Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * fs/dcache.c |
| 3 | * |
| 4 | * Complete reimplementation |
| 5 | * (C) 1997 Thomas Schoebel-Theuer, |
| 6 | * with heavy changes by Linus Torvalds |
| 7 | */ |
| 8 | |
| 9 | /* |
| 10 | * Notes on the allocation strategy: |
| 11 | * |
| 12 | * The dcache is a master of the icache - whenever a dcache entry |
| 13 | * exists, the inode will always exist. "iput()" is done either when |
| 14 | * the dcache entry is deleted or garbage collected. |
| 15 | */ |
| 16 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 17 | #include <linux/syscalls.h> |
| 18 | #include <linux/string.h> |
| 19 | #include <linux/mm.h> |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 20 | #include <linux/fdtable.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | #include <linux/fs.h> |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 22 | #include <linux/fsnotify.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 23 | #include <linux/slab.h> |
| 24 | #include <linux/init.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | #include <linux/hash.h> |
| 26 | #include <linux/cache.h> |
| 27 | #include <linux/module.h> |
| 28 | #include <linux/mount.h> |
| 29 | #include <linux/file.h> |
| 30 | #include <asm/uaccess.h> |
| 31 | #include <linux/security.h> |
| 32 | #include <linux/seqlock.h> |
| 33 | #include <linux/swap.h> |
| 34 | #include <linux/bootmem.h> |
David Howells | 07f3f05 | 2006-09-30 20:52:18 +0200 | [diff] [blame] | 35 | #include "internal.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 36 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 37 | |
Eric Dumazet | fa3536c | 2006-03-26 01:37:24 -0800 | [diff] [blame] | 38 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 39 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
| 40 | |
| 41 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock); |
Al Viro | 74c3cbe | 2007-07-22 08:04:18 -0400 | [diff] [blame] | 42 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | |
| 44 | EXPORT_SYMBOL(dcache_lock); |
| 45 | |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 46 | static struct kmem_cache *dentry_cache __read_mostly; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 47 | |
| 48 | #define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname)) |
| 49 | |
| 50 | /* |
| 51 | * This is the single most critical data structure when it comes |
| 52 | * to the dcache: the hashtable for lookups. Somebody should try |
| 53 | * to make this good - I've just made it work. |
| 54 | * |
| 55 | * This hash-function tries to avoid losing too many bits of hash |
| 56 | * information, yet avoid using a prime hash-size or similar. |
| 57 | */ |
| 58 | #define D_HASHBITS d_hash_shift |
| 59 | #define D_HASHMASK d_hash_mask |
| 60 | |
Eric Dumazet | fa3536c | 2006-03-26 01:37:24 -0800 | [diff] [blame] | 61 | static unsigned int d_hash_mask __read_mostly; |
| 62 | static unsigned int d_hash_shift __read_mostly; |
| 63 | static struct hlist_head *dentry_hashtable __read_mostly; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 64 | |
| 65 | /* Statistics gathering. */ |
| 66 | struct dentry_stat_t dentry_stat = { |
| 67 | .age_limit = 45, |
| 68 | }; |
| 69 | |
Eric Dumazet | b342341 | 2006-12-06 20:38:48 -0800 | [diff] [blame] | 70 | static void __d_free(struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 71 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 72 | if (dname_external(dentry)) |
| 73 | kfree(dentry->d_name.name); |
| 74 | kmem_cache_free(dentry_cache, dentry); |
| 75 | } |
| 76 | |
Eric Dumazet | b342341 | 2006-12-06 20:38:48 -0800 | [diff] [blame] | 77 | static void d_callback(struct rcu_head *head) |
| 78 | { |
| 79 | struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu); |
| 80 | __d_free(dentry); |
| 81 | } |
| 82 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 83 | /* |
| 84 | * no dcache_lock, please. The caller must decrement dentry_stat.nr_dentry |
| 85 | * inside dcache_lock. |
| 86 | */ |
| 87 | static void d_free(struct dentry *dentry) |
| 88 | { |
| 89 | if (dentry->d_op && dentry->d_op->d_release) |
| 90 | dentry->d_op->d_release(dentry); |
Eric Dumazet | b342341 | 2006-12-06 20:38:48 -0800 | [diff] [blame] | 91 | /* if dentry was never inserted into hash, immediate free is OK */ |
Akinobu Mita | e8462ca | 2008-02-06 01:37:07 -0800 | [diff] [blame] | 92 | if (hlist_unhashed(&dentry->d_hash)) |
Eric Dumazet | b342341 | 2006-12-06 20:38:48 -0800 | [diff] [blame] | 93 | __d_free(dentry); |
| 94 | else |
| 95 | call_rcu(&dentry->d_u.d_rcu, d_callback); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | } |
| 97 | |
| 98 | /* |
| 99 | * Release the dentry's inode, using the filesystem |
| 100 | * d_iput() operation if defined. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | */ |
Arjan van de Ven | 858119e | 2006-01-14 13:20:43 -0800 | [diff] [blame] | 102 | static void dentry_iput(struct dentry * dentry) |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 103 | __releases(dentry->d_lock) |
| 104 | __releases(dcache_lock) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 105 | { |
| 106 | struct inode *inode = dentry->d_inode; |
| 107 | if (inode) { |
| 108 | dentry->d_inode = NULL; |
| 109 | list_del_init(&dentry->d_alias); |
| 110 | spin_unlock(&dentry->d_lock); |
| 111 | spin_unlock(&dcache_lock); |
Linus Torvalds | f805fbd | 2005-09-19 19:54:29 -0700 | [diff] [blame] | 112 | if (!inode->i_nlink) |
| 113 | fsnotify_inoderemove(inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | if (dentry->d_op && dentry->d_op->d_iput) |
| 115 | dentry->d_op->d_iput(dentry, inode); |
| 116 | else |
| 117 | iput(inode); |
| 118 | } else { |
| 119 | spin_unlock(&dentry->d_lock); |
| 120 | spin_unlock(&dcache_lock); |
| 121 | } |
| 122 | } |
| 123 | |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 124 | /* |
| 125 | * dentry_lru_(add|add_tail|del|del_init) must be called with dcache_lock held. |
| 126 | */ |
| 127 | static void dentry_lru_add(struct dentry *dentry) |
| 128 | { |
| 129 | list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
| 130 | dentry->d_sb->s_nr_dentry_unused++; |
| 131 | dentry_stat.nr_unused++; |
| 132 | } |
| 133 | |
| 134 | static void dentry_lru_add_tail(struct dentry *dentry) |
| 135 | { |
| 136 | list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
| 137 | dentry->d_sb->s_nr_dentry_unused++; |
| 138 | dentry_stat.nr_unused++; |
| 139 | } |
| 140 | |
| 141 | static void dentry_lru_del(struct dentry *dentry) |
| 142 | { |
| 143 | if (!list_empty(&dentry->d_lru)) { |
| 144 | list_del(&dentry->d_lru); |
| 145 | dentry->d_sb->s_nr_dentry_unused--; |
| 146 | dentry_stat.nr_unused--; |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | static void dentry_lru_del_init(struct dentry *dentry) |
| 151 | { |
| 152 | if (likely(!list_empty(&dentry->d_lru))) { |
| 153 | list_del_init(&dentry->d_lru); |
| 154 | dentry->d_sb->s_nr_dentry_unused--; |
| 155 | dentry_stat.nr_unused--; |
| 156 | } |
| 157 | } |
| 158 | |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 159 | /** |
| 160 | * d_kill - kill dentry and return parent |
| 161 | * @dentry: dentry to kill |
| 162 | * |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 163 | * The dentry must already be unhashed and removed from the LRU. |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 164 | * |
| 165 | * If this is the root of the dentry tree, return NULL. |
| 166 | */ |
| 167 | static struct dentry *d_kill(struct dentry *dentry) |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 168 | __releases(dentry->d_lock) |
| 169 | __releases(dcache_lock) |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 170 | { |
| 171 | struct dentry *parent; |
| 172 | |
| 173 | list_del(&dentry->d_u.d_child); |
| 174 | dentry_stat.nr_dentry--; /* For d_free, below */ |
| 175 | /*drops the locks, at that point nobody can reach this dentry */ |
| 176 | dentry_iput(dentry); |
| 177 | parent = dentry->d_parent; |
| 178 | d_free(dentry); |
| 179 | return dentry == parent ? NULL : parent; |
| 180 | } |
| 181 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 182 | /* |
| 183 | * This is dput |
| 184 | * |
| 185 | * This is complicated by the fact that we do not want to put |
| 186 | * dentries that are no longer on any hash chain on the unused |
| 187 | * list: we'd much rather just get rid of them immediately. |
| 188 | * |
| 189 | * However, that implies that we have to traverse the dentry |
| 190 | * tree upwards to the parents which might _also_ now be |
| 191 | * scheduled for deletion (it may have been only waiting for |
| 192 | * its last child to go away). |
| 193 | * |
| 194 | * This tail recursion is done by hand as we don't want to depend |
| 195 | * on the compiler to always get this right (gcc generally doesn't). |
| 196 | * Real recursion would eat up our stack space. |
| 197 | */ |
| 198 | |
| 199 | /* |
| 200 | * dput - release a dentry |
| 201 | * @dentry: dentry to release |
| 202 | * |
| 203 | * Release a dentry. This will drop the usage count and if appropriate |
| 204 | * call the dentry unlink method as well as removing it from the queues and |
| 205 | * releasing its resources. If the parent dentries were scheduled for release |
| 206 | * they too may now get deleted. |
| 207 | * |
| 208 | * no dcache lock, please. |
| 209 | */ |
| 210 | |
| 211 | void dput(struct dentry *dentry) |
| 212 | { |
| 213 | if (!dentry) |
| 214 | return; |
| 215 | |
| 216 | repeat: |
| 217 | if (atomic_read(&dentry->d_count) == 1) |
| 218 | might_sleep(); |
| 219 | if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock)) |
| 220 | return; |
| 221 | |
| 222 | spin_lock(&dentry->d_lock); |
| 223 | if (atomic_read(&dentry->d_count)) { |
| 224 | spin_unlock(&dentry->d_lock); |
| 225 | spin_unlock(&dcache_lock); |
| 226 | return; |
| 227 | } |
| 228 | |
| 229 | /* |
| 230 | * AV: ->d_delete() is _NOT_ allowed to block now. |
| 231 | */ |
| 232 | if (dentry->d_op && dentry->d_op->d_delete) { |
| 233 | if (dentry->d_op->d_delete(dentry)) |
| 234 | goto unhash_it; |
| 235 | } |
| 236 | /* Unreachable? Get rid of it */ |
| 237 | if (d_unhashed(dentry)) |
| 238 | goto kill_it; |
| 239 | if (list_empty(&dentry->d_lru)) { |
| 240 | dentry->d_flags |= DCACHE_REFERENCED; |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 241 | dentry_lru_add(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 242 | } |
| 243 | spin_unlock(&dentry->d_lock); |
| 244 | spin_unlock(&dcache_lock); |
| 245 | return; |
| 246 | |
| 247 | unhash_it: |
| 248 | __d_drop(dentry); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 249 | kill_it: |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 250 | /* if dentry was on the d_lru list delete it from there */ |
| 251 | dentry_lru_del(dentry); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 252 | dentry = d_kill(dentry); |
| 253 | if (dentry) |
| 254 | goto repeat; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 255 | } |
| 256 | |
| 257 | /** |
| 258 | * d_invalidate - invalidate a dentry |
| 259 | * @dentry: dentry to invalidate |
| 260 | * |
| 261 | * Try to invalidate the dentry if it turns out to be |
| 262 | * possible. If there are other dentries that can be |
| 263 | * reached through this one we can't delete it and we |
| 264 | * return -EBUSY. On success we return 0. |
| 265 | * |
| 266 | * no dcache lock. |
| 267 | */ |
| 268 | |
| 269 | int d_invalidate(struct dentry * dentry) |
| 270 | { |
| 271 | /* |
| 272 | * If it's already been dropped, return OK. |
| 273 | */ |
| 274 | spin_lock(&dcache_lock); |
| 275 | if (d_unhashed(dentry)) { |
| 276 | spin_unlock(&dcache_lock); |
| 277 | return 0; |
| 278 | } |
| 279 | /* |
| 280 | * Check whether to do a partial shrink_dcache |
| 281 | * to get rid of unused child entries. |
| 282 | */ |
| 283 | if (!list_empty(&dentry->d_subdirs)) { |
| 284 | spin_unlock(&dcache_lock); |
| 285 | shrink_dcache_parent(dentry); |
| 286 | spin_lock(&dcache_lock); |
| 287 | } |
