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 #include <linux/iversion.h>
  22
  23 #include "internal.h"
  24 #include "iostat.h"
  25 #include "fscache.h"
  26
  27 #define NFSDBG_FACILITY         NFSDBG_FSCACHE
  28
  29 static struct rb_root nfs_fscache_keys = RB_ROOT;
  30 static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
  31
  32 /*
  33  * Layout of the key for an NFS server cache object.
  34  */
  35 struct nfs_server_key {
  36         struct {
  37                 uint16_t        nfsversion;             /* NFS protocol version */
  38                 uint16_t        family;                 /* address family */
  39                 __be16          port;                   /* IP port */
  40         } hdr;
  41         union {
  42                 struct in_addr  ipv4_addr;      /* IPv4 address */
  43                 struct in6_addr ipv6_addr;      /* IPv6 address */
  44         };
  45 } __packed;
  46
  47 /*
  48  * Get the per-client index cookie for an NFS client if the appropriate mount
  49  * flag was set
  50  * - We always try and get an index cookie for the client, but get filehandle
  51  *   cookies on a per-superblock basis, depending on the mount flags
  52  */
  53 void nfs_fscache_get_client_cookie(struct nfs_client *clp)
  54 {
  55         const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
  56         const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
  57         struct nfs_server_key key;
  58         uint16_t len = sizeof(key.hdr);
  59
  60         memset(&key, 0, sizeof(key));
  61         key.hdr.nfsversion = clp->rpc_ops->version;
  62         key.hdr.family = clp->cl_addr.ss_family;
  63
  64         switch (clp->cl_addr.ss_family) {
  65         case AF_INET:
  66                 key.hdr.port = sin->sin_port;
  67                 key.ipv4_addr = sin->sin_addr;
  68                 len += sizeof(key.ipv4_addr);
  69                 break;
  70
  71         case AF_INET6:
  72                 key.hdr.port = sin6->sin6_port;
  73                 key.ipv6_addr = sin6->sin6_addr;
  74                 len += sizeof(key.ipv6_addr);
  75                 break;
  76
  77         default:
  78                 printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
  79                        clp->cl_addr.ss_family);
  80                 clp->fscache = NULL;
  81                 return;
  82         }
  83
  84         /* create a cache index for looking up filehandles */
  85         clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
  86                                               &nfs_fscache_server_index_def,
  87                                               &key, len,
  88                                               NULL, 0,
  89                                               clp, 0, true);
  90         dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
  91                  clp, clp->fscache);
  92 }
  93
  94 /*
  95  * Dispose of a per-client cookie
  96  */
  97 void nfs_fscache_release_client_cookie(struct nfs_client *clp)
  98 {
  99         dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
 100                  clp, clp->fscache);
 101
 102         fscache_relinquish_cookie(clp->fscache, NULL, false);
 103         clp->fscache = NULL;
 104 }
 105
 106 /*
 107  * Get the cache cookie for an NFS superblock.  We have to handle
 108  * uniquification here because the cache doesn't do it for us.
 109  *
 110  * The default uniquifier is just an empty string, but it may be overridden
 111  * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
 112  * superblock across an automount point of some nature.
 113  */
 114 void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
 115 {
 116         struct nfs_fscache_key *key, *xkey;
 117         struct nfs_server *nfss = NFS_SB(sb);
 118         struct rb_node **p, *parent;
 119         int diff;
 120
 121         nfss->fscache_key = NULL;
 122         nfss->fscache = NULL;
 123         if (!(nfss->options & NFS_OPTION_FSCACHE))
 124                 return;
 125         if (!uniq) {
 126                 uniq = "";
 127                 ulen = 1;
 128         }
 129
 130         key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
 131         if (!key)
 132                 return;
 133
 134         key->nfs_client = nfss->nfs_client;
 135         key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
 136         key->key.nfs_server.flags = nfss->flags;
 137         key->key.nfs_server.rsize = nfss->rsize;
 138         key->key.nfs_server.wsize = nfss->wsize;
 139         key->key.nfs_server.acregmin = nfss->acregmin;
 140         key->key.nfs_server.acregmax = nfss->acregmax;
 141         key->key.nfs_server.acdirmin = nfss->acdirmin;
 142         key->key.nfs_server.acdirmax = nfss->acdirmax;
 143         key->key.nfs_server.fsid = nfss->fsid;
 144         key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
 145
 146         key->key.uniq_len = ulen;
 147         memcpy(key->key.uniquifier, uniq, ulen);
 148
 149         spin_lock(&nfs_fscache_keys_lock);
 150         p = &nfs_fscache_keys.rb_node;
