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/stat.h>
  26 #include <linux/sched.h>
  27 #include <linux/fs.h>
  28 #include <net/9p/9p.h>
  29
  30 #include "v9fs.h"
  31 #include "cache.h"
  32
  33 #define CACHETAG_LEN  11
  34
  35 struct kmem_cache *vcookie_cache;
  36
  37 struct fscache_netfs v9fs_cache_netfs = {
  38         .name           = "9p",
  39         .version        = 0,
  40 };
  41
  42 static void init_once(void *foo)
  43 {
  44         struct v9fs_cookie *vcookie = (struct v9fs_cookie *) foo;
  45         vcookie->fscache = NULL;
  46         vcookie->qid = NULL;
  47         inode_init_once(&vcookie->inode);
  48 }
  49
  50 /**
  51  * v9fs_init_vcookiecache - initialize a cache for vcookies to maintain
  52  *                          vcookie to inode mapping
  53  *
  54  * Returns 0 on success.
  55  */
  56
  57 static int v9fs_init_vcookiecache(void)
  58 {
  59         vcookie_cache = kmem_cache_create("vcookie_cache",
  60                                           sizeof(struct v9fs_cookie),
  61                                           0, (SLAB_RECLAIM_ACCOUNT|
  62                                               SLAB_MEM_SPREAD),
  63                                           init_once);
  64         if (!vcookie_cache)
  65                 return -ENOMEM;
  66
  67         return 0;
  68 }
  69
  70 /**
  71  * v9fs_destroy_vcookiecache - destroy the cache of vcookies
  72  *
  73  */
  74
  75 static void v9fs_destroy_vcookiecache(void)
  76 {
  77         kmem_cache_destroy(vcookie_cache);
  78 }
  79
  80 int __v9fs_cache_register(void)
  81 {
  82         int ret;
  83         ret = v9fs_init_vcookiecache();
  84         if (ret < 0)
  85                 return ret;
  86
  87         return fscache_register_netfs(&v9fs_cache_netfs);
  88 }
  89
  90 void __v9fs_cache_unregister(void)
  91 {
  92         v9fs_destroy_vcookiecache();
  93         fscache_unregister_netfs(&v9fs_cache_netfs);
  94 }
  95
  96 /**
  97  * v9fs_random_cachetag - Generate a random tag to be associated
  98  *                        with a new cache session.
  99  *
 100  * The value of jiffies is used for a fairly randomly cache tag.
 101  */
 102
 103 static
 104 int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
 105 {
 106         v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
 107         if (!v9ses->cachetag)
 108                 return -ENOMEM;
 109
 110         return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
 111 }
 112
 113 static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,
 114                                            void *buffer, uint16_t bufmax)
 115 {
 116         struct v9fs_session_info *v9ses;
 117         uint16_t klen = 0;
 118
 119         v9ses = (struct v9fs_session_info *)cookie_netfs_data;
 120         P9_DPRINTK(P9_DEBUG_FSC, "session %p buf %p size %u", v9ses,
 121                    buffer, bufmax);
 122
 123         if (v9ses->cachetag)
 124                 klen = strlen(v9ses->cachetag);
 125
 126         if (klen > bufmax)
 127                 return 0;
 128
 129         memcpy(buffer, v9ses->cachetag, klen);
 130         P9_DPRINTK(P9_DEBUG_FSC, "cache session tag %s", v9ses->cachetag);
 131         return klen;
 132 }
 133
 134 const struct fscache_cookie_def v9fs_cache_session_index_def = {
 135         .name           = "9P.session",
 136         .type           = FSCACHE_COOKIE_TYPE_INDEX,
 137         .get_key        = v9fs_cache_session_get_key,
 138 };
 139
 140 void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
 141 {
 142         /* If no cache session tag was specified, we generate a random one. */
 143         if (!v9ses->cachetag)
 144                 v9fs_random_cachetag(v9ses);
 145
 146         v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
 147                                                 &v9fs_cache_session_index_def,
 148                                                 v9ses);
 149         P9_DPRINTK(P9_DEBUG_FSC, "session %p get cookie %p", v9ses,
 150                    v9ses->fscache);
 151 }
 152
 153 void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
 154 {
 155         P9_DPRINTK(P9_DEBUG_FSC, "session %p put cookie %p", v9ses,
 156                    v9ses->fscache);
 157         fscache_relinquish_cookie(v9ses->fscache, 0);
 158         v9ses->fscache = NULL;
 159 }
 160
 161
 162 static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,
 163                                          void *buffer, uint16_t bufmax)
 164 {
 165         const struct v9fs_cookie *vcookie = cookie_netfs_data;
 166         memcpy(buffer, &vcookie->qid->path, sizeof(vcookie->qid->path));
 167
 168         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get key %llu", &vcookie->inode,
 169                    vcookie->qid->path);
 170         return sizeof(vcookie->qid->path);
 171 }
 172
 173 static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,
 174                                       uint64_t *size)
 175 {
 176         const struct v9fs_cookie *vcookie = cookie_netfs_data;
 177         *size = i_size_read(&vcookie->inode);
 178
 179         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get attr %llu", &vcookie->inode,
