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 22 #include "internal.h" 23 #include "iostat.h" 24 #include "fscache.h" 25 26 #define NFSDBG_FACILITY NFSDBG_FSCACHE 27 28 static struct rb_root nfs_fscache_keys = RB_ROOT; 29 static DEFINE_SPINLOCK(nfs_fscache_keys_lock); 30 31 /* 32 * Get the per-client index cookie for an NFS client if the appropriate mount 33 * flag was set 34 * - We always try and get an index cookie for the client, but get filehandle 35 * cookies on a per-superblock basis, depending on the mount flags 36 */ 37 void nfs_fscache_get_client_cookie(struct nfs_client *clp) 38 { 39 /* create a cache index for looking up filehandles */ 40 clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index, 41 &nfs_fscache_server_index_def, 42 clp, true); 43 dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n", 44 clp, clp->fscache); 45 } 46 47 /* 48 * Dispose of a per-client cookie 49 */ 50 void nfs_fscache_release_client_cookie(struct nfs_client *clp) 51 { 52 dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n", 53 clp, clp->fscache); 54 55 fscache_relinquish_cookie(clp->fscache, 0); 56 clp->fscache = NULL; 57 } 58 59 /* 60 * Get the cache cookie for an NFS superblock. We have to handle 61 * uniquification here because the cache doesn't do it for us. 62 * 63 * The default uniquifier is just an empty string, but it may be overridden 64 * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent 65 * superblock across an automount point of some nature. 66 */ 67 void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen) 68 { 69 struct nfs_fscache_key *key, *xkey; 70 struct nfs_server *nfss = NFS_SB(sb); 71 struct rb_node **p, *parent; 72 int diff; 73 74 if (!uniq) { 75 uniq = ""; 76 ulen = 1; 77 } 78 79 key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL); 80 if (!key) 81 return; 82 83 key->nfs_client = nfss->nfs_client; 84 key->key.super.s_flags = sb->s_flags & NFS_MS_MASK; 85 key->key.nfs_server.flags = nfss->flags; 86 key->key.nfs_server.rsize = nfss->rsize; 87 key->key.nfs_server.wsize = nfss->wsize; 88 key->key.nfs_server.acregmin = nfss->acregmin; 89 key->key.nfs_server.acregmax = nfss->acregmax; 90 key->key.nfs_server.acdirmin = nfss->acdirmin; 91 key->key.nfs_server.acdirmax = nfss->acdirmax; 92 key->key.nfs_server.fsid = nfss->fsid; 93 key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor; 94 95 key->key.uniq_len = ulen; 96 memcpy(key->key.uniquifier, uniq, ulen); 97 98 spin_lock(&nfs_fscache_keys_lock); 99 p = &nfs_fscache_keys.rb_node; 100 parent = NULL; 101 while (*p) { 102 parent = *p; 103 xkey = rb_entry(parent, struct nfs_fscache_key, node); 104 105 if (key->nfs_client < xkey->nfs_client) 106 goto go_left; 107 if (key->nfs_client > xkey->nfs_client) 108 goto go_right; 109 110 diff = memcmp(&key->key, &xkey->key, sizeof(key->key)); 111 if (diff < 0) 112 goto go_left; 113 if (diff > 0) 114 goto go_right; 115 116 if (key->key.uniq_len == 0) 117 goto non_unique; 118 diff = memcmp(key->key.uniquifier, 119 xkey->key.uniquifier, 120 key->key.uniq_len); 121 if (diff < 0) 122 goto go_left; 123 if (diff > 0) 124 goto go_right; 125 goto non_unique; 126 127 go_left: 128 p = &(*p)->rb_left; 129 continue; 130 go_right: 131 p = &(*p)->rb_right; 132 } 133 134 rb_link_node(&key->node, parent, p); 135 rb_insert_color(&key->node, &nfs_fscache_keys); 136 spin_unlock(&nfs_fscache_keys_lock); 137 nfss->fscache_key = key; 138 139 /* create a cache index for looking up filehandles */ 140 nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache, 141 &nfs_fscache_super_index_def, 142 nfss, true); 143 dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n", 144 nfss, nfss->fscache); 145 return; 146 147 non_unique: 148 spin_unlock(&nfs_fscache_keys_lock); 149 kfree(key); 150 nfss->fscache_key = NULL; 151 nfss->fscache = NULL; 152 printk(KERN_WARNING "NFS:" 153 " Cache request denied due to non-unique superblock keys\n"); 154 } 155 156 /* 157 * release a per-superblock cookie 158 */ 159 void nfs_fscache_release_super_cookie(struct super_block *sb) 160 { 161 struct nfs_server *nfss = NFS_SB(sb); 162 163 dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n", 164 nfss, nfss->fscache); 165 166 fscache_relinquish_cookie(nfss->fscache, 0); 167 nfss->fscache = NULL; 168 169 if (nfss->fscache_key) { 170 spin_lock(&nfs_fscache_keys_lock); 171 rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys); 172 spin_unlock(&nfs_fscache_keys_lock); 173 kfree(nfss->fscache_key); 174 nfss->fscache_key = NULL; 175 } 176 } 177 178 /* 179 * Initialise the per-inode cache cookie pointer for an NFS inode. 