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 #include <linux/slab.h>
  21
  22 #include "internal.h"
  23 #include "iostat.h"
  24 #include "fscache.h"
  25
  26 #define NFSDBG_FACILITY         NFSDBG_FSCACHE
  27
  28 static struct rb_root nfs_fscache_keys = RB_ROOT;
  29 static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
  30
  31 /*
  32  * Get the per-client index cookie for an NFS client if the appropriate mount
  33  * flag was set
  34  * - We always try and get an index cookie for the client, but get filehandle
  35  *   cookies on a per-superblock basis, depending on the mount flags
  36  */
  37 void nfs_fscache_get_client_cookie(struct nfs_client *clp)
  38 {
  39         /* create a cache index for looking up filehandles */
  40         clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
  41                                               &nfs_fscache_server_index_def,
  42                                               clp);
  43         dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
  44                  clp, clp->fscache);
  45 }
  46
  47 /*
  48  * Dispose of a per-client cookie
  49  */
  50 void nfs_fscache_release_client_cookie(struct nfs_client *clp)
  51 {
  52         dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
  53                  clp, clp->fscache);
  54
  55         fscache_relinquish_cookie(clp->fscache, 0);
  56         clp->fscache = NULL;
  57 }
  58
  59 /*
  60  * Get the cache cookie for an NFS superblock.  We have to handle
  61  * uniquification here because the cache doesn't do it for us.
  62  *
  63  * The default uniquifier is just an empty string, but it may be overridden
  64  * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
  65  * superblock across an automount point of some nature.
  66  */
  67 void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq,
  68                                   struct nfs_clone_mount *mntdata)
  69 {
  70         struct nfs_fscache_key *key, *xkey;
  71         struct nfs_server *nfss = NFS_SB(sb);
  72         struct rb_node **p, *parent;
  73         int diff, ulen;
  74
  75         if (uniq) {
  76                 ulen = strlen(uniq);
  77         } else if (mntdata) {
  78                 struct nfs_server *mnt_s = NFS_SB(mntdata->sb);
  79                 if (mnt_s->fscache_key) {
  80                         uniq = mnt_s->fscache_key->key.uniquifier;
  81                         ulen = mnt_s->fscache_key->key.uniq_len;
  82                 }
  83         }
  84
  85         if (!uniq) {
  86                 uniq = "";
  87                 ulen = 1;
  88         }
  89
  90         key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
  91         if (!key)
  92                 return;
  93
  94         key->nfs_client = nfss->nfs_client;
  95         key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
  96         key->key.nfs_server.flags = nfss->flags;
  97         key->key.nfs_server.rsize = nfss->rsize;
  98         key->key.nfs_server.wsize = nfss->wsize;
  99         key->key.nfs_server.acregmin = nfss->acregmin;
 100         key->key.nfs_server.acregmax = nfss->acregmax;
 101         key->key.nfs_server.acdirmin = nfss->acdirmin;
 102         key->key.nfs_server.acdirmax = nfss->acdirmax;
 103         key->key.nfs_server.fsid = nfss->fsid;
 104         key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
 105
 106         key->key.uniq_len = ulen;
 107         memcpy(key->key.uniquifier, uniq, ulen);
 108
 109         spin_lock(&nfs_fscache_keys_lock);
 110         p = &nfs_fscache_keys.rb_node;
 111         parent = NULL;
 112         while (*p) {
 113                 parent = *p;
 114                 xkey = rb_entry(parent, struct nfs_fscache_key, node);
 115
 116                 if (key->nfs_client < xkey->nfs_client)
 117                         goto go_left;
 118                 if (key->nfs_client > xkey->nfs_client)
 119                         goto go_right;
 120
 121                 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
 122                 if (diff < 0)
 123                         goto go_left;
 124                 if (diff > 0)
 125                         goto go_right;
 126
 127                 if (key->key.uniq_len == 0)
 128                         goto non_unique;
 129                 diff = memcmp(key->key.uniquifier,
 130                               xkey->key.uniquifier,
 131                               key->key.uniq_len);
 132                 if (diff < 0)
 133                         goto go_left;
 134                 if (diff > 0)
 135                         goto go_right;
 136                 goto non_unique;
 137
 138         go_left:
 139                 p = &(*p)->rb_left;
 140                 continue;
 141         go_right:
 142                 p = &(*p)->rb_right;
 143         }
 144
 145         rb_link_node(&key->node, parent, p);
 146         rb_insert_color(&key->node, &nfs_fscache_keys);
 147         spin_unlock(&nfs_fscache_keys_lock);
 148         nfss->fscache_key = key;
 149
 150         /* create a cache index for looking up filehandles */
 151         nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
 152                                                &nfs_fscache_super_index_def,
