fs/nfs/fscache.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* NFS filesystem cache interface
   3  *
   4  * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/kernel.h>
  10 #include <linux/sched.h>
  11 #include <linux/mm.h>
  12 #include <linux/nfs_fs.h>
  13 #include <linux/nfs_fs_sb.h>
  14 #include <linux/in6.h>
  15 #include <linux/seq_file.h>
  16 #include <linux/slab.h>
  17 #include <linux/iversion.h>
  18
  19 #include "internal.h"
  20 #include "iostat.h"
  21 #include "fscache.h"
  22
  23 #define NFSDBG_FACILITY         NFSDBG_FSCACHE
  24
  25 static struct rb_root nfs_fscache_keys = RB_ROOT;
  26 static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
  27
  28 /*
  29  * Layout of the key for an NFS server cache object.
  30  */
  31 struct nfs_server_key {
  32         struct {
  33                 uint16_t        nfsversion;             /* NFS protocol version */
  34                 uint32_t        minorversion;           /* NFSv4 minor version */
  35                 uint16_t        family;                 /* address family */
  36                 __be16          port;                   /* IP port */
  37         } hdr;
  38         union {
  39                 struct in_addr  ipv4_addr;      /* IPv4 address */
  40                 struct in6_addr ipv6_addr;      /* IPv6 address */
  41         };
  42 } __packed;
  43
  44 /*
  45  * Get the per-client index cookie for an NFS client if the appropriate mount
  46  * flag was set
  47  * - We always try and get an index cookie for the client, but get filehandle
  48  *   cookies on a per-superblock basis, depending on the mount flags
  49  */
  50 void nfs_fscache_get_client_cookie(struct nfs_client *clp)
  51 {
  52         const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
  53         const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
  54         struct nfs_server_key key;
  55         uint16_t len = sizeof(key.hdr);
  56
  57         memset(&key, 0, sizeof(key));
  58         key.hdr.nfsversion = clp->rpc_ops->version;
  59         key.hdr.minorversion = clp->cl_minorversion;
  60         key.hdr.family = clp->cl_addr.ss_family;
  61
  62         switch (clp->cl_addr.ss_family) {
  63         case AF_INET:
  64                 key.hdr.port = sin->sin_port;
  65                 key.ipv4_addr = sin->sin_addr;
  66                 len += sizeof(key.ipv4_addr);
  67                 break;
  68
  69         case AF_INET6:
  70                 key.hdr.port = sin6->sin6_port;
  71                 key.ipv6_addr = sin6->sin6_addr;
  72                 len += sizeof(key.ipv6_addr);
  73                 break;
  74
  75         default:
  76                 printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
  77                        clp->cl_addr.ss_family);
  78                 clp->fscache = NULL;
  79                 return;
  80         }
  81
  82         /* create a cache index for looking up filehandles */
  83         clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
  84                                               &nfs_fscache_server_index_def,
  85                                               &key, len,
  86                                               NULL, 0,
  87                                               clp, 0, true);
  88         dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
  89                  clp, clp->fscache);
  90 }
  91
  92 /*
  93  * Dispose of a per-client cookie
  94  */
  95 void nfs_fscache_release_client_cookie(struct nfs_client *clp)
  96 {
  97         dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
  98                  clp, clp->fscache);
  99
 100         fscache_relinquish_cookie(clp->fscache, NULL, false);
 101         clp->fscache = NULL;
 102 }
 103
 104 /*
 105  * Get the cache cookie for an NFS superblock.  We have to handle
 106  * uniquification here because the cache doesn't do it for us.
 107  *
 108  * The default uniquifier is just an empty string, but it may be overridden
 109  * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
 110  * superblock across an automount point of some nature.
