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 (!uniq) {
 122                 uniq = "";
 123                 ulen = 1;
 124         }
 125
 126         key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
 127         if (!key)
 128                 return;
 129
 130         key->nfs_client = nfss->nfs_client;
 131         key->key.super.s_flags = sb->s_flags & NFS_SB_MASK;
 132         key->key.nfs_server.flags = nfss->flags;
 133         key->key.nfs_server.rsize = nfss->rsize;
 134         key->key.nfs_server.wsize = nfss->wsize;
 135         key->key.nfs_server.acregmin = nfss->acregmin;
 136         key->key.nfs_server.acregmax = nfss->acregmax;
 137         key->key.nfs_server.acdirmin = nfss->acdirmin;
 138         key->key.nfs_server.acdirmax = nfss->acdirmax;
 139         key->key.nfs_server.fsid = nfss->fsid;
 140         key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
 141
 142         key->key.uniq_len = ulen;
 143         memcpy(key->key.uniquifier, uniq, ulen);
 144
 145         spin_lock(&nfs_fscache_keys_lock);
 146         p = &nfs_fscache_keys.rb_node;
 147         parent = NULL;
 148         while (*p) {
 149                 parent = *p;
 150                 xkey = rb_entry(parent, struct nfs_fscache_key, node);
 151
 152                 if (key->nfs_client < xkey->nfs_client)
 153                         goto go_left;
 154                 if (key->nfs_client > xkey->nfs_client)
 155                         goto go_right;
 156
 157                 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
 158                 if (diff < 0)
 159                         goto go_left;
 160                 if (diff > 0)
 161                         goto go_right;
 162
 163                 if (key->key.uniq_len == 0)
 164                         goto non_unique;
 165                 diff = memcmp(key->key.uniquifier,
 166                               xkey->key.uniquifier,
 167                               key->key.uniq_len);
 168                 if (diff < 0)
 169                         goto go_left;
 170                 if (diff > 0)
 171                         goto go_right;
 172                 goto non_unique;
 173
 174         go_left:
 175                 p = &(*p)->rb_left;
 176                 continue;
 177         go_right:
 178                 p = &(*p)->rb_right;
 179         }
 180
 181         rb_link_node(&key->node, parent, p);
 182         rb_insert_color(&key->node, &nfs_fscache_keys);
 183         spin_unlock(&nfs_fscache_keys_lock);
 184         nfss->fscache_key = key;
 185
 186         /* create a cache index for looking up filehandles */
 187         nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
 188                                                &nfs_fscache_super_index_def,
 189                                                &key->key,
 190                                                sizeof(key->key) + ulen,
 191                                                NULL, 0,
 192                                                nfss, 0, true);
 193         dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
 194                  nfss, nfss->fscache);
 195         return;
 196
 197 non_unique:
 198         spin_unlock(&nfs_fscache_keys_lock);
 199         kfree(key);
 200         nfss->fscache_key = NULL;
 201         nfss->fscache = NULL;
 202         printk(KERN_WARNING "NFS:"
 203                " Cache request denied due to non-unique superblock keys\n");
 204 }
 205
 206 /*
 207  * release a per-superblock cookie
 208  */
 209 void nfs_fscache_release_super_cookie(struct super_block *sb)
 210 {
 211         struct nfs_server *nfss = NFS_SB(sb);
 212
 213         dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
 214                  nfss, nfss->fscache);
 215
 216         fscache_relinquish_cookie(nfss->fscache, NULL, false);
 217         nfss->fscache = NULL;
 218
 219         if (nfss->fscache_key) {
 220                 spin_lock(&nfs_fscache_keys_lock);
 221                 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
 222                 spin_unlock(&nfs_fscache_keys_lock);
 223                 kfree(nfss->fscache_key);
 224                 nfss->fscache_key = NULL;
 225         }
 226 }
 227
 228 static void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
 229                                   struct nfs_inode *nfsi)
 230 {
 231         memset(auxdata, 0, sizeof(*auxdata));
 232         auxdata->mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
 233         auxdata->mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
 234         auxdata->ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
 235         auxdata->ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
 236
 237         if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
 238                 auxdata->change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);
 239 }
 240
 241 /*
 242  * Initialise the per-inode cache cookie pointer for an NFS inode.
