1 /* -*- mode: c; c-basic-offset: 8; -*- 2 * vim: noexpandtab sw=8 ts=8 sts=0: 3 * 4 * dcache.c 5 * 6 * dentry cache handling code 7 * 8 * Copyright (C) 2002, 2004 Oracle. All rights reserved. 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public 12 * License as published by the Free Software Foundation; either 13 * version 2 of the License, or (at your option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, 16 * but WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 18 * General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public 21 * License along with this program; if not, write to the 22 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 23 * Boston, MA 021110-1307, USA. 24 */ 25 26 #include <linux/fs.h> 27 #include <linux/types.h> 28 #include <linux/slab.h> 29 #include <linux/namei.h> 30 31 #define MLOG_MASK_PREFIX ML_DCACHE 32 #include <cluster/masklog.h> 33 34 #include "ocfs2.h" 35 36 #include "alloc.h" 37 #include "dcache.h" 38 #include "dlmglue.h" 39 #include "file.h" 40 #include "inode.h" 41 #include "super.h" 42 43 void ocfs2_dentry_attach_gen(struct dentry *dentry) 44 { 45 unsigned long gen = 46 OCFS2_I(dentry->d_parent->d_inode)->ip_dir_lock_gen; 47 BUG_ON(dentry->d_inode); 48 dentry->d_fsdata = (void *)gen; 49 } 50 51 52 static int ocfs2_dentry_revalidate(struct dentry *dentry, 53 struct nameidata *nd) 54 { 55 struct inode *inode; 56 int ret = 0; /* if all else fails, just return false */ 57 struct ocfs2_super *osb; 58 59 if (nd && nd->flags & LOOKUP_RCU) 60 return -ECHILD; 61 62 inode = dentry->d_inode; 63 osb = OCFS2_SB(dentry->d_sb); 64 65 mlog(0, "(0x%p, '%.*s')\n", dentry, 66 dentry->d_name.len, dentry->d_name.name); 67 68 /* For a negative dentry - 69 * check the generation number of the parent and compare with the 70 * one stored in the inode. 71 */ 72 if (inode == NULL) { 73 unsigned long gen = (unsigned long) dentry->d_fsdata; 74 unsigned long pgen = 75 OCFS2_I(dentry->d_parent->d_inode)->ip_dir_lock_gen; 76 mlog(0, "negative dentry: %.*s parent gen: %lu " 77 "dentry gen: %lu\n", 78 dentry->d_name.len, dentry->d_name.name, pgen, gen); 79 if (gen != pgen) 80 goto bail; 81 goto valid; 82 } 83 84 BUG_ON(!osb); 85 86 if (inode == osb->root_inode || is_bad_inode(inode)) 87 goto bail; 88 89 spin_lock(&OCFS2_I(inode)->ip_lock); 90 /* did we or someone else delete this inode? */ 91 if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) { 92 spin_unlock(&OCFS2_I(inode)->ip_lock); 93 mlog(0, "inode (%llu) deleted, returning false\n", 94 (unsigned long long)OCFS2_I(inode)->ip_blkno); 95 goto bail; 96 } 97 spin_unlock(&OCFS2_I(inode)->ip_lock); 98 99 /* 100 * We don't need a cluster lock to test this because once an 101 * inode nlink hits zero, it never goes back. 102 */ 103 if (inode->i_nlink == 0) { 104 mlog(0, "Inode %llu orphaned, returning false " 105 "dir = %d\n", 106 (unsigned long long)OCFS2_I(inode)->ip_blkno, 107 S_ISDIR(inode->i_mode)); 108 goto bail; 109 } 110 111 /* 112 * If the last lookup failed to create dentry lock, let us 113 * redo it. 114 */ 115 if (!dentry->d_fsdata) { 116 mlog(0, "Inode %llu doesn't have dentry lock, " 117 "returning false\n", 118 (unsigned long long)OCFS2_I(inode)->ip_blkno); 119 goto bail; 120 } 121 122 valid: 123 ret = 1; 124 125 bail: 126 mlog(0, "ret = %d\n", ret); 127 return ret; 128 } 129 130 static int ocfs2_match_dentry(struct dentry *dentry, 131 u64 parent_blkno, 132 int skip_unhashed) 133 { 134 struct inode *parent; 135 136 /* 137 * ocfs2_lookup() does a d_splice_alias() _before_ attaching 138 * to the lock data, so we skip those here, otherwise 139 * ocfs2_dentry_attach_lock() will get its original dentry 140 * back. 141 */ 142 if (!dentry->d_fsdata) 143 return 0; 144 145 if (!dentry->d_parent) 146 return 0; 147 148 if (skip_unhashed && d_unhashed(dentry)) 149 return 0; 150 151 parent = dentry->d_parent->d_inode; 152 /* Negative parent dentry? */ 153 if (!parent) 154 return 0; 155 156 /* Name is in a different directory. */ 157 if (OCFS2_I(parent)->ip_blkno != parent_blkno) 158 return 0; 159 160 return 1; 161 } 162 163 /* 164 * Walk the inode alias list, and find a dentry which has a given 165 * parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it 166 * is looking for a dentry_lock reference. The downconvert thread is 167 * looking to unhash aliases, so we allow it to skip any that already 168 * have that property. 