release/src-rt-6.x.4708/linux/linux-2.6.36/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 void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq,
  60                                   struct nfs_clone_mount *mntdata)
  61 {
  62         struct nfs_fscache_key *key, *xkey;
  63         struct nfs_server *nfss = NFS_SB(sb);
  64         struct rb_node **p, *parent;
  65         int diff, ulen;
  66
  67         if (uniq) {
  68                 ulen = strlen(uniq);
  69         } else if (mntdata) {
  70                 struct nfs_server *mnt_s = NFS_SB(mntdata->sb);
  71                 if (mnt_s->fscache_key) {
  72                         uniq = mnt_s->fscache_key->key.uniquifier;
  73                         ulen = mnt_s->fscache_key->key.uniq_len;
  74                 }
  75         }
  76
  77         if (!uniq) {
  78                 uniq = "";
  79                 ulen = 1;
  80         }
  81
  82         key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
  83         if (!key)
  84                 return;
  85
  86         key->nfs_client = nfss->nfs_client;
  87         key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
  88         key->key.nfs_server.flags = nfss->flags;
  89         key->key.nfs_server.rsize = nfss->rsize;
  90         key->key.nfs_server.wsize = nfss->wsize;
  91         key->key.nfs_server.acregmin = nfss->acregmin;
  92         key->key.nfs_server.acregmax = nfss->acregmax;
  93         key->key.nfs_server.acdirmin = nfss->acdirmin;
  94         key->key.nfs_server.acdirmax = nfss->acdirmax;
  95         key->key.nfs_server.fsid = nfss->fsid;
  96         key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
  97
  98         key->key.uniq_len = ulen;
  99         memcpy(key->key.uniquifier, uniq, ulen);
 100
 101         spin_lock(&nfs_fscache_keys_lock);
 102         p = &nfs_fscache_keys.rb_node;
 103         parent = NULL;
 104         while (*p) {
 105                 parent = *p;
 106                 xkey = rb_entry(parent, struct nfs_fscache_key, node);
 107
 108                 if (key->nfs_client < xkey->nfs_client)
 109                         goto go_left;
 110                 if (key->nfs_client > xkey->nfs_client)
 111                         goto go_right;
 112
 113                 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
 114                 if (diff < 0)
 115                         goto go_left;
 116                 if (diff > 0)
 117                         goto go_right;
 118
 119                 if (key->key.uniq_len == 0)
 120                         goto non_unique;
 121                 diff = memcmp(key->key.uniquifier,
 122                               xkey->key.uniquifier,
 123                               key->key.uniq_len);
 124                 if (diff < 0)
 125                         goto go_left;
 126                 if (diff > 0)
 127                         goto go_right;
 128                 goto non_unique;
 129
 130         go_left:
 131                 p = &(*p)->rb_left;
 132                 continue;
 133         go_right:
 134                 p = &(*p)->rb_right;
 135         }
 136
 137         rb_link_node(&key->node, parent, p);
 138         rb_insert_color(&key->node, &nfs_fscache_keys);
 139         spin_unlock(&nfs_fscache_keys_lock);
 140         nfss->fscache_key = key;
 141
 142         /* create a cache index for looking up filehandles */
 143         nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
 144                                                &nfs_fscache_super_index_def,
 145                                                nfss);
 146         dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
 147                  nfss, nfss->fscache);
 148         return;
 149
 150 non_unique:
 151         spin_unlock(&nfs_fscache_keys_lock);
 152         kfree(key);
 153         nfss->fscache_key = NULL;
 154         nfss->fscache = NULL;
 155         printk(KERN_WARNING "NFS:"
 156                " Cache request denied due to non-unique superblock keys\n");
 157 }
 158
 159 /*
 160  * release a per-superblock cookie
 161  */
 162 void nfs_fscache_release_super_cookie(struct super_block *sb)
 163 {
 164         struct nfs_server *nfss = NFS_SB(sb);
 165
 166         dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
 167                  nfss, nfss->fscache);
 168
 169         fscache_relinquish_cookie(nfss->fscache, 0);
 170         nfss->fscache = NULL;
 171
 172         if (nfss->fscache_key) {
 173                 spin_lock(&nfs_fscache_keys_lock);
 174                 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
 175                 spin_unlock(&nfs_fscache_keys_lock);
 176                 kfree(nfss->fscache_key);
 177                 nfss->fscache_key = NULL;
 178         }
 179 }
 180
 181 /*
 182  * Initialise the per-inode cache cookie pointer for an NFS inode.
 183  */
 184 void nfs_fscache_init_inode_cookie(struct inode *inode)
 185 {
 186         NFS_I(inode)->fscache = NULL;
 187         if (S_ISREG(inode->i_mode))
 188                 set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 189 }
 190
 191 /*
 192  * Get the per-inode cache cookie for an NFS inode.
