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 ([email protected])
   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_MS_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 = timespec64_to_timespec(nfsi->vfs_inode.i_mtime);
 242         auxdata.ctime = timespec64_to_timespec(nfsi->vfs_inode.i_ctime);
 243
 244         if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
 245                 auxdata.change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);
 246
 247         nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
 248                                                &nfs_fscache_inode_object_def,
 249                                                nfsi->fh.data, nfsi->fh.size,
 250                                                &auxdata, sizeof(auxdata),
 251                                                nfsi, nfsi->vfs_inode.i_size, false);
 252 }
 253
 254 /*
 255  * Release a per-inode cookie.
 256  */
 257 void nfs_fscache_clear_inode(struct inode *inode)
 258 {
 259         struct nfs_fscache_inode_auxdata auxdata;
 260         struct nfs_inode *nfsi = NFS_I(inode);
 261         struct fscache_cookie *cookie = nfs_i_fscache(inode);
 262
 263         dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);
 264
 265         memset(&auxdata, 0, sizeof(auxdata));
 266         auxdata.mtime = timespec64_to_timespec(nfsi->vfs_inode.i_mtime);
 267         auxdata.ctime = timespec64_to_timespec(nfsi->vfs_inode.i_ctime);
 268         fscache_relinquish_cookie(cookie, &auxdata, false);
 269         nfsi->fscache = NULL;
 270 }
 271
 272 static bool nfs_fscache_can_enable(void *data)
 273 {
 274         struct inode *inode = data;
 275
 276         return !inode_is_open_for_write(inode);
 277 }
 278
 279 /*
 280  * Enable or disable caching for a file that is being opened as appropriate.
 281  * The cookie is allocated when the inode is initialised, but is not enabled at
 282  * that time.  Enablement is deferred to file-open time to avoid stat() and
 283  * access() thrashing the cache.
 284  *
 285  * For now, with NFS, only regular files that are open read-only will be able
 286  * to use the cache.
 287  *
 288  * We enable the cache for an inode if we open it read-only and it isn't
 289  * currently open for writing.  We disable the cache if the inode is open
 290  * write-only.
 291  *
 292  * The caller uses the file struct to pin i_writecount on the inode before
 293  * calling us when a file is opened for writing, so we can make use of that.
 294  *
 295  * Note that this may be invoked multiple times in parallel by parallel
 296  * nfs_open() functions.
 297  */
 298 void nfs_fscache_open_file(struct inode *inode, struct file *filp)
 299 {
 300         struct nfs_fscache_inode_auxdata auxdata;
 301         struct nfs_inode *nfsi = NFS_I(inode);
 302         struct fscache_cookie *cookie = nfs_i_fscache(inode);
 303
 304         if (!fscache_cookie_valid(cookie))
 305                 return;
 306
 307         memset(&auxdata, 0, sizeof(auxdata));
 308         auxdata.mtime = timespec64_to_timespec(nfsi->vfs_inode.i_mtime);
 309         auxdata.ctime = timespec64_to_timespec(nfsi->vfs_inode.i_ctime);
 310
 311         if (inode_is_open_for_write(inode)) {
 312                 dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);
 313                 clear_bit(NFS_INO_FSCACHE, &nfsi->flags);
 314                 fscache_disable_cookie(cookie, &auxdata, true);
 315                 fscache_uncache_all_inode_pages(cookie, inode);
 316         } else {
 317                 dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi);
 318                 fscache_enable_cookie(cookie, &auxdata, nfsi->vfs_inode.i_size,
 319                                       nfs_fscache_can_enable, inode);
 320                 if (fscache_cookie_enabled(cookie))
 321                         set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 322         }
 323 }
 324 EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
 325
 326 /*
 327  * Release the caching state associated with a page, if the page isn't busy
 328  * interacting with the cache.
 329  * - Returns true (can release page) or false (page busy).
 330  */
 331 int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 332 {
 333         if (PageFsCache(page)) {
 334                 struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
 335
 336                 BUG_ON(!cookie);
 337                 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
 338                          cookie, page, NFS_I(page->mapping->host));
 339
 340                 if (!fscache_maybe_release_page(cookie, page, gfp))
 341                         return 0;
 342
 343                 nfs_inc_fscache_stats(page->mapping->host,
 344                                       NFSIOS_FSCACHE_PAGES_UNCACHED);
 345         }
 346
 347         return 1;
 348 }
 349
 350 /*
 351  * Release the caching state associated with a page if undergoing complete page
 352  * invalidation.
