diff options
Diffstat (limited to 'fs/dcache.c')
| -rw-r--r-- | fs/dcache.c | 1530 |
1 files changed, 1065 insertions, 465 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 83293be4814..18b2a1f10ed 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -33,20 +33,59 @@ #include <linux/bootmem.h> #include <linux/fs_struct.h> #include <linux/hardirq.h> +#include <linux/bit_spinlock.h> +#include <linux/rculist_bl.h> +#include <linux/prefetch.h> #include "internal.h" +/* + * Usage: + * dcache->d_inode->i_lock protects: + * - i_dentry, d_alias, d_inode of aliases + * dcache_hash_bucket lock protects: + * - the dcache hash table + * s_anon bl list spinlock protects: + * - the s_anon list (see __d_drop) + * dcache_lru_lock protects: + * - the dcache lru lists and counters + * d_lock protects: + * - d_flags + * - d_name + * - d_lru + * - d_count + * - d_unhashed() + * - d_parent and d_subdirs + * - childrens' d_child and d_parent + * - d_alias, d_inode + * + * Ordering: + * dentry->d_inode->i_lock + * dentry->d_lock + * dcache_lru_lock + * dcache_hash_bucket lock + * s_anon lock + * + * If there is an ancestor relationship: + * dentry->d_parent->...->d_parent->d_lock + * ... + * dentry->d_parent->d_lock + * dentry->d_lock + * + * If no ancestor relationship: + * if (dentry1 < dentry2) + * dentry1->d_lock + * dentry2->d_lock + */ int sysctl_vfs_cache_pressure __read_mostly = 100; EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); - __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock); +static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock); __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); -EXPORT_SYMBOL(dcache_lock); +EXPORT_SYMBOL(rename_lock); static struct kmem_cache *dentry_cache __read_mostly; -#define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname)) - /* * This is the single most critical data structure when it comes * to the dcache: the hashtable for lookups. Somebody should try @@ -60,56 +99,98 @@ static struct kmem_cache *dentry_cache __read_mostly; static unsigned int d_hash_mask __read_mostly; static unsigned int d_hash_shift __read_mostly; -static struct hlist_head *dentry_hashtable __read_mostly; + +static struct hlist_bl_head *dentry_hashtable __read_mostly; + +static inline struct hlist_bl_head *d_hash(struct dentry *parent, + unsigned long hash) +{ + hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; + hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); + return dentry_hashtable + (hash & D_HASHMASK); +} /* Statistics gathering. */ struct dentry_stat_t dentry_stat = { .age_limit = 45, }; -static void __d_free(struct dentry *dentry) +static DEFINE_PER_CPU(unsigned int, nr_dentry); + +#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) +static int get_nr_dentry(void) { + int i; + int sum = 0; + for_each_possible_cpu(i) + sum += per_cpu(nr_dentry, i); + return sum < 0 ? 0 : sum; +} + +int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, + size_t *lenp, loff_t *ppos) +{ + dentry_stat.nr_dentry = get_nr_dentry(); + return proc_dointvec(table, write, buffer, lenp, ppos); +} +#endif + +static void __d_free(struct rcu_head *head) +{ + struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); + WARN_ON(!list_empty(&dentry->d_alias)); if (dname_external(dentry)) kfree(dentry->d_name.name); kmem_cache_free(dentry_cache, dentry); } -static void d_callback(struct rcu_head *head) -{ - struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu); - __d_free(dentry); -} - /* - * no dcache_lock, please. The caller must decrement dentry_stat.nr_dentry - * inside dcache_lock. + * no locks, please. */ static void d_free(struct dentry *dentry) { + BUG_ON(dentry->d_count); + this_cpu_dec(nr_dentry); if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); - /* if dentry was never inserted into hash, immediate free is OK */ - if (hlist_unhashed(&dentry->d_hash)) - __d_free(dentry); + + /* if dentry was never visible to RCU, immediate free is OK */ + if (!