| 288 | |
| 289 | /* |
| 290 | * Somebody else still using it? |
| 291 | * |
| 292 | * If it's a directory, we can't drop it |
| 293 | * for fear of somebody re-populating it |
| 294 | * with children (even though dropping it |
| 295 | * would make it unreachable from the root, |
| 296 | * we might still populate it if it was a |
| 297 | * working directory or similar). |
| 298 | */ |
| 299 | spin_lock(&dentry->d_lock); |
| 300 | if (atomic_read(&dentry->d_count) > 1) { |
| 301 | if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { |
| 302 | spin_unlock(&dentry->d_lock); |
| 303 | spin_unlock(&dcache_lock); |
| 304 | return -EBUSY; |
| 305 | } |
| 306 | } |
| 307 | |
| 308 | __d_drop(dentry); |
| 309 | spin_unlock(&dentry->d_lock); |
| 310 | spin_unlock(&dcache_lock); |
| 311 | return 0; |
| 312 | } |
| 313 | |
| 314 | /* This should be called _only_ with dcache_lock held */ |
| 315 | |
| 316 | static inline struct dentry * __dget_locked(struct dentry *dentry) |
| 317 | { |
| 318 | atomic_inc(&dentry->d_count); |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 319 | dentry_lru_del_init(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 320 | return dentry; |
| 321 | } |
| 322 | |
| 323 | struct dentry * dget_locked(struct dentry *dentry) |
| 324 | { |
| 325 | return __dget_locked(dentry); |
| 326 | } |
| 327 | |
| 328 | /** |
| 329 | * d_find_alias - grab a hashed alias of inode |
| 330 | * @inode: inode in question |
| 331 | * @want_discon: flag, used by d_splice_alias, to request |
| 332 | * that only a DISCONNECTED alias be returned. |
| 333 | * |
| 334 | * If inode has a hashed alias, or is a directory and has any alias, |
| 335 | * acquire the reference to alias and return it. Otherwise return NULL. |
| 336 | * Notice that if inode is a directory there can be only one alias and |
| 337 | * it can be unhashed only if it has no children, or if it is the root |
| 338 | * of a filesystem. |
| 339 | * |
NeilBrown | 21c0d8f | 2006-10-04 02:16:16 -0700 | [diff] [blame] | 340 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 341 | * any other hashed alias over that one unless @want_discon is set, |
NeilBrown | 21c0d8f | 2006-10-04 02:16:16 -0700 | [diff] [blame] | 342 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 343 | */ |
| 344 | |
| 345 | static struct dentry * __d_find_alias(struct inode *inode, int want_discon) |
| 346 | { |
| 347 | struct list_head *head, *next, *tmp; |
| 348 | struct dentry *alias, *discon_alias=NULL; |
| 349 | |
| 350 | head = &inode->i_dentry; |
| 351 | next = inode->i_dentry.next; |
| 352 | while (next != head) { |
| 353 | tmp = next; |
| 354 | next = tmp->next; |
| 355 | prefetch(next); |
| 356 | alias = list_entry(tmp, struct dentry, d_alias); |
| 357 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
NeilBrown | 21c0d8f | 2006-10-04 02:16:16 -0700 | [diff] [blame] | 358 | if (IS_ROOT(alias) && |
| 359 | (alias->d_flags & DCACHE_DISCONNECTED)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 360 | discon_alias = alias; |
| 361 | else if (!want_discon) { |
| 362 | __dget_locked(alias); |
| 363 | return alias; |
| 364 | } |
| 365 | } |
| 366 | } |
| 367 | if (discon_alias) |
| 368 | __dget_locked(discon_alias); |
| 369 | return discon_alias; |
| 370 | } |
| 371 | |
| 372 | struct dentry * d_find_alias(struct inode *inode) |
| 373 | { |
David Howells | 214fda1 | 2006-03-25 03:06:36 -0800 | [diff] [blame] | 374 | struct dentry *de = NULL; |
| 375 | |
| 376 | if (!list_empty(&inode->i_dentry)) { |
| 377 | spin_lock(&dcache_lock); |
| 378 | de = __d_find_alias(inode, 0); |
| 379 | spin_unlock(&dcache_lock); |
| 380 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 381 | return de; |
| 382 | } |
| 383 | |
| 384 | /* |
| 385 | * Try to kill dentries associated with this inode. |
| 386 | * WARNING: you must own a reference to inode. |
| 387 | */ |
| 388 | void d_prune_aliases(struct inode *inode) |
| 389 | { |
Domen Puncer | 0cdca3f | 2005-09-10 00:27:07 -0700 | [diff] [blame] | 390 | struct dentry *dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 391 | restart: |
| 392 | spin_lock(&dcache_lock); |
Domen Puncer | 0cdca3f | 2005-09-10 00:27:07 -0700 | [diff] [blame] | 393 | list_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 394 | spin_lock(&dentry->d_lock); |
| 395 | if (!atomic_read(&dentry->d_count)) { |
| 396 | __dget_locked(dentry); |
| 397 | __d_drop(dentry); |
| 398 | spin_unlock(&dentry->d_lock); |
| 399 | spin_unlock(&dcache_lock); |
| 400 | dput(dentry); |
| 401 | goto restart; |
| 402 | } |
| 403 | spin_unlock(&dentry->d_lock); |
| 404 | } |
| 405 | spin_unlock(&dcache_lock); |
| 406 | } |
| 407 | |
| 408 | /* |
Andrew Morton | d702ccb | 2006-06-22 14:47:31 -0700 | [diff] [blame] | 409 | * Throw away a dentry - free the inode, dput the parent. This requires that |
| 410 | * the LRU list has already been removed. |
| 411 | * |
Miklos Szeredi | 85864e1 | 2007-10-16 23:27:09 -0700 | [diff] [blame] | 412 | * Try to prune ancestors as well. This is necessary to prevent |
| 413 | * quadratic behavior of shrink_dcache_parent(), but is also expected |
| 414 | * to be beneficial in reducing dentry cache fragmentation. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 415 | */ |
Miklos Szeredi | 85864e1 | 2007-10-16 23:27:09 -0700 | [diff] [blame] | 416 | static void prune_one_dentry(struct dentry * dentry) |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 417 | __releases(dentry->d_lock) |
| 418 | __releases(dcache_lock) |
| 419 | __acquires(dcache_lock) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 420 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 421 | __d_drop(dentry); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 422 | dentry = d_kill(dentry); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 423 | |
| 424 | /* |
| 425 | * Prune ancestors. Locking is simpler than in dput(), |
| 426 | * because dcache_lock needs to be taken anyway. |
| 427 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 428 | spin_lock(&dcache_lock); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 429 | while (dentry) { |
| 430 | if (!atomic_dec_and_lock(&dentry->d_count, &dentry->d_lock)) |
| 431 | return; |
| 432 | |
| 433 | if (dentry->d_op && dentry->d_op->d_delete) |
| 434 | dentry->d_op->d_delete(dentry); |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 435 | dentry_lru_del_init(dentry); |
Miklos Szeredi | d52b908 | 2007-05-08 00:23:46 -0700 | [diff] [blame] | 436 | __d_drop(dentry); |
| 437 | dentry = d_kill(dentry); |
| 438 | spin_lock(&dcache_lock); |
| 439 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 440 | } |
| 441 | |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 442 | /* |
| 443 | * Shrink the dentry LRU on a given superblock. |
| 444 | * @sb : superblock to shrink dentry LRU. |
| 445 | * @count: If count is NULL, we prune all dentries on superblock. |
| 446 | * @flags: If flags is non-zero, we need to do special processing based on |
| 447 | * which flags are set. This means we don't need to maintain multiple |
| 448 | * similar copies of this loop. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 449 | */ |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 450 | static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 451 | { |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 452 | LIST_HEAD(referenced); |
| 453 | LIST_HEAD(tmp); |
| 454 | struct dentry *dentry; |
| 455 | int cnt = 0; |
| 456 | |
| 457 | BUG_ON(!sb); |
| 458 | BUG_ON((flags & DCACHE_REFERENCED) && count == NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 459 | spin_lock(&dcache_lock); |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 460 | if (count != NULL) |
| 461 | /* called from prune_dcache() and shrink_dcache_parent() */ |
| 462 | cnt = *count; |
| 463 | restart: |
| 464 | if (count == NULL) |
| 465 | list_splice_init(&sb->s_dentry_lru, &tmp); |
| 466 | else { |
| 467 | while (!list_empty(&sb->s_dentry_lru)) { |
| 468 | dentry = list_entry(sb->s_dentry_lru.prev, |
| 469 | struct dentry, d_lru); |
| 470 | BUG_ON(dentry->d_sb != sb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 471 | |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 472 | spin_lock(&dentry->d_lock); |
| 473 | /* |
| 474 | * If we are honouring the DCACHE_REFERENCED flag and |
| 475 | * the dentry has this flag set, don't free it. Clear |
| 476 | * the flag and put it back on the LRU. |
NeilBrown | 0feae5c | 2006-06-22 14:47:28 -0700 | [diff] [blame] | 477 | */ |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 478 | if ((flags & DCACHE_REFERENCED) |
| 479 | && (dentry->d_flags & DCACHE_REFERENCED)) { |
| 480 | dentry->d_flags &= ~DCACHE_REFERENCED; |
| 481 | list_move_tail(&dentry->d_lru, &referenced); |
| 482 | spin_unlock(&dentry->d_lock); |
| 483 | } else { |
| 484 | list_move_tail(&dentry->d_lru, &tmp); |
| 485 | spin_unlock(&dentry->d_lock); |
| 486 | cnt--; |
| 487 | if (!cnt) |
| 488 | break; |
NeilBrown | 0feae5c | 2006-06-22 14:47:28 -0700 | [diff] [blame] | 489 | } |
| 490 | } |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 491 | } |
| 492 | while (!list_empty(&tmp)) { |
| 493 | dentry = list_entry(tmp.prev, struct dentry, d_lru); |
| 494 | dentry_lru_del_init(dentry); |
| 495 | spin_lock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 496 | /* |
| 497 | * We found an inuse dentry which was not removed from |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 498 | * the LRU because of laziness during lookup. Do not free |
| 499 | * it - just keep it off the LRU list. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 500 | */ |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 501 | if (atomic_read(&dentry->d_count)) { |
| 502 | spin_unlock(&dentry->d_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 503 | continue; |
| 504 | } |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 505 | prune_one_dentry(dentry); |
| 506 | /* dentry->d_lock was dropped in prune_one_dentry() */ |
| 507 | cond_resched_lock(&dcache_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 508 | } |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 509 | if (count == NULL && !list_empty(&sb->s_dentry_lru)) |
| 510 | goto restart; |
| 511 | if (count != NULL) |
| 512 | *count = cnt; |
| 513 | if (!list_empty(&referenced)) |
| 514 | list_splice(&referenced, &sb->s_dentry_lru); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 515 | spin_unlock(&dcache_lock); |
| 516 | } |
| 517 | |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 518 | /** |
| 519 | * prune_dcache - shrink the dcache |
| 520 | * @count: number of entries to try to free |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 521 | * |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 522 | * Shrink the dcache. This is done when we need more memory, or simply when we |
| 523 | * need to unmount something (at which point we need to unuse all dentries). |
| 524 | * |
| 525 | * This function may fail to free any resources if all the dentries are in use. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 526 | */ |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 527 | static void prune_dcache(int count) |
| 528 | { |
| 529 | struct super_block *sb; |
| 530 | int w_count; |
| 531 | int unused = dentry_stat.nr_unused; |
| 532 | int prune_ratio; |
| 533 | int pruned; |
| 534 | |
| 535 | if (unused == 0 || count == 0) |
| 536 | return; |
| 537 | spin_lock(&dcache_lock); |
| 538 | restart: |
| 539 | if (count >= unused) |
| 540 | prune_ratio = 1; |
| 541 | else |
| 542 | prune_ratio = unused / count; |
| 543 | spin_lock(&sb_lock); |
| 544 | list_for_each_entry(sb, &super_blocks, s_list) { |
| 545 | if (sb->s_nr_dentry_unused == 0) |
| 546 | continue; |
| 547 | sb->s_count++; |
| 548 | /* Now, we reclaim unused dentrins with fairness. |
| 549 | * We reclaim them same percentage from each superblock. |
| 550 | * We calculate number of dentries to scan on this sb |
| 551 | * as follows, but the implementation is arranged to avoid |