 193  */
 194 static void nfs_fscache_enable_inode_cookie(struct inode *inode)
 195 {
 196         struct super_block *sb = inode->i_sb;
 197         struct nfs_inode *nfsi = NFS_I(inode);
 198
 199         if (nfsi->fscache || !NFS_FSCACHE(inode))
 200                 return;
 201
 202         if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
 203                 nfsi->fscache = fscache_acquire_cookie(
 204                         NFS_SB(sb)->fscache,
 205                         &nfs_fscache_inode_object_def,
 206                         nfsi);
 207
 208                 dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
 209                          sb, nfsi, nfsi->fscache);
 210         }
 211 }
 212
 213 /*
 214  * Release a per-inode cookie.
 215  */
 216 void nfs_fscache_release_inode_cookie(struct inode *inode)
 217 {
 218         struct nfs_inode *nfsi = NFS_I(inode);
 219
 220         dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
 221                  nfsi, nfsi->fscache);
 222
 223         fscache_relinquish_cookie(nfsi->fscache, 0);
 224         nfsi->fscache = NULL;
 225 }
 226
 227 /*
 228  * Retire a per-inode cookie, destroying the data attached to it.
 229  */
 230 void nfs_fscache_zap_inode_cookie(struct inode *inode)
 231 {
 232         struct nfs_inode *nfsi = NFS_I(inode);
 233
 234         dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
 235                  nfsi, nfsi->fscache);
 236
 237         fscache_relinquish_cookie(nfsi->fscache, 1);
 238         nfsi->fscache = NULL;
 239 }
 240
 241 /*
 242  * Turn off the cache with regard to a per-inode cookie if opened for writing,
 243  * invalidating all the pages in the page cache relating to the associated
 244  * inode to clear the per-page caching.
 245  */
 246 static void nfs_fscache_disable_inode_cookie(struct inode *inode)
 247 {
 248         clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 249
 250         if (NFS_I(inode)->fscache) {
 251                 dfprintk(FSCACHE,
 252                          "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
 253
 254                 /* Need to invalidate any mapped pages that were read in before
 255                  * turning off the cache.
 256                  */
 257                 if (inode->i_mapping && inode->i_mapping->nrpages)
 258                         invalidate_inode_pages2(inode->i_mapping);
 259
 260                 nfs_fscache_zap_inode_cookie(inode);
 261         }
 262 }
 263
 264 /*
 265  * wait_on_bit() sleep function for uninterruptible waiting
 266  */
 267 static int nfs_fscache_wait_bit(void *flags)
 268 {
 269         schedule();
 270         return 0;
 271 }
 272
 273 /*
 274  * Lock against someone else trying to also acquire or relinquish a cookie
 275  */
 276 static inline void nfs_fscache_inode_lock(struct inode *inode)
 277 {
 278         struct nfs_inode *nfsi = NFS_I(inode);
 279
 280         while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
 281                 wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
 282                             nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
 283 }
 284
 285 /*
 286  * Unlock cookie management lock
 287  */
 288 static inline void nfs_fscache_inode_unlock(struct inode *inode)
 289 {
 290         struct nfs_inode *nfsi = NFS_I(inode);
 291
 292         smp_mb__before_clear_bit();
 293         clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
 294         smp_mb__after_clear_bit();
 295         wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
 296 }
 297
 298 /*
 299  * Decide if we should enable or disable local caching for this inode.
 300  * - For now, with NFS, only regular files that are open read-only will be able
 301  *   to use the cache.
 302  * - May be invoked multiple times in parallel by parallel nfs_open() functions.
 303  */
 304 void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
 305 {
 306         if (NFS_FSCACHE(inode)) {
 307                 nfs_fscache_inode_lock(inode);
 308                 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 309                         nfs_fscache_disable_inode_cookie(inode);
 310                 else
 311                         nfs_fscache_enable_inode_cookie(inode);
 312                 nfs_fscache_inode_unlock(inode);
 313         }
 314 }
 315
 316 /*
 317  * Replace a per-inode cookie due to revalidation detecting a file having
 318  * changed on the server.
 319  */
 320 void nfs_fscache_reset_inode_cookie(struct inode *inode)
 321 {
 322         struct nfs_inode *nfsi = NFS_I(inode);
 323         struct nfs_server *nfss = NFS_SERVER(inode);
 324         struct fscache_cookie *old = nfsi->fscache;
 325
 326         nfs_fscache_inode_lock(inode);
 327         if (nfsi->fscache) {
 328                 /* retire the current fscache cache and get a new one */
 329                 fscache_relinquish_cookie(nfsi->fscache, 1);
 330
 331                 nfsi->fscache = fscache_acquire_cookie(
 332                         nfss->nfs_client->fscache,
 333                         &nfs_fscache_inode_object_def,
 334                         nfsi);
 335
 336                 dfprintk(FSCACHE,
 337                          "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
 338                          nfss, nfsi, old, nfsi->fscache);
 339         }
 340         nfs_fscache_inode_unlock(inode);
 341 }
 342
 343 /*
 344  * Release the caching state associated with a page, if the page isn't busy
 345  * interacting with the cache.
 346  * - Returns true (can release page) or false (page busy).