 153                                                nfss);
 154         dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
 155                  nfss, nfss->fscache);
 156         return;
 157
 158 non_unique:
 159         spin_unlock(&nfs_fscache_keys_lock);
 160         kfree(key);
 161         nfss->fscache_key = NULL;
 162         nfss->fscache = NULL;
 163         printk(KERN_WARNING "NFS:"
 164                " Cache request denied due to non-unique superblock keys\n");
 165 }
 166
 167 /*
 168  * release a per-superblock cookie
 169  */
 170 void nfs_fscache_release_super_cookie(struct super_block *sb)
 171 {
 172         struct nfs_server *nfss = NFS_SB(sb);
 173
 174         dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
 175                  nfss, nfss->fscache);
 176
 177         fscache_relinquish_cookie(nfss->fscache, 0);
 178         nfss->fscache = NULL;
 179
 180         if (nfss->fscache_key) {
 181                 spin_lock(&nfs_fscache_keys_lock);
 182                 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
 183                 spin_unlock(&nfs_fscache_keys_lock);
 184                 kfree(nfss->fscache_key);
 185                 nfss->fscache_key = NULL;
 186         }
 187 }
 188
 189 /*
 190  * Initialise the per-inode cache cookie pointer for an NFS inode.
 191  */
 192 void nfs_fscache_init_inode_cookie(struct inode *inode)
 193 {
 194         NFS_I(inode)->fscache = NULL;
 195         if (S_ISREG(inode->i_mode))
 196                 set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 197 }
 198
 199 /*
 200  * Get the per-inode cache cookie for an NFS inode.
 201  */
 202 static void nfs_fscache_enable_inode_cookie(struct inode *inode)
 203 {
 204         struct super_block *sb = inode->i_sb;
 205         struct nfs_inode *nfsi = NFS_I(inode);
 206
 207         if (nfsi->fscache || !NFS_FSCACHE(inode))
 208                 return;
 209
 210         if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
 211                 nfsi->fscache = fscache_acquire_cookie(
 212                         NFS_SB(sb)->fscache,
 213                         &nfs_fscache_inode_object_def,
 214                         nfsi);
 215
 216                 dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
 217                          sb, nfsi, nfsi->fscache);
 218         }
 219 }
 220
 221 /*
 222  * Release a per-inode cookie.
 223  */
 224 void nfs_fscache_release_inode_cookie(struct inode *inode)
 225 {
 226         struct nfs_inode *nfsi = NFS_I(inode);
 227
 228         dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
 229                  nfsi, nfsi->fscache);
 230
 231         fscache_relinquish_cookie(nfsi->fscache, 0);
 232         nfsi->fscache = NULL;
 233 }
 234
 235 /*
 236  * Retire a per-inode cookie, destroying the data attached to it.
 237  */
 238 void nfs_fscache_zap_inode_cookie(struct inode *inode)
 239 {
 240         struct nfs_inode *nfsi = NFS_I(inode);
 241
 242         dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
 243                  nfsi, nfsi->fscache);
 244
 245         fscache_relinquish_cookie(nfsi->fscache, 1);
 246         nfsi->fscache = NULL;
 247 }
 248
 249 /*
 250  * Turn off the cache with regard to a per-inode cookie if opened for writing,
 251  * invalidating all the pages in the page cache relating to the associated
 252  * inode to clear the per-page caching.
 253  */
 254 static void nfs_fscache_disable_inode_cookie(struct inode *inode)
 255 {
 256         clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 257
 258         if (NFS_I(inode)->fscache) {
 259                 dfprintk(FSCACHE,
 260                          "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
 261
 262                 /* Need to invalidate any mapped pages that were read in before
 263                  * turning off the cache.
 264                  */
 265                 if (inode->i_mapping && inode->i_mapping->nrpages)
 266                         invalidate_inode_pages2(inode->i_mapping);
 267
 268                 nfs_fscache_zap_inode_cookie(inode);
 269         }
 270 }
 271
 272 /*
 273  * wait_on_bit() sleep function for uninterruptible waiting
 274  */
 275 static int nfs_fscache_wait_bit(void *flags)
 276 {
 277         schedule();
 278         return 0;
 279 }
 280
 281 /*
 282  * Lock against someone else trying to also acquire or relinquish a cookie
 283  */
 284 static inline void nfs_fscache_inode_lock(struct inode *inode)
 285 {
 286         struct nfs_inode *nfsi = NFS_I(inode);
 287
 288         while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
 289                 wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
 290                             nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
 291 }
 292
 293 /*
 294  * Unlock cookie management lock
 295  */
 296 static inline void nfs_fscache_inode_unlock(struct inode *inode)
 297 {
 298         struct nfs_inode *nfsi = NFS_I(inode);
 299
 300         smp_mb__before_clear_bit();
 301         clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
 302         smp_mb__after_clear_bit();
 303         wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
 304 }
 305
 306 /*
 307  * Decide if we should enable or disable local caching for this inode.