| 552 | * overflows: |
| 553 | * number of dentries to scan on this sb = |
| 554 | * count * (number of dentries on this sb / |
| 555 | * number of dentries in the machine) |
| 556 | */ |
| 557 | spin_unlock(&sb_lock); |
| 558 | if (prune_ratio != 1) |
| 559 | w_count = (sb->s_nr_dentry_unused / prune_ratio) + 1; |
| 560 | else |
| 561 | w_count = sb->s_nr_dentry_unused; |
| 562 | pruned = w_count; |
| 563 | /* |
| 564 | * We need to be sure this filesystem isn't being unmounted, |
| 565 | * otherwise we could race with generic_shutdown_super(), and |
| 566 | * end up holding a reference to an inode while the filesystem |
| 567 | * is unmounted. So we try to get s_umount, and make sure |
| 568 | * s_root isn't NULL. |
| 569 | */ |
| 570 | if (down_read_trylock(&sb->s_umount)) { |
| 571 | if ((sb->s_root != NULL) && |
| 572 | (!list_empty(&sb->s_dentry_lru))) { |
| 573 | spin_unlock(&dcache_lock); |
| 574 | __shrink_dcache_sb(sb, &w_count, |
| 575 | DCACHE_REFERENCED); |
| 576 | pruned -= w_count; |
| 577 | spin_lock(&dcache_lock); |
| 578 | } |
| 579 | up_read(&sb->s_umount); |
| 580 | } |
| 581 | spin_lock(&sb_lock); |
| 582 | count -= pruned; |
| 583 | /* |
| 584 | * restart only when sb is no longer on the list and |
| 585 | * we have more work to do. |
| 586 | */ |
| 587 | if (__put_super_and_need_restart(sb) && count > 0) { |
| 588 | spin_unlock(&sb_lock); |
| 589 | goto restart; |
| 590 | } |
| 591 | } |
| 592 | spin_unlock(&sb_lock); |
| 593 | spin_unlock(&dcache_lock); |
| 594 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 595 | |
| 596 | /** |
| 597 | * shrink_dcache_sb - shrink dcache for a superblock |
| 598 | * @sb: superblock |
| 599 | * |
| 600 | * Shrink the dcache for the specified super block. This |
| 601 | * is used to free the dcache before unmounting a file |
| 602 | * system |
| 603 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 604 | void shrink_dcache_sb(struct super_block * sb) |
| 605 | { |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 606 | __shrink_dcache_sb(sb, NULL, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 607 | } |
| 608 | |
| 609 | /* |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 610 | * destroy a single subtree of dentries for unmount |
| 611 | * - see the comments on shrink_dcache_for_umount() for a description of the |
| 612 | * locking |
| 613 | */ |
| 614 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) |
| 615 | { |
| 616 | struct dentry *parent; |
David Howells | f871357 | 2006-10-28 10:38:46 -0700 | [diff] [blame] | 617 | unsigned detached = 0; |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 618 | |
| 619 | BUG_ON(!IS_ROOT(dentry)); |
| 620 | |
| 621 | /* detach this root from the system */ |
| 622 | spin_lock(&dcache_lock); |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 623 | dentry_lru_del_init(dentry); |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 624 | __d_drop(dentry); |
| 625 | spin_unlock(&dcache_lock); |
| 626 | |
| 627 | for (;;) { |
| 628 | /* descend to the first leaf in the current subtree */ |
| 629 | while (!list_empty(&dentry->d_subdirs)) { |
| 630 | struct dentry *loop; |
| 631 | |
| 632 | /* this is a branch with children - detach all of them |
| 633 | * from the system in one go */ |
| 634 | spin_lock(&dcache_lock); |
| 635 | list_for_each_entry(loop, &dentry->d_subdirs, |
| 636 | d_u.d_child) { |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 637 | dentry_lru_del_init(loop); |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 638 | __d_drop(loop); |
| 639 | cond_resched_lock(&dcache_lock); |
| 640 | } |
| 641 | spin_unlock(&dcache_lock); |
| 642 | |
| 643 | /* move to the first child */ |
| 644 | dentry = list_entry(dentry->d_subdirs.next, |
| 645 | struct dentry, d_u.d_child); |
| 646 | } |
| 647 | |
| 648 | /* consume the dentries from this leaf up through its parents |
| 649 | * until we find one with children or run out altogether */ |
| 650 | do { |
| 651 | struct inode *inode; |
| 652 | |
| 653 | if (atomic_read(&dentry->d_count) != 0) { |
| 654 | printk(KERN_ERR |
| 655 | "BUG: Dentry %p{i=%lx,n=%s}" |
| 656 | " still in use (%d)" |
| 657 | " [unmount of %s %s]\n", |
| 658 | dentry, |
| 659 | dentry->d_inode ? |
| 660 | dentry->d_inode->i_ino : 0UL, |
| 661 | dentry->d_name.name, |
| 662 | atomic_read(&dentry->d_count), |
| 663 | dentry->d_sb->s_type->name, |
| 664 | dentry->d_sb->s_id); |
| 665 | BUG(); |
| 666 | } |
| 667 | |
| 668 | parent = dentry->d_parent; |
| 669 | if (parent == dentry) |
| 670 | parent = NULL; |
| 671 | else |
| 672 | atomic_dec(&parent->d_count); |
| 673 | |
| 674 | list_del(&dentry->d_u.d_child); |
David Howells | f871357 | 2006-10-28 10:38:46 -0700 | [diff] [blame] | 675 | detached++; |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 676 | |
| 677 | inode = dentry->d_inode; |
| 678 | if (inode) { |
| 679 | dentry->d_inode = NULL; |
| 680 | list_del_init(&dentry->d_alias); |
| 681 | if (dentry->d_op && dentry->d_op->d_iput) |
| 682 | dentry->d_op->d_iput(dentry, inode); |
| 683 | else |
| 684 | iput(inode); |
| 685 | } |
| 686 | |
| 687 | d_free(dentry); |
| 688 | |
| 689 | /* finished when we fall off the top of the tree, |
| 690 | * otherwise we ascend to the parent and move to the |
| 691 | * next sibling if there is one */ |
| 692 | if (!parent) |
David Howells | f871357 | 2006-10-28 10:38:46 -0700 | [diff] [blame] | 693 | goto out; |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 694 | |
| 695 | dentry = parent; |
| 696 | |
| 697 | } while (list_empty(&dentry->d_subdirs)); |
| 698 | |
| 699 | dentry = list_entry(dentry->d_subdirs.next, |
| 700 | struct dentry, d_u.d_child); |
| 701 | } |
David Howells | f871357 | 2006-10-28 10:38:46 -0700 | [diff] [blame] | 702 | out: |
| 703 | /* several dentries were freed, need to correct nr_dentry */ |
| 704 | spin_lock(&dcache_lock); |
| 705 | dentry_stat.nr_dentry -= detached; |
| 706 | spin_unlock(&dcache_lock); |
David Howells | c636ebd | 2006-10-11 01:22:19 -0700 | [diff] [blame] | 707 | } |
| 708 | |
| 709 | /* |
| 710 | * destroy the dentries attached to a superblock on unmounting |
| 711 | * - we don't need to use dentry->d_lock, and only need dcache_lock when |
| 712 | * removing the dentry from the system lists and hashes because: |
| 713 | * - the superblock is detached from all mountings and open files, so the |
| 714 | * dentry trees will not be rearranged by the VFS |
| 715 | * - s_umount is write-locked, so the memory pressure shrinker will ignore |
| 716 | * any dentries belonging to this superblock that it comes across |
| 717 | * - the filesystem itself is no longer permitted to rearrange the dentries |
| 718 | * in this superblock |
| 719 | */ |
| 720 | void shrink_dcache_for_umount(struct super_block *sb) |
| 721 | { |
| 722 | struct dentry *dentry; |
| 723 | |
| 724 | if (down_read_trylock(&sb->s_umount)) |
| 725 | BUG(); |
| 726 | |
| 727 | dentry = sb->s_root; |
| 728 | sb->s_root = NULL; |
| 729 | atomic_dec(&dentry->d_count); |
| 730 | shrink_dcache_for_umount_subtree(dentry); |
| 731 | |
| 732 | while (!hlist_empty(&sb->s_anon)) { |
| 733 | dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash); |
| 734 | shrink_dcache_for_umount_subtree(dentry); |
| 735 | } |
| 736 | } |
| 737 | |
| 738 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 739 | * Search for at least 1 mount point in the dentry's subdirs. |
| 740 | * We descend to the next level whenever the d_subdirs |
| 741 | * list is non-empty and continue searching. |
| 742 | */ |
| 743 | |
| 744 | /** |
| 745 | * have_submounts - check for mounts over a dentry |
| 746 | * @parent: dentry to check. |
| 747 | * |
| 748 | * Return true if the parent or its subdirectories contain |
| 749 | * a mount point |
| 750 | */ |
| 751 | |
| 752 | int have_submounts(struct dentry *parent) |
| 753 | { |
| 754 | struct dentry *this_parent = parent; |
| 755 | struct list_head *next; |
| 756 | |
| 757 | spin_lock(&dcache_lock); |
| 758 | if (d_mountpoint(parent)) |
| 759 | goto positive; |
| 760 | repeat: |
| 761 | next = this_parent->d_subdirs.next; |
| 762 | resume: |
| 763 | while (next != &this_parent->d_subdirs) { |
| 764 | struct list_head *tmp = next; |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 765 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 766 | next = tmp->next; |
| 767 | /* Have we found a mount point ? */ |
| 768 | if (d_mountpoint(dentry)) |
| 769 | goto positive; |
| 770 | if (!list_empty(&dentry->d_subdirs)) { |
| 771 | this_parent = dentry; |
| 772 | goto repeat; |
| 773 | } |
| 774 | } |
| 775 | /* |
| 776 | * All done at this level ... ascend and resume the search. |
| 777 | */ |
| 778 | if (this_parent != parent) { |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 779 | next = this_parent->d_u.d_child.next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 780 | this_parent = this_parent->d_parent; |
| 781 | goto resume; |
| 782 | } |
| 783 | spin_unlock(&dcache_lock); |
| 784 | return 0; /* No mount points found in tree */ |
| 785 | positive: |
| 786 | spin_unlock(&dcache_lock); |
| 787 | return 1; |
| 788 | } |
| 789 | |
| 790 | /* |
| 791 | * Search the dentry child list for the specified parent, |
| 792 | * and move any unused dentries to the end of the unused |
| 793 | * list for prune_dcache(). We descend to the next level |
| 794 | * whenever the d_subdirs list is non-empty and continue |
| 795 | * searching. |
| 796 | * |
| 797 | * It returns zero iff there are no unused children, |
| 798 | * otherwise it returns the number of children moved to |
| 799 | * the end of the unused list. This may not be the total |
| 800 | * number of unused children, because select_parent can |
| 801 | * drop the lock and return early due to latency |
| 802 | * constraints. |
| 803 | */ |
| 804 | static int select_parent(struct dentry * parent) |
| 805 | { |
| 806 | struct dentry *this_parent = parent; |
| 807 | struct list_head *next; |
| 808 | int found = 0; |
| 809 | |
| 810 | spin_lock(&dcache_lock); |
| 811 | repeat: |
| 812 | next = this_parent->d_subdirs.next; |
| 813 | resume: |
| 814 | while (next != &this_parent->d_subdirs) { |
| 815 | struct list_head *tmp = next; |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 816 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 817 | next = tmp->next; |
| 818 | |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 819 | dentry_lru_del_init(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 820 | /* |
| 821 | * move only zero ref count dentries to the end |
| 822 | * of the unused list for prune_dcache |
| 823 | */ |
| 824 | if (!atomic_read(&dentry->d_count)) { |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 825 | dentry_lru_add_tail(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 826 | found++; |
| 827 | } |
| 828 | |
| 829 | /* |
| 830 | * We can return to the caller if we have found some (this |
| 831 | * ensures forward progress). We'll be coming back to find |
| 832 | * the rest. |
| 833 | */ |
| 834 | if (found && need_resched()) |
| 835 | goto out; |
| 836 | |
| 837 | /* |
| 838 | * Descend a level if the d_subdirs list is non-empty. |
| 839 | */ |
| 840 | if (!list_empty(&dentry->d_subdirs)) { |
| 841 | this_parent = dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 842 | goto repeat; |
| 843 | } |
| 844 | } |
| 845 | /* |
| 846 | * All done at this level ... ascend and resume the search. |
| 847 | */ |
| 848 | if (this_parent != parent) { |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 849 | next = this_parent->d_u.d_child.next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 850 | this_parent = this_parent->d_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 851 | goto resume; |
| 852 | } |
| 853 | out: |
| 854 | spin_unlock(&dcache_lock); |
| 855 | return found; |
| 856 | } |
| 857 | |
| 858 | /** |
| 859 | * shrink_dcache_parent - prune dcache |
| 860 | * @parent: parent of entries to prune |
| 861 | * |
