fs/nfs/fscache.c

   1 /* NFS filesystem cache interface
   2  *
   3  * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11
  12 #include <linux/init.h>
  13 #include <linux/kernel.h>
  14 #include <linux/sched.h>
  15 #include <linux/mm.h>
  16 #include <linux/nfs_fs.h>
  17 #include <linux/nfs_fs_sb.h>
  18 #include <linux/in6.h>
  19 #include <linux/seq_file.h>
  20
  21 #include "internal.h"
  22 #include "iostat.h"
  23 #include "fscache.h"
  24
  25 #define NFSDBG_FACILITY         NFSDBG_FSCACHE
  26
  27 static struct rb_root nfs_fscache_keys = RB_ROOT;
  28 static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
  29
  30 /*
  31  * Get the per-client index cookie for an NFS client if the appropriate mount
  32  * flag was set
  33  * - We always try and get an index cookie for the client, but get filehandle
  34  *   cookies on a per-superblock basis, depending on the mount flags
  35  */
  36 void nfs_fscache_get_client_cookie(struct nfs_client *clp)
  37 {
  38         /* create a cache index for looking up filehandles */
  39         clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
  40                                               &nfs_fscache_server_index_def,
  41                                               clp);
  42         dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
  43                  clp, clp->fscache);
  44 }
  45
  46 /*
  47  * Dispose of a per-client cookie
  48  */
  49 void nfs_fscache_release_client_cookie(struct nfs_client *clp)
  50 {
  51         dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
  52                  clp, clp->fscache);
  53
  54         fscache_relinquish_cookie(clp->fscache, 0);
  55         clp->fscache = NULL;
  56 }
  57
  58 /*
  59  * Get the cache cookie for an NFS superblock.  We have to handle
  60  * uniquification here because the cache doesn't do it for us.
  61  *
  62  * The default uniquifier is just an empty string, but it may be overridden
  63  * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
  64  * superblock across an automount point of some nature.
  65  */
  66 void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq,
  67                                   struct nfs_clone_mount *mntdata)
  68 {
  69         struct nfs_fscache_key *key, *xkey;
  70         struct nfs_server *nfss = NFS_SB(sb);
  71         struct rb_node **p, *parent;
  72         int diff, ulen;
  73
  74         if (uniq) {
  75                 ulen = strlen(uniq);
  76         } else if (mntdata) {
  77                 struct nfs_server *mnt_s = NFS_SB(mntdata->sb);
  78                 if (mnt_s->fscache_key) {
  79                         uniq = mnt_s->fscache_key->key.uniquifier;
  80                         ulen = mnt_s->fscache_key->key.uniq_len;
  81                 }
  82         }
  83
  84         if (!uniq) {
  85                 uniq = "";
  86                 ulen = 1;
  87         }
  88
  89         key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
  90         if (!key)
  91                 return;
  92
  93         key->nfs_client = nfss->nfs_client;
  94         key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
  95         key->key.nfs_server.flags = nfss->flags;
  96         key->key.nfs_server.rsize = nfss->rsize;
  97         key->key.nfs_server.wsize = nfss->wsize;
  98         key->key.nfs_server.acregmin = nfss->acregmin;
  99         key->key.nfs_server.acregmax = nfss->acregmax;
 100         key->key.nfs_server.acdirmin = nfss->acdirmin;
 101         key->key.nfs_server.acdirmax = nfss->acdirmax;
 102         key->key.nfs_server.fsid = nfss->fsid;
 103         key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
 104
 105         key->key.uniq_len = ulen;
 106         memcpy(key->key.uniquifier, uniq, ulen);
 107
 108         spin_lock(&nfs_fscache_keys_lock);
 109         p = &nfs_fscache_keys.rb_node;
 110         parent = NULL;
 111         while (*p) {
 112                 parent = *p;
 113                 xkey = rb_entry(parent, struct nfs_fscache_key, node);
 114
 115                 if (key->nfs_client < xkey->nfs_client)
 116                         goto go_left;
 117                 if (key->nfs_client > xkey->nfs_client)
 118                         goto go_right;
 119
 120                 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
 121                 if (diff < 0)
 122                         goto go_left;
 123                 if (diff > 0)
 124                         goto go_right;