 347  */
 348 int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 349 {
 350         if (PageFsCache(page)) {
 351                 struct nfs_inode *nfsi = NFS_I(page->mapping->host);
 352                 struct fscache_cookie *cookie = nfsi->fscache;
 353
 354                 BUG_ON(!cookie);
 355                 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
 356                          cookie, page, nfsi);
 357
 358                 if (!fscache_maybe_release_page(cookie, page, gfp))
 359                         return 0;
 360
 361                 nfs_add_fscache_stats(page->mapping->host,
 362                                       NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
 363         }
 364
 365         return 1;
 366 }
 367
 368 /*
 369  * Release the caching state associated with a page if undergoing complete page
 370  * invalidation.
 371  */
 372 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
 373 {
 374         struct nfs_inode *nfsi = NFS_I(inode);
 375         struct fscache_cookie *cookie = nfsi->fscache;
 376
 377         BUG_ON(!cookie);
 378
 379         dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
 380                  cookie, page, nfsi);
 381
 382         fscache_wait_on_page_write(cookie, page);
 383
 384         BUG_ON(!PageLocked(page));
 385         fscache_uncache_page(cookie, page);
 386         nfs_add_fscache_stats(page->mapping->host,
 387                               NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
 388 }
 389
 390 /*
 391  * Handle completion of a page being read from the cache.
 392  * - Called in process (keventd) context.
 393  */
 394 static void nfs_readpage_from_fscache_complete(struct page *page,
 395                                                void *context,
 396                                                int error)
 397 {
 398         dfprintk(FSCACHE,
 399                  "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
 400                  page, context, error);
 401
 402         /* if the read completes with an error, we just unlock the page and let
 403          * the VM reissue the readpage */
 404         if (!error) {
 405                 SetPageUptodate(page);
 406                 unlock_page(page);
 407         } else {
 408                 error = nfs_readpage_async(context, page->mapping->host, page);
 409                 if (error)
 410                         unlock_page(page);
 411         }
 412 }
 413
 414 /*
 415  * Retrieve a page from fscache
 416  */
 417 int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
 418                                 struct inode *inode, struct page *page)
 419 {
 420         int ret;
 421
 422         dfprintk(FSCACHE,
 423                  "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
 424                  NFS_I(inode)->fscache, page, page->index, page->flags, inode);
 425
 426         ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
 427                                          page,
 428                                          nfs_readpage_from_fscache_complete,
 429                                          ctx,
 430                                          GFP_KERNEL);
 431
 432         switch (ret) {
 433         case 0: /* read BIO submitted (page in fscache) */
 434                 dfprintk(FSCACHE,
 435                          "NFS:    readpage_from_fscache: BIO submitted\n");
 436                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1);
 437                 return ret;
 438
 439         case -ENOBUFS: /* inode not in cache */
 440         case -ENODATA: /* page not in cache */
 441                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
 442                 dfprintk(FSCACHE,
 443                          "NFS:    readpage_from_fscache %d\n", ret);
 444                 return 1;
 445
 446         default:
 447                 dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
 448                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
 449         }
 450         return ret;
 451 }
 452
 453 /*
 454  * Retrieve a set of pages from fscache
 455  */
 456 int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 457                                  struct inode *inode,
 458                                  struct address_space *mapping,
 459                                  struct list_head *pages,
 460                                  unsigned *nr_pages)
 461 {
 462         unsigned npages = *nr_pages;
 463         int ret;
 464
 465         dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
 466                  NFS_I(inode)->fscache, npages, inode);
 467
 468         ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
 469                                           mapping, pages, nr_pages,
 470                                           nfs_readpage_from_fscache_complete,
 471                                           ctx,
 472                                           mapping_gfp_mask(mapping));
 473         if (*nr_pages < npages)
 474                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
 475                                       npages);
 476         if (*nr_pages > 0)
 477                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
 478                                       *nr_pages);
 479
 480         switch (ret) {
 481         case 0: /* read submitted to the cache for all pages */
 482                 BUG_ON(!list_empty(pages));
 483                 BUG_ON(*nr_pages != 0);
 484                 dfprintk(FSCACHE,
 485                          "NFS: nfs_getpages_from_fscache: submitted\n");
 486
 487                 return ret;
 488
 489         case -ENOBUFS: /* some pages aren't cached and can't be */
 490         case -ENODATA: /* some pages aren't cached */
 491                 dfprintk(FSCACHE,
 492                          "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
 493                 return 1;
 494
 495         default:
 496                 dfprintk(FSCACHE,
 497                          "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
 498         }
 499
 500         return ret;
 501 }
 502
 503 /*
 504  * Store a newly fetched page in fscache
 505  * - PG_fscache must be set on the page
 506  */
 507 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
 508 {
 509         int ret;
 510
 511         dfprintk(FSCACHE,
 512                  "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
 513                  NFS_I(inode)->fscache, page, page->index, page->flags, sync);
 514
 515         ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
 516         dfprintk(FSCACHE,
 517                  "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
 518                  page, page->index, page->flags, ret);
 519
 520         if (ret != 0) {
 521                 fscache_uncache_page(NFS_I(inode)->fscache, page);
 522                 nfs_add_fscache_stats(inode,
 523                                       NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
 524                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
 525         } else {
 526                 nfs_add_fscache_stats(inode,
 527                                       NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
 528         }
 529 }