180 */ 181 void nfs_fscache_init_inode(struct inode *inode) 182 { 183 struct nfs_inode *nfsi = NFS_I(inode); 184 185 nfsi->fscache = NULL; 186 if (!S_ISREG(inode->i_mode)) 187 return; 188 nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache, 189 &nfs_fscache_inode_object_def, 190 nfsi, false); 191 } 192 193 /* 194 * Release a per-inode cookie. 195 */ 196 void nfs_fscache_clear_inode(struct inode *inode) 197 { 198 struct nfs_inode *nfsi = NFS_I(inode); 199 struct fscache_cookie *cookie = nfs_i_fscache(inode); 200 201 dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie); 202 203 fscache_relinquish_cookie(cookie, false); 204 nfsi->fscache = NULL; 205 } 206 207 static bool nfs_fscache_can_enable(void *data) 208 { 209 struct inode *inode = data; 210 211 return !inode_is_open_for_write(inode); 212 } 213 214 /* 215 * Enable or disable caching for a file that is being opened as appropriate. 216 * The cookie is allocated when the inode is initialised, but is not enabled at 217 * that time. Enablement is deferred to file-open time to avoid stat() and 218 * access() thrashing the cache. 219 * 220 * For now, with NFS, only regular files that are open read-only will be able 221 * to use the cache. 222 * 223 * We enable the cache for an inode if we open it read-only and it isn't 224 * currently open for writing. We disable the cache if the inode is open 225 * write-only. 226 * 227 * The caller uses the file struct to pin i_writecount on the inode before 228 * calling us when a file is opened for writing, so we can make use of that. 229 * 230 * Note that this may be invoked multiple times in parallel by parallel 231 * nfs_open() functions. 232 */ 233 void nfs_fscache_open_file(struct inode *inode, struct file *filp) 234 { 235 struct nfs_inode *nfsi = NFS_I(inode); 236 struct fscache_cookie *cookie = nfs_i_fscache(inode); 237 238 if (!fscache_cookie_valid(cookie)) 239 return; 240 241 if (inode_is_open_for_write(inode)) { 242 dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi); 243 clear_bit(NFS_INO_FSCACHE, &nfsi->flags); 244 fscache_disable_cookie(cookie, true); 245 fscache_uncache_all_inode_pages(cookie, inode); 246 } else { 247 dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi); 248 fscache_enable_cookie(cookie, nfs_fscache_can_enable, inode); 249 if (fscache_cookie_enabled(cookie)) 250 set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags); 251 } 252 } 253 EXPORT_SYMBOL_GPL(nfs_fscache_open_file); 254 255 /* 256 * Release the caching state associated with a page, if the page isn't busy 257 * interacting with the cache. 258 * - Returns true (can release page) or false (page busy). 259 */ 260 int nfs_fscache_release_page(struct page *page, gfp_t gfp) 261 { 262 if (PageFsCache(page)) { 263 struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host); 264 265 BUG_ON(!cookie); 266 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n", 267 cookie, page, NFS_I(page->mapping->host)); 268 269 if (!fscache_maybe_release_page(cookie, page, gfp)) 270 return 0; 271 272 nfs_add_fscache_stats(page->mapping->host, 273 NFSIOS_FSCACHE_PAGES_UNCACHED, 1); 274 } 275 276 return 1; 277 } 278 279 /* 280 * Release the caching state associated with a page if undergoing complete page 281 * invalidation. 282 */ 283 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode) 284 { 285 struct fscache_cookie *cookie = nfs_i_fscache(inode); 286 287 BUG_ON(!cookie); 288 289 dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n", 290 cookie, page, NFS_I(inode)); 291 292 fscache_wait_on_page_write(cookie, page); 293 294 BUG_ON(!PageLocked(page)); 295 fscache_uncache_page(cookie, page); 296 nfs_add_fscache_stats(page->mapping->host, 297 NFSIOS_FSCACHE_PAGES_UNCACHED, 1); 298 } 299 300 /* 301 * Handle completion of a page being read from the cache. 