| 862 | * Prune the dcache to remove unused children of the parent dentry. |
| 863 | */ |
| 864 | |
| 865 | void shrink_dcache_parent(struct dentry * parent) |
| 866 | { |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 867 | struct super_block *sb = parent->d_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 868 | int found; |
| 869 | |
| 870 | while ((found = select_parent(parent)) != 0) |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 871 | __shrink_dcache_sb(sb, &found, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 872 | } |
| 873 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 874 | /* |
| 875 | * Scan `nr' dentries and return the number which remain. |
| 876 | * |
| 877 | * We need to avoid reentering the filesystem if the caller is performing a |
| 878 | * GFP_NOFS allocation attempt. One example deadlock is: |
| 879 | * |
| 880 | * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache-> |
| 881 | * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode-> |
| 882 | * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK. |
| 883 | * |
| 884 | * In this case we return -1 to tell the caller that we baled. |
| 885 | */ |
Al Viro | 27496a8 | 2005-10-21 03:20:48 -0400 | [diff] [blame] | 886 | static int shrink_dcache_memory(int nr, gfp_t gfp_mask) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 887 | { |
| 888 | if (nr) { |
| 889 | if (!(gfp_mask & __GFP_FS)) |
| 890 | return -1; |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 891 | prune_dcache(nr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 892 | } |
| 893 | return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; |
| 894 | } |
| 895 | |
Rusty Russell | 8e1f936 | 2007-07-17 04:03:17 -0700 | [diff] [blame] | 896 | static struct shrinker dcache_shrinker = { |
| 897 | .shrink = shrink_dcache_memory, |
| 898 | .seeks = DEFAULT_SEEKS, |
| 899 | }; |
| 900 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 901 | /** |
| 902 | * d_alloc - allocate a dcache entry |
| 903 | * @parent: parent of entry to allocate |
| 904 | * @name: qstr of the name |
| 905 | * |
| 906 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
| 907 | * available. On a success the dentry is returned. The name passed in is |
| 908 | * copied and the copy passed in may be reused after this call. |
| 909 | */ |
| 910 | |
| 911 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) |
| 912 | { |
| 913 | struct dentry *dentry; |
| 914 | char *dname; |
| 915 | |
Mel Gorman | e12ba74 | 2007-10-16 01:25:52 -0700 | [diff] [blame] | 916 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 917 | if (!dentry) |
| 918 | return NULL; |
| 919 | |
| 920 | if (name->len > DNAME_INLINE_LEN-1) { |
| 921 | dname = kmalloc(name->len + 1, GFP_KERNEL); |
| 922 | if (!dname) { |
| 923 | kmem_cache_free(dentry_cache, dentry); |
| 924 | return NULL; |
| 925 | } |
| 926 | } else { |
| 927 | dname = dentry->d_iname; |
| 928 | } |
| 929 | dentry->d_name.name = dname; |
| 930 | |
| 931 | dentry->d_name.len = name->len; |
| 932 | dentry->d_name.hash = name->hash; |
| 933 | memcpy(dname, name->name, name->len); |
| 934 | dname[name->len] = 0; |
| 935 | |
| 936 | atomic_set(&dentry->d_count, 1); |
| 937 | dentry->d_flags = DCACHE_UNHASHED; |
| 938 | spin_lock_init(&dentry->d_lock); |
| 939 | dentry->d_inode = NULL; |
| 940 | dentry->d_parent = NULL; |
| 941 | dentry->d_sb = NULL; |
| 942 | dentry->d_op = NULL; |
| 943 | dentry->d_fsdata = NULL; |
| 944 | dentry->d_mounted = 0; |
Marcelo Tosatti | 47ba87e | 2006-02-03 03:04:06 -0800 | [diff] [blame] | 945 | #ifdef CONFIG_PROFILING |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 946 | dentry->d_cookie = NULL; |
Marcelo Tosatti | 47ba87e | 2006-02-03 03:04:06 -0800 | [diff] [blame] | 947 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 948 | INIT_HLIST_NODE(&dentry->d_hash); |
| 949 | INIT_LIST_HEAD(&dentry->d_lru); |
| 950 | INIT_LIST_HEAD(&dentry->d_subdirs); |
| 951 | INIT_LIST_HEAD(&dentry->d_alias); |
| 952 | |
| 953 | if (parent) { |
| 954 | dentry->d_parent = dget(parent); |
| 955 | dentry->d_sb = parent->d_sb; |
| 956 | } else { |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 957 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 958 | } |
| 959 | |
| 960 | spin_lock(&dcache_lock); |
| 961 | if (parent) |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 962 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 963 | dentry_stat.nr_dentry++; |
| 964 | spin_unlock(&dcache_lock); |
| 965 | |
| 966 | return dentry; |
| 967 | } |
| 968 | |
| 969 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
| 970 | { |
| 971 | struct qstr q; |
| 972 | |
| 973 | q.name = name; |
| 974 | q.len = strlen(name); |
| 975 | q.hash = full_name_hash(q.name, q.len); |
| 976 | return d_alloc(parent, &q); |
| 977 | } |
| 978 | |
| 979 | /** |
| 980 | * d_instantiate - fill in inode information for a dentry |
| 981 | * @entry: dentry to complete |
| 982 | * @inode: inode to attach to this dentry |
| 983 | * |
| 984 | * Fill in inode information in the entry. |
| 985 | * |
| 986 | * This turns negative dentries into productive full members |
| 987 | * of society. |
| 988 | * |
| 989 | * NOTE! This assumes that the inode count has been incremented |
| 990 | * (or otherwise set) by the caller to indicate that it is now |
| 991 | * in use by the dcache. |
| 992 | */ |
| 993 | |
| 994 | void d_instantiate(struct dentry *entry, struct inode * inode) |
| 995 | { |
Eric Sesterhenn | 28133c7 | 2006-03-26 18:25:39 +0200 | [diff] [blame] | 996 | BUG_ON(!list_empty(&entry->d_alias)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 997 | spin_lock(&dcache_lock); |
| 998 | if (inode) |
| 999 | list_add(&entry->d_alias, &inode->i_dentry); |
| 1000 | entry->d_inode = inode; |
Nick Piggin | c32ccd8 | 2006-03-25 03:07:09 -0800 | [diff] [blame] | 1001 | fsnotify_d_instantiate(entry, inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1002 | spin_unlock(&dcache_lock); |
| 1003 | security_d_instantiate(entry, inode); |
| 1004 | } |
| 1005 | |
| 1006 | /** |
| 1007 | * d_instantiate_unique - instantiate a non-aliased dentry |
| 1008 | * @entry: dentry to instantiate |
| 1009 | * @inode: inode to attach to this dentry |
| 1010 | * |
| 1011 | * Fill in inode information in the entry. On success, it returns NULL. |
| 1012 | * If an unhashed alias of "entry" already exists, then we return the |
Oleg Drokin | e866cfa | 2006-01-09 20:52:51 -0800 | [diff] [blame] | 1013 | * aliased dentry instead and drop one reference to inode. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1014 | * |
| 1015 | * Note that in order to avoid conflicts with rename() etc, the caller |
| 1016 | * had better be holding the parent directory semaphore. |
Oleg Drokin | e866cfa | 2006-01-09 20:52:51 -0800 | [diff] [blame] | 1017 | * |
| 1018 | * This also assumes that the inode count has been incremented |
| 1019 | * (or otherwise set) by the caller to indicate that it is now |
| 1020 | * in use by the dcache. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1021 | */ |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1022 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
| 1023 | struct inode *inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1024 | { |
| 1025 | struct dentry *alias; |
| 1026 | int len = entry->d_name.len; |
| 1027 | const char *name = entry->d_name.name; |
| 1028 | unsigned int hash = entry->d_name.hash; |
| 1029 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1030 | if (!inode) { |
| 1031 | entry->d_inode = NULL; |
| 1032 | return NULL; |
| 1033 | } |
| 1034 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1035 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
| 1036 | struct qstr *qstr = &alias->d_name; |
| 1037 | |
| 1038 | if (qstr->hash != hash) |
| 1039 | continue; |
| 1040 | if (alias->d_parent != entry->d_parent) |
| 1041 | continue; |
| 1042 | if (qstr->len != len) |
| 1043 | continue; |
| 1044 | if (memcmp(qstr->name, name, len)) |
| 1045 | continue; |
| 1046 | dget_locked(alias); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1047 | return alias; |
| 1048 | } |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1049 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1050 | list_add(&entry->d_alias, &inode->i_dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1051 | entry->d_inode = inode; |
Nick Piggin | c32ccd8 | 2006-03-25 03:07:09 -0800 | [diff] [blame] | 1052 | fsnotify_d_instantiate(entry, inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1053 | return NULL; |
| 1054 | } |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1055 | |
| 1056 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) |
| 1057 | { |
| 1058 | struct dentry *result; |
| 1059 | |
| 1060 | BUG_ON(!list_empty(&entry->d_alias)); |
| 1061 | |
| 1062 | spin_lock(&dcache_lock); |
| 1063 | result = __d_instantiate_unique(entry, inode); |
| 1064 | spin_unlock(&dcache_lock); |
| 1065 | |
| 1066 | if (!result) { |
| 1067 | security_d_instantiate(entry, inode); |
| 1068 | return NULL; |
| 1069 | } |
| 1070 | |
| 1071 | BUG_ON(!d_unhashed(result)); |
| 1072 | iput(inode); |
| 1073 | return result; |
| 1074 | } |
| 1075 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1076 | EXPORT_SYMBOL(d_instantiate_unique); |
| 1077 | |
| 1078 | /** |
| 1079 | * d_alloc_root - allocate root dentry |
| 1080 | * @root_inode: inode to allocate the root for |
| 1081 | * |
| 1082 | * Allocate a root ("/") dentry for the inode given. The inode is |
| 1083 | * instantiated and returned. %NULL is returned if there is insufficient |
| 1084 | * memory or the inode passed is %NULL. |
| 1085 | */ |
| 1086 | |
| 1087 | struct dentry * d_alloc_root(struct inode * root_inode) |
| 1088 | { |
| 1089 | struct dentry *res = NULL; |
| 1090 | |
| 1091 | if (root_inode) { |
| 1092 | static const struct qstr name = { .name = "/", .len = 1 }; |
| 1093 | |
| 1094 | res = d_alloc(NULL, &name); |
| 1095 | if (res) { |
| 1096 | res->d_sb = root_inode->i_sb; |
| 1097 | res->d_parent = res; |
| 1098 | d_instantiate(res, root_inode); |
| 1099 | } |
| 1100 | } |
| 1101 | return res; |
| 1102 | } |
| 1103 | |
| 1104 | static inline struct hlist_head *d_hash(struct dentry *parent, |
| 1105 | unsigned long hash) |
| 1106 | { |
| 1107 | hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; |
| 1108 | hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); |
| 1109 | return dentry_hashtable + (hash & D_HASHMASK); |
| 1110 | } |
| 1111 | |
| 1112 | /** |
| 1113 | * d_alloc_anon - allocate an anonymous dentry |
| 1114 | * @inode: inode to allocate the dentry for |
| 1115 | * |
| 1116 | * This is similar to d_alloc_root. It is used by filesystems when |
| 1117 | * creating a dentry for a given inode, often in the process of |
| 1118 | * mapping a filehandle to a dentry. The returned dentry may be |
| 1119 | * anonymous, or may have a full name (if the inode was already |
| 1120 | * in the cache). The file system may need to make further |
| 1121 | * efforts to connect this dentry into the dcache properly. |
| 1122 | * |
| 1123 | * When called on a directory inode, we must ensure that |
| 1124 | * the inode only ever has one dentry. If a dentry is |
| 1125 | * found, that is returned instead of allocating a new one. |
| 1126 | * |
| 1127 | * On successful return, the reference to the inode has been transferred |
| 1128 | * to the dentry. If %NULL is returned (indicating kmalloc failure), |
| 1129 | * the reference on the inode has not been released. |
| 1130 | */ |
| 1131 | |
| 1132 | struct dentry * d_alloc_anon(struct inode *inode) |
| 1133 | { |
| 1134 | static const struct qstr anonstring = { .name = "" }; |
| 1135 | struct dentry *tmp; |
| 1136 | struct dentry *res; |
| 1137 | |
| 1138 | if ((res = d_find_alias(inode))) { |
| 1139 | iput(inode); |
| 1140 | return res; |
| 1141 | } |
| 1142 | |
| 1143 | tmp = d_alloc(NULL, &anonstring); |
| 1144 | if (!tmp) |
| 1145 | return NULL; |
| 1146 | |
| 1147 | tmp->d_parent = tmp; /* make sure dput doesn't croak */ |
| 1148 | |