(dentry->d_flags & DCACHE_RCUACCESS)) + __d_free(&dentry->d_u.d_rcu); else - call_rcu(&dentry->d_u.d_rcu, d_callback); + call_rcu(&dentry->d_u.d_rcu, __d_free); +} + +/** + * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups + * @dentry: the target dentry + * After this call, in-progress rcu-walk path lookup will fail. This + * should be called after unhashing, and after changing d_inode (if + * the dentry has not already been unhashed). + */ +static inline void dentry_rcuwalk_barrier(struct dentry *dentry) +{ + assert_spin_locked(&dentry->d_lock); + /* Go through a barrier */ + write_seqcount_barrier(&dentry->d_seq); } /* * Release the dentry's inode, using the filesystem - * d_iput() operation if defined. + * d_iput() operation if defined. Dentry has no refcount + * and is unhashed. */ static void dentry_iput(struct dentry * dentry) __releases(dentry->d_lock) - __releases(dcache_lock) + __releases(dentry->d_inode->i_lock) { struct inode *inode = dentry->d_inode; if (inode) { dentry->d_inode = NULL; list_del_init(&dentry->d_alias); spin_unlock(&dentry->d_lock); - spin_unlock(&dcache_lock); + spin_unlock(&inode->i_lock); if (!inode->i_nlink) fsnotify_inoderemove(inode); if (dentry->d_op && dentry->d_op->d_iput) @@ -118,69 +199,186 @@ static void dentry_iput(struct dentry * dentry) iput(inode); } else { spin_unlock(&dentry->d_lock); - spin_unlock(&dcache_lock); } } /* - * dentry_lru_(add|add_tail|del|del_init) must be called with dcache_lock held. + * Release the dentry's inode, using the filesystem + * d_iput() operation if defined. dentry remains in-use. + */ +static void dentry_unlink_inode(struct dentry * dentry) + __releases(dentry->d_lock) + __releases(dentry->d_inode->i_lock) +{ + struct inode *inode = dentry->d_inode; + dentry->d_inode = NULL; + list_del_init(&dentry->d_alias); + dentry_rcuwalk_barrier(dentry); + spin_unlock(&dentry->d_lock); + spin_unlock(&inode->i_lock); + if (!inode->i_nlink) + fsnotify_inoderemove(inode); + if (dentry->d_op && dentry->d_op->d_iput) + dentry->d_op->d_iput(dentry, inode); + else + iput(inode); +} + +/* + * dentry_lru_(add|del|move_tail) must be called with d_lock held. */ static void dentry_lru_add(struct dentry *dentry) { - list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); - dentry->d_sb->s_nr_dentry_unused++; - dentry_stat.nr_unused++; + if (list_empty(&dentry->d_lru)) { + spin_lock(&dcache_lru_lock); + list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); + dentry->d_sb->s_nr_dentry_unused++; + dentry_stat.nr_unused++; + spin_unlock(&dcache_lru_lock); + } } -static void dentry_lru_add_tail(struct dentry *dentry) +static void __dentry_lru_del(struct dentry *dentry) { - list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); - dentry->d_sb->s_nr_dentry_unused++; - dentry_stat.nr_unused++; + list_del_init(&dentry->d_lru); + dentry->d_sb->s_nr_dentry_unused--; + dentry_stat.nr_unused--; } static void dentry_lru_del(struct dentry *dentry) { if (!list_empty(&dentry->d_lru)) { - list_del(&dentry->d_lru); - dentry->d_sb->s_nr_dentry_unused--; - dentry_stat.nr_unused--; + spin_lock(&dcache_lru_lock); + __dentry_lru_del(dentry); + spin_unlock(&dcache_lru_lock); } } -static void dentry_lru_del_init(struct dentry *dentry) +static void dentry_lru_move_tail(struct dentry *dentry) { - if (likely(!list_empty(&dentry->d_lru))) { - list_del_init(&dentry->d_lru); - dentry->d_sb->s_nr_dentry_unused--; - dentry_stat.nr_unused--; + spin_lock(&dcache_lru_lock); + if (list_empty(&dentry->d_lru)) { + list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); + dentry->d_sb->s_nr_dentry_unused++; + dentry_stat.nr_unused++; + } else { + list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); } + spin_unlock(&dcache_lru_lock); } /** * d_kill - kill dentry and return parent * @dentry: dentry to kill + * @parent: parent dentry * * The dentry must already be unhashed and removed from the LRU. * * If this is the root of the dentry tree, return NULL. + * + * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by + * d_kill. */ -static struct dentry *d_kill(struct dentry *dentry) +static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) __releases(dentry->d_lock) - __releases(dcache_lock) + __releases(parent->d_lock) + __releases(dentry->d_inode->i_lock) { - struct dentry *parent; - list_del(&dentry->d_u.d_child); - dentry_stat.nr_dentry--; /* For d_free, below */ - /*drops the locks, at that point nobody can reach this dentry */ + /* + * Inform try_to_ascend() that we are no longer attached to the + * dentry tree + */ + dentry->d_flags |= DCACHE_DISCONNECTED; + if (parent) + spin_unlock(&parent->d_lock); dentry_iput(dentry); + /* + * dentry_iput drops the locks, at which point nobody (except + * transient RCU lookups) can reach this dentry. + */ + d_free(dentry); + return parent; +} + +/** + * d_drop - drop a dentry + * @dentry: dentry to drop + * + * d_drop() unhashes the entry from the parent dentry hashes, so that it won't + * be found through a VFS lookup any more. Note that this is different from + * deleting the dentry - d_delete will try to mark the dentry negative if + * possible, giving a successful _negative_ lookup, while d_drop will + * just make the cache lookup fail. + * + * d_drop() is used mainly for stuff that wants to invalidate a dentry for some + * reason (NFS timeouts or autofs deletes). + * + * __d_drop requires dentry->d_lock. + */ +void __d_drop(struct dentry *dentry) +{ + if (!d_unhashed(dentry)) { + struct hlist_bl_head *b; + if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) + b = &dentry->d_sb->s_anon; + else + b = d_hash(dentry->d_parent, dentry->d_name.hash); + + hlist_bl_lock(b); + __hlist_bl_del(&dentry->d_hash); + dentry->d_hash.pprev = NULL; + hlist_bl_unlock(b); + + dentry_rcuwalk_barrier(dentry); + } +} +EXPORT_SYMBOL(__d_drop); + +void d_drop(struct dentry *dentry) +{ + spin_lock(&dentry->d_lock); + __d_drop(dentry); + spin_unlock(&dentry->d_lock); +} +EXPORT_SYMBOL(d_drop); + +/* + * Finish off a dentry we've decided to kill. + * dentry->d_lock must be held, returns with it unlocked. + * If ref is non-zero, then decrement the refcount too. + * Returns dentry requiring refcount drop, or NULL if we're done. + */ +static inline struct dentry *dentry_kill(struct dentry *dentry, int ref) + __releases(dentry->d_lock) +{ + struct inode *inode; + struct dentry *parent; + + inode = dentry->d_inode; + if (inode && !spin_trylock(&inode->i_lock)) { +relock: + spin_unlock(&dentry->d_lock); + cpu_relax(); + return dentry; /* try again with same dentry */ + } if (IS_ROOT(dentry)) parent = NULL; else parent = dentry->d_parent; - d_free(dentry); - return parent; + if (parent && !spin_trylock(&parent->d_lock)) { + if (inode) + spin_unlock(&inode->i_lock); + goto relock; + } + + if (ref) + dentry->d_count--; + /* if dentry was on the d_lru list delete it from there */ + dentry_lru_del(dentry); + /* if it was on the hash then remove it */ + __d_drop(dentry); + return d_kill(dentry, parent); } /* @@ -208,52 +406,42 @@ static struct dentry *d_kill(struct dentry *dentry) * call the dentry unlink method as well as removing it from the queues and * releasing its resources. If the parent dentries were scheduled for release * they too may now get deleted. - * - * no dcache lock, please. */ - void dput(struct dentry *dentry) { if (!dentry) return; repeat: - if (atomic_read(&dentry->d_count) == 1) + if (dentry->d_count == 1) might_sleep(); - if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock)) - return; - spin_lock(&dentry->d_lock); - if (atomic_read(&dentry->d_count)) { + BUG_ON(!dentry->d_count); + if (dentry->d_count > 1) { + dentry->d_count--; spin_unlock(&dentry->d_lock); - spin_unlock(&dcache_lock); return; } - /* - * AV: ->d_delete() is _NOT_ allowed to block now. - */ - if (dentry->d_op && dentry->d_op->d_delete) { + if (dentry->d_flags & DCACHE_OP_DELETE) { if (dentry->d_op->d_delete(dentry)) - goto unhash_it; + goto kill_it; } + /* Unreachable? Get rid of it */ if (d_unhashed(dentry)) goto kill_it; - if (list_empty(&dentry->d_lru)) { - dentry->d_flags |= DCACHE_REFERENCED; - dentry_lru_add(dentry); - } - spin_unlock(&dentry->d_lock); - spin_unlock(&dcache_lock); + + /* Otherwise leave it cached and ensure it's on the LRU */ + dentry->d_flags |= DCACHE_REFERENCED; + dentry_lru_add(dentry); + + dentry->d_count--; + spin_unlock(&dentry->d_lock); return; -unhash_it: - __d_drop(dentry); kill_it: - /* if dentry was on the d_lru list delete it from there */ - dentry_lru_del(dentry); - dentry = d_kill(dentry); + dentry = dentry_kill(dentry, 1); if (dentry) goto repeat; } @@ -276,9 +464,9 @@ int d_invalidate(struct dentry * dentry) /* * If it's already been dropped, return OK. */ - spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); if (d_unhashed(dentry)) { - spin_unlock(&dcache_lock); + spin_unlock(&dentry->d_lock); return 0; } /* @@ -286,9 +474,9 @@ int d_invalidate(struct dentry * dentry) * to get rid of unused child entries. */ if (!list_empty(&dentry->d_subdirs)) { - spin_unlock(&dcache_lock); + spin_unlock(&dentry->d_lock); shrink_dcache_parent(dentry); - spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); } /* @@ -301,36 +489,61 @@ int d_invalidate(struct dentry * dentry) * we might still populate it if