 243  */
 244 void nfs_fscache_init_inode(struct inode *inode)
 245 {
 246         struct nfs_fscache_inode_auxdata auxdata;
 247         struct nfs_server *nfss = NFS_SERVER(inode);
 248         struct nfs_inode *nfsi = NFS_I(inode);
 249
 250         nfsi->fscache = NULL;
 251         if (!(nfss->fscache && S_ISREG(inode->i_mode)))
 252                 return;
 253
 254         nfs_fscache_update_auxdata(&auxdata, nfsi);
 255
 256         nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
 257                                                &nfs_fscache_inode_object_def,
 258                                                nfsi->fh.data, nfsi->fh.size,
 259                                                &auxdata, sizeof(auxdata),
 260                                                nfsi, nfsi->vfs_inode.i_size, false);
 261 }
 262
 263 /*
 264  * Release a per-inode cookie.
 265  */
 266 void nfs_fscache_clear_inode(struct inode *inode)
 267 {
 268         struct nfs_fscache_inode_auxdata auxdata;
 269         struct nfs_inode *nfsi = NFS_I(inode);
 270         struct fscache_cookie *cookie = nfs_i_fscache(inode);
 271
 272         dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);
 273
 274         nfs_fscache_update_auxdata(&auxdata, nfsi);
 275         fscache_relinquish_cookie(cookie, &auxdata, false);
 276         nfsi->fscache = NULL;
 277 }
 278
 279 static bool nfs_fscache_can_enable(void *data)
 280 {
 281         struct inode *inode = data;
 282
 283         return !inode_is_open_for_write(inode);
 284 }
 285
 286 /*
 287  * Enable or disable caching for a file that is being opened as appropriate.
 288  * The cookie is allocated when the inode is initialised, but is not enabled at
 289  * that time.  Enablement is deferred to file-open time to avoid stat() and
 290  * access() thrashing the cache.
 291  *
 292  * For now, with NFS, only regular files that are open read-only will be able
 293  * to use the cache.
 294  *
 295  * We enable the cache for an inode if we open it read-only and it isn't
 296  * currently open for writing.  We disable the cache if the inode is open
 297  * write-only.
 298  *
 299  * The caller uses the file struct to pin i_writecount on the inode before
 300  * calling us when a file is opened for writing, so we can make use of that.
 301  *
 302  * Note that this may be invoked multiple times in parallel by parallel
 303  * nfs_open() functions.
 304  */
 305 void nfs_fscache_open_file(struct inode *inode, struct file *filp)
 306 {
 307         struct nfs_fscache_inode_auxdata auxdata;
 308         struct nfs_inode *nfsi = NFS_I(inode);
 309         struct fscache_cookie *cookie = nfs_i_fscache(inode);
 310
 311         if (!fscache_cookie_valid(cookie))
 312                 return;
 313
 314         nfs_fscache_update_auxdata(&auxdata, nfsi);
 315
 316         if (inode_is_open_for_write(inode)) {
 317                 dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);
 318                 clear_bit(NFS_INO_FSCACHE, &nfsi->flags);
 319                 fscache_disable_cookie(cookie, &auxdata, true);
 320                 fscache_uncache_all_inode_pages(cookie, inode);
 321         } else {
 322                 dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi);
 323                 fscache_enable_cookie(cookie, &auxdata, nfsi->vfs_inode.i_size,
 324                                       nfs_fscache_can_enable, inode);
 325                 if (fscache_cookie_enabled(cookie))
 326                         set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 327         }
 328 }
 329 EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
 330
 331 /*
 332  * Release the caching state associated with a page, if the page isn't busy
 333  * interacting with the cache.
 334  * - Returns true (can release page) or false (page busy).
 335  */
 336 int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 337 {
 338         if (PageFsCache(page)) {
 339                 struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
 340
 341                 BUG_ON(!cookie);
 342                 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
 343                          cookie, page, NFS_I(page->mapping->host));
 344
 345                 if (!fscache_maybe_release_page(cookie, page, gfp))
 346                         return 0;
 347
 348                 nfs_inc_fscache_stats(page->mapping->host,
 349                                       NFSIOS_FSCACHE_PAGES_UNCACHED);
 350         }
 351
 352         return 1;
 353 }
 354
 355 /*
 356  * Release the caching state associated with a page if undergoing complete page
 357  * invalidation.
 358  */
 359 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
 360 {
 361         struct fscache_cookie *cookie = nfs_i_fscache(inode);
 362
 363         BUG_ON(!cookie);
 364
 365         dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
 366                  cookie, page, NFS_I(inode));
 367
 368         fscache_wait_on_page_write(cookie, page);
 369
 370         BUG_ON(!PageLocked(page));
 371         fscache_uncache_page(cookie, page);
 372         nfs_inc_fscache_stats(page->mapping->host,
 373                               NFSIOS_FSCACHE_PAGES_UNCACHED);
 374 }
 375
 376 /*
 377  * Handle completion of a page being read from the cache.