 125
 126                 if (key->key.uniq_len == 0)
 127                         goto non_unique;
 128                 diff = memcmp(key->key.uniquifier,
 129                               xkey->key.uniquifier,
 130                               key->key.uniq_len);
 131                 if (diff < 0)
 132                         goto go_left;
 133                 if (diff > 0)
 134                         goto go_right;
 135                 goto non_unique;
 136
 137         go_left:
 138                 p = &(*p)->rb_left;
 139                 continue;
 140         go_right:
 141                 p = &(*p)->rb_right;
 142         }
 143
 144         rb_link_node(&key->node, parent, p);
 145         rb_insert_color(&key->node, &nfs_fscache_keys);
 146         spin_unlock(&nfs_fscache_keys_lock);
 147         nfss->fscache_key = key;
 148
 149         /* create a cache index for looking up filehandles */
 150         nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
 151                                                &nfs_fscache_super_index_def,
 152                                                nfss);
 153         dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
 154                  nfss, nfss->fscache);
 155         return;
 156
 157 non_unique:
 158         spin_unlock(&nfs_fscache_keys_lock);
 159         kfree(key);
 160         nfss->fscache_key = NULL;
 161         nfss->fscache = NULL;
 162         printk(KERN_WARNING "NFS:"
 163                " Cache request denied due to non-unique superblock keys\n");
 164 }
 165
 166 /*
 167  * release a per-superblock cookie
 168  */
 169 void nfs_fscache_release_super_cookie(struct super_block *sb)
 170 {
 171         struct nfs_server *nfss = NFS_SB(sb);
 172
 173         dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
 174                  nfss, nfss->fscache);
 175
 176         fscache_relinquish_cookie(nfss->fscache, 0);
 177         nfss->fscache = NULL;
 178
 179         if (nfss->fscache_key) {
 180                 spin_lock(&nfs_fscache_keys_lock);
 181                 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
 182                 spin_unlock(&nfs_fscache_keys_lock);
 183                 kfree(nfss->fscache_key);
 184                 nfss->fscache_key = NULL;
 185         }
 186 }
 187
 188 /*
 189  * Initialise the per-inode cache cookie pointer for an NFS inode.
 190  */
 191 void nfs_fscache_init_inode_cookie(struct inode *inode)
 192 {
 193         NFS_I(inode)->fscache = NULL;
 194         if (S_ISREG(inode->i_mode))
 195                 set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 196 }
 197
 198 /*
 199  * Get the per-inode cache cookie for an NFS inode.
 200  */
 201 static void nfs_fscache_enable_inode_cookie(struct inode *inode)
 202 {
 203         struct super_block *sb = inode->i_sb;
 204         struct nfs_inode *nfsi = NFS_I(inode);
 205
 206         if (nfsi->fscache || !NFS_FSCACHE(inode))
 207                 return;
 208
 209         if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
 210                 nfsi->fscache = fscache_acquire_cookie(
 211                         NFS_SB(sb)->fscache,
 212                         &nfs_fscache_inode_object_def,
 213                         nfsi);
 214
 215                 dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
 216                          sb, nfsi, nfsi->fscache);
 217         }
 218 }
 219
 220 /*
 221  * Release a per-inode cookie.
 222  */
 223 void nfs_fscache_release_inode_cookie(struct inode *inode)
 224 {
 225         struct nfs_inode *nfsi = NFS_I(inode);
 226
 227         dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
 228                  nfsi, nfsi->fscache);
 229
 230         fscache_relinquish_cookie(nfsi->fscache, 0);
 231         nfsi->fscache = NULL;
 232 }
 233
 234 /*
 235  * Retire a per-inode cookie, destroying the data attached to it.
 236  */
 237 void nfs_fscache_zap_inode_cookie(struct inode *inode)
 238 {
 239         struct nfs_inode *nfsi = NFS_I(inode);
 240
 241         dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
 242                  nfsi, nfsi->fscache);
 243
 244         fscache_relinquish_cookie(nfsi->fscache, 1);
 245         nfsi->fscache = NULL;
 246 }
 247
 248 /*
 249  * Turn off the cache with regard to a per-inode cookie if opened for writing,
 250  * invalidating all the pages in the page cache relating to the associated
 251  * inode to clear the per-page caching.
