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, int ulen)
  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;
  73
  74         if (!uniq) {
  75                 uniq = "";
  76                 ulen = 1;
  77         }
  78
  79         key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
  80         if (!key)
  81                 return;
  82
  83         key->nfs_client = nfss->nfs_client;
  84         key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
  85         key->key.nfs_server.flags = nfss->flags;
  86         key->key.nfs_server.rsize = nfss->rsize;
  87         key->key.nfs_server.wsize = nfss->wsize;
  88         key->key.nfs_server.acregmin = nfss->acregmin;
  89         key->key.nfs_server.acregmax = nfss->acregmax;
  90         key->key.nfs_server.acdirmin = nfss->acdirmin;
  91         key->key.nfs_server.acdirmax = nfss->acdirmax;
  92         key->key.nfs_server.fsid = nfss->fsid;
  93         key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
  94
  95         key->key.uniq_len = ulen;
  96         memcpy(key->key.uniquifier, uniq, ulen);
  97
  98         spin_lock(&nfs_fscache_keys_lock);
  99         p = &nfs_fscache_keys.rb_node;
 100         parent = NULL;
 101         while (*p) {
 102                 parent = *p;
 103                 xkey = rb_entry(parent, struct nfs_fscache_key, node);
 104
 105                 if (key->nfs_client < xkey->nfs_client)
 106                         goto go_left;
 107                 if (key->nfs_client > xkey->nfs_client)
 108                         goto go_right;
 109
 110                 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
 111                 if (diff < 0)
 112                         goto go_left;
 113                 if (diff > 0)
 114                         goto go_right;
 115
 116                 if (key->key.uniq_len == 0)
 117                         goto non_unique;
 118                 diff = memcmp(key->key.uniquifier,
 119                               xkey->key.uniquifier,
 120                               key->key.uniq_len);
 121                 if (diff < 0)
 122                         goto go_left;
 123                 if (diff > 0)
 124                         goto go_right;
 125                 goto non_unique;
 126
 127         go_left:
 128                 p = &(*p)->rb_left;
 129                 continue;
 130         go_right:
 131                 p = &(*p)->rb_right;
 132         }
 133
 134         rb_link_node(&key->node, parent, p);
 135         rb_insert_color(&key->node, &nfs_fscache_keys);
 136         spin_unlock(&nfs_fscache_keys_lock);
 137         nfss->fscache_key = key;
 138
 139         /* create a cache index for looking up filehandles */
 140         nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
 141                                                &nfs_fscache_super_index_def,
 142                                                nfss);
 143         dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
 144                  nfss, nfss->fscache);
 145         return;
 146
 147 non_unique:
 148         spin_unlock(&nfs_fscache_keys_lock);
 149         kfree(key);
 150         nfss->fscache_key = NULL;
 151         nfss->fscache = NULL;
 152         printk(KERN_WARNING "NFS:"
 153                " Cache request denied due to non-unique superblock keys\n");
 154 }
 155
 156 /*
 157  * release a per-superblock cookie
 158  */
 159 void nfs_fscache_release_super_cookie(struct super_block *sb)
 160 {
 161         struct nfs_server *nfss = NFS_SB(sb);
 162
 163         dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
 164                  nfss, nfss->fscache);
 165
 166         fscache_relinquish_cookie(nfss->fscache, 0);
 167         nfss->fscache = NULL;
 168
 169         if (nfss->fscache_key) {
 170                 spin_lock(&nfs_fscache_keys_lock);
 171                 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
 172                 spin_unlock(&nfs_fscache_keys_lock);
 173                 kfree(nfss->fscache_key);
 174                 nfss->fscache_key = NULL;
 175         }
 176 }
 177
 178 /*
 179  * Initialise the per-inode cache cookie pointer for an NFS inode.
 180  */
 181 void nfs_fscache_init_inode_cookie(struct inode *inode)
 182 {
 183         NFS_I(inode)->fscache = NULL;
 184         if (S_ISREG(inode->i_mode))
 185                 set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 186 }
 187
 188 /*
 189  * Get the per-inode cache cookie for an NFS inode.
 190  */
 191 static void nfs_fscache_enable_inode_cookie(struct inode *inode)
 192 {
 193         struct super_block *sb = inode->i_sb;
 194         struct nfs_inode *nfsi = NFS_I(inode);
 195
 196         if (nfsi->fscache || !NFS_FSCACHE(inode))
 197                 return;
 198
 199         if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
 200                 nfsi->fscache = fscache_acquire_cookie(
 201                         NFS_SB(sb)->fscache,
 202                         &nfs_fscache_inode_object_def,
 203                         nfsi);
 204
 205                 dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
 206                          sb, nfsi, nfsi->fscache);
 207         }
 208 }
 209
 210 /*
 211  * Release a per-inode cookie.