 378  * - Called in process (keventd) context.
 379  */
 380 static void nfs_readpage_from_fscache_complete(struct page *page,
 381                                                void *context,
 382                                                int error)
 383 {
 384         dfprintk(FSCACHE,
 385                  "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
 386                  page, context, error);
 387
 388         /*
 389          * If the read completes with an error, mark the page with PG_checked,
 390          * unlock the page, and let the VM reissue the readpage.
 391          */
 392         if (!error)
 393                 SetPageUptodate(page);
 394         else
 395                 SetPageChecked(page);
 396         unlock_page(page);
 397 }
 398
 399 /*
 400  * Retrieve a page from fscache
 401  */
 402 int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
 403                                 struct inode *inode, struct page *page)
 404 {
 405         int ret;
 406
 407         dfprintk(FSCACHE,
 408                  "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
 409                  nfs_i_fscache(inode), page, page->index, page->flags, inode);
 410
 411         if (PageChecked(page)) {
 412                 ClearPageChecked(page);
 413                 return 1;
 414         }
 415
 416         ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
 417                                          page,
 418                                          nfs_readpage_from_fscache_complete,
 419                                          ctx,
 420                                          GFP_KERNEL);
 421
 422         switch (ret) {
 423         case 0: /* read BIO submitted (page in fscache) */
 424                 dfprintk(FSCACHE,
 425                          "NFS:    readpage_from_fscache: BIO submitted\n");
 426                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
 427                 return ret;
 428
 429         case -ENOBUFS: /* inode not in cache */
 430         case -ENODATA: /* page not in cache */
 431                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
 432                 dfprintk(FSCACHE,
 433                          "NFS:    readpage_from_fscache %d\n", ret);
 434                 return 1;
 435
 436         default:
 437                 dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
 438                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
 439         }
 440         return ret;
 441 }
 442
 443 /*
 444  * Retrieve a set of pages from fscache
 445  */
 446 int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 447                                  struct inode *inode,
 448                                  struct address_space *mapping,
 449                                  struct list_head *pages,
 450                                  unsigned *nr_pages)
 451 {
 452         unsigned npages = *nr_pages;
 453         int ret;
 454
 455         dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
 456                  nfs_i_fscache(inode), npages, inode);
 457
 458         ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
 459                                           mapping, pages, nr_pages,
 460                                           nfs_readpage_from_fscache_complete,
 461                                           ctx,
 462                                           mapping_gfp_mask(mapping));
 463         if (*nr_pages < npages)
 464                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
 465                                       npages);
 466         if (*nr_pages > 0)
 467                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
 468                                       *nr_pages);
 469
 470         switch (ret) {
 471         case 0: /* read submitted to the cache for all pages */
 472                 BUG_ON(!list_empty(pages));
 473                 BUG_ON(*nr_pages != 0);
 474                 dfprintk(FSCACHE,
 475                          "NFS: nfs_getpages_from_fscache: submitted\n");
 476
 477                 return ret;
 478
 479         case -ENOBUFS: /* some pages aren't cached and can't be */
 480         case -ENODATA: /* some pages aren't cached */
 481                 dfprintk(FSCACHE,
 482                          "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
 483                 return 1;
 484
 485         default:
 486                 dfprintk(FSCACHE,
 487                          "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
 488         }
 489
 490         return ret;
 491 }
 492
 493 /*
 494  * Store a newly fetched page in fscache
 495  * - PG_fscache must be set on the page
 496  */
 497 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
 498 {
 499         int ret;
 500
 501         dfprintk(FSCACHE,
 502                  "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
 503                  nfs_i_fscache(inode), page, page->index, page->flags, sync);
 504
 505         ret = fscache_write_page(nfs_i_fscache(inode), page,
 506                                  inode->i_size, GFP_KERNEL);
 507         dfprintk(FSCACHE,
 508                  "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
 509                  page, page->index, page->flags, ret);
 510
 511         if (ret != 0) {
 512                 fscache_uncache_page(nfs_i_fscache(inode), page);
 513                 nfs_inc_fscache_stats(inode,
 514                                       NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
 515                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
 516         } else {
 517                 nfs_inc_fscache_stats(inode,
 518                                       NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
 519         }
 520 }