 180                    *size);
 181 }
 182
 183 static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,
 184                                          void *buffer, uint16_t buflen)
 185 {
 186         const struct v9fs_cookie *vcookie = cookie_netfs_data;
 187         memcpy(buffer, &vcookie->qid->version, sizeof(vcookie->qid->version));
 188
 189         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get aux %u", &vcookie->inode,
 190                    vcookie->qid->version);
 191         return sizeof(vcookie->qid->version);
 192 }
 193
 194 static enum
 195 fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
 196                                             const void *buffer,
 197                                             uint16_t buflen)
 198 {
 199         const struct v9fs_cookie *vcookie = cookie_netfs_data;
 200
 201         if (buflen != sizeof(vcookie->qid->version))
 202                 return FSCACHE_CHECKAUX_OBSOLETE;
 203
 204         if (memcmp(buffer, &vcookie->qid->version,
 205                    sizeof(vcookie->qid->version)))
 206                 return FSCACHE_CHECKAUX_OBSOLETE;
 207
 208         return FSCACHE_CHECKAUX_OKAY;
 209 }
 210
 211 static void v9fs_cache_inode_now_uncached(void *cookie_netfs_data)
 212 {
 213         struct v9fs_cookie *vcookie = cookie_netfs_data;
 214         struct pagevec pvec;
 215         pgoff_t first;
 216         int loop, nr_pages;
 217
 218         pagevec_init(&pvec, 0);
 219         first = 0;
 220
 221         for (;;) {
 222                 nr_pages = pagevec_lookup(&pvec, vcookie->inode.i_mapping,
 223                                           first,
 224                                           PAGEVEC_SIZE - pagevec_count(&pvec));
 225                 if (!nr_pages)
 226                         break;
 227
 228                 for (loop = 0; loop < nr_pages; loop++)
 229                         ClearPageFsCache(pvec.pages[loop]);
 230
 231                 first = pvec.pages[nr_pages - 1]->index + 1;
 232
 233                 pvec.nr = nr_pages;
 234                 pagevec_release(&pvec);
 235                 cond_resched();
 236         }
 237 }
 238
 239 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
 240         .name           = "9p.inode",
 241         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 242         .get_key        = v9fs_cache_inode_get_key,
 243         .get_attr       = v9fs_cache_inode_get_attr,
 244         .get_aux        = v9fs_cache_inode_get_aux,
 245         .check_aux      = v9fs_cache_inode_check_aux,
 246         .now_uncached   = v9fs_cache_inode_now_uncached,
 247 };
 248
 249 void v9fs_cache_inode_get_cookie(struct inode *inode)
 250 {
 251         struct v9fs_cookie *vcookie;
 252         struct v9fs_session_info *v9ses;
 253
 254         if (!S_ISREG(inode->i_mode))
 255                 return;
 256
 257         vcookie = v9fs_inode2cookie(inode);
 258         if (vcookie->fscache)
 259                 return;
 260
 261         v9ses = v9fs_inode2v9ses(inode);
 262         vcookie->fscache = fscache_acquire_cookie(v9ses->fscache,
 263                                                   &v9fs_cache_inode_index_def,
 264                                                   vcookie);
 265
 266         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get cookie %p", inode,
 267                    vcookie->fscache);
 268 }
 269
 270 void v9fs_cache_inode_put_cookie(struct inode *inode)
 271 {
 272         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 273
 274         if (!vcookie->fscache)
 275                 return;
 276         P9_DPRINTK(P9_DEBUG_FSC, "inode %p put cookie %p", inode,
 277                    vcookie->fscache);
 278
 279         fscache_relinquish_cookie(vcookie->fscache, 0);
 280         vcookie->fscache = NULL;
 281 }
 282
 283 void v9fs_cache_inode_flush_cookie(struct inode *inode)
 284 {
 285         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 286
 287         if (!vcookie->fscache)
 288                 return;
 289         P9_DPRINTK(P9_DEBUG_FSC, "inode %p flush cookie %p", inode,
 290                    vcookie->fscache);
 291
 292         fscache_relinquish_cookie(vcookie->fscache, 1);
 293         vcookie->fscache = NULL;
 294 }
 295
 296 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
 297 {
 298         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 299         struct p9_fid *fid;
 300
 301         if (!vcookie->fscache)
 302                 return;
 303
 304         spin_lock(&vcookie->lock);
 305         fid = filp->private_data;
 306         if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 307                 v9fs_cache_inode_flush_cookie(inode);
 308         else
 309                 v9fs_cache_inode_get_cookie(inode);
 310
 311         spin_unlock(&vcookie->lock);
 312 }
 313
 314 void v9fs_cache_inode_reset_cookie(struct inode *inode)
 315 {
 316         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 317         struct v9fs_session_info *v9ses;
 318         struct fscache_cookie *old;
 319
 320         if (!vcookie->fscache)
 321                 return;
 322
