 p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
 274                 return 1;
 275         case 0:
 276                 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
 277                 return ret;
 278         default:
 279                 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
 280                 return ret;
 281         }
 282 }
 283
 284 /**
 285  * __v9fs_readpages_from_fscache - read multiple pages 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_readpages_from_fscache(struct inode *inode,
 292                                   struct address_space *mapping,
 293                                   struct list_head *pages,
 294                                   unsigned *nr_pages)
 295 {
 296         int ret;
 297         const struct v9fs_inode *v9inode = V9FS_I(inode);
 298
 299         p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
 300         if (!v9inode->fscache)
 301                 return -ENOBUFS;
 302
 303         ret = fscache_read_or_alloc_pages(v9inode->fscache,
 304                                           mapping, pages, nr_pages,
 305                                           v9fs_vfs_readpage_complete,
 306                                           NULL,
 307                                           mapping_gfp_mask(mapping));
 308         switch (ret) {
 309         case -ENOBUFS:
 310         case -ENODATA:
 311                 p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
 312                 return 1;
 313         case 0:
 314                 BUG_ON(!list_empty(pages));
 315                 BUG_ON(*nr_pages != 0);
 316                 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
 317                 return ret;
 318         default:
 319                 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
 320                 return ret;
 321         }
 322 }
 323
 324 /**
 325  * __v9fs_readpage_to_fscache - write a page to the cache
 326  *
 327  */
 328
 329 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
 330 {
 331         int ret;
 332         const struct v9fs_inode *v9inode = V9FS_I(inode);
 333
 334         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 335         ret = fscache_write_page(v9inode->fscache, page,
 336                                  i_size_read(&v9inode->vfs_inode), GFP_KERNEL);
 337         p9_debug(P9_DEBUG_FSC, "ret =  %d\n", ret);
 338         if (ret != 0)
 339                 v9fs_uncache_page(inode, page);
 340 }
 341
 342 /*
 343  * wait for a page to complete writing to the cache
 344  */
 345 void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
 346 {
 347         const struct v9fs_inode *v9inode = V9FS_I(inode);
 348         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 349         if (PageFsCache(page))
 350                 fscache_wait_on_page_write(v9inode->fscache, page);
 351 }