302 * - Called in process (keventd) context. 303 */ 304 static void nfs_readpage_from_fscache_complete(struct page *page, 305 void *context, 306 int error) 307 { 308 dfprintk(FSCACHE, 309 "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n", 310 page, context, error); 311 312 /* if the read completes with an error, we just unlock the page and let 313 * the VM reissue the readpage */ 314 if (!error) { 315 SetPageUptodate(page); 316 unlock_page(page); 317 } else { 318 error = nfs_readpage_async(context, page->mapping->host, page); 319 if (error) 320 unlock_page(page); 321 } 322 } 323 324 /* 325 * Retrieve a page from fscache 326 */ 327 int __nfs_readpage_from_fscache(struct nfs_open_context *ctx, 328 struct inode *inode, struct page *page) 329 { 330 int ret; 331 332 dfprintk(FSCACHE, 333 "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n", 334 nfs_i_fscache(inode), page, page->index, page->flags, inode); 335 336 ret = fscache_read_or_alloc_page(nfs_i_fscache(inode), 337 page, 338 nfs_readpage_from_fscache_complete, 339 ctx, 340 GFP_KERNEL); 341 342 switch (ret) { 343 case 0: /* read BIO submitted (page in fscache) */ 344 dfprintk(FSCACHE, 345 "NFS: readpage_from_fscache: BIO submitted\n"); 346 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1); 347 return ret; 348 349 case -ENOBUFS: /* inode not in cache */ 350 case -ENODATA: /* page not in cache */ 351 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1); 352 dfprintk(FSCACHE, 353 "NFS: readpage_from_fscache %d\n", ret); 354 return 1; 355 356 default: 357 dfprintk(FSCACHE, "NFS: readpage_from_fscache %d\n", ret); 358 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1); 359 } 360 return ret; 361 } 362 363 /* 364 * Retrieve a set of pages from fscache 365 */ 366 int __nfs_readpages_from_fscache(struct nfs_open_context *ctx, 367 struct inode *inode, 368 struct address_space *mapping, 369 struct list_head *pages, 370 unsigned *nr_pages) 371 { 372 unsigned npages = *nr_pages; 373 int ret; 374 375 dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n", 376 nfs_i_fscache(inode), npages, inode); 377 378 ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode), 379 mapping, pages, nr_pages, 380 nfs_readpage_from_fscache_complete, 381 ctx, 382 mapping_gfp_mask(mapping)); 383 if (*nr_pages < npages) 384 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 385 npages); 386 if (*nr_pages > 0) 387 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 388 *nr_pages); 389 390 switch (ret) { 391 case 0: /* read submitted to the cache for all pages */ 392 BUG_ON(!list_empty(pages)); 393 BUG_ON(*nr_pages != 0); 394 dfprintk(FSCACHE, 395 "NFS: nfs_getpages_from_fscache: submitted\n"); 396 397 return ret; 398 399 case -ENOBUFS: /* some pages aren't cached and can't be */ 400 case -ENODATA: /* some pages aren't cached */ 401 dfprintk(FSCACHE, 402 "NFS: nfs_getpages_from_fscache: no page: %d\n", ret); 403 return 1; 404 405 default: 406 dfprintk(FSCACHE, 407 "NFS: nfs_getpages_from_fscache: ret %d\n", ret); 408 } 409 410 return ret; 411 } 412 413 /* 414 * Store a newly fetched page in fscache 415 * - PG_fscache must be set on the page 416 */ 417 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync) 418 { 419 int ret; 420 421 dfprintk(FSCACHE, 422 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n", 423 nfs_i_fscache(inode), page, page->index, page->flags, sync); 424 425 ret = fscache_write_page(nfs_i_fscache(inode), page, GFP_KERNEL); 426 dfprintk(FSCACHE, 427 "NFS: readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n", 428 page, page->index, page->flags, ret); 429 430 if (ret != 0) { 431 fscache_uncache_page(nfs_i_fscache(inode), page); 432 nfs_add_fscache_stats(inode, 433 NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1); 434 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1); 435 } else { 436 nfs_add_fscache_stats(inode, 437 NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1); 438 } 439 } 440