| 1149 | spin_lock(&dcache_lock); |
| 1150 | res = __d_find_alias(inode, 0); |
| 1151 | if (!res) { |
| 1152 | /* attach a disconnected dentry */ |
| 1153 | res = tmp; |
| 1154 | tmp = NULL; |
| 1155 | spin_lock(&res->d_lock); |
| 1156 | res->d_sb = inode->i_sb; |
| 1157 | res->d_parent = res; |
| 1158 | res->d_inode = inode; |
| 1159 | res->d_flags |= DCACHE_DISCONNECTED; |
| 1160 | res->d_flags &= ~DCACHE_UNHASHED; |
| 1161 | list_add(&res->d_alias, &inode->i_dentry); |
| 1162 | hlist_add_head(&res->d_hash, &inode->i_sb->s_anon); |
| 1163 | spin_unlock(&res->d_lock); |
| 1164 | |
| 1165 | inode = NULL; /* don't drop reference */ |
| 1166 | } |
| 1167 | spin_unlock(&dcache_lock); |
| 1168 | |
| 1169 | if (inode) |
| 1170 | iput(inode); |
| 1171 | if (tmp) |
| 1172 | dput(tmp); |
| 1173 | return res; |
| 1174 | } |
| 1175 | |
| 1176 | |
| 1177 | /** |
| 1178 | * d_splice_alias - splice a disconnected dentry into the tree if one exists |
| 1179 | * @inode: the inode which may have a disconnected dentry |
| 1180 | * @dentry: a negative dentry which we want to point to the inode. |
| 1181 | * |
| 1182 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and |
| 1183 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry |
| 1184 | * and return it, else simply d_add the inode to the dentry and return NULL. |
| 1185 | * |
| 1186 | * This is needed in the lookup routine of any filesystem that is exportable |
| 1187 | * (via knfsd) so that we can build dcache paths to directories effectively. |
| 1188 | * |
| 1189 | * If a dentry was found and moved, then it is returned. Otherwise NULL |
| 1190 | * is returned. This matches the expected return value of ->lookup. |
| 1191 | * |
| 1192 | */ |
| 1193 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) |
| 1194 | { |
| 1195 | struct dentry *new = NULL; |
| 1196 | |
NeilBrown | 21c0d8f | 2006-10-04 02:16:16 -0700 | [diff] [blame] | 1197 | if (inode && S_ISDIR(inode->i_mode)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1198 | spin_lock(&dcache_lock); |
| 1199 | new = __d_find_alias(inode, 1); |
| 1200 | if (new) { |
| 1201 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); |
Nick Piggin | c32ccd8 | 2006-03-25 03:07:09 -0800 | [diff] [blame] | 1202 | fsnotify_d_instantiate(new, inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1203 | spin_unlock(&dcache_lock); |
| 1204 | security_d_instantiate(new, inode); |
| 1205 | d_rehash(dentry); |
| 1206 | d_move(new, dentry); |
| 1207 | iput(inode); |
| 1208 | } else { |
| 1209 | /* d_instantiate takes dcache_lock, so we do it by hand */ |
| 1210 | list_add(&dentry->d_alias, &inode->i_dentry); |
| 1211 | dentry->d_inode = inode; |
Nick Piggin | c32ccd8 | 2006-03-25 03:07:09 -0800 | [diff] [blame] | 1212 | fsnotify_d_instantiate(dentry, inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1213 | spin_unlock(&dcache_lock); |
| 1214 | security_d_instantiate(dentry, inode); |
| 1215 | d_rehash(dentry); |
| 1216 | } |
| 1217 | } else |
| 1218 | d_add(dentry, inode); |
| 1219 | return new; |
| 1220 | } |
| 1221 | |
| 1222 | |
| 1223 | /** |
| 1224 | * d_lookup - search for a dentry |
| 1225 | * @parent: parent dentry |
| 1226 | * @name: qstr of name we wish to find |
| 1227 | * |
| 1228 | * Searches the children of the parent dentry for the name in question. If |
| 1229 | * the dentry is found its reference count is incremented and the dentry |
| 1230 | * is returned. The caller must use d_put to free the entry when it has |
| 1231 | * finished using it. %NULL is returned on failure. |
| 1232 | * |
| 1233 | * __d_lookup is dcache_lock free. The hash list is protected using RCU. |
| 1234 | * Memory barriers are used while updating and doing lockless traversal. |
| 1235 | * To avoid races with d_move while rename is happening, d_lock is used. |
| 1236 | * |
| 1237 | * Overflows in memcmp(), while d_move, are avoided by keeping the length |
| 1238 | * and name pointer in one structure pointed by d_qstr. |
| 1239 | * |
| 1240 | * rcu_read_lock() and rcu_read_unlock() are used to disable preemption while |
| 1241 | * lookup is going on. |
| 1242 | * |
Kentaro Makita | da3bbdd | 2008-07-23 21:27:13 -0700 | [diff] [blame^] | 1243 | * The dentry unused LRU is not updated even if lookup finds the required dentry |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1244 | * in there. It is updated in places such as prune_dcache, shrink_dcache_sb, |
| 1245 | * select_parent and __dget_locked. This laziness saves lookup from dcache_lock |
| 1246 | * acquisition. |
| 1247 | * |
| 1248 | * d_lookup() is protected against the concurrent renames in some unrelated |
| 1249 | * directory using the seqlockt_t rename_lock. |
| 1250 | */ |
| 1251 | |
| 1252 | struct dentry * d_lookup(struct dentry * parent, struct qstr * name) |
| 1253 | { |
| 1254 | struct dentry * dentry = NULL; |
| 1255 | unsigned long seq; |
| 1256 | |
| 1257 | do { |
| 1258 | seq = read_seqbegin(&rename_lock); |
| 1259 | dentry = __d_lookup(parent, name); |
| 1260 | if (dentry) |
| 1261 | break; |
| 1262 | } while (read_seqretry(&rename_lock, seq)); |
| 1263 | return dentry; |
| 1264 | } |
| 1265 | |
| 1266 | struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) |
| 1267 | { |
| 1268 | unsigned int len = name->len; |
| 1269 | unsigned int hash = name->hash; |
| 1270 | const unsigned char *str = name->name; |
| 1271 | struct hlist_head *head = d_hash(parent,hash); |
| 1272 | struct dentry *found = NULL; |
| 1273 | struct hlist_node *node; |
Paul E. McKenney | 665a758 | 2005-11-07 00:59:17 -0800 | [diff] [blame] | 1274 | struct dentry *dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1275 | |
| 1276 | rcu_read_lock(); |
| 1277 | |
Paul E. McKenney | 665a758 | 2005-11-07 00:59:17 -0800 | [diff] [blame] | 1278 | hlist_for_each_entry_rcu(dentry, node, head, d_hash) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1279 | struct qstr *qstr; |
| 1280 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1281 | if (dentry->d_name.hash != hash) |
| 1282 | continue; |
| 1283 | if (dentry->d_parent != parent) |
| 1284 | continue; |
| 1285 | |
| 1286 | spin_lock(&dentry->d_lock); |
| 1287 | |
| 1288 | /* |
| 1289 | * Recheck the dentry after taking the lock - d_move may have |
| 1290 | * changed things. Don't bother checking the hash because we're |
| 1291 | * about to compare the whole name anyway. |
| 1292 | */ |
| 1293 | if (dentry->d_parent != parent) |
| 1294 | goto next; |
| 1295 | |
| 1296 | /* |
| 1297 | * It is safe to compare names since d_move() cannot |
| 1298 | * change the qstr (protected by d_lock). |
| 1299 | */ |
| 1300 | qstr = &dentry->d_name; |
| 1301 | if (parent->d_op && parent->d_op->d_compare) { |
| 1302 | if (parent->d_op->d_compare(parent, qstr, name)) |
| 1303 | goto next; |
| 1304 | } else { |
| 1305 | if (qstr->len != len) |
| 1306 | goto next; |
| 1307 | if (memcmp(qstr->name, str, len)) |
| 1308 | goto next; |
| 1309 | } |
| 1310 | |
| 1311 | if (!d_unhashed(dentry)) { |
| 1312 | atomic_inc(&dentry->d_count); |
| 1313 | found = dentry; |
| 1314 | } |
| 1315 | spin_unlock(&dentry->d_lock); |
| 1316 | break; |
| 1317 | next: |
| 1318 | spin_unlock(&dentry->d_lock); |
| 1319 | } |
| 1320 | rcu_read_unlock(); |
| 1321 | |
| 1322 | return found; |
| 1323 | } |
| 1324 | |
| 1325 | /** |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 1326 | * d_hash_and_lookup - hash the qstr then search for a dentry |
| 1327 | * @dir: Directory to search in |
| 1328 | * @name: qstr of name we wish to find |
| 1329 | * |
| 1330 | * On hash failure or on lookup failure NULL is returned. |
| 1331 | */ |
| 1332 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) |
| 1333 | { |
| 1334 | struct dentry *dentry = NULL; |
| 1335 | |
| 1336 | /* |
| 1337 | * Check for a fs-specific hash function. Note that we must |
| 1338 | * calculate the standard hash first, as the d_op->d_hash() |
| 1339 | * routine may choose to leave the hash value unchanged. |
| 1340 | */ |
| 1341 | name->hash = full_name_hash(name->name, name->len); |
| 1342 | if (dir->d_op && dir->d_op->d_hash) { |
| 1343 | if (dir->d_op->d_hash(dir, name) < 0) |
| 1344 | goto out; |
| 1345 | } |
| 1346 | dentry = d_lookup(dir, name); |
| 1347 | out: |
| 1348 | return dentry; |
| 1349 | } |
| 1350 | |
| 1351 | /** |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1352 | * d_validate - verify dentry provided from insecure source |
| 1353 | * @dentry: The dentry alleged to be valid child of @dparent |
| 1354 | * @dparent: The parent dentry (known to be valid) |
| 1355 | * @hash: Hash of the dentry |
| 1356 | * @len: Length of the name |
| 1357 | * |
| 1358 | * An insecure source has sent us a dentry, here we verify it and dget() it. |
| 1359 | * This is used by ncpfs in its readdir implementation. |
| 1360 | * Zero is returned in the dentry is invalid. |
| 1361 | */ |
| 1362 | |
| 1363 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
| 1364 | { |
| 1365 | struct hlist_head *base; |
| 1366 | struct hlist_node *lhp; |
| 1367 | |
| 1368 | /* Check whether the ptr might be valid at all.. */ |
| 1369 | if (!kmem_ptr_validate(dentry_cache, dentry)) |
| 1370 | goto out; |
| 1371 | |
| 1372 | if (dentry->d_parent != dparent) |
| 1373 | goto out; |
| 1374 | |
| 1375 | spin_lock(&dcache_lock); |
| 1376 | base = d_hash(dparent, dentry->d_name.hash); |
| 1377 | hlist_for_each(lhp,base) { |
Paul E. McKenney | 665a758 | 2005-11-07 00:59:17 -0800 | [diff] [blame] | 1378 | /* hlist_for_each_entry_rcu() not required for d_hash list |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1379 | * as it is parsed under dcache_lock |
| 1380 | */ |
| 1381 | if (dentry == hlist_entry(lhp, struct dentry, d_hash)) { |
| 1382 | __dget_locked(dentry); |
| 1383 | spin_unlock(&dcache_lock); |
| 1384 | return 1; |
| 1385 | } |
| 1386 | } |
| 1387 | spin_unlock(&dcache_lock); |
| 1388 | out: |
| 1389 | return 0; |
| 1390 | } |
| 1391 | |
| 1392 | /* |
| 1393 | * When a file is deleted, we have two options: |
| 1394 | * - turn this dentry into a negative dentry |
| 1395 | * - unhash this dentry and free it. |
| 1396 | * |
| 1397 | * Usually, we want to just turn this into |
| 1398 | * a negative dentry, but if anybody else is |
| 1399 | * currently using the dentry or the inode |
| 1400 | * we can't do that and we fall back on removing |
| 1401 | * it from the hash queues and waiting for |
| 1402 | * it to be deleted later when it has no users |
| 1403 | */ |
| 1404 | |
| 1405 | /** |
| 1406 | * d_delete - delete a dentry |
| 1407 | * @dentry: The dentry to delete |
| 1408 | * |
| 1409 | * Turn the dentry into a negative dentry if possible, otherwise |
| 1410 | * remove it from the hash queues so it can be deleted later |
| 1411 | */ |
| 1412 | |
| 1413 | void d_delete(struct dentry * dentry) |
| 1414 | { |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 1415 | int isdir = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1416 | /* |
| 1417 | * Are we the only user? |
| 1418 | */ |
| 1419 | spin_lock(&dcache_lock); |
| 1420 | spin_lock(&dentry->d_lock); |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 1421 | isdir = S_ISDIR(dentry->d_inode->i_mode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1422 | if (atomic_read(&dentry->d_count) == 1) { |
| 1423 | dentry_iput(dentry); |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 1424 | fsnotify_nameremove(dentry, isdir); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1425 | return; |
| 1426 | } |
| 1427 | |
| 1428 | if (!d_unhashed(dentry)) |
| 1429 | __d_drop(dentry); |
| 1430 | |
| 1431 | spin_unlock(&dentry->d_lock); |
| 1432 | spin_unlock(&dcache_lock); |
John McCutchan | 7a91bf7 | 2005-08-08 13:52:16 -0400 | [diff] [blame] | 1433 | |
| 1434 | fsnotify_nameremove(dentry, isdir); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1435 | } |
| 1436 | |
| 1437 | static void __d_rehash(struct dentry * entry, struct hlist_head *list) |
| 1438 | { |
| 1439 | |
| 1440 | entry->d_flags &= ~DCACHE_UNHASHED; |