 111  */
 112 void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
 113 {
 114         struct nfs_fscache_key *key, *xkey;
 115         struct nfs_server *nfss = NFS_SB(sb);
 116         struct rb_node **p, *parent;
 117         int diff;
 118
 119         nfss->fscache_key = NULL;
 120         nfss->fscache = NULL;
 121         if (!(nfss->options & NFS_OPTION_FSCACHE))
 122                 return;
 123         if (!uniq) {
 124                 uniq = "";
 125                 ulen = 1;
 126         }
 127
 128         key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
 129         if (!key)
 130                 return;
 131
 132         key->nfs_client = nfss->nfs_client;
 133         key->key.super.s_flags = sb->s_flags & NFS_SB_MASK;
 134         key->key.nfs_server.flags = nfss->flags;
 135         key->key.nfs_server.rsize = nfss->rsize;
 136         key->key.nfs_server.wsize = nfss->wsize;
 137         key->key.nfs_server.acregmin = nfss->acregmin;
 138         key->key.nfs_server.acregmax = nfss->acregmax;
 139         key->key.nfs_server.acdirmin = nfss->acdirmin;
 140         key->key.nfs_server.acdirmax = nfss->acdirmax;
 141         key->key.nfs_server.fsid = nfss->fsid;
 142         key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
 143
 144         key->key.uniq_len = ulen;
 145         memcpy(key->key.uniquifier, uniq, ulen);
 146
 147         spin_lock(&nfs_fscache_keys_lock);
 148         p = &nfs_fscache_keys.rb_node;
 149         parent = NULL;
 150         while (*p) {
 151                 parent = *p;
 152                 xkey = rb_entry(parent, struct nfs_fscache_key, node);
 153
 154                 if (key->nfs_client < xkey->nfs_client)
 155                         goto go_left;
 156                 if (key->nfs_client > xkey->nfs_client)
 157                         goto go_right;
 158
 159                 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
 160                 if (diff < 0)
 161                         goto go_left;
 162                 if (diff > 0)
 163                         goto go_right;
 164
 165                 if (key->key.uniq_len == 0)
 166                         goto non_unique;
 167                 diff = memcmp(key->key.uniquifier,
 168                               xkey->key.uniquifier,
 169                               key->key.uniq_len);
 170                 if (diff < 0)
 171                         goto go_left;
 172                 if (diff > 0)
 173                         goto go_right;
 174                 goto non_unique;
 175
 176         go_left:
 177                 p = &(*p)->rb_left;
 178                 continue;
 179         go_right:
 180                 p = &(*p)->rb_right;
 181         }
 182
 183         rb_link_node(&key->node, parent, p);
 184         rb_insert_color(&key->node, &nfs_fscache_keys);
 185         spin_unlock(&nfs_fscache_keys_lock);
 186         nfss->fscache_key = key;
 187
 188         /* create a cache index for looking up filehandles */
 189         nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
 190                                                &nfs_fscache_super_index_def,
 191                                                key, sizeof(*key) + ulen,
 192                                                NULL, 0,
 193                                                nfss, 0, true);
 194         dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
 195                  nfss, nfss->fscache);
 196         return;
 197
 198 non_unique:
 199         spin_unlock(&nfs_fscache_keys_lock);
 200         kfree(key);
 201         nfss->fscache_key = NULL;
 202         nfss->fscache = NULL;
 203         printk(KERN_WARNING "NFS:"
 204                " Cache request denied due to non-unique superblock keys\n");
 205 }
 206
 207 /*
 208  * release a per-superblock cookie
 209  */
 210 void nfs_fscache_release_super_cookie(struct super_block *sb)
 211 {
 212         struct nfs_server *nfss = NFS_SB(sb);
 213
 214         dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
 215                  nfss, nfss->fscache);
 216
 217         fscache_relinquish_cookie(nfss->fscache, NULL, false);
 218         nfss->fscache = NULL;
 219
 220         if (nfss->fscache_key) {
 221                 spin_lock(&nfs_fscache_keys_lock);
 222                 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
 223                 spin_unlock(&nfs_fscache_keys_lock);
 224                 kfree(nfss->fscache_key);
 225                 nfss->fscache_key = NULL;
 226         }
 227 }
 228
 229 /*
 230  * Initialise the per-inode cache cookie pointer for an NFS inode.
 231  */
 232 void nfs_fscache_init_inode(struct inode *inode)
 233 {
 234         struct nfs_fscache_inode_auxdata auxdata;
 235         struct nfs_server *nfss = NFS_SERVER(inode);
 236         struct nfs_inode *nfsi = NFS_I(inode);
 237
 238         nfsi->fscache = NULL;
 239         if (!(nfss->fscache && S_ISREG(inode->i_mode)))
 240                 return;
 241
 242         memset(&auxdata, 0, sizeof(auxdata));
 243         auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
 244         auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
 245         auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
 246         auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
 247
 248         if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
 249                 auxdata.change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);
 250
 251         nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
 252                                                &nfs_fscache_inode_object_def,
 253                                                nfsi->fh.data, nfsi->fh.size,
 254                                                &auxdata, sizeof(auxdata),
 255                                                nfsi, nfsi->vfs_inode.i_size, false);
 256 }
 257
 258 /*
 259  * Release a per-inode cookie.