 151         parent = NULL;
 152         while (*p) {
 153                 parent = *p;
 154                 xkey = rb_entry(parent, struct nfs_fscache_key, node);
 155
 156                 if (key->nfs_client < xkey->nfs_client)
 157                         goto go_left;
 158                 if (key->nfs_client > xkey->nfs_client)
 159                         goto go_right;
 160
 161                 diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
 162                 if (diff < 0)
 163                         goto go_left;
 164                 if (diff > 0)
 165                         goto go_right;
 166
 167                 if (key->key.uniq_len == 0)
 168                         goto non_unique;
 169                 diff = memcmp(key->key.uniquifier,
 170                               xkey->key.uniquifier,
 171                               key->key.uniq_len);
 172                 if (diff < 0)
 173                         goto go_left;
 174                 if (diff > 0)
 175                         goto go_right;
 176                 goto non_unique;
 177
 178         go_left:
 179                 p = &(*p)->rb_left;
 180                 continue;
 181         go_right:
 182                 p = &(*p)->rb_right;
 183         }
 184
 185         rb_link_node(&key->node, parent, p);
 186         rb_insert_color(&key->node, &nfs_fscache_keys);
 187         spin_unlock(&nfs_fscache_keys_lock);
 188         nfss->fscache_key = key;
 189
 190         /* create a cache index for looking up filehandles */
 191         nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
 192                                                &nfs_fscache_super_index_def,
 193                                                key, sizeof(*key) + ulen,
 194                                                NULL, 0,
 195                                                nfss, 0, true);
 196         dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
 197                  nfss, nfss->fscache);
 198         return;
 199
 200 non_unique:
 201         spin_unlock(&nfs_fscache_keys_lock);
 202         kfree(key);
 203         nfss->fscache_key = NULL;
 204         nfss->fscache = NULL;
 205         printk(KERN_WARNING "NFS:"
 206                " Cache request denied due to non-unique superblock keys\n");
 207 }
 208
 209 /*
 210  * release a per-superblock cookie
 211  */
 212 void nfs_fscache_release_super_cookie(struct super_block *sb)
 213 {
 214         struct nfs_server *nfss = NFS_SB(sb);
 215
 216         dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
 217                  nfss, nfss->fscache);
 218
 219         fscache_relinquish_cookie(nfss->fscache, NULL, false);
 220         nfss->fscache = NULL;
 221
 222         if (nfss->fscache_key) {
 223                 spin_lock(&nfs_fscache_keys_lock);
 224                 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
 225                 spin_unlock(&nfs_fscache_keys_lock);
 226                 kfree(nfss->fscache_key);
 227                 nfss->fscache_key = NULL;
 228         }
 229 }
 230
 231 /*
 232  * Initialise the per-inode cache cookie pointer for an NFS inode.
 233  */
 234 void nfs_fscache_init_inode(struct inode *inode)
 235 {
 236         struct nfs_fscache_inode_auxdata auxdata;
 237         struct nfs_server *nfss = NFS_SERVER(inode);
 238         struct nfs_inode *nfsi = NFS_I(inode);
 239
 240         nfsi->fscache = NULL;
 241         if (!(nfss->fscache && S_ISREG(inode->i_mode)))
 242                 return;
 243
 244         memset(&auxdata, 0, sizeof(auxdata));
 245         auxdata.mtime = timespec64_to_timespec(nfsi->vfs_inode.i_mtime);
 246         auxdata.ctime = timespec64_to_timespec(nfsi->vfs_inode.i_ctime);
 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 = timespec64_to_timespec(nfsi->vfs_inode.i_mtime);
 271         auxdata.ctime = timespec64_to_timespec(nfsi->vfs_inode.i_ctime);
 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 = timespec64_to_timespec(nfsi->vfs_inode.i_mtime);
 313         auxdata.ctime = timespec64_to_timespec(nfsi->vfs_inode.i_ctime);
 314
 315         if (inode_is_open_for_write(inode)) {
 316                 dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);
 317                 clear_bit(NFS_INO_FSCACHE, &nfsi->flags);
 318                 fscache_disable_cookie(cookie, &auxdata, true);
 319                 fscache_uncache_all_inode_pages(cookie, inode);
 320         } else {
 321                 dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi);
 322                 fscache_enable_cookie(cookie, &auxdata, nfsi->vfs_inode.i_size,
 323                                       nfs_fscache_can_enable, inode);
 324                 if (fscache_cookie_enabled(cookie))
 325                         set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
 326         }
 327 }
 328 EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
 329
 330 /*
 331  * Release the caching state associated with a page, if the page isn't busy
 332  * interacting with the cache.
 333  * - Returns true (can release page) or false (page busy).