 252  */
 253 static void nfs_fscache_disable_inode_cookie(struct inode *inode)
 254 {
 255         clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 256
 257         if (NFS_I(inode)->fscache) {
 258                 dfprintk(FSCACHE,
 259                          "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
 260
 261                 /* Need to invalidate any mapped pages that were read in before
 262                  * turning off the cache.
 263                  */
 264                 if (inode->i_mapping && inode->i_mapping->nrpages)
 265                         invalidate_inode_pages2(inode->i_mapping);
 266
 267                 nfs_fscache_zap_inode_cookie(inode);
 268         }
 269 }
 270
 271 /*
 272  * wait_on_bit() sleep function for uninterruptible waiting
 273  */
 274 static int nfs_fscache_wait_bit(void *flags)
 275 {
 276         schedule();
 277         return 0;
 278 }
 279
 280 /*
 281  * Lock against someone else trying to also acquire or relinquish a cookie
 282  */
 283 static inline void nfs_fscache_inode_lock(struct inode *inode)
 284 {
 285         struct nfs_inode *nfsi = NFS_I(inode);
 286
 287         while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
 288                 wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
 289                             nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
 290 }
 291
 292 /*
 293  * Unlock cookie management lock
 294  */
 295 static inline void nfs_fscache_inode_unlock(struct inode *inode)
 296 {
 297         struct nfs_inode *nfsi = NFS_I(inode);
 298
 299         smp_mb__before_clear_bit();
 300         clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
 301         smp_mb__after_clear_bit();
 302         wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
 303 }
 304
 305 /*
 306  * Decide if we should enable or disable local caching for this inode.
 307  * - For now, with NFS, only regular files that are open read-only will be able
 308  *   to use the cache.
 309  * - May be invoked multiple times in parallel by parallel nfs_open() functions.
 310  */
 311 void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
 312 {
 313         if (NFS_FSCACHE(inode)) {
 314                 nfs_fscache_inode_lock(inode);
 315                 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 316                         nfs_fscache_disable_inode_cookie(inode);
 317                 else
 318                         nfs_fscache_enable_inode_cookie(inode);
 319                 nfs_fscache_inode_unlock(inode);
 320         }
 321 }
 322
 323 /*
 324  * Replace a per-inode cookie due to revalidation detecting a file having
 325  * changed on the server.
 326  */
 327 void nfs_fscache_reset_inode_cookie(struct inode *inode)
 328 {
 329         struct nfs_inode *nfsi = NFS_I(inode);
 330         struct nfs_server *nfss = NFS_SERVER(inode);
 331         struct fscache_cookie *old = nfsi->fscache;
 332
 333         nfs_fscache_inode_lock(inode);
 334         if (nfsi->fscache) {
 335                 /* retire the current fscache cache and get a new one */
 336                 fscache_relinquish_cookie(nfsi->fscache, 1);
 337
 338                 nfsi->fscache = fscache_acquire_cookie(
 339                         nfss->nfs_client->fscache,
 340                         &nfs_fscache_inode_object_def,
 341                         nfsi);
 342
 343                 dfprintk(FSCACHE,
 344                          "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
 345                          nfss, nfsi, old, nfsi->fscache);
 346         }
 347         nfs_fscache_inode_unlock(inode);
 348 }
 349
 350 /*
 351  * Release the caching state associated with a page, if the page isn't busy
 352  * interacting with the cache.
 353  * - Returns true (can release page) or false (page busy).
 354  */
 355 int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 356 {
 357         struct nfs_inode *nfsi = NFS_I(page->mapping->host);
 358         struct fscache_cookie *cookie = nfsi->fscache;
 359
 360         BUG_ON(!cookie);
 361
 362         if (PageFsCache(page)) {
 363                 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
 364                          cookie, page, nfsi);
 365
 366                 if (!fscache_maybe_release_page(cookie, page, gfp))
 367                         return 0;
 368
 369                 nfs_add_fscache_stats(page->mapping->host,
 370                                       NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
 371         }
 372
 373         return 1;
 374 }
 375
 376 /*
 377  * Release the caching state associated with a page if undergoing complete page
 378  * invalidation.
 379  */
 380 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
 381 {
 382         struct nfs_inode *nfsi = NFS_I(inode);
 383         struct fscache_cookie *cookie = nfsi->fscache;
 384
 385         BUG_ON(!cookie);
 386
 387         dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
 388                  cookie, page, nfsi);
 389
 390         fscache_wait_on_page_write(cookie, page);
 391
 392         BUG_ON(!PageLocked(page));
 393         fscache_uncache_page(cookie, page);
 394         nfs_add_fscache_stats(page->mapping->host,
 395                               NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
 396 }
 397
 398 /*
 399  * Handle completion of a page being read from the cache.