it was a * working directory or similar). */ - spin_lock(&dentry->d_lock); - if (atomic_read(&dentry->d_count) > 1) { + if (dentry->d_count > 1) { if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { spin_unlock(&dentry->d_lock); - spin_unlock(&dcache_lock); return -EBUSY; } } __d_drop(dentry); spin_unlock(&dentry->d_lock); - spin_unlock(&dcache_lock); return 0; } EXPORT_SYMBOL(d_invalidate); -/* This should be called _only_ with dcache_lock held */ +/* This must be called with d_lock held */ +static inline void __dget_dlock(struct dentry *dentry) +{ + dentry->d_count++; +} -static inline struct dentry * __dget_locked(struct dentry *dentry) +static inline void __dget(struct dentry *dentry) { - atomic_inc(&dentry->d_count); - dentry_lru_del_init(dentry); - return dentry; + spin_lock(&dentry->d_lock); + __dget_dlock(dentry); + spin_unlock(&dentry->d_lock); } -struct dentry * dget_locked(struct dentry *dentry) +struct dentry *dget_parent(struct dentry *dentry) { - return __dget_locked(dentry); + struct dentry *ret; + +repeat: + /* + * Don't need rcu_dereference because we re-check it was correct under + * the lock. + */ + rcu_read_lock(); + ret = dentry->d_parent; + if (!ret) { + rcu_read_unlock(); + goto out; + } + spin_lock(&ret->d_lock); + if (unlikely(ret != dentry->d_parent)) { + spin_unlock(&ret->d_lock); + rcu_read_unlock(); + goto repeat; + } + rcu_read_unlock(); + BUG_ON(!ret->d_count); + ret->d_count++; + spin_unlock(&ret->d_lock); +out: + return ret; } -EXPORT_SYMBOL(dget_locked); +EXPORT_SYMBOL(dget_parent); /** * d_find_alias - grab a hashed alias of inode @@ -348,42 +561,51 @@ EXPORT_SYMBOL(dget_locked); * any other hashed alias over that one unless @want_discon is set, * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. */ - -static struct dentry * __d_find_alias(struct inode *inode, int want_discon) +static struct dentry *__d_find_alias(struct inode *inode, int want_discon) { - struct list_head *head, *next, *tmp; - struct dentry *alias, *discon_alias=NULL; + struct dentry *alias, *discon_alias; - head = &inode->i_dentry; - next = inode->i_dentry.next; - while (next != head) { - tmp = next; - next = tmp->next; - prefetch(next); - alias = list_entry(tmp, struct dentry, d_alias); +again: + discon_alias = NULL; + list_for_each_entry(alias, &inode->i_dentry, d_alias) { + spin_lock(&alias->d_lock); if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { if (IS_ROOT(alias) && - (alias->d_flags & DCACHE_DISCONNECTED)) + (alias->d_flags & DCACHE_DISCONNECTED)) { discon_alias = alias; - else if (!want_discon) { - __dget_locked(alias); + } else if (!want_discon) { + __dget_dlock(alias); + spin_unlock(&alias->d_lock); + return alias; + } + } + spin_unlock(&alias->d_lock); + } + if (discon_alias) { + alias = discon_alias; + spin_lock(&alias->d_lock); + if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { + if (IS_ROOT(alias) && + (alias->d_flags & DCACHE_DISCONNECTED)) { + __dget_dlock(alias); + spin_unlock(&alias->d_lock); return alias; } } + spin_unlock(&alias->d_lock); + goto again; } - if (discon_alias) - __dget_locked(discon_alias); - return discon_alias; + return NULL; } -struct dentry * d_find_alias(struct inode *inode) +struct dentry *d_find_alias(struct inode *inode) { struct dentry *de = NULL; if (!list_empty(&inode->i_dentry)) { - spin_lock(&dcache_lock); + spin_lock(&inode->i_lock); de = __d_find_alias(inode, 0); - spin_unlock(&dcache_lock); + spin_unlock(&inode->i_lock); } return de; } @@ -397,132 +619,153 @@ void d_prune_aliases(struct inode *inode) { struct dentry *dentry; restart: - spin_lock(&dcache_lock); + spin_lock(&inode->i_lock); list_for_each_entry(dentry, &inode->i_dentry, d_alias) { spin_lock(&dentry->d_lock); - if (!atomic_read(&dentry->d_count)) { - __dget_locked(dentry); + if (!dentry->d_count) { + __dget_dlock(dentry); __d_drop(dentry); spin_unlock(&dentry->d_lock); - spin_unlock(&dcache_lock); + spin_unlock(&inode->i_lock); dput(dentry); goto restart; } spin_unlock(&dentry->d_lock); } - spin_unlock(&dcache_lock); + spin_unlock(&inode->i_lock); } EXPORT_SYMBOL(d_prune_aliases); /* - * Throw away a dentry - free the inode, dput the parent. This requires that - * the LRU list has already been removed. + * Try to throw away a dentry - free the inode, dput the parent. + * Requires dentry->d_lock is held, and dentry->d_count == 0. + * Releases dentry->d_lock. * - * Try to prune ancestors as