169 */ 170 struct dentry *ocfs2_find_local_alias(struct inode *inode, 171 u64 parent_blkno, 172 int skip_unhashed) 173 { 174 struct list_head *p; 175 struct dentry *dentry = NULL; 176 177 spin_lock(&inode->i_lock); 178 list_for_each(p, &inode->i_dentry) { 179 dentry = list_entry(p, struct dentry, d_alias); 180 181 spin_lock(&dentry->d_lock); 182 if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) { 183 mlog(0, "dentry found: %.*s\n", 184 dentry->d_name.len, dentry->d_name.name); 185 186 dget_dlock(dentry); 187 spin_unlock(&dentry->d_lock); 188 break; 189 } 190 spin_unlock(&dentry->d_lock); 191 192 dentry = NULL; 193 } 194 195 spin_unlock(&inode->i_lock); 196 197 return dentry; 198 } 199 200 DEFINE_SPINLOCK(dentry_attach_lock); 201 202 /* 203 * Attach this dentry to a cluster lock. 204 * 205 * Dentry locks cover all links in a given directory to a particular 206 * inode. We do this so that ocfs2 can build a lock name which all 207 * nodes in the cluster can agree on at all times. Shoving full names 208 * in the cluster lock won't work due to size restrictions. Covering 209 * links inside of a directory is a good compromise because it still 210 * allows us to use the parent directory lock to synchronize 211 * operations. 212 * 213 * Call this function with the parent dir semaphore and the parent dir 214 * cluster lock held. 215 * 216 * The dir semaphore will protect us from having to worry about 217 * concurrent processes on our node trying to attach a lock at the 218 * same time. 219 * 220 * The dir cluster lock (held at either PR or EX mode) protects us 221 * from unlink and rename on other nodes. 222 * 223 * A dput() can happen asynchronously due to pruning, so we cover 224 * attaching and detaching the dentry lock with a 225 * dentry_attach_lock. 226 * 227 * A node which has done lookup on a name retains a protected read 228 * lock until final dput. If the user requests and unlink or rename, 229 * the protected read is upgraded to an exclusive lock. Other nodes 230 * who have seen the dentry will then be informed that they need to 231 * downgrade their lock, which will involve d_delete on the 232 * dentry. This happens in ocfs2_dentry_convert_worker(). 233 */ 234 int ocfs2_dentry_attach_lock(struct dentry *dentry, 235 struct inode *inode, 236 u64 parent_blkno) 237 { 238 int ret; 239 struct dentry *alias; 240 struct ocfs2_dentry_lock *dl = dentry->d_fsdata; 241 242 mlog(0, "Attach \"%.*s\", parent %llu, fsdata: %p\n", 243 dentry->d_name.len, dentry->d_name.name, 244 (unsigned long long)parent_blkno, dl); 245 246 /* 247 * Negative dentry. We ignore these for now. 248 * 249 * XXX: Could we can improve ocfs2_dentry_revalidate() by 250 * tracking these? 251 */ 252 if (!inode) 253 return 0; 254 255 if (!dentry->d_inode && dentry->d_fsdata) { 256 /* Converting a negative dentry to positive 257 Clear dentry->d_fsdata */ 258 dentry->d_fsdata = dl = NULL; 259 } 260 261 if (dl) { 262 mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno, 263 " \"%.*s\": old parent: %llu, new: %llu\n", 264 dentry->d_name.len, dentry->d_name.name, 265 (unsigned long long)parent_blkno, 266 (unsigned long long)dl->dl_parent_blkno); 267 return 0; 268 } 269 270 alias = ocfs2_find_local_alias(inode, parent_blkno, 0); 271 if (alias) { 272 /* 273 * Great, an alias exists, which means we must have a 274 * dentry lock already. We can just grab the lock off 275 * the alias and add it to the list. 276 * 277 * We're depending here on the fact that this dentry 278 * was found and exists in the dcache and so must have 279 * a reference to the dentry_lock because we can't 280 * race creates. Final dput() cannot happen on it 281 * since we have it pinned, so our reference is safe. 282 */ 283 dl = alias->d_fsdata; 284 mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n", 285 (unsigned long long)parent_blkno, 286 (unsigned long long)OCFS2_I(inode)->ip_blkno); 287 288 mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno, 289 " \"%.