| 1441 | hlist_add_head_rcu(&entry->d_hash, list); |
| 1442 | } |
| 1443 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1444 | static void _d_rehash(struct dentry * entry) |
| 1445 | { |
| 1446 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); |
| 1447 | } |
| 1448 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1449 | /** |
| 1450 | * d_rehash - add an entry back to the hash |
| 1451 | * @entry: dentry to add to the hash |
| 1452 | * |
| 1453 | * Adds a dentry to the hash according to its name. |
| 1454 | */ |
| 1455 | |
| 1456 | void d_rehash(struct dentry * entry) |
| 1457 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1458 | spin_lock(&dcache_lock); |
| 1459 | spin_lock(&entry->d_lock); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1460 | _d_rehash(entry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1461 | spin_unlock(&entry->d_lock); |
| 1462 | spin_unlock(&dcache_lock); |
| 1463 | } |
| 1464 | |
| 1465 | #define do_switch(x,y) do { \ |
| 1466 | __typeof__ (x) __tmp = x; \ |
| 1467 | x = y; y = __tmp; } while (0) |
| 1468 | |
| 1469 | /* |
| 1470 | * When switching names, the actual string doesn't strictly have to |
| 1471 | * be preserved in the target - because we're dropping the target |
| 1472 | * anyway. As such, we can just do a simple memcpy() to copy over |
| 1473 | * the new name before we switch. |
| 1474 | * |
| 1475 | * Note that we have to be a lot more careful about getting the hash |
| 1476 | * switched - we have to switch the hash value properly even if it |
| 1477 | * then no longer matches the actual (corrupted) string of the target. |
| 1478 | * The hash value has to match the hash queue that the dentry is on.. |
| 1479 | */ |
| 1480 | static void switch_names(struct dentry *dentry, struct dentry *target) |
| 1481 | { |
| 1482 | if (dname_external(target)) { |
| 1483 | if (dname_external(dentry)) { |
| 1484 | /* |
| 1485 | * Both external: swap the pointers |
| 1486 | */ |
| 1487 | do_switch(target->d_name.name, dentry->d_name.name); |
| 1488 | } else { |
| 1489 | /* |
| 1490 | * dentry:internal, target:external. Steal target's |
| 1491 | * storage and make target internal. |
| 1492 | */ |
J. Bruce Fields | 321bcf9 | 2007-10-21 16:41:38 -0700 | [diff] [blame] | 1493 | memcpy(target->d_iname, dentry->d_name.name, |
| 1494 | dentry->d_name.len + 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1495 | dentry->d_name.name = target->d_name.name; |
| 1496 | target->d_name.name = target->d_iname; |
| 1497 | } |
| 1498 | } else { |
| 1499 | if (dname_external(dentry)) { |
| 1500 | /* |
| 1501 | * dentry:external, target:internal. Give dentry's |
| 1502 | * storage to target and make dentry internal |
| 1503 | */ |
| 1504 | memcpy(dentry->d_iname, target->d_name.name, |
| 1505 | target->d_name.len + 1); |
| 1506 | target->d_name.name = dentry->d_name.name; |
| 1507 | dentry->d_name.name = dentry->d_iname; |
| 1508 | } else { |
| 1509 | /* |
| 1510 | * Both are internal. Just copy target to dentry |
| 1511 | */ |
| 1512 | memcpy(dentry->d_iname, target->d_name.name, |
| 1513 | target->d_name.len + 1); |
| 1514 | } |
| 1515 | } |
| 1516 | } |
| 1517 | |
| 1518 | /* |
| 1519 | * We cannibalize "target" when moving dentry on top of it, |
| 1520 | * because it's going to be thrown away anyway. We could be more |
| 1521 | * polite about it, though. |
| 1522 | * |
| 1523 | * This forceful removal will result in ugly /proc output if |
| 1524 | * somebody holds a file open that got deleted due to a rename. |
| 1525 | * We could be nicer about the deleted file, and let it show |
J. Bruce Fields | bc154b1 | 2007-10-16 23:29:42 -0700 | [diff] [blame] | 1526 | * up under the name it had before it was deleted rather than |
| 1527 | * under the original name of the file that was moved on top of it. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1528 | */ |
| 1529 | |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 1530 | /* |
| 1531 | * d_move_locked - move a dentry |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1532 | * @dentry: entry to move |
| 1533 | * @target: new dentry |
| 1534 | * |
| 1535 | * Update the dcache to reflect the move of a file name. Negative |
| 1536 | * dcache entries should not be moved in this way. |
| 1537 | */ |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 1538 | static void d_move_locked(struct dentry * dentry, struct dentry * target) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1539 | { |
| 1540 | struct hlist_head *list; |
| 1541 | |
| 1542 | if (!dentry->d_inode) |
| 1543 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); |
| 1544 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1545 | write_seqlock(&rename_lock); |
| 1546 | /* |
| 1547 | * XXXX: do we really need to take target->d_lock? |
| 1548 | */ |
| 1549 | if (target < dentry) { |
| 1550 | spin_lock(&target->d_lock); |
Ingo Molnar | a90b9c0 | 2006-07-03 00:25:04 -0700 | [diff] [blame] | 1551 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1552 | } else { |
| 1553 | spin_lock(&dentry->d_lock); |
Ingo Molnar | a90b9c0 | 2006-07-03 00:25:04 -0700 | [diff] [blame] | 1554 | spin_lock_nested(&target->d_lock, DENTRY_D_LOCK_NESTED); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1555 | } |
| 1556 | |
| 1557 | /* Move the dentry to the target hash queue, if on different bucket */ |
Denis Cheng | f77e349 | 2007-10-16 23:30:11 -0700 | [diff] [blame] | 1558 | if (d_unhashed(dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1559 | goto already_unhashed; |
| 1560 | |
| 1561 | hlist_del_rcu(&dentry->d_hash); |
| 1562 | |
| 1563 | already_unhashed: |
| 1564 | list = d_hash(target->d_parent, target->d_name.hash); |
| 1565 | __d_rehash(dentry, list); |
| 1566 | |
| 1567 | /* Unhash the target: dput() will then get rid of it */ |
| 1568 | __d_drop(target); |
| 1569 | |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 1570 | list_del(&dentry->d_u.d_child); |
| 1571 | list_del(&target->d_u.d_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1572 | |
| 1573 | /* Switch the names.. */ |
| 1574 | switch_names(dentry, target); |
| 1575 | do_switch(dentry->d_name.len, target->d_name.len); |
| 1576 | do_switch(dentry->d_name.hash, target->d_name.hash); |
| 1577 | |
| 1578 | /* ... and switch the parents */ |
| 1579 | if (IS_ROOT(dentry)) { |
| 1580 | dentry->d_parent = target->d_parent; |
| 1581 | target->d_parent = target; |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 1582 | INIT_LIST_HEAD(&target->d_u.d_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1583 | } else { |
| 1584 | do_switch(dentry->d_parent, target->d_parent); |
| 1585 | |
| 1586 | /* And add them back to the (new) parent lists */ |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 1587 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1588 | } |
| 1589 | |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 1590 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1591 | spin_unlock(&target->d_lock); |
Nick Piggin | c32ccd8 | 2006-03-25 03:07:09 -0800 | [diff] [blame] | 1592 | fsnotify_d_move(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1593 | spin_unlock(&dentry->d_lock); |
| 1594 | write_sequnlock(&rename_lock); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 1595 | } |
| 1596 | |
| 1597 | /** |
| 1598 | * d_move - move a dentry |
| 1599 | * @dentry: entry to move |
| 1600 | * @target: new dentry |
| 1601 | * |
| 1602 | * Update the dcache to reflect the move of a file name. Negative |
| 1603 | * dcache entries should not be moved in this way. |
| 1604 | */ |
| 1605 | |
| 1606 | void d_move(struct dentry * dentry, struct dentry * target) |
| 1607 | { |
| 1608 | spin_lock(&dcache_lock); |
| 1609 | d_move_locked(dentry, target); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1610 | spin_unlock(&dcache_lock); |
| 1611 | } |
| 1612 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1613 | /* |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 1614 | * Helper that returns 1 if p1 is a parent of p2, else 0 |
| 1615 | */ |
| 1616 | static int d_isparent(struct dentry *p1, struct dentry *p2) |
| 1617 | { |
| 1618 | struct dentry *p; |
| 1619 | |
| 1620 | for (p = p2; p->d_parent != p; p = p->d_parent) { |
| 1621 | if (p->d_parent == p1) |
| 1622 | return 1; |
| 1623 | } |
| 1624 | return 0; |
| 1625 | } |
| 1626 | |
| 1627 | /* |
| 1628 | * This helper attempts to cope with remotely renamed directories |
| 1629 | * |
| 1630 | * It assumes that the caller is already holding |
| 1631 | * dentry->d_parent->d_inode->i_mutex and the dcache_lock |
| 1632 | * |
| 1633 | * Note: If ever the locking in lock_rename() changes, then please |
| 1634 | * remember to update this too... |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 1635 | */ |
| 1636 | static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 1637 | __releases(dcache_lock) |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 1638 | { |
| 1639 | struct mutex *m1 = NULL, *m2 = NULL; |
| 1640 | struct dentry *ret; |
| 1641 | |
| 1642 | /* If alias and dentry share a parent, then no extra locks required */ |
| 1643 | if (alias->d_parent == dentry->d_parent) |
| 1644 | goto out_unalias; |
| 1645 | |
| 1646 | /* Check for loops */ |
| 1647 | ret = ERR_PTR(-ELOOP); |
| 1648 | if (d_isparent(alias, dentry)) |
| 1649 | goto out_err; |
| 1650 | |
| 1651 | /* See lock_rename() */ |
| 1652 | ret = ERR_PTR(-EBUSY); |
| 1653 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
| 1654 | goto out_err; |
| 1655 | m1 = &dentry->d_sb->s_vfs_rename_mutex; |
| 1656 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) |
| 1657 | goto out_err; |
| 1658 | m2 = &alias->d_parent->d_inode->i_mutex; |
| 1659 | out_unalias: |
| 1660 | d_move_locked(alias, dentry); |
| 1661 | ret = alias; |
| 1662 | out_err: |
| 1663 | spin_unlock(&dcache_lock); |
| 1664 | if (m2) |
| 1665 | mutex_unlock(m2); |
| 1666 | if (m1) |
| 1667 | mutex_unlock(m1); |
| 1668 | return ret; |
| 1669 | } |
| 1670 | |
| 1671 | /* |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1672 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a |
| 1673 | * named dentry in place of the dentry to be replaced. |
| 1674 | */ |
| 1675 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) |
| 1676 | { |
| 1677 | struct dentry *dparent, *aparent; |
| 1678 | |
| 1679 | switch_names(dentry, anon); |
| 1680 | do_switch(dentry->d_name.len, anon->d_name.len); |
| 1681 | do_switch(dentry->d_name.hash, anon->d_name.hash); |
| 1682 | |
| 1683 | dparent = dentry->d_parent; |
| 1684 | aparent = anon->d_parent; |
| 1685 | |
| 1686 | dentry->d_parent = (aparent == anon) ? dentry : aparent; |
| 1687 | list_del(&dentry->d_u.d_child); |
| 1688 | if (!IS_ROOT(dentry)) |
| 1689 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
| 1690 | else |
| 1691 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
| 1692 | |
| 1693 | anon->d_parent = (dparent == dentry) ? anon : dparent; |
| 1694 | list_del(&anon->d_u.d_child); |
| 1695 | if (!IS_ROOT(anon)) |
| 1696 | list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs); |
| 1697 | else |
| 1698 | INIT_LIST_HEAD(&anon->d_u.d_child); |
| 1699 | |
| 1700 | anon->d_flags &= ~DCACHE_DISCONNECTED; |
| 1701 | } |
| 1702 | |
| 1703 | /** |
| 1704 | * d_materialise_unique - introduce an inode into the tree |
| 1705 | * @dentry: candidate dentry |
| 1706 | * @inode: inode to bind to the dentry, to which aliases may be attached |
| 1707 | * |
| 1708 | * Introduces an dentry into the tree, substituting an extant disconnected |
| 1709 | * root directory alias in its place if there is one |
| 1710 | */ |
| 1711 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) |
| 1712 | { |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 1713 | struct dentry *actual; |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1714 | |
| 1715 | BUG_ON(!d_unhashed(dentry)); |
| 1716 | |
| 1717 | spin_lock(&dcache_lock); |
| 1718 | |
| 1719 | if (!inode) { |
| 1720 | actual = dentry; |
| 1721 | dentry->d_inode = NULL; |
| 1722 | goto found_lock; |
