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                         kfree(v9ses->cachetag);
  70                         v9ses->cachetag = NULL;
  71                         return;
  72                 }
  73         }
  74
  75         v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
  76                                                 &v9fs_cache_session_index_def,
  77                                                 v9ses->cachetag,
  78                                                 strlen(v9ses->cachetag),
  79                                                 NULL, 0,
  80                                                 v9ses, 0, true);
  81         p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
  82                  v9ses, v9ses->fscache);
  83 }
  84
  85 void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
  86 {
  87         p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
  88                  v9ses, v9ses->fscache);
  89         fscache_relinquish_cookie(v9ses->fscache, NULL, false);
  90         v9ses->fscache = NULL;
  91 }
  92
  93 static enum
  94 fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
  95                                             const void *buffer,
  96                                             uint16_t buflen,
  97                                             loff_t object_size)
  98 {
  99         const struct v9fs_inode *v9inode = cookie_netfs_data;
 100
 101         if (buflen != sizeof(v9inode->qid.version))
 102                 return FSCACHE_CHECKAUX_OBSOLETE;
 103
 104         if (memcmp(buffer, &v9inode->qid.version,
 105                    sizeof(v9inode->qid.version)))
 106                 return FSCACHE_CHECKAUX_OBSOLETE;
 107
 108         return FSCACHE_CHECKAUX_OKAY;
 109 }
 110
 111 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
 112         .name           = "9p.inode",
 113         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 114         .check_aux      = v9fs_cache_inode_check_aux,
 115 };
 116
 117 void v9fs_cache_inode_get_cookie(struct inode *inode)
 118 {
 119         struct v9fs_inode *v9inode;
 120         struct v9fs_session_info *v9ses;
 121
 122         if (!S_ISREG(inode->i_mode))
 123                 return;
 124
 125         v9inode = V9FS_I(inode);
 126         if (v9inode->fscache)
 127                 return;
 128
 129         v9ses = v9fs_inode2v9ses(inode);
 130         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 131                                                   &v9fs_cache_inode_index_def,
 132                                                   &v9inode->qid.path,
 133                                                   sizeof(v9inode->qid.path),
 134                                                   &v9inode->qid.version,
 135                                                   sizeof(v9inode->qid.version),
 136                                                   v9inode,
 137                                                   i_size_read(&v9inode->vfs_inode),
 138                                                   true);
 139
 140         p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
 141                  inode, v9inode->fscache);
 142 }
 143
 144 void v9fs_cache_inode_put_cookie(struct inode *inode)
 145 {
 146         struct v9fs_inode *v9inode = V9FS_I(inode);
 147
 148         if (!v9inode->fscache)
 149                 return;
 150         p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
 151                  inode, v9inode->fscache);
 152
 153         fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,
 154                                   false);
 155         v9inode->fscache = NULL;
 156 }
 157
 158 void v9fs_cache_inode_flush_cookie(struct inode *inode)
 159 {
 160         struct v9fs_inode *v9inode = V9FS_I(inode);
 161
 162         if (!v9inode->fscache)
 163                 return;
 164         p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
 165                  inode, v9inode->fscache);
 166
 167         fscache_relinquish_cookie(v9inode->fscache, NULL, true);
 168         v9inode->fscache = NULL;
 169 }
 170
 171 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
 172 {
 173         struct v9fs_inode *v9inode = V9FS_I(inode);
 174
 175         if (!v9inode->fscache)
 176                 return;
 177
 178         mutex_lock(&v9inode->fscache_lock);
 179
 180         if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 181                 v9fs_cache_inode_flush_cookie(inode);
 182         else
 183                 v9fs_cache_inode_get_cookie(inode);
 184
 185         mutex_unlock(&v9inode->fscache_lock);
 186 }
 187
 188 void v9fs_cache_inode_reset_cookie(struct inode *inode)
 189 {
 190         struct v9fs_inode *v9inode = V9FS_I(inode);
 191         struct v9fs_session_info *v9ses;
 192         struct fscache_cookie *old;
 193
 194         if (!v9inode->fscache)
 195                 return;
 196
 197         old = v9inode->fscache;
 198
 199         mutex_lock(&v9inode->fscache_lock);
 200         fscache_relinquish_cookie(v9inode->fscache, NULL, true);
 201
 202         v9ses = v9fs_inode2v9ses(inode);
 203         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 204                                                   &v9fs_cache_inode_index_def,
 205                                                   &v9inode->qid.path,
 206                                                   sizeof(v9inode->qid.path),