well. This is necessary to prevent - * quadratic behavior of shrink_dcache_parent(), but is also expected - * to be beneficial in reducing dentry cache fragmentation. + * This may fail if locks cannot be acquired no problem, just try again. */ -static void prune_one_dentry(struct dentry * dentry) +static void try_prune_one_dentry(struct dentry *dentry) __releases(dentry->d_lock) - __releases(dcache_lock) - __acquires(dcache_lock) { - __d_drop(dentry); - dentry = d_kill(dentry); + struct dentry *parent; + parent = dentry_kill(dentry, 0); /* - * Prune ancestors. Locking is simpler than in dput(), - * because dcache_lock needs to be taken anyway. + * If dentry_kill returns NULL, we have nothing more to do. + * if it returns the same dentry, trylocks failed. In either + * case, just loop again. + * + * Otherwise, we need to prune ancestors too. This is necessary + * to prevent quadratic behavior of shrink_dcache_parent(), but + * is also expected to be beneficial in reducing dentry cache + * fragmentation. */ - spin_lock(&dcache_lock); + if (!parent) + return; + if (parent == dentry) + return; + + /* Prune ancestors. */ + dentry = parent; while (dentry) { - if (!atomic_dec_and_lock(&dentry->d_count, &dentry->d_lock)) + spin_lock(&dentry->d_lock); + if (dentry->d_count > 1) { + dentry->d_count--; + spin_unlock(&dentry->d_lock); return; - - if (dentry->d_op && dentry->d_op->d_delete) - dentry->d_op->d_delete(dentry); - dentry_lru_del_init(dentry); - __d_drop(dentry); - dentry = d_kill(dentry); - spin_lock(&dcache_lock); + } + dentry = dentry_kill(dentry, 1); } } -/* - * Shrink the dentry LRU on a given superblock. - * @sb : superblock to shrink dentry LRU. - * @count: If count is NULL, we prune all dentries on superblock. - * @flags: If flags is non-zero, we need to do special processing based on - * which flags are set. This means we don't need to maintain multiple - * similar copies of this loop. - */ -static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) +static void shrink_dentry_list(struct list_head *list) { - LIST_HEAD(referenced); - LIST_HEAD(tmp); struct dentry *dentry; - int cnt = 0; - - BUG_ON(!sb); - BUG_ON((flags & DCACHE_REFERENCED) && count == NULL); - spin_lock(&dcache_lock); - if (count != NULL) - /* called from prune_dcache() and shrink_dcache_parent() */ - cnt = *count; -restart: - if (count == NULL) - list_splice_init(&sb->s_dentry_lru, &tmp); - else { - while (!list_empty(&sb->s_dentry_lru)) { - dentry = list_entry(sb->s_dentry_lru.prev, - struct dentry, d_lru); - BUG_ON(dentry->d_sb != sb); - spin_lock(&dentry->d_lock); - /* - * If we are honouring the DCACHE_REFERENCED flag and - * the dentry has this flag set, don't free it. Clear - * the flag and put it back on the LRU. - */ - if ((flags & DCACHE_REFERENCED) - && (dentry->d_flags & DCACHE_REFERENCED)) { - dentry->d_flags &= ~DCACHE_REFERENCED; - list_move(&dentry->d_lru, &referenced); - spin_unlock(&dentry->d_lock); - } else { - list_move_tail(&dentry->d_lru, &tmp); - spin_unlock(&dentry->d_lock); - cnt--; - if (!cnt) - break; - } - cond_resched_lock(&dcache_lock); - } - } - while (!list_empty(&tmp)) { - dentry = list_entry(tmp.prev, struct dentry, d_lru); - dentry_lru_del_init(dentry); + rcu_read_lock(); + for (;;) { + dentry = list_entry_rcu(list->prev, struct dentry, d_lru); + if (&dentry->d_lru == list) + break; /* empty */ spin_lock(&dentry->d_lock); + if (dentry != list_entry(list->prev, struct dentry, d_lru)) { + spin_unlock(&dentry->d_lock); + continue; + } + /* * We found an inuse dentry which was not removed from * the LRU because of laziness during lookup. Do not free * it - just keep it off the LRU list. */ - if (atomic_read(&dentry->d_count)) { + if (dentry->d_count) { + dentry_lru_del(dentry); spin_unlock(&dentry->d_lock); continue; } - prune_one_dentry(dentry); - /* dentry->d_lock was dropped in prune_one_dentry() */ - cond_resched_lock(&dcache_lock); - } - if (count == NULL && !list_empty(&sb->s_dentry_lru)) - goto restart; - if (count != NULL) - *count = cnt; + + rcu_read_unlock(); + + try_prune_one_dentry(dentry); + + rcu_read_lock(); + } + rcu_read_unlock(); +} + +/** + * __shrink_dcache_sb - shrink the dentry LRU on a given superblock + * @sb: superblock to shrink dentry LRU. + * @count: number of entries to prune + * @flags: flags to control the dentry processing + * + * If flags contains DCACHE_REFERENCED reference dentries will not be