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 kmem_cache *vcookie_cache;
  37
  38 struct fscache_netfs v9fs_cache_netfs = {
  39         .name           = "9p",
  40         .version        = 0,
  41 };
  42
  43 static void init_once(void *foo)
  44 {
  45         struct v9fs_cookie *vcookie = (struct v9fs_cookie *) foo;
  46         vcookie->fscache = NULL;
  47         vcookie->qid = NULL;
  48         inode_init_once(&vcookie->inode);
  49 }
  50
  51 /**
  52  * v9fs_init_vcookiecache - initialize a cache for vcookies to maintain
  53  *                          vcookie to inode mapping
  54  *
  55  * Returns 0 on success.
  56  */
  57
  58 static int v9fs_init_vcookiecache(void)
  59 {
  60         vcookie_cache = kmem_cache_create("vcookie_cache",
  61                                           sizeof(struct v9fs_cookie),
  62                                           0, (SLAB_RECLAIM_ACCOUNT|
  63                                               SLAB_MEM_SPREAD),
  64                                           init_once);
  65         if (!vcookie_cache)
  66                 return -ENOMEM;
  67
  68         return 0;
  69 }
  70
  71 /**
  72  * v9fs_destroy_vcookiecache - destroy the cache of vcookies
  73  *
  74  */
  75
  76 static void v9fs_destroy_vcookiecache(void)
  77 {
  78         kmem_cache_destroy(vcookie_cache);
  79 }
  80
  81 int __v9fs_cache_register(void)
  82 {
  83         int ret;
  84         ret = v9fs_init_vcookiecache();
  85         if (ret < 0)
  86                 return ret;
  87
  88         return fscache_register_netfs(&v9fs_cache_netfs);
  89 }
  90
  91 void __v9fs_cache_unregister(void)
  92 {
  93         v9fs_destroy_vcookiecache();
  94         fscache_unregister_netfs(&v9fs_cache_netfs);
  95 }
  96
  97 /**
  98  * v9fs_random_cachetag - Generate a random tag to be associated
  99  *                        with a new cache session.
 100  *
 101  * The value of jiffies is used for a fairly randomly cache tag.
 102  */
 103
 104 static
 105 int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
 106 {
 107         v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
 108         if (!v9ses->cachetag)
 109                 return -ENOMEM;
 110
 111         return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
 112 }
 113
 114 static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,
 115                                            void *buffer, uint16_t bufmax)
 116 {
 117         struct v9fs_session_info *v9ses;
 118         uint16_t klen = 0;
 119
 120         v9ses = (struct v9fs_session_info *)cookie_netfs_data;
 121         P9_DPRINTK(P9_DEBUG_FSC, "session %p buf %p size %u", v9ses,
 122                    buffer, bufmax);
 123
 124         if (v9ses->cachetag)
 125                 klen = strlen(v9ses->cachetag);
 126
 127         if (klen > bufmax)
 128                 return 0;
 129
 130         memcpy(buffer, v9ses->cachetag, klen);
 131         P9_DPRINTK(P9_DEBUG_FSC, "cache session tag %s", v9ses->cachetag);
 132         return klen;
 133 }
 134
 135 const struct fscache_cookie_def v9fs_cache_session_index_def = {
 136         .name           = "9P.session",
 137         .type           = FSCACHE_COOKIE_TYPE_INDEX,
 138         .get_key        = v9fs_cache_session_get_key,
 139 };
 140
 141 void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
 142 {
 143         /* If no cache session tag was specified, we generate a random one. */
 144         if (!v9ses->cachetag)
 145                 v9fs_random_cachetag(v9ses);
 146
 147         v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
 148                                                 &v9fs_cache_session_index_def,
 149                                                 v9ses);
 150         P9_DPRINTK(P9_DEBUG_FSC, "session %p get cookie %p", v9ses,
 151                    v9ses->fscache);
 152 }
 153
 154 void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
 155 {
 156         P9_DPRINTK(P9_DEBUG_FSC, "session %p put cookie %p", v9ses,
 157                    v9ses->fscache);
 158         fscache_relinquish_cookie(v9ses->fscache, 0);
 159         v9ses->fscache = NULL;
 160 }
 161
 162
 163 static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,
 164                                          void *buffer, uint16_t bufmax)
 165 {
 166         const struct v9fs_cookie *vcookie = cookie_netfs_data;
 167         memcpy(buffer, &vcookie->qid->path, sizeof(vcookie->qid->path));
 168
 169         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get key %llu", &vcookie->inode,
 170                    vcookie->qid->path);
 171         return sizeof(vcookie->qid->path);
 172 }
 173
 174 static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,
 175                                       uint64_t *size)
 176 {
 177         const struct v9fs_cookie *vcookie = cookie_netfs_data;
 178         *size = i_size_read(&vcookie->inode);
 179
 180         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get attr %llu", &vcookie->inode,
 181                    *size);
 182 }
 183
 184 static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,
