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