| 1723 | } |
| 1724 | |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 1725 | if (S_ISDIR(inode->i_mode)) { |
| 1726 | struct dentry *alias; |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1727 | |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 1728 | /* Does an aliased dentry already exist? */ |
| 1729 | alias = __d_find_alias(inode, 0); |
| 1730 | if (alias) { |
| 1731 | actual = alias; |
| 1732 | /* Is this an anonymous mountpoint that we could splice |
| 1733 | * into our tree? */ |
| 1734 | if (IS_ROOT(alias)) { |
| 1735 | spin_lock(&alias->d_lock); |
| 1736 | __d_materialise_dentry(dentry, alias); |
| 1737 | __d_drop(alias); |
| 1738 | goto found; |
| 1739 | } |
| 1740 | /* Nope, but we must(!) avoid directory aliasing */ |
| 1741 | actual = __d_unalias(dentry, alias); |
| 1742 | if (IS_ERR(actual)) |
| 1743 | dput(alias); |
| 1744 | goto out_nolock; |
| 1745 | } |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1746 | } |
| 1747 | |
| 1748 | /* Add a unique reference */ |
| 1749 | actual = __d_instantiate_unique(dentry, inode); |
| 1750 | if (!actual) |
| 1751 | actual = dentry; |
| 1752 | else if (unlikely(!d_unhashed(actual))) |
| 1753 | goto shouldnt_be_hashed; |
| 1754 | |
| 1755 | found_lock: |
| 1756 | spin_lock(&actual->d_lock); |
| 1757 | found: |
| 1758 | _d_rehash(actual); |
| 1759 | spin_unlock(&actual->d_lock); |
| 1760 | spin_unlock(&dcache_lock); |
Trond Myklebust | 9eaef27 | 2006-10-21 10:24:20 -0700 | [diff] [blame] | 1761 | out_nolock: |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1762 | if (actual == dentry) { |
| 1763 | security_d_instantiate(dentry, inode); |
| 1764 | return NULL; |
| 1765 | } |
| 1766 | |
| 1767 | iput(inode); |
| 1768 | return actual; |
| 1769 | |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1770 | shouldnt_be_hashed: |
| 1771 | spin_unlock(&dcache_lock); |
| 1772 | BUG(); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 1773 | } |
| 1774 | |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 1775 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1776 | { |
| 1777 | *buflen -= namelen; |
| 1778 | if (*buflen < 0) |
| 1779 | return -ENAMETOOLONG; |
| 1780 | *buffer -= namelen; |
| 1781 | memcpy(*buffer, str, namelen); |
| 1782 | return 0; |
| 1783 | } |
| 1784 | |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 1785 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
| 1786 | { |
| 1787 | return prepend(buffer, buflen, name->name, name->len); |
| 1788 | } |
| 1789 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1790 | /** |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 1791 | * __d_path - return the path of a dentry |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 1792 | * @path: the dentry/vfsmount to report |
| 1793 | * @root: root vfsmnt/dentry (may be modified by this function) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1794 | * @buffer: buffer to return value in |
| 1795 | * @buflen: buffer length |
| 1796 | * |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1797 | * Convert a dentry into an ASCII path name. If the entry has been deleted |
| 1798 | * the string " (deleted)" is appended. Note that this is ambiguous. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1799 | * |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1800 | * Returns the buffer or an error code if the path was too long. |
| 1801 | * |
| 1802 | * "buflen" should be positive. Caller holds the dcache_lock. |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 1803 | * |
| 1804 | * If path is not reachable from the supplied root, then the value of |
| 1805 | * root is changed (without modifying refcounts). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1806 | */ |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 1807 | char *__d_path(const struct path *path, struct path *root, |
| 1808 | char *buffer, int buflen) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1809 | { |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 1810 | struct dentry *dentry = path->dentry; |
| 1811 | struct vfsmount *vfsmnt = path->mnt; |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 1812 | char *end = buffer + buflen; |
| 1813 | char *retval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1814 | |
Andreas Gruenbacher | be285c7 | 2008-06-16 13:28:07 +0200 | [diff] [blame] | 1815 | spin_lock(&vfsmount_lock); |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1816 | prepend(&end, &buflen, "\0", 1); |
| 1817 | if (!IS_ROOT(dentry) && d_unhashed(dentry) && |
| 1818 | (prepend(&end, &buflen, " (deleted)", 10) != 0)) |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1819 | goto Elong; |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1820 | |
| 1821 | if (buflen < 1) |
| 1822 | goto Elong; |
| 1823 | /* Get '/' right */ |
| 1824 | retval = end-1; |
| 1825 | *retval = '/'; |
| 1826 | |
| 1827 | for (;;) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1828 | struct dentry * parent; |
| 1829 | |
Jan Blunck | 329c97f | 2008-02-14 19:38:31 -0800 | [diff] [blame] | 1830 | if (dentry == root->dentry && vfsmnt == root->mnt) |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1831 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1832 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1833 | /* Global root? */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1834 | if (vfsmnt->mnt_parent == vfsmnt) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1835 | goto global_root; |
| 1836 | } |
| 1837 | dentry = vfsmnt->mnt_mountpoint; |
| 1838 | vfsmnt = vfsmnt->mnt_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1839 | continue; |
| 1840 | } |
| 1841 | parent = dentry->d_parent; |
| 1842 | prefetch(parent); |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 1843 | if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) || |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1844 | (prepend(&end, &buflen, "/", 1) != 0)) |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1845 | goto Elong; |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1846 | retval = end; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1847 | dentry = parent; |
| 1848 | } |
| 1849 | |
Andreas Gruenbacher | be285c7 | 2008-06-16 13:28:07 +0200 | [diff] [blame] | 1850 | out: |
| 1851 | spin_unlock(&vfsmount_lock); |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1852 | return retval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1853 | |
| 1854 | global_root: |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1855 | retval += 1; /* hit the slash */ |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 1856 | if (prepend_name(&retval, &buflen, &dentry->d_name) != 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1857 | goto Elong; |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 1858 | root->mnt = vfsmnt; |
| 1859 | root->dentry = dentry; |
Andreas Gruenbacher | be285c7 | 2008-06-16 13:28:07 +0200 | [diff] [blame] | 1860 | goto out; |
| 1861 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1862 | Elong: |
Andreas Gruenbacher | be285c7 | 2008-06-16 13:28:07 +0200 | [diff] [blame] | 1863 | retval = ERR_PTR(-ENAMETOOLONG); |
| 1864 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1865 | } |
| 1866 | |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 1867 | /** |
| 1868 | * d_path - return the path of a dentry |
Jan Blunck | cf28b48 | 2008-02-14 19:38:44 -0800 | [diff] [blame] | 1869 | * @path: path to report |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 1870 | * @buf: buffer to return value in |
| 1871 | * @buflen: buffer length |
| 1872 | * |
| 1873 | * Convert a dentry into an ASCII path name. If the entry has been deleted |
| 1874 | * the string " (deleted)" is appended. Note that this is ambiguous. |
| 1875 | * |
| 1876 | * Returns the buffer or an error code if the path was too long. |
| 1877 | * |
Miklos Szeredi | 31f3e0b | 2008-06-23 18:11:52 +0200 | [diff] [blame] | 1878 | * "buflen" should be positive. |
Jan Blunck | a03a8a70 | 2008-02-14 19:38:32 -0800 | [diff] [blame] | 1879 | */ |
Jan Engelhardt | 20d4fdc | 2008-06-09 16:40:36 -0700 | [diff] [blame] | 1880 | char *d_path(const struct path *path, char *buf, int buflen) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1881 | { |
| 1882 | char *res; |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 1883 | struct path root; |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 1884 | struct path tmp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1885 | |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 1886 | /* |
| 1887 | * We have various synthetic filesystems that never get mounted. On |
| 1888 | * these filesystems dentries are never used for lookup purposes, and |
| 1889 | * thus don't need to be hashed. They also don't need a name until a |
| 1890 | * user wants to identify the object in /proc/pid/fd/. The little hack |
| 1891 | * below allows us to generate a name for these objects on demand: |
| 1892 | */ |
Jan Blunck | cf28b48 | 2008-02-14 19:38:44 -0800 | [diff] [blame] | 1893 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
| 1894 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 1895 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1896 | read_lock(¤t->fs->lock); |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 1897 | root = current->fs->root; |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1898 | path_get(&root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1899 | read_unlock(¤t->fs->lock); |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1900 | spin_lock(&dcache_lock); |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 1901 | tmp = root; |
| 1902 | res = __d_path(path, &tmp, buf, buflen); |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1903 | spin_unlock(&dcache_lock); |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 1904 | path_put(&root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1905 | return res; |
| 1906 | } |
| 1907 | |
| 1908 | /* |
Eric Dumazet | c23fbb6 | 2007-05-08 00:26:18 -0700 | [diff] [blame] | 1909 | * Helper function for dentry_operations.d_dname() members |
| 1910 | */ |
| 1911 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, |
| 1912 | const char *fmt, ...) |
| 1913 | { |
| 1914 | va_list args; |
| 1915 | char temp[64]; |
| 1916 | int sz; |
| 1917 | |
| 1918 | va_start(args, fmt); |
| 1919 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; |
| 1920 | va_end(args); |
| 1921 | |
| 1922 | if (sz > sizeof(temp) || sz > buflen) |
| 1923 | return ERR_PTR(-ENAMETOOLONG); |
| 1924 | |
| 1925 | buffer += buflen - sz; |
| 1926 | return memcpy(buffer, temp, sz); |
| 1927 | } |
| 1928 | |
| 1929 | /* |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1930 | * Write full pathname from the root of the filesystem into the buffer. |
| 1931 | */ |
| 1932 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) |
| 1933 | { |
| 1934 | char *end = buf + buflen; |
| 1935 | char *retval; |
| 1936 | |
| 1937 | spin_lock(&dcache_lock); |
| 1938 | prepend(&end, &buflen, "\0", 1); |
| 1939 | if (!IS_ROOT(dentry) && d_unhashed(dentry) && |
| 1940 | (prepend(&end, &buflen, "//deleted", 9) != 0)) |
| 1941 | goto Elong; |
| 1942 | if (buflen < 1) |
| 1943 | goto Elong; |
| 1944 | /* Get '/' right */ |
| 1945 | retval = end-1; |
| 1946 | *retval = '/'; |
| 1947 | |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 1948 | while (!IS_ROOT(dentry)) { |
| 1949 | struct dentry *parent = dentry->d_parent; |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1950 | |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1951 | prefetch(parent); |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 1952 | if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) || |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1953 | (prepend(&end, &buflen, "/", 1) != 0)) |
| 1954 | goto Elong; |
| 1955 | |
| 1956 | retval = end; |
| 1957 | dentry = parent; |
| 1958 | } |
| 1959 | spin_unlock(&dcache_lock); |