 212  */
 213 void nfs_fscache_release_inode_cookie(struct inode *inode)
 214 {
 215         struct nfs_inode *nfsi = NFS_I(inode);
 216
 217         dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
 218                  nfsi, nfsi->fscache);
 219
 220         fscache_relinquish_cookie(nfsi->fscache, 0);
 221         nfsi->fscache = NULL;
 222 }
 223
 224 /*
 225  * Retire a per-inode cookie, destroying the data attached to it.
 226  */
 227 void nfs_fscache_zap_inode_cookie(struct inode *inode)
 228 {
 229         struct nfs_inode *nfsi = NFS_I(inode);
 230
 231         dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
 232                  nfsi, nfsi->fscache);
 233
 234         fscache_relinquish_cookie(nfsi->fscache, 1);
 235         nfsi->fscache = NULL;
 236 }
 237
 238 /*
 239  * Turn off the cache with regard to a per-inode cookie if opened for writing,
 240  * invalidating all the pages in the page cache relating to the associated
 241  * inode to clear the per-page caching.
 242  */
 243 static void nfs_fscache_disable_inode_cookie(struct inode *inode)
 244 {
 245         clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 246
 247         if (NFS_I(inode)->fscache) {
 248                 dfprintk(FSCACHE,
 249                          "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
 250
 251                 /* Need to uncache any pages attached to this inode that
 252                  * fscache knows about before turning off the cache.
 253                  */
 254                 fscache_uncache_all_inode_pages(NFS_I(inode)->fscache, inode);
 255                 nfs_fscache_zap_inode_cookie(inode);
 256         }
 257 }
 258
 259 /*
 260  * wait_on_bit() sleep function for uninterruptible waiting
 261  */
 262 static int nfs_fscache_wait_bit(void *flags)
 263 {
 264         schedule();
 265         return 0;
 266 }
 267
 268 /*
 269  * Lock against someone else trying to also acquire or relinquish a cookie
 270  */
 271 static inline void nfs_fscache_inode_lock(struct inode *inode)
 272 {
 273         struct nfs_inode *nfsi = NFS_I(inode);
 274
 275         while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
 276                 wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
 277                             nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
 278 }
 279
 280 /*
 281  * Unlock cookie management lock
 282  */
 283 static inline void nfs_fscache_inode_unlock(struct inode *inode)
 284 {
 285         struct nfs_inode *nfsi = NFS_I(inode);
 286
 287         smp_mb__before_clear_bit();
 288         clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
 289         smp_mb__after_clear_bit();
 290         wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
 291 }
 292
 293 /*
 294  * Decide if we should enable or disable local caching for this inode.
 295  * - For now, with NFS, only regular files that are open read-only will be able
 296  *   to use the cache.
 297  * - May be invoked multiple times in parallel by parallel nfs_open() functions.
 298  */
 299 void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
 300 {
 301         if (NFS_FSCACHE(inode)) {
 302                 nfs_fscache_inode_lock(inode);
 303                 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 304                         nfs_fscache_disable_inode_cookie(inode);
 305                 else
 306                         nfs_fscache_enable_inode_cookie(inode);
 307                 nfs_fscache_inode_unlock(inode);
 308         }
 309 }
 310 EXPORT_SYMBOL_GPL(nfs_fscache_set_inode_cookie);
 311
 312 /*
 313  * Replace a per-inode cookie due to revalidation detecting a file having
 314  * changed on the server.
 315  */
 316 void nfs_fscache_reset_inode_cookie(struct inode *inode)
 317 {
 318         struct nfs_inode *nfsi = NFS_I(inode);
 319         struct nfs_server *nfss = NFS_SERVER(inode);
 320         NFS_IFDEBUG(struct fscache_cookie *old = nfsi->fscache);
 321
 322         nfs_fscache_inode_lock(inode);
 323         if (nfsi->fscache) {
 324                 /* retire the current fscache cache and get a new one */
 325                 fscache_relinquish_cookie(nfsi->fscache, 1);
 326
 327                 nfsi->fscache = fscache_acquire_cookie(
 328                         nfss->nfs_client->fscache,
 329                         &nfs_fscache_inode_object_def,
 330                         nfsi);
 331
 332                 dfprintk(FSCACHE,
 333                          "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
 334                          nfss, nfsi, old, nfsi->fscache);
 335         }
 336         nfs_fscache_inode_unlock(inode);
 337 }
 338
 339 /*
 340  * Release the caching state associated with a page, if the page isn't busy
 341  * interacting with the cache.
 342  * - Returns true (can release page) or false (page busy).
 343  */
 344 int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 345 {
 346         if (PageFsCache(page)) {
 347                 struct nfs_inode *nfsi = NFS_I(page->mapping->host);
 348                 struct fscache_cookie *cookie = nfsi->fscache;
 349
 350                 BUG_ON(!cookie);
 351                 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
 352                          cookie, page, nfsi);
 353
 354                 if (!fscache_maybe_release_page(cookie, page, gfp))
 355                         return 0;
 356
 357                 nfs_add_fscache_stats(page->mapping->host,
 358                                       NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
 359         }
 360
 361         return 1;
 362 }
 363
 364 /*
 365  * Release the caching state associated with a page if undergoing complete page
 366  * invalidation.