 207                                                   &v9inode->qid.version,
 208                                                   sizeof(v9inode->qid.version),
 209                                                   v9inode,
 210                                                   i_size_read(&v9inode->vfs_inode),
 211                                                   true);
 212         p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
 213                  inode, old, v9inode->fscache);
 214
 215         mutex_unlock(&v9inode->fscache_lock);
 216 }
 217
 218 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
 219 {
 220         struct inode *inode = page->mapping->host;
 221         struct v9fs_inode *v9inode = V9FS_I(inode);
 222
 223         BUG_ON(!v9inode->fscache);
 224
 225         return fscache_maybe_release_page(v9inode->fscache, page, gfp);
 226 }
 227
 228 void __v9fs_fscache_invalidate_page(struct page *page)
 229 {
 230         struct inode *inode = page->mapping->host;
 231         struct v9fs_inode *v9inode = V9FS_I(inode);
 232
 233         BUG_ON(!v9inode->fscache);
 234
 235         if (PageFsCache(page)) {
 236                 fscache_wait_on_page_write(v9inode->fscache, page);
 237                 BUG_ON(!PageLocked(page));
 238                 fscache_uncache_page(v9inode->fscache, page);
 239         }
 240 }
 241
 242 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
 243                                        int error)
 244 {
 245         if (!error)
 246                 SetPageUptodate(page);
 247
 248         unlock_page(page);
 249 }
 250
 251 /**
 252  * __v9fs_readpage_from_fscache - read a page from cache
 253  *
 254  * Returns 0 if the pages are in cache and a BIO is submitted,
 255  * 1 if the pages are not in cache and -error otherwise.
 256  */
 257
 258 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
 259 {
 260         int ret;
 261         const struct v9fs_inode *v9inode = V9FS_I(inode);
 262
 263         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 264         if (!v9inode->fscache)
 265                 return -ENOBUFS;
 266
 267         ret = fscache_read_or_alloc_page(v9inode->fscache,
 268                                          page,
 269                                          v9fs_vfs_readpage_complete,
 270                                          NULL,
 271                                          GFP_KERNEL);
 272         switch (ret) {
 273         case -ENOBUFS:
 274         case -ENODATA:
 275                 p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
 276                 return 1;
 277         case 0:
 278                 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
 279                 return ret;
 280         default:
 281                 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
 282                 return ret;
 283         }
 284 }
 285
 286 /**
 287  * __v9fs_readpages_from_fscache - read multiple pages from cache
 288  *
 289  * Returns 0 if the pages are in cache and a BIO is submitted,
 290  * 1 if the pages are not in cache and -error otherwise.
 291  */
 292
 293 int __v9fs_readpages_from_fscache(struct inode *inode,
 294                                   struct address_space *mapping,
 295                                   struct list_head *pages,
 296                                   unsigned *nr_pages)
 297 {
 298         int ret;
 299         const struct v9fs_inode *v9inode = V9FS_I(inode);
 300
 301         p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
 302         if (!v9inode->fscache)
 303                 return -ENOBUFS;
 304
 305         ret = fscache_read_or_alloc_pages(v9inode->fscache,
 306                                           mapping, pages, nr_pages,
 307                                           v9fs_vfs_readpage_complete,
 308                                           NULL,
 309                                           mapping_gfp_mask(mapping));
 310         switch (ret) {
 311         case -ENOBUFS:
 312         case -ENODATA:
 313                 p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
 314                 return 1;
 315         case 0:
 316                 BUG_ON(!list_empty(pages));
 317                 BUG_ON(*nr_pages != 0);
 318                 p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
 319                 return ret;
 320         default:
 321                 p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
 322                 return ret;
 323         }
 324 }
 325
 326 /**
 327  * __v9fs_readpage_to_fscache - write a page to the cache
 328  *
 329  */
 330
 331 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
 332 {
 333         int ret;
 334         const struct v9fs_inode *v9inode = V9FS_I(inode);
 335
 336         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 337         ret = fscache_write_page(v9inode->fscache, page,
 338                                  i_size_read(&v9inode->vfs_inode), GFP_KERNEL);
 339         p9_debug(P9_DEBUG_FSC, "ret =  %d\n", ret);
 340         if (ret != 0)
 341                 v9fs_uncache_page(inode, page);
 342 }
 343
 344 /*
 345  * wait for a page to complete writing to the cache
 346  */
 347 void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
 348 {
 349         const struct v9fs_inode *v9inode = V9FS_I(inode);
 350         p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 351         if (PageFsCache(page))
 352                 fscache_wait_on_page_write(v9inode->fscache, page);
 353 }