| 1960 | return retval; |
| 1961 | Elong: |
| 1962 | spin_unlock(&dcache_lock); |
| 1963 | return ERR_PTR(-ENAMETOOLONG); |
| 1964 | } |
| 1965 | |
| 1966 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1967 | * NOTE! The user-level library version returns a |
| 1968 | * character pointer. The kernel system call just |
| 1969 | * returns the length of the buffer filled (which |
| 1970 | * includes the ending '\0' character), or a negative |
| 1971 | * error value. So libc would do something like |
| 1972 | * |
| 1973 | * char *getcwd(char * buf, size_t size) |
| 1974 | * { |
| 1975 | * int retval; |
| 1976 | * |
| 1977 | * retval = sys_getcwd(buf, size); |
| 1978 | * if (retval >= 0) |
| 1979 | * return buf; |
| 1980 | * errno = -retval; |
| 1981 | * return NULL; |
| 1982 | * } |
| 1983 | */ |
| 1984 | asmlinkage long sys_getcwd(char __user *buf, unsigned long size) |
| 1985 | { |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1986 | int error; |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 1987 | struct path pwd, root; |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 1988 | char *page = (char *) __get_free_page(GFP_USER); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1989 | |
| 1990 | if (!page) |
| 1991 | return -ENOMEM; |
| 1992 | |
| 1993 | read_lock(¤t->fs->lock); |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 1994 | pwd = current->fs->pwd; |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1995 | path_get(&pwd); |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 1996 | root = current->fs->root; |
Ram Pai | 6092d04 | 2008-03-27 13:06:20 +0100 | [diff] [blame] | 1997 | path_get(&root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1998 | read_unlock(¤t->fs->lock); |
| 1999 | |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 2000 | error = -ENOENT; |
| 2001 | /* Has the current directory has been unlinked? */ |
| 2002 | spin_lock(&dcache_lock); |
Miklos Szeredi | cdd16d0 | 2008-06-23 18:11:53 +0200 | [diff] [blame] | 2003 | if (IS_ROOT(pwd.dentry) || !d_unhashed(pwd.dentry)) { |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 2004 | unsigned long len; |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 2005 | struct path tmp = root; |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 2006 | char * cwd; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2007 | |
Miklos Szeredi | 9d1bc601 | 2008-03-27 13:06:21 +0100 | [diff] [blame] | 2008 | cwd = __d_path(&pwd, &tmp, page, PAGE_SIZE); |
Linus Torvalds | 552ce54 | 2007-02-13 12:08:18 -0800 | [diff] [blame] | 2009 | spin_unlock(&dcache_lock); |
| 2010 | |
| 2011 | error = PTR_ERR(cwd); |
| 2012 | if (IS_ERR(cwd)) |
| 2013 | goto out; |
| 2014 | |
| 2015 | error = -ERANGE; |
| 2016 | len = PAGE_SIZE + page - cwd; |
| 2017 | if (len <= size) { |
| 2018 | error = len; |
| 2019 | if (copy_to_user(buf, cwd, len)) |
| 2020 | error = -EFAULT; |
| 2021 | } |
| 2022 | } else |
| 2023 | spin_unlock(&dcache_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2024 | |
| 2025 | out: |
Jan Blunck | 6ac08c3 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 2026 | path_put(&pwd); |
| 2027 | path_put(&root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2028 | free_page((unsigned long) page); |
| 2029 | return error; |
| 2030 | } |
| 2031 | |
| 2032 | /* |
| 2033 | * Test whether new_dentry is a subdirectory of old_dentry. |
| 2034 | * |
| 2035 | * Trivially implemented using the dcache structure |
| 2036 | */ |
| 2037 | |
| 2038 | /** |
| 2039 | * is_subdir - is new dentry a subdirectory of old_dentry |
| 2040 | * @new_dentry: new dentry |
| 2041 | * @old_dentry: old dentry |
| 2042 | * |
| 2043 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). |
| 2044 | * Returns 0 otherwise. |
| 2045 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() |
| 2046 | */ |
| 2047 | |
| 2048 | int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry) |
| 2049 | { |
| 2050 | int result; |
| 2051 | struct dentry * saved = new_dentry; |
| 2052 | unsigned long seq; |
| 2053 | |
| 2054 | /* need rcu_readlock to protect against the d_parent trashing due to |
| 2055 | * d_move |
| 2056 | */ |
| 2057 | rcu_read_lock(); |
| 2058 | do { |
| 2059 | /* for restarting inner loop in case of seq retry */ |
| 2060 | new_dentry = saved; |
| 2061 | result = 0; |
| 2062 | seq = read_seqbegin(&rename_lock); |
| 2063 | for (;;) { |
| 2064 | if (new_dentry != old_dentry) { |
| 2065 | struct dentry * parent = new_dentry->d_parent; |
| 2066 | if (parent == new_dentry) |
| 2067 | break; |
| 2068 | new_dentry = parent; |
| 2069 | continue; |
| 2070 | } |
| 2071 | result = 1; |
| 2072 | break; |
| 2073 | } |
| 2074 | } while (read_seqretry(&rename_lock, seq)); |
| 2075 | rcu_read_unlock(); |
| 2076 | |
| 2077 | return result; |
| 2078 | } |
| 2079 | |
| 2080 | void d_genocide(struct dentry *root) |
| 2081 | { |
| 2082 | struct dentry *this_parent = root; |
| 2083 | struct list_head *next; |
| 2084 | |
| 2085 | spin_lock(&dcache_lock); |
| 2086 | repeat: |
| 2087 | next = this_parent->d_subdirs.next; |
| 2088 | resume: |
| 2089 | while (next != &this_parent->d_subdirs) { |
| 2090 | struct list_head *tmp = next; |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 2091 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2092 | next = tmp->next; |
| 2093 | if (d_unhashed(dentry)||!dentry->d_inode) |
| 2094 | continue; |
| 2095 | if (!list_empty(&dentry->d_subdirs)) { |
| 2096 | this_parent = dentry; |
| 2097 | goto repeat; |
| 2098 | } |
| 2099 | atomic_dec(&dentry->d_count); |
| 2100 | } |
| 2101 | if (this_parent != root) { |
Eric Dumazet | 5160ee6 | 2006-01-08 01:03:32 -0800 | [diff] [blame] | 2102 | next = this_parent->d_u.d_child.next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2103 | atomic_dec(&this_parent->d_count); |
| 2104 | this_parent = this_parent->d_parent; |
| 2105 | goto resume; |
| 2106 | } |
| 2107 | spin_unlock(&dcache_lock); |
| 2108 | } |
| 2109 | |
| 2110 | /** |
| 2111 | * find_inode_number - check for dentry with name |
| 2112 | * @dir: directory to check |
| 2113 | * @name: Name to find. |
| 2114 | * |
| 2115 | * Check whether a dentry already exists for the given name, |
| 2116 | * and return the inode number if it has an inode. Otherwise |
| 2117 | * 0 is returned. |
| 2118 | * |
| 2119 | * This routine is used to post-process directory listings for |
| 2120 | * filesystems using synthetic inode numbers, and is necessary |
| 2121 | * to keep getcwd() working. |
| 2122 | */ |
| 2123 | |
| 2124 | ino_t find_inode_number(struct dentry *dir, struct qstr *name) |
| 2125 | { |
| 2126 | struct dentry * dentry; |
| 2127 | ino_t ino = 0; |
| 2128 | |
Eric W. Biederman | 3e7e241 | 2006-03-31 02:31:43 -0800 | [diff] [blame] | 2129 | dentry = d_hash_and_lookup(dir, name); |
| 2130 | if (dentry) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2131 | if (dentry->d_inode) |
| 2132 | ino = dentry->d_inode->i_ino; |
| 2133 | dput(dentry); |
| 2134 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2135 | return ino; |
| 2136 | } |
| 2137 | |
| 2138 | static __initdata unsigned long dhash_entries; |
| 2139 | static int __init set_dhash_entries(char *str) |
| 2140 | { |
| 2141 | if (!str) |
| 2142 | return 0; |
| 2143 | dhash_entries = simple_strtoul(str, &str, 0); |
| 2144 | return 1; |
| 2145 | } |
| 2146 | __setup("dhash_entries=", set_dhash_entries); |
| 2147 | |
| 2148 | static void __init dcache_init_early(void) |
| 2149 | { |
| 2150 | int loop; |
| 2151 | |
| 2152 | /* If hashes are distributed across NUMA nodes, defer |
| 2153 | * hash allocation until vmalloc space is available. |
| 2154 | */ |
| 2155 | if (hashdist) |
| 2156 | return; |
| 2157 | |
| 2158 | dentry_hashtable = |
| 2159 | alloc_large_system_hash("Dentry cache", |
| 2160 | sizeof(struct hlist_head), |
| 2161 | dhash_entries, |
| 2162 | 13, |
| 2163 | HASH_EARLY, |
| 2164 | &d_hash_shift, |
| 2165 | &d_hash_mask, |
| 2166 | 0); |
| 2167 | |
| 2168 | for (loop = 0; loop < (1 << d_hash_shift); loop++) |
| 2169 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); |
| 2170 | } |
| 2171 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 2172 | static void __init dcache_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2173 | { |
| 2174 | int loop; |
| 2175 | |
| 2176 | /* |
| 2177 | * A constructor could be added for stable state like the lists, |
| 2178 | * but it is probably not worth it because of the cache nature |
| 2179 | * of the dcache. |
| 2180 | */ |
Christoph Lameter | 0a31bd5 | 2007-05-06 14:49:57 -0700 | [diff] [blame] | 2181 | dentry_cache = KMEM_CACHE(dentry, |
| 2182 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2183 | |
Rusty Russell | 8e1f936 | 2007-07-17 04:03:17 -0700 | [diff] [blame] | 2184 | register_shrinker(&dcache_shrinker); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2185 | |
| 2186 | /* Hash may have been set up in dcache_init_early */ |
| 2187 | if (!hashdist) |
| 2188 | return; |
| 2189 | |
| 2190 | dentry_hashtable = |
| 2191 | alloc_large_system_hash("Dentry cache", |
| 2192 | sizeof(struct hlist_head), |
| 2193 | dhash_entries, |
| 2194 | 13, |
| 2195 | 0, |
| 2196 | &d_hash_shift, |
| 2197 | &d_hash_mask, |
| 2198 | 0); |
| 2199 | |
| 2200 | for (loop = 0; loop < (1 << d_hash_shift); loop++) |
| 2201 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); |
| 2202 | } |
| 2203 | |
| 2204 | /* SLAB cache for __getname() consumers */ |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 2205 | struct kmem_cache *names_cachep __read_mostly; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2206 | |
| 2207 | /* SLAB cache for file structures */ |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 2208 | struct kmem_cache *filp_cachep __read_mostly; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2209 | |
| 2210 | EXPORT_SYMBOL(d_genocide); |
| 2211 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2212 | void __init vfs_caches_init_early(void) |
| 2213 | { |
| 2214 | dcache_init_early(); |
| 2215 | inode_init_early(); |
| 2216 | } |
| 2217 | |
| 2218 | void __init vfs_caches_init(unsigned long mempages) |
| 2219 | { |
| 2220 | unsigned long reserve; |
| 2221 | |
| 2222 | /* Base hash sizes on available memory, with a reserve equal to |
| 2223 | 150% of current kernel size */ |
| 2224 | |
| 2225 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); |
| 2226 | mempages -= reserve; |
| 2227 | |
| 2228 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 2229 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2230 | |
| 2231 | filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 2232 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2233 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 2234 | dcache_init(); |
| 2235 | inode_init(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2236 | files_init(mempages); |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 2237 | mnt_init(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2238 | bdev_cache_init(); |
| 2239 | chrdev_init(); |
| 2240 | } |
| 2241 | |
| 2242 | EXPORT_SYMBOL(d_alloc); |
| 2243 | EXPORT_SYMBOL(d_alloc_anon); |
| 2244 | EXPORT_SYMBOL(d_alloc_root); |
| 2245 | EXPORT_SYMBOL(d_delete); |
| 2246 | EXPORT_SYMBOL(d_find_alias); |
| 2247 | EXPORT_SYMBOL(d_instantiate); |
| 2248 | EXPORT_SYMBOL(d_invalidate); |
| 2249 | EXPORT_SYMBOL(d_lookup); |
| 2250 | EXPORT_SYMBOL(d_move); |
David Howells | 770bfad | 2006-08-22 20:06:07 -0400 | [diff] [blame] | 2251 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2252 | EXPORT_SYMBOL(d_path); |
| 2253 | EXPORT_SYMBOL(d_prune_aliases); |
| 2254 | EXPORT_SYMBOL(d_rehash); |
| 2255 | EXPORT_SYMBOL(d_splice_alias); |
| 2256 | EXPORT_SYMBOL(d_validate); |
| 2257 | EXPORT_SYMBOL(dget_locked); |
| 2258 | EXPORT_SYMBOL(dput); |
| 2259 | EXPORT_SYMBOL(find_inode_number); |
| 2260 | EXPORT_SYMBOL(have_submounts); |
| 2261 | EXPORT_SYMBOL(names_cachep); |
| 2262 | EXPORT_SYMBOL(shrink_dcache_parent); |
| 2263 | EXPORT_SYMBOL(shrink_dcache_sb); |