 185                                          void *buffer, uint16_t buflen)
 186 {
 187         const struct v9fs_cookie *vcookie = cookie_netfs_data;
 188         memcpy(buffer, &vcookie->qid->version, sizeof(vcookie->qid->version));
 189
 190         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get aux %u", &vcookie->inode,
 191                    vcookie->qid->version);
 192         return sizeof(vcookie->qid->version);
 193 }
 194
 195 static enum
 196 fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
 197                                             const void *buffer,
 198                                             uint16_t buflen)
 199 {
 200         const struct v9fs_cookie *vcookie = cookie_netfs_data;
 201
 202         if (buflen != sizeof(vcookie->qid->version))
 203                 return FSCACHE_CHECKAUX_OBSOLETE;
 204
 205         if (memcmp(buffer, &vcookie->qid->version,
 206                    sizeof(vcookie->qid->version)))
 207                 return FSCACHE_CHECKAUX_OBSOLETE;
 208
 209         return FSCACHE_CHECKAUX_OKAY;
 210 }
 211
 212 static void v9fs_cache_inode_now_uncached(void *cookie_netfs_data)
 213 {
 214         struct v9fs_cookie *vcookie = cookie_netfs_data;
 215         struct pagevec pvec;
 216         pgoff_t first;
 217         int loop, nr_pages;
 218
 219         pagevec_init(&pvec, 0);
 220         first = 0;
 221
 222         for (;;) {
 223                 nr_pages = pagevec_lookup(&pvec, vcookie->inode.i_mapping,
 224                                           first,
 225                                           PAGEVEC_SIZE - pagevec_count(&pvec));
 226                 if (!nr_pages)
 227                         break;
 228
 229                 for (loop = 0; loop < nr_pages; loop++)
 230                         ClearPageFsCache(pvec.pages[loop]);
 231
 232                 first = pvec.pages[nr_pages - 1]->index + 1;
 233
 234                 pvec.nr = nr_pages;
 235                 pagevec_release(&pvec);
 236                 cond_resched();
 237         }
 238 }
 239
 240 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
 241         .name           = "9p.inode",
 242         .type           = FSCACHE_COOKIE_TYPE_DATAFILE,
 243         .get_key        = v9fs_cache_inode_get_key,
 244         .get_attr       = v9fs_cache_inode_get_attr,
 245         .get_aux        = v9fs_cache_inode_get_aux,
 246         .check_aux      = v9fs_cache_inode_check_aux,
 247         .now_uncached   = v9fs_cache_inode_now_uncached,
 248 };
 249
 250 void v9fs_cache_inode_get_cookie(struct inode *inode)
 251 {
 252         struct v9fs_cookie *vcookie;
 253         struct v9fs_session_info *v9ses;
 254
 255         if (!S_ISREG(inode->i_mode))
 256                 return;
 257
 258         vcookie = v9fs_inode2cookie(inode);
 259         if (vcookie->fscache)
 260                 return;
 261
 262         v9ses = v9fs_inode2v9ses(inode);
 263         vcookie->fscache = fscache_acquire_cookie(v9ses->fscache,
 264                                                   &v9fs_cache_inode_index_def,
 265                                                   vcookie);
 266
 267         P9_DPRINTK(P9_DEBUG_FSC, "inode %p get cookie %p", inode,
 268                    vcookie->fscache);
 269 }
 270
 271 void v9fs_cache_inode_put_cookie(struct inode *inode)
 272 {
 273         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 274
 275         if (!vcookie->fscache)
 276                 return;
 277         P9_DPRINTK(P9_DEBUG_FSC, "inode %p put cookie %p", inode,
 278                    vcookie->fscache);
 279
 280         fscache_relinquish_cookie(vcookie->fscache, 0);
 281         vcookie->fscache = NULL;
 282 }
 283
 284 void v9fs_cache_inode_flush_cookie(struct inode *inode)
 285 {
 286         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 287
 288         if (!vcookie->fscache)
 289                 return;
 290         P9_DPRINTK(P9_DEBUG_FSC, "inode %p flush cookie %p", inode,
 291                    vcookie->fscache);
 292
 293         fscache_relinquish_cookie(vcookie->fscache, 1);
 294         vcookie->fscache = NULL;
 295 }
 296
 297 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
 298 {
 299         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 300         struct p9_fid *fid;
 301
 302         if (!vcookie->fscache)
 303                 return;
 304
 305         spin_lock(&vcookie->lock);
 306         fid = filp->private_data;
 307         if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 308                 v9fs_cache_inode_flush_cookie(inode);
 309         else
 310                 v9fs_cache_inode_get_cookie(inode);
 311
 312         spin_unlock(&vcookie->lock);
 313 }
 314
 315 void v9fs_cache_inode_reset_cookie(struct inode *inode)
 316 {
 317         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 318         struct v9fs_session_info *v9ses;
 319         struct fscache_cookie *old;
 320
 321         if (!vcookie->fscache)
 322                 return;
 323
 324         old = vcookie->fscache;
 325
 326         spin_lock(&vcookie->lock);