*s\": old parent: %llu, new: %llu\n", 290 dentry->d_name.len, dentry->d_name.name, 291 (unsigned long long)parent_blkno, 292 (unsigned long long)dl->dl_parent_blkno); 293 294 mlog(0, "Found: %s\n", dl->dl_lockres.l_name); 295 296 goto out_attach; 297 } 298 299 /* 300 * There are no other aliases 301 */ 302 dl = kmalloc(sizeof(*dl), GFP_NOFS); 303 if (!dl) { 304 ret = -ENOMEM; 305 mlog_errno(ret); 306 return ret; 307 } 308 309 dl->dl_count = 0; 310 /* 311 * Does this have to happen below, for all attaches, in case 312 * the struct inode gets blown away by the downconvert thread? 313 */ 314 dl->dl_inode = igrab(inode); 315 dl->dl_parent_blkno = parent_blkno; 316 ocfs2_dentry_lock_res_init(dl, parent_blkno, inode); 317 318 out_attach: 319 spin_lock(&dentry_attach_lock); 320 dentry->d_fsdata = dl; 321 dl->dl_count++; 322 spin_unlock(&dentry_attach_lock); 323 324 /* 325 * This actually gets us our PRMODE level lock. From now on, 326 * we'll have a notification if one of these names is 327 * destroyed on another node. 328 */ 329 ret = ocfs2_dentry_lock(dentry, 0); 330 if (!ret) 331 ocfs2_dentry_unlock(dentry, 0); 332 else 333 mlog_errno(ret); 334 335 /* 336 * In case of error, manually free the allocation and do the iput(). 337 * We need to do this because error here means no d_instantiate(), 338 * which means iput() will not be called during dput(dentry). 339 */ 340 if (ret < 0 && !alias) { 341 ocfs2_lock_res_free(&dl->dl_lockres); 342 BUG_ON(dl->dl_count != 1); 343 spin_lock(&dentry_attach_lock); 344 dentry->d_fsdata = NULL; 345 spin_unlock(&dentry_attach_lock); 346 kfree(dl); 347 iput(inode); 348 } 349 350 dput(alias); 351 352 return ret; 353 } 354 355 DEFINE_SPINLOCK(dentry_list_lock); 356 357 /* We limit the number of dentry locks to drop in one go. We have 358 * this limit so that we don't starve other users of ocfs2_wq. */ 359 #define DL_INODE_DROP_COUNT 64 360 361 /* Drop inode references from dentry locks */ 362 static void __ocfs2_drop_dl_inodes(struct ocfs2_super *osb, int drop_count) 363 { 364 struct ocfs2_dentry_lock *dl; 365 366 spin_lock(&dentry_list_lock); 367 while (osb->dentry_lock_list && (drop_count < 0 || drop_count--)) { 368 dl = osb->dentry_lock_list; 369 osb->dentry_lock_list = dl->dl_next; 370 spin_unlock(&dentry_list_lock); 371 iput(dl->dl_inode); 372 kfree(dl); 373 spin_lock(&dentry_list_lock); 374 } 375 spin_unlock(&dentry_list_lock); 376 } 377 378 void ocfs2_drop_dl_inodes(struct work_struct *work) 379 { 380 struct ocfs2_super *osb = container_of(work, struct ocfs2_super, 381 dentry_lock_work); 382 383 __ocfs2_drop_dl_inodes(osb, DL_INODE_DROP_COUNT); 384 /* 385 * Don't queue dropping if umount is in progress. We flush the 386 * list in ocfs2_dismount_volume 387 */ 388 spin_lock(&dentry_list_lock); 389 if (osb->dentry_lock_list && 390 !ocfs2_test_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED)) 391 queue_work(ocfs2_wq, &osb->dentry_lock_work); 392 spin_unlock(&dentry_list_lock); 393 } 394 395 /* Flush the whole work queue */ 396 void ocfs2_drop_all_dl_inodes(struct ocfs2_super *osb) 397 { 398 __ocfs2_drop_dl_inodes(osb, -1); 399 } 400 401 /* 402 * ocfs2_dentry_iput() and friends. 