 334  */
 335 int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 336 {
 337         if (PageFsCache(page)) {
 338                 struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
 339
 340                 BUG_ON(!cookie);
 341                 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
 342                          cookie, page, NFS_I(page->mapping->host));
 343
 344                 if (!fscache_maybe_release_page(cookie, page, gfp))
 345                         return 0;
 346
 347                 nfs_inc_fscache_stats(page->mapping->host,
 348                                       NFSIOS_FSCACHE_PAGES_UNCACHED);
 349         }
 350
 351         return 1;
 352 }
 353
 354 /*
 355  * Release the caching state associated with a page if undergoing complete page
 356  * invalidation.
 357  */
 358 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
 359 {
 360         struct fscache_cookie *cookie = nfs_i_fscache(inode);
 361
 362         BUG_ON(!cookie);
 363
 364         dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
 365                  cookie, page, NFS_I(inode));
 366
 367         fscache_wait_on_page_write(cookie, page);
 368
 369         BUG_ON(!PageLocked(page));
 370         fscache_uncache_page(cookie, page);
 371         nfs_inc_fscache_stats(page->mapping->host,
 372                               NFSIOS_FSCACHE_PAGES_UNCACHED);
 373 }
 374
 375 /*
 376  * Handle completion of a page being read from the cache.
 377  * - Called in process (keventd) context.
 378  */
 379 static void nfs_readpage_from_fscache_complete(struct page *page,
 380                                                void *context,
 381                                                int error)
 382 {
 383         dfprintk(FSCACHE,
 384                  "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
 385                  page, context, error);
 386
 387         /* if the read completes with an error, we just unlock the page and let
 388          * the VM reissue the readpage */
 389         if (!error) {
 390                 SetPageUptodate(page);
 391                 unlock_page(page);
 392         } else {
 393                 error = nfs_readpage_async(context, page->mapping->host, page);
 394                 if (error)
 395                         unlock_page(page);
 396         }
 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         ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
 412                                          page,
 413                                          nfs_readpage_from_fscache_complete,
 414                                          ctx,
 415                                          GFP_KERNEL);
 416
 417         switch (ret) {
 418         case 0: /* read BIO submitted (page in fscache) */
 419                 dfprintk(FSCACHE,
 420                          "NFS:    readpage_from_fscache: BIO submitted\n");
 421                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
 422                 return ret;
 423
 424         case -ENOBUFS: /* inode not in cache */
 425         case -ENODATA: /* page not in cache */
 426                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
 427                 dfprintk(FSCACHE,
 428                          "NFS:    readpage_from_fscache %d\n", ret);
 429                 return 1;
 430
 431         default:
 432                 dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
 433                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
 434         }
 435         return ret;
 436 }
 437
 438 /*
 439  * Retrieve a set of pages from fscache
 440  */
 441 int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 442                                  struct inode *inode,
 443                                  struct address_space *mapping,
 444                                  struct list_head *pages,
 445                                  unsigned *nr_pages)
 446 {
 447         unsigned npages = *nr_pages;
 448         int ret;
 449
 450         dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
 451                  nfs_i_fscache(inode), npages, inode);
 452
 453         ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
 454                                           mapping, pages, nr_pages,
 455                                           nfs_readpage_from_fscache_complete,
 456                                           ctx,
 457                                           mapping_gfp_mask(mapping));
 458         if (*nr_pages < npages)
 459                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
 460                                       npages);
 461         if (*nr_pages > 0)
 462                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
 463                                       *nr_pages);
 464
 465         switch (ret) {
 466         case 0: /* read submitted to the cache for all pages */
 467                 BUG_ON(!list_empty(pages));
 468                 BUG_ON(*nr_pages != 0);
 469                 dfprintk(FSCACHE,
 470                          "NFS: nfs_getpages_from_fscache: submitted\n");
 471
 472                 return ret;
 473
 474         case -ENOBUFS: /* some pages aren't cached and can't be */
 475         case -ENODATA: /* some pages aren't cached */
 476                 dfprintk(FSCACHE,
 477                          "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
 478                 return 1;
 479
 480         default:
 481                 dfprintk(FSCACHE,
 482                          "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
 483         }
 484
 485         return ret;
 486 }
 487
 488 /*
 489  * Store a newly fetched page in fscache
 490  * - PG_fscache must be set on the page
 491  */
 492 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
 493 {
 494         int ret;
 495
 496         dfprintk(FSCACHE,
 497                  "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
 498                  nfs_i_fscache(inode), page, page->index, page->flags, sync);
 499
 500         ret = fscache_write_page(nfs_i_fscache(inode), page,
 501                                  inode->i_size, GFP_KERNEL);
 502         dfprintk(FSCACHE,
 503                  "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
 504                  page, page->index, page->flags, ret);
 505
 506         if (ret != 0) {
 507                 fscache_uncache_page(nfs_i_fscache(inode), page);
 508                 nfs_inc_fscache_stats(inode,
 509                                       NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
 510                 nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
 511         } else {
 512                 nfs_inc_fscache_stats(inode,
 513                                       NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
 514         }
 515 }