 327         fscache_relinquish_cookie(vcookie->fscache, 1);
 328
 329         v9ses = v9fs_inode2v9ses(inode);
 330         vcookie->fscache = fscache_acquire_cookie(v9ses->fscache,
 331                                                   &v9fs_cache_inode_index_def,
 332                                                   vcookie);
 333
 334         P9_DPRINTK(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p",
 335                    inode, old, vcookie->fscache);
 336
 337         spin_unlock(&vcookie->lock);
 338 }
 339
 340 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
 341 {
 342         struct inode *inode = page->mapping->host;
 343         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 344
 345         BUG_ON(!vcookie->fscache);
 346
 347         return fscache_maybe_release_page(vcookie->fscache, page, gfp);
 348 }
 349
 350 void __v9fs_fscache_invalidate_page(struct page *page)
 351 {
 352         struct inode *inode = page->mapping->host;
 353         struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 354
 355         BUG_ON(!vcookie->fscache);
 356
 357         if (PageFsCache(page)) {
 358                 fscache_wait_on_page_write(vcookie->fscache, page);
 359                 BUG_ON(!PageLocked(page));
 360                 fscache_uncache_page(vcookie->fscache, page);
 361         }
 362 }
 363
 364 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
 365                                        int error)
 366 {
 367         if (!error)
 368                 SetPageUptodate(page);
 369
 370         unlock_page(page);
 371 }
 372
 373 /**
 374  * __v9fs_readpage_from_fscache - read a page from cache
 375  *
 376  * Returns 0 if the pages are in cache and a BIO is submitted,
 377  * 1 if the pages are not in cache and -error otherwise.
 378  */
 379
 380 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
 381 {
 382         int ret;
 383         const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 384
 385         P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
 386         if (!vcookie->fscache)
 387                 return -ENOBUFS;
 388
 389         ret = fscache_read_or_alloc_page(vcookie->fscache,
 390                                          page,
 391                                          v9fs_vfs_readpage_complete,
 392                                          NULL,
 393                                          GFP_KERNEL);
 394         switch (ret) {
 395         case -ENOBUFS:
 396         case -ENODATA:
 397                 P9_DPRINTK(P9_DEBUG_FSC, "page/inode not in cache %d", ret);
 398                 return 1;
 399         case 0:
 400                 P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");
 401                 return ret;
 402         default:
 403                 P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);
 404                 return ret;
 405         }
 406 }
 407
 408 /**
 409  * __v9fs_readpages_from_fscache - read multiple pages from cache
 410  *
 411  * Returns 0 if the pages are in cache and a BIO is submitted,
 412  * 1 if the pages are not in cache and -error otherwise.
 413  */
 414
 415 int __v9fs_readpages_from_fscache(struct inode *inode,
 416                                   struct address_space *mapping,
 417                                   struct list_head *pages,
 418                                   unsigned *nr_pages)
 419 {
 420         int ret;
 421         const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 422
 423         P9_DPRINTK(P9_DEBUG_FSC, "inode %p pages %u", inode, *nr_pages);
 424         if (!vcookie->fscache)
 425                 return -ENOBUFS;
 426
 427         ret = fscache_read_or_alloc_pages(vcookie->fscache,
 428                                           mapping, pages, nr_pages,
 429                                           v9fs_vfs_readpage_complete,
 430                                           NULL,
 431                                           mapping_gfp_mask(mapping));
 432         switch (ret) {
 433         case -ENOBUFS:
 434         case -ENODATA:
 435                 P9_DPRINTK(P9_DEBUG_FSC, "pages/inodes not in cache %d", ret);
 436                 return 1;
 437         case 0:
 438                 BUG_ON(!list_empty(pages));
 439                 BUG_ON(*nr_pages != 0);
 440                 P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");
 441                 return ret;
 442         default:
 443                 P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);
 444                 return ret;
 445         }
 446 }
 447
 448 /**
 449  * __v9fs_readpage_to_fscache - write a page to the cache
 450  *
 451  */
 452
 453 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
 454 {
 455         int ret;
 456         const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
 457
 458         P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);
 459         ret = fscache_write_page(vcookie->fscache, page, GFP_KERNEL);
 460         P9_DPRINTK(P9_DEBUG_FSC, "ret =  %d", ret);
 461         if (ret != 0)
 462                 v9fs_uncache_page(inode, page);
 463 }