403 * 404 * At this point, our particular dentry is detached from the inodes 405 * alias list, so there's no way that the locking code can find it. 406 * 407 * The interesting stuff happens when we determine that our lock needs 408 * to go away because this is the last subdir alias in the 409 * system. This function needs to handle a couple things: 410 * 411 * 1) Synchronizing lock shutdown with the downconvert threads. This 412 * is already handled for us via the lockres release drop function 413 * called in ocfs2_release_dentry_lock() 414 * 415 * 2) A race may occur when we're doing our lock shutdown and 416 * another process wants to create a new dentry lock. Right now we 417 * let them race, which means that for a very short while, this 418 * node might have two locks on a lock resource. This should be a 419 * problem though because one of them is in the process of being 420 * thrown out. 421 */ 422 static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb, 423 struct ocfs2_dentry_lock *dl) 424 { 425 ocfs2_simple_drop_lockres(osb, &dl->dl_lockres); 426 ocfs2_lock_res_free(&dl->dl_lockres); 427 428 /* We leave dropping of inode reference to ocfs2_wq as that can 429 * possibly lead to inode deletion which gets tricky */ 430 spin_lock(&dentry_list_lock); 431 if (!osb->dentry_lock_list && 432 !ocfs2_test_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED)) 433 queue_work(ocfs2_wq, &osb->dentry_lock_work); 434 dl->dl_next = osb->dentry_lock_list; 435 osb->dentry_lock_list = dl; 436 spin_unlock(&dentry_list_lock); 437 } 438 439 void ocfs2_dentry_lock_put(struct ocfs2_super *osb, 440 struct ocfs2_dentry_lock *dl) 441 { 442 int unlock; 443 444 BUG_ON(dl->dl_count == 0); 445 446 spin_lock(&dentry_attach_lock); 447 dl->dl_count--; 448 unlock = !dl->dl_count; 449 spin_unlock(&dentry_attach_lock); 450 451 if (unlock) 452 ocfs2_drop_dentry_lock(osb, dl); 453 } 454 455 static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode) 456 { 457 struct ocfs2_dentry_lock *dl = dentry->d_fsdata; 458 459 if (!dl) { 460 /* 461 * No dentry lock is ok if we're disconnected or 462 * unhashed. 463 */ 464 if (!(dentry->d_flags & DCACHE_DISCONNECTED) && 465 !d_unhashed(dentry)) { 466 unsigned long long ino = 0ULL; 467 if (inode) 468 ino = (unsigned long long)OCFS2_I(inode)->ip_blkno; 469 mlog(ML_ERROR, "Dentry is missing cluster lock. " 470 "inode: %llu, d_flags: 0x%x, d_name: %.*s\n", 471 ino, dentry->d_flags, dentry->d_name.len, 472 dentry->d_name.name); 473 } 474 475 goto out; 476 } 477 478 mlog_bug_on_msg(dl->dl_count == 0, "dentry: %.*s, count: %u\n", 479 dentry->d_name.len, dentry->d_name.name, 480 dl->dl_count); 481 482 ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl); 483 484 out: 485 iput(inode); 486 } 487 488 /* 489 * d_move(), but keep the locks in sync. 490 * 491 * When we are done, "dentry" will have the parent dir and name of 492 * "target", which will be thrown away. 493 * 494 * We manually update the lock of "dentry" if need be. 495 * 496 * "target" doesn't have it's dentry lock touched - we allow the later 497 * dput() to handle this for us. 498 * 499 * This is called during ocfs2_rename(), while holding parent 500 * directory locks. The dentries have already been deleted on other 501 * nodes via ocfs2_remote_dentry_delete(). 502 * 503 * Normally, the VFS handles the d_move() for the file system, after 504 * the ->rename() callback. OCFS2 wants to handle this internally, so 505 * the new lock can be created atomically with respect to the cluster. 506 */ 507 void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target, 508 struct inode *old_dir, struct inode *new_dir) 509 { 510 int ret; 511 struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb); 512 struct inode *inode = dentry->d_inode; 513 514 /* 515 * Move within the same directory, so the actual lock info won't 516 * change. 517 * 518 * XXX: Is there any advantage to dropping the lock here? 519 */ 520 if (old_dir == new_dir) 521 goto out_move; 522 523 ocfs2_dentry_lock_put(osb, dentry->d_fsdata); 524 525 dentry->d_fsdata = NULL; 526 ret = ocfs2_dentry_attach_lock(dentry, inode, OCFS2_I(new_dir)->ip_blkno); 527 if (ret) 528 mlog_errno(ret); 529 530 out_move: 531 d_move(dentry, target); 532 } 533 534 const struct dentry_operations ocfs2_dentry_ops = { 535 .d_revalidate = ocfs2_dentry_revalidate, 536 .d_iput = ocfs2_dentry_iput, 537 }; 538