 260  */
 261 void nfs_fscache_clear_inode(struct inode *inode)
 262 {
 263         struct nfs_fscache_inode_auxdata auxdata;
 264         struct nfs_inode *nfsi = NFS_I(inode);
 265         struct fscache_cookie *cookie = nfs_i_fscache(inode);
 266
 267         dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);
 268
 269         memset(&auxdata, 0, sizeof(auxdata));
 270         auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
 271         auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
 272         auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
 273         auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
 274         fscache_relinquish_cookie(cookie, &auxdata, false);
 275         nfsi->fscache = NULL;
 276 }
 277
 278 static bool nfs_fscache_can_enable(void *data)
 279 {
 280         struct inode *inode = data;
 281
 282         return !inode_is_open_for_write(inode);
 283 }
 284
 285 /*
 286  * Enable or disable caching for a file that is being opened as appropriate.
 287  * The cookie is allocated when the inode is initialised, but is not enabled at
 288  * that time.  Enablement is deferred to file-open time to avoid stat() and
 289  * access() thrashing the cache.
 290  *
 291  * For now, with NFS, only regular files that are open read-only will be able
 292  * to use the cache.
 293  *
 294  * We enable the cache for an inode if we open it read-only and it isn't
 295  * currently open for writing.  We disable the cache if the inode is open
 296  * write-only.
 297  *
 298  * The caller uses the file struct to pin i_writecount on the inode before
 299  * calling us when a file is opened for writing, so we can make use of that.
 300  *
 301  * Note that this may be invoked multiple times in parallel by parallel
 302  * nfs_open() functions.
 303  */
 304 void nfs_fscache_open_file(struct inode *inode, struct file *filp)
 305 {
 306         struct nfs_fscache_inode_auxdata auxdata;
 307         struct nfs_inode *nfsi = NFS_I(inode);
 308         struct fscache_cookie *cookie = nfs_i_fscache(inode);
 309
 310         if (!fscache_cookie_valid(cookie))
 311                 return;
 312
 313         memset(&auxdata, 0, sizeof(auxdata));
 314         auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
 315         auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
 316         auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
 317         auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
 318
 319         if (inode_is_open_for_write(inode)) {
 320                 dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);
 321                 clear_bit(NFS_INO_FSCACHE, &nfsi->flags);
 322                 fscache_disable_cookie(cookie, &auxdata, true);
 323                 fscache_uncache_all_inode_pages(cookie, inode);
 324         } else {
 325                 dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi);
 326                 fscache_enable_cookie(cookie, &auxdata, nfsi->vfs_inode.i_size,
 327                                       nfs_fscache_can_enable, inode);
 328                 if (fscache_cookie_enabled(cookie))
 329                         set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 330         }
 331 }
 332 EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
 333
 334 /*
 335  * Release the caching state associated with a page, if the page isn't busy
 336  * interacting with the cache.
 337  * - Returns true (can release page) or false (page busy).
 338  */
 339 int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 340 {
 341         if (PageFsCache(page)) {
 342                 struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
 343
 344                 BUG_ON(!cookie);
 345                 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
 346                          cookie, page, NFS_I(page->mapping->host));
 347
 348                 if (!fscache_maybe_release_page(cookie, page, gfp))
 349                         return 0;
 350
 351                 nfs_inc_fscache_stats(page->mapping->host,
 352                                       NFSIOS_FSCACHE_PAGES_UNCACHED);
 353         }
 354
 355         return 1;
 356 }
 357
 358 /*
 359  * Release the caching state associated with a page if undergoing complete page
 360  * invalidation.
 361  */
 362 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
 363 {
 364         struct fscache_cookie *cookie = nfs_i_fscache(inode);
 365
 366         BUG_ON(!cookie);
 367
 368         dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
 369                  cookie, page, NFS_I(inode));
 370
 371         fscache_wait_on_page_write(cookie, page);
 372
 373         BUG_ON(!PageLocked(page));
 374         fscache_uncache_page(cookie, page);
 375         nfs_inc_fscache_stats(page->mapping->host,
 376                               NFSIOS_FSCACHE_PAGES_UNCACHED);
 377 }
 378
 379 /*
 380  * Handle completion of a page being read from the cache.
