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