 323         old = vcookie->fscache;
 324
 325         spin_lock(&vcookie->lock);
 326         fscache_relinquish_cookie(vcookie->fscache, 1);
 327
 328         v9ses = v9fs_inode2v9ses(inode);
 329         vcookie->fscache = fscache_acquire_cookie(v9ses->fscache,
 330                                                   &v9fs_cache_inode_index_def,
 331                                                   vcookie);
 332
 333         P9_DPRINTK(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p",
 334                    inode, old, vcookie->fscache);
 335
 336         spin_unlock(&vcookie->lock);
 337 }
 338
 339 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
 340 {
 341         struct inode *inode = page->mapping->host;
 342         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 343
 344         BUG_ON(!vcookie->fscache);
 345
 346         return fscache_maybe_release_page(vcookie->fscache, page, gfp);
 347 }
 348
 349 void __v9fs_fscache_invalidate_page(struct page *page)
 350 {
 351         struct inode *inode = page->mapping->host;
 352         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 353
 354         BUG_ON(!vcookie->fscache);
 355
 356         if (PageFsCache(page)) {
 357                 fscache_wait_on_page_write(vcookie->fscache, page);
 358                 BUG_ON(!PageLocked(page));
 359                 fscache_uncache_page(vcookie->fscache, page);
 360         }
 361 }
 362
 363 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
 364                                        int error)
 365 {
 366         if (!error)
 367                 SetPageUptodate(page);
 368
 369         unlock_page(page);
 370 }
 371
 372 /**
 373  * __v9fs_readpage_from_fscache - read a page from cache
 374  *
 375  * Returns 0 if the pages are in cache and a BIO is submitted,
 376  * 1 if the pages are not in cache and -error otherwise.
 377  */
 378
 379 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
 380 {
 381         int ret;
 382         const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 383
 384         P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
 385         if (!vcookie->fscache)
 386                 return -ENOBUFS;
 387
 388         ret = fscache_read_or_alloc_page(vcookie->fscache,
 389                                          page,
 390                                          v9fs_vfs_readpage_complete,
 391                                          NULL,
 392                                          GFP_KERNEL);
 393         switch (ret) {
 394         case -ENOBUFS:
 395         case -ENODATA:
 396                 P9_DPRINTK(P9_DEBUG_FSC, "page/inode not in cache %d", ret);
 397                 return 1;
 398         case 0:
 399                 P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");
 400                 return ret;
 401         default:
 402                 P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);
 403                 return ret;
 404         }
 405 }
 406
 407 /**
 408  * __v9fs_readpages_from_fscache - read multiple pages from cache
 409  *
 410  * Returns 0 if the pages are in cache and a BIO is submitted,
 411  * 1 if the pages are not in cache and -error otherwise.
 412  */
 413
 414 int __v9fs_readpages_from_fscache(struct inode *inode,
 415                                   struct address_space *mapping,
 416                                   struct list_head *pages,
 417                                   unsigned *nr_pages)
 418 {
 419         int ret;
 420         const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 421
 422         P9_DPRINTK(P9_DEBUG_FSC, "inode %p pages %u", inode, *nr_pages);
 423         if (!vcookie->fscache)
 424                 return -ENOBUFS;
 425
 426         ret = fscache_read_or_alloc_pages(vcookie->fscache,
 427                                           mapping, pages, nr_pages,
 428                                           v9fs_vfs_readpage_complete,
 429                                           NULL,
 430                                           mapping_gfp_mask(mapping));
 431         switch (ret) {
 432         case -ENOBUFS:
 433         case -ENODATA:
 434                 P9_DPRINTK(P9_DEBUG_FSC, "pages/inodes not in cache %d", ret);
 435                 return 1;
 436         case 0:
 437                 BUG_ON(!list_empty(pages));
 438                 BUG_ON(*nr_pages != 0);
 439                 P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");
 440                 return ret;
 441         default:
 442                 P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);
 443                 return ret;
 444         }
 445 }
 446
 447 /**
 448  * __v9fs_readpage_to_fscache - write a page to the cache
 449  *
 450  */
 451
 452 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
 453 {
 454         int ret;
 455         const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 456
 457         P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
 458         ret = fscache_write_page(vcookie->fscache, page, GFP_KERNEL);
 459         P9_DPRINTK(P9_DEBUG_FSC, "ret =  %d", ret);
 460         if (ret != 0)
 461                 v9fs_uncache_page(inode, page);
 462 }