 381  * - Called in process (keventd) context.
 382  */
 383 static void nfs_readpage_from_fscache_complete(struct page *page,
 384                                                void *context,
 385                                                int error)
 386 {
 387         dfprintk(FSCACHE,
 388                  "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
 389                  page, context, error);
 390
 391         /* if the read completes with an error, we just unlock the page and let
 392          * the VM reissue the readpage */
 393         if (!error) {
 394                 SetPageUptodate(page);
 395                 unlock_page(page);
 396         } else {
 397                 error = nfs_readpage_async(context, page->mapping->host, page);
 398                 if (error)
 399                         unlock_page(page);
 400         }
 401 }
 402
 403 /*
 404  * Retrieve a page from fscache
 405  */
 406 int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
 407                                 struct inode *inode, struct page *page)
 408 {
 409         int ret;
 410
 411         dfprintk(FSCACHE,
 412                  "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
 413                  nfs_i_fscache(inode), page, page->index, page->flags, inode);
 414
 415         ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
 416                                          page,
 417                                          nfs_readpage_from_fscache_complete,
 418                                          ctx,
 419                                          GFP_KERNEL);
 420
 421         switch (ret) {
 422         case 0: /* read BIO submitted (page in fscache) */
 423                 dfprintk(FSCACHE,
 424                          "NFS:    readpage_from_fscache: BIO submitted\n");
 425                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
 426                 return ret;
 427
 428         case -ENOBUFS: /* inode not in cache */
 429         case -ENODATA: /* page not in cache */
 430                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
 431                 dfprintk(FSCACHE,
 432                          "NFS:    readpage_from_fscache %d\n", ret);
 433                 return 1;
 434
 435         default:
 436                 dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
 437                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
 438         }
 439         return ret;
 440 }
 441
 442 /*
 443  * Retrieve a set of pages from fscache
 444  */
 445 int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 446                                  struct inode *inode,
 447                                  struct address_space *mapping,
 448                                  struct list_head *pages,
 449                                  unsigned *nr_pages)
 450 {
 451         unsigned npages = *nr_pages;
 452         int ret;
 453
 454         dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
 455                  nfs_i_fscache(inode), npages, inode);
 456
 457         ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
 458                                           mapping, pages, nr_pages,
 459                                           nfs_readpage_from_fscache_complete,
 460                                           ctx,
 461                                           mapping_gfp_mask(mapping));
 462         if (*nr_pages < npages)
 463                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
 464                                       npages);
 465         if (*nr_pages > 0)
 466                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
 467                                       *nr_pages);
 468
 469         switch (ret) {
 470         case 0: /* read submitted to the cache for all pages */
 471                 BUG_ON(!list_empty(pages));
 472                 BUG_ON(*nr_pages != 0);
 473                 dfprintk(FSCACHE,
 474                          "NFS: nfs_getpages_from_fscache: submitted\n");
 475
 476                 return ret;
 477
 478         case -ENOBUFS: /* some pages aren't cached and can't be */
 479         case -ENODATA: /* some pages aren't cached */
 480                 dfprintk(FSCACHE,
 481                          "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
 482                 return 1;
 483
 484         default:
 485                 dfprintk(FSCACHE,
 486                          "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
 487         }
 488
 489         return ret;
 490 }
 491
 492 /*
 493  * Store a newly fetched page in fscache
 494  * - PG_fscache must be set on the page
 495  */
 496 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
 497 {
 498         int ret;
 499
 500         dfprintk(FSCACHE,
 501                  "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
 502                  nfs_i_fscache(inode), page, page->index, page->flags, sync);
 503
 504         ret = fscache_write_page(nfs_i_fscache(inode), page,
 505                                  inode->i_size, GFP_KERNEL);
 506         dfprintk(FSCACHE,
 507                  "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
 508                  page, page->index, page->flags, ret);
 509
 510         if (ret != 0) {
 511                 fscache_uncache_page(nfs_i_fscache(inode), page);
 512                 nfs_inc_fscache_stats(inode,
 513                                       NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
 514                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
 515         } else {
 516                 nfs_inc_fscache_stats(inode,
 517                                       NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
 518         }
 519 }