pruned. + */ +static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) +{ + /* called from prune_dcache() and shrink_dcache_parent() */ + struct dentry *dentry; + LIST_HEAD(referenced); + LIST_HEAD(tmp); + int cnt = *count; + +relock: + spin_lock(&dcache_lru_lock); + while (!list_empty(&sb->s_dentry_lru)) { + dentry = list_entry(sb->s_dentry_lru.prev, + struct dentry, d_lru); + BUG_ON(dentry->d_sb != sb); + + if (!spin_trylock(&dentry->d_lock)) { + spin_unlock(&dcache_lru_lock); + cpu_relax(); + goto relock; + } + + /* + * If we are honouring the DCACHE_REFERENCED flag and the + * dentry has this flag set, don't free it. Clear the flag + * and put it back on the LRU. + */ + if (flags & DCACHE_REFERENCED && + dentry->d_flags & DCACHE_REFERENCED) { + dentry->d_flags &= ~DCACHE_REFERENCED; + list_move(&dentry->d_lru, &referenced); + spin_unlock(&dentry->d_lock); + } else { + list_move_tail(&dentry->d_lru, &tmp); + spin_unlock(&dentry->d_lock); + if (!--cnt) + break; + } + cond_resched_lock(&dcache_lru_lock); + } if (!list_empty(&referenced)) list_splice(&referenced, &sb->s_dentry_lru); - spin_unlock(&dcache_lock); + spin_unlock(&dcache_lru_lock); + + shrink_dentry_list(&tmp); + + *count = cnt; } /** @@ -544,7 +787,6 @@ static void prune_dcache(int count) if (unused == 0 || count == 0) return; - spin_lock(&dcache_lock); if (count >= unused) prune_ratio = 1; else @@ -581,11 +823,9 @@ static void prune_dcache(int count) if (down_read_trylock(&sb->s_umount)) { if ((sb->s_root != NULL) && (!list_empty(&sb->s_dentry_lru))) { - spin_unlock(&dcache_lock); __shrink_dcache_sb(sb, &w_count, DCACHE_REFERENCED); pruned -= w_count; - spin_lock(&dcache_lock); } up_read(&sb->s_umount); } @@ -601,20 +841,27 @@ static void prune_dcache(int count) if (p) __put_super(p); spin_unlock(&sb_lock); - spin_unlock(&dcache_lock); } /** * shrink_dcache_sb - shrink dcache for a superblock * @sb: superblock * - * Shrink the dcache for the specified super block. This - * is used to free the dcache before unmounting a file - * system + * Shrink the dcache for the specified super block. This is used to free + * the dcache before unmounting a file system. */ -void shrink_dcache_sb(struct super_block * sb) +void shrink_dcache_sb(struct super_block *sb) { - __shrink_dcache_sb(sb, NULL, 0); + LIST_HEAD(tmp); + + spin_lock(&dcache_lru_lock); + while (!list_empty(&sb->s_dentry_lru)) { + list_splice_init(&sb->s_dentry_lru, &tmp); + spin_unlock(&dcache_lru_lock); + shrink_dentry_list(&tmp); + spin_lock(&dcache_lru_lock); + } + spin_unlock(&dcache_lru_lock); } EXPORT_SYMBOL(shrink_dcache_sb); @@ -631,10 +878,10 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) BUG_ON(!IS_ROOT(dentry)); /* detach this root from the system */ - spin_lock(&dcache_lock); - dentry_lru_del_init(dentry); + spin_lock(&dentry->d_lock); + dentry_lru_del(dentry); __d_drop(dentry); - spin_unlock(&dcache_lock); + spin_unlock(&dentry->d_lock); for (;;) { /* descend to the first leaf in the current subtree */ @@ -643,14 +890,16 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) /* this is a branch with children - detach all of them * from the system in one go */ - spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); list_for_each_entry(loop, &dentry->d_subdirs, d_u.d_child) { - dentry_lru_del_init(loop); + spin_lock_nested(&loop->d_lock, + DENTRY_D_LOCK_NESTED); + dentry_lru_del(loop); __d_drop(loop); - cond_resched_lock(&dcache_lock); + spin_unlock(&loop->d_lock); } - spin_unlock(&dcache_lock); + spin_unlock(&dentry->d_lock); /* move to the first child */ dentry = list_entry(dentry->d_subdirs.next, @@ -662,7 +911,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) do { struct inode *inode; - if (atomic_read(&dentry->d_count) != 0) { + if (dentry->d_count != 0) { printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%s}" " still in use (%d)" @@ -671,20 +920,23 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) dentry->d_inode ? dentry->d_inode->i_ino : 0UL, dentry->d_name.name, - atomic_read(&dentry->d_count), + dentry->d_count, dentry->d_sb->s_type->name, dentry->d_sb->s_id); BUG(); } - if (IS_ROOT(dentry)) + if (IS_ROOT(dentry)) { parent = NULL; - else { + list_del(&dentry->d_u.d_child); + } else { parent = dentry->d_parent; - atomic_dec(&parent->d_count); + spin_lock(&parent->d_lock); + parent->d_count--; + list_del(&dentry->d_u.d_child); + spin_unlock(&parent->d_lock); } - list_del(&dentry->d_u.d_child); detached++; inode = dentry->d_inode; @@ -703,26 +955,18 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) * otherwise we ascend to the parent and move to the * next sibling if there is one */ if (!parent) - goto out; - + return; dentry = parent; - } while (list_empty(&dentry->d_subdirs)); dentry = list_entry(dentry->d_subdirs.next, struct dentry, d_u.d_child); } -out: - /* several dentries were freed, need to correct nr_dentry */ - spin_lock(&dcache_lock); - dentry_stat.nr_dentry -= detached; - spin_unlock(&dcache_lock); } /* * destroy the dentries attached to a superblock on unmounting - * - we don't need to use dentry->d_lock, and only need dcache_lock when - * removing the dentry from the system lists and hashes because: + * - we don't need to use dentry->d_lock because: * - the superblock is detached from all mountings and open files, so the * dentry trees will not be rearranged by the VFS * - s_umount is write-locked, so the memory pressure shrinker will ignore @@ -739,16 +983,47 @@ void shrink_dcache_for_umount(struct super_block *sb) dentry = sb->s_root; sb->s_root = NULL; - atomic_dec(&dentry->d_count); + spin_lock(&dentry->d_lock); + dentry->d_count--; + spin_unlock(&dentry->d_lock); shrink_dcache_for_umount_subtree(dentry); - while (!hlist_empty(&sb->s_anon)) { - dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash); + while (!hlist_bl_empty(&sb->s_anon)) { + dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash); shrink_dcache_for_umount_subtree(dentry); } } /* + * This tries to ascend one level of parenthood, but + * we can race with renaming, so we need to re-check + * the parenthood after dropping the lock and check + * that the sequence number still matches. + */ +static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq) +{ + struct dentry *new = old->d_parent; + + rcu_read_lock(); + spin_unlock(&old->d_lock); + spin_lock(&new->d_lock); + + /* + * might go back up the wrong parent if we have had a rename + * or deletion + */ + if (new != old->d_parent || + (old->d_flags & DCACHE_DISCONNECTED) || + (!locked && read_seqretry(&rename_lock, seq))) { + spin_unlock(&new->d_lock); + new = NULL; + } + rcu_read_unlock(); + return new; +} + + +/* * Search for at least 1 mount point in the dentry's subdirs. * We descend to the next level whenever the d_subdirs * list is non-empty and continue searching. @@ -761,15 +1036,20 @@ void shrink_dcache_for_umount(struct super_block *sb) * Return true if the parent or its subdirectories contain * a mount point */ - int have_submounts(struct dentry *parent) { - struct dentry *this_parent = parent; + struct dentry *this_parent; struct list_head *next; + unsigned seq; + int locked = 0; + + seq = read_seqbegin(&rename_lock); +again: + this_parent = parent; - spin_lock(&dcache_lock); if (d_mountpoint(parent)) goto positive; + spin_lock(&this_parent->d_lock); repeat: next = this_parent->d_subdirs.next; resume: @@ -777,27 +1057,51 @@ resume: struct list_head *tmp = next; struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); next = tmp->next; + + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); /* Have we found a mount point ? */ - if (d_mountpoint(dentry)) + if (d_mountpoint(dentry)) { + spin_unlock(&dentry->d_lock); + spin_unlock(&this_parent->d_lock); goto positive; + } if (!list_empty(&dentry->d_subdirs)) { + spin_unlock(&this_parent->d_lock); + spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); this_parent = dentry; + spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); goto repeat; } + spin_unlock(&dentry->d_lock); } /* * All done at this level ... ascend and resume the search. */ if (this_parent != parent) { - next = this_parent->d_u.d_child.next; - this_parent = this_parent->d_parent; + struct dentry *child = this_parent; + this_parent = try_to_ascend(this_parent, locked, seq); + if (!this_parent) + goto rename_retry; + next = child->d_u.d_child.next; goto resume; } - spin_unlock(&dcache_lock); + spin_unlock(&this_parent->d_lock); + if (!locked && read_seqretry(&rename_lock, seq)) + goto rename_retry; + if (locked) + write_sequnlock(&rename_lock); return 0; /* No mount points found in tree */ positive: - spin_unlock(&dcache_lock); + if (!locked && read_seqretry(&rename_lock, seq)) + goto rename_retry; + if (locked) + write_sequnlock(&rename_lock); return 1; + +rename_retry: + locked = 1; + write_seqlock(&rename_lock); + goto