 400  * - Called in process (keventd) context.
 401  */
 402 static void nfs_readpage_from_fscache_complete(struct page *page,
 403                                                void *context,
 404                                                int error)
 405 {
 406         dfprintk(FSCACHE,
 407                  "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
 408                  page, context, error);
 409
 410         /* if the read completes with an error, we just unlock the page and let
 411          * the VM reissue the readpage */
 412         if (!error) {
 413                 SetPageUptodate(page);
 414                 unlock_page(page);
 415         } else {
 416                 error = nfs_readpage_async(context, page->mapping->host, page);
 417                 if (error)
 418                         unlock_page(page);
 419         }
 420 }
 421
 422 /*
 423  * Retrieve a page from fscache
 424  */
 425 int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
 426                                 struct inode *inode, struct page *page)
 427 {
 428         int ret;
 429
 430         dfprintk(FSCACHE,
 431                  "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
 432                  NFS_I(inode)->fscache, page, page->index, page->flags, inode);
 433
 434         ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
 435                                          page,
 436                                          nfs_readpage_from_fscache_complete,
 437                                          ctx,
 438                                          GFP_KERNEL);
 439
 440         switch (ret) {
 441         case 0: /* read BIO submitted (page in fscache) */
 442                 dfprintk(FSCACHE,
 443                          "NFS:    readpage_from_fscache: BIO submitted\n");
 444                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1);
 445                 return ret;
 446
 447         case -ENOBUFS: /* inode not in cache */
 448         case -ENODATA: /* page not in cache */
 449                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
 450                 dfprintk(FSCACHE,
 451                          "NFS:    readpage_from_fscache %d\n", ret);
 452                 return 1;
 453
 454         default:
 455                 dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
 456                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
 457         }
 458         return ret;
 459 }
 460
 461 /*
 462  * Retrieve a set of pages from fscache
 463  */
 464 int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 465                                  struct inode *inode,
 466                                  struct address_space *mapping,
 467                                  struct list_head *pages,
 468                                  unsigned *nr_pages)
 469 {
 470         int ret, npages = *nr_pages;
 471
 472         dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
 473                  NFS_I(inode)->fscache, npages, inode);
 474
 475         ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
 476                                           mapping, pages, nr_pages,
 477                                           nfs_readpage_from_fscache_complete,
 478                                           ctx,
 479                                           mapping_gfp_mask(mapping));
 480         if (*nr_pages < npages)
 481                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
 482                                       npages);
 483         if (*nr_pages > 0)
 484                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
 485                                       *nr_pages);
 486
 487         switch (ret) {
 488         case 0: /* read submitted to the cache for all pages */
 489                 BUG_ON(!list_empty(pages));
 490                 BUG_ON(*nr_pages != 0);
 491                 dfprintk(FSCACHE,
 492                          "NFS: nfs_getpages_from_fscache: submitted\n");
 493
 494                 return ret;
 495
 496         case -ENOBUFS: /* some pages aren't cached and can't be */
 497         case -ENODATA: /* some pages aren't cached */
 498                 dfprintk(FSCACHE,
 499                          "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
 500                 return 1;
 501
 502         default:
 503                 dfprintk(FSCACHE,
 504                          "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
 505         }
 506
 507         return ret;
 508 }
 509
 510 /*
 511  * Store a newly fetched page in fscache
 512  * - PG_fscache must be set on the page
 513  */
 514 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
 515 {
 516         int ret;
 517
 518         dfprintk(FSCACHE,
 519                  "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
 520                  NFS_I(inode)->fscache, page, page->index, page->flags, sync);
 521
 522         ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
 523         dfprintk(FSCACHE,
 524                  "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
 525                  page, page->index, page->flags, ret);
 526
 527         if (ret != 0) {
 528                 fscache_uncache_page(NFS_I(inode)->fscache, page);
 529                 nfs_add_fscache_stats(inode,
 530                                       NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
 531                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
 532         } else {
 533                 nfs_add_fscache_stats(inode,
 534                                       NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
 535         }
 536 }