 353  */
 354 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
 355 {
 356         struct fscache_cookie *cookie = nfs_i_fscache(inode);
 357
 358         BUG_ON(!cookie);
 359
 360         dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
 361                  cookie, page, NFS_I(inode));
 362
 363         fscache_wait_on_page_write(cookie, page);
 364
 365         BUG_ON(!PageLocked(page));
 366         fscache_uncache_page(cookie, page);
 367         nfs_inc_fscache_stats(page->mapping->host,
 368                               NFSIOS_FSCACHE_PAGES_UNCACHED);
 369 }
 370
 371 /*
 372  * Handle completion of a page being read from the cache.
 373  * - Called in process (keventd) context.
 374  */
 375 static void nfs_readpage_from_fscache_complete(struct page *page,
 376                                                void *context,
 377                                                int error)
 378 {
 379         dfprintk(FSCACHE,
 380                  "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
 381                  page, context, error);
 382
 383         /* if the read completes with an error, we just unlock the page and let
 384          * the VM reissue the readpage */
 385         if (!error) {
 386                 SetPageUptodate(page);
 387                 unlock_page(page);
 388         } else {
 389                 error = nfs_readpage_async(context, page->mapping->host, page);
 390                 if (error)
 391                         unlock_page(page);
 392         }
 393 }
 394
 395 /*
 396  * Retrieve a page from fscache
 397  */
 398 int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
 399                                 struct inode *inode, struct page *page)
 400 {
 401         int ret;
 402
 403         dfprintk(FSCACHE,
 404                  "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
 405                  nfs_i_fscache(inode), page, page->index, page->flags, inode);
 406
 407         ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
 408                                          page,
 409                                          nfs_readpage_from_fscache_complete,
 410                                          ctx,
 411                                          GFP_KERNEL);
 412
 413         switch (ret) {
 414         case 0: /* read BIO submitted (page in fscache) */
 415                 dfprintk(FSCACHE,
 416                          "NFS:    readpage_from_fscache: BIO submitted\n");
 417                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
 418                 return ret;
 419
 420         case -ENOBUFS: /* inode not in cache */
 421         case -ENODATA: /* page not in cache */
 422                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
 423                 dfprintk(FSCACHE,
 424                          "NFS:    readpage_from_fscache %d\n", ret);
 425                 return 1;
 426
 427         default:
 428                 dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
 429                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
 430         }
 431         return ret;
 432 }
 433
 434 /*
 435  * Retrieve a set of pages from fscache
 436  */
 437 int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 438                                  struct inode *inode,
 439                                  struct address_space *mapping,
 440                                  struct list_head *pages,
 441                                  unsigned *nr_pages)
 442 {
 443         unsigned npages = *nr_pages;
 444         int ret;
 445
 446         dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
 447                  nfs_i_fscache(inode), npages, inode);
 448
 449         ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
 450                                           mapping, pages, nr_pages,
 451                                           nfs_readpage_from_fscache_complete,
 452                                           ctx,
 453                                           mapping_gfp_mask(mapping));
 454         if (*nr_pages < npages)
 455                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
 456                                       npages);
 457         if (*nr_pages > 0)
 458                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
 459                                       *nr_pages);
 460
 461         switch (ret) {
 462         case 0: /* read submitted to the cache for all pages */
 463                 BUG_ON(!list_empty(pages));
 464                 BUG_ON(*nr_pages != 0);
 465                 dfprintk(FSCACHE,
 466                          "NFS: nfs_getpages_from_fscache: submitted\n");
 467
 468                 return ret;
 469
 470         case -ENOBUFS: /* some pages aren't cached and can't be */
 471         case -ENODATA: /* some pages aren't cached */
 472                 dfprintk(FSCACHE,
 473                          "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
 474                 return 1;
 475
 476         default:
 477                 dfprintk(FSCACHE,
 478                          "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
 479         }
 480
 481         return ret;
 482 }
 483
 484 /*
 485  * Store a newly fetched page in fscache
 486  * - PG_fscache must be set on the page
 487  */
 488 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
 489 {
 490         int ret;
 491
 492         dfprintk(FSCACHE,
 493                  "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
 494                  nfs_i_fscache(inode), page, page->index, page->flags, sync);
 495
 496         ret = fscache_write_page(nfs_i_fscache(inode), page,
 497                                  inode->i_size, GFP_KERNEL);
 498         dfprintk(FSCACHE,
 499                  "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
 500                  page, page->index, page->flags, ret);
 501
 502         if (ret != 0) {
 503                 fscache_uncache_page(nfs_i_fscache(inode), page);
 504                 nfs_inc_fscache_stats(inode,
 505                                       NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
 506                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
 507         } else {
 508                 nfs_inc_fscache_stats(inode,
 509                                       NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
 510         }
 511 }