again; } EXPORT_SYMBOL(have_submounts); @@ -817,11 +1121,16 @@ EXPORT_SYMBOL(have_submounts); */ static int select_parent(struct dentry * parent) { - struct dentry *this_parent = parent; + struct dentry *this_parent; struct list_head *next; + unsigned seq; int found = 0; + int locked = 0; - spin_lock(&dcache_lock); + seq = read_seqbegin(&rename_lock); +again: + this_parent = parent; + spin_lock(&this_parent->d_lock); repeat: next = this_parent->d_subdirs.next; resume: @@ -830,14 +1139,17 @@ resume: struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); next = tmp->next; - dentry_lru_del_init(dentry); + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); + /* * move only zero ref count dentries to the end * of the unused list for prune_dcache */ - if (!atomic_read(&dentry->d_count)) { - dentry_lru_add_tail(dentry); + if (!dentry->d_count) { + dentry_lru_move_tail(dentry); found++; + } else { + dentry_lru_del(dentry); } /* @@ -845,28 +1157,49 @@ resume: * ensures forward progress). We'll be coming back to find * the rest. */ - if (found && need_resched()) + if (found && need_resched()) { + spin_unlock(&dentry->d_lock); goto out; + } /* * Descend a level if the d_subdirs list is non-empty. */ if (!list_empty(&dentry->d_subdirs)) { + spin_unlock(&this_parent->d_lock); + spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); this_parent = dentry; + spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); goto repeat; } + + spin_unlock(&dentry->d_lock); } /* * All done at this level ... ascend and resume the search. */ if (this_parent != parent) { - next = this_parent->d_u.d_child.next; - this_parent = this_parent->d_parent; + struct dentry *child = this_parent; + this_parent = try_to_ascend(this_parent, locked, seq); + if (!this_parent) + goto rename_retry; + next = child->d_u.d_child.next; goto resume; } out: - spin_unlock(&dcache_lock); + spin_unlock(&this_parent->d_lock); + if (!locked && read_seqretry(&rename_lock, seq)) + goto rename_retry; + if (locked) + write_sequnlock(&rename_lock); return found; + +rename_retry: + if (found) + return found; + locked = 1; + write_seqlock(&rename_lock); + goto again; } /** @@ -905,6 +1238,7 @@ static int shrink_dcache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask) return -1; prune_dcache(nr); } + return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; } @@ -948,37 +1282,54 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) memcpy(dname, name->name, name->len); dname[name->len] = 0; - atomic_set(&dentry->d_count, 1); - dentry->d_flags = DCACHE_UNHASHED; + dentry->d_count = 1; + dentry->d_flags = 0; spin_lock_init(&dentry->d_lock); + seqcount_init(&dentry->d_seq); dentry->d_inode = NULL; dentry->d_parent = NULL; dentry->d_sb = NULL; dentry->d_op = NULL; dentry->d_fsdata = NULL; - dentry->d_mounted = 0; - INIT_HLIST_NODE(&dentry->d_hash); + INIT_HLIST_BL_NODE(&dentry->d_hash); INIT_LIST_HEAD(&dentry->d_lru); INIT_LIST_HEAD(&dentry->d_subdirs); INIT_LIST_HEAD(&dentry->d_alias); + INIT_LIST_HEAD(&dentry->d_u.d_child); if (parent) { - dentry->d_parent = dget(parent); + spin_lock(&parent->d_lock); + /* + * don't need child lock because it is not subject + * to concurrency here + */ + __dget_dlock(parent); + dentry->d_parent = parent; dentry->d_sb = parent->d_sb; - } else { - INIT_LIST_HEAD(&dentry->d_u.d_child); + d_set_d_op(dentry, dentry->d_sb->s_d_op); + list_add(&dentry->d_u.d_child, &parent->d_subdirs); + spin_unlock(&parent->d_lock); } - spin_lock(&dcache_lock); - if (parent) - list_add(&dentry->d_u.d_child, &parent->d_subdirs); - dentry_stat.nr_dentry++; - spin_unlock(&dcache_lock); + this_cpu_inc(nr_dentry); return dentry; } EXPORT_SYMBOL(d_alloc); +struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) +{ + struct dentry *dentry = d_alloc(NULL, name); + if (dentry) { + dentry->d_sb = sb; + d_set_d_op(dentry, dentry->d_sb->s_d_op); + dentry->d_parent = dentry; + dentry->d_flags |= DCACHE_DISCONNECTED; + } + return dentry; +} +EXPORT_SYMBOL(d_alloc_pseudo); + struct dentry *d_alloc_name(struct dentry *parent, const char *name) { struct qstr q; @@ -990,12 +1341,39 @@ struct dentry *d_alloc_name(struct dentry *parent, const char *name) } EXPORT_SYMBOL(d_alloc_name); -/* the caller must hold dcache_lock */ +void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) +{ + WARN_ON_ONCE(dentry->d_op); + WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | + DCACHE_OP_