 367  */
 368 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
 369 {
 370         struct nfs_inode *nfsi = NFS_I(inode);
 371         struct fscache_cookie *cookie = nfsi->fscache;
 372
 373         BUG_ON(!cookie);
 374
 375         dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
 376                  cookie, page, nfsi);
 377
 378         fscache_wait_on_page_write(cookie, page);
 379
 380         BUG_ON(!PageLocked(page));
 381         fscache_uncache_page(cookie, page);
 382         nfs_add_fscache_stats(page->mapping->host,
 383                               NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
 384 }
 385
 386 /*
 387  * Handle completion of a page being read from the cache.
 388  * - Called in process (keventd) context.
 389  */
 390 static void nfs_readpage_from_fscache_complete(struct page *page,
 391                                                void *context,
 392                                                int error)
 393 {
 394         dfprintk(FSCACHE,
 395                  "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
 396                  page, context, error);
 397
 398         /* if the read completes with an error, we just unlock the page and let
 399          * the VM reissue the readpage */
 400         if (!error) {
 401                 SetPageUptodate(page);
 402                 unlock_page(page);
 403         } else {
 404                 error = nfs_readpage_async(context, page->mapping->host, page);
 405                 if (error)
 406                         unlock_page(page);
 407         }
 408 }
 409
 410 /*
 411  * Retrieve a page from fscache
 412  */
 413 int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
 414                                 struct inode *inode, struct page *page)
 415 {
 416         int ret;
 417
 418         dfprintk(FSCACHE,
 419                  "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
 420                  NFS_I(inode)->fscache, page, page->index, page->flags, inode);
 421
 422         ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
 423                                          page,
 424                                          nfs_readpage_from_fscache_complete,
 425                                          ctx,
 426                                          GFP_KERNEL);
 427
 428         switch (ret) {
 429         case 0: /* read BIO submitted (page in fscache) */
 430                 dfprintk(FSCACHE,
 431                          "NFS:    readpage_from_fscache: BIO submitted\n");
 432                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1);
 433                 return ret;
 434
 435         case -ENOBUFS: /* inode not in cache */
 436         case -ENODATA: /* page not in cache */
 437                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
 438                 dfprintk(FSCACHE,
 439                          "NFS:    readpage_from_fscache %d\n", ret);
 440                 return 1;
 441
 442         default:
 443                 dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
 444                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
 445         }
 446         return ret;
 447 }
 448
 449 /*
 450  * Retrieve a set of pages from fscache
 451  */
 452 int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 453                                  struct inode *inode,
 454                                  struct address_space *mapping,
 455                                  struct list_head *pages,
 456                                  unsigned *nr_pages)
 457 {
 458         unsigned npages = *nr_pages;
 459         int ret;
 460
 461         dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
 462                  NFS_I(inode)->fscache, npages, inode);
 463
 464         ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
 465                                           mapping, pages, nr_pages,
 466                                           nfs_readpage_from_fscache_complete,
 467                                           ctx,
 468                                           mapping_gfp_mask(mapping));
 469         if (*nr_pages < npages)
 470                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
 471                                       npages);
 472         if (*nr_pages > 0)
 473                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
 474                                       *nr_pages);
 475
 476         switch (ret) {
 477         case 0: /* read submitted to the cache for all pages */
 478                 BUG_ON(!list_empty(pages));
 479                 BUG_ON(*nr_pages != 0);
 480                 dfprintk(FSCACHE,
 481                          "NFS: nfs_getpages_from_fscache: submitted\n");
 482
 483                 return ret;
 484
 485         case -ENOBUFS: /* some pages aren't cached and can't be */
 486         case -ENODATA: /* some pages aren't cached */
 487                 dfprintk(FSCACHE,
 488                          "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
 489                 return 1;
 490
 491         default:
 492                 dfprintk(FSCACHE,
 493                          "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
 494         }
 495
 496         return ret;
 497 }
 498
 499 /*
 500  * Store a newly fetched page in fscache
 501  * - PG_fscache must be set on the page
 502  */
 503 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
 504 {
 505         int ret;
 506
 507         dfprintk(FSCACHE,
 508                  "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
 509                  NFS_I(inode)->fscache, page, page->index, page->flags, sync);
 510
 511         ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
 512         dfprintk(FSCACHE,
 513                  "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
 514                  page, page->index, page->flags, ret);
 515
 516         if (ret != 0) {
 517                 fscache_uncache_page(NFS_I(inode)->fscache, page);
 518                 nfs_add_fscache_stats(inode,
 519                                       NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
 520                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
 521         } else {
 522                 nfs_add_fscache_stats(inode,
 523                                       NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
 524         }
 525 }