 308  * - For now, with NFS, only regular files that are open read-only will be able
 309  *   to use the cache.
 310  * - May be invoked multiple times in parallel by parallel nfs_open() functions.
 311  */
 312 void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
 313 {
 314         if (NFS_FSCACHE(inode)) {
 315                 nfs_fscache_inode_lock(inode);
 316                 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 317                         nfs_fscache_disable_inode_cookie(inode);
 318                 else
 319                         nfs_fscache_enable_inode_cookie(inode);
 320                 nfs_fscache_inode_unlock(inode);
 321         }
 322 }
 323
 324 /*
 325  * Replace a per-inode cookie due to revalidation detecting a file having
 326  * changed on the server.
 327  */
 328 void nfs_fscache_reset_inode_cookie(struct inode *inode)
 329 {
 330         struct nfs_inode *nfsi = NFS_I(inode);
 331         struct nfs_server *nfss = NFS_SERVER(inode);
 332         struct fscache_cookie *old = nfsi->fscache;
 333
 334         nfs_fscache_inode_lock(inode);
 335         if (nfsi->fscache) {
 336                 /* retire the current fscache cache and get a new one */
 337                 fscache_relinquish_cookie(nfsi->fscache, 1);
 338
 339                 nfsi->fscache = fscache_acquire_cookie(
 340                         nfss->nfs_client->fscache,
 341                         &nfs_fscache_inode_object_def,
 342                         nfsi);
 343
 344                 dfprintk(FSCACHE,
 345                          "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
 346                          nfss, nfsi, old, nfsi->fscache);
 347         }
 348         nfs_fscache_inode_unlock(inode);
 349 }
 350
 351 /*
 352  * Release the caching state associated with a page, if the page isn't busy
 353  * interacting with the cache.
 354  * - Returns true (can release page) or false (page busy).
 355  */
 356 int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 357 {
 358         if (PageFsCache(page)) {
 359                 struct nfs_inode *nfsi = NFS_I(page->mapping->host);
 360                 struct fscache_cookie *cookie = nfsi->fscache;
 361
 362                 BUG_ON(!cookie);
 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         unsigned npages = *nr_pages;
 471         int ret;
 472
 473         dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
 474                  NFS_I(inode)->fscache, npages, inode);
 475
 476         ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
 477                                           mapping, pages, nr_pages,
 478                                           nfs_readpage_from_fscache_complete,
 479                                           ctx,
 480                                           mapping_gfp_mask(mapping));
 481         if (*nr_pages < npages)
 482                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
 483                                       npages);
 484         if (*nr_pages > 0)
 485                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
 486                                       *nr_pages);
 487
 488         switch (ret) {
 489         case 0: /* read submitted to the cache for all pages */
 490                 BUG_ON(!list_empty(pages));
 491                 BUG_ON(*nr_pages != 0);
 492                 dfprintk(FSCACHE,
 493                          "NFS: nfs_getpages_from_fscache: submitted\n");
 494
 495                 return ret;
 496
 497         case -ENOBUFS: /* some pages aren't cached and can't be */
 498         case -ENODATA: /* some pages aren't cached */
 499                 dfprintk(FSCACHE,
 500                          "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
 501                 return 1;
 502
 503         default:
 504                 dfprintk(FSCACHE,
 505                          "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
 506         }
 507
 508         return ret;
 509 }
 510
 511 /*
 512  * Store a newly fetched page in fscache
 513  * - PG_fscache must be set on the page
 514  */
 515 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
 516 {
 517         int ret;
 518
 519         dfprintk(FSCACHE,
 520                  "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
 521                  NFS_I(inode)->fscache, page, page->index, page->flags, sync);
 522
 523         ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
 524         dfprintk(FSCACHE,
 525                  "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
 526                  page, page->index, page->flags, ret);
 527
 528         if (ret != 0) {
 529                 fscache_uncache_page(NFS_I(inode)->fscache, page);
 530                 nfs_add_fscache_stats(inode,
 531                                       NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
 532                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
 533         } else {
 534                 nfs_add_fscache_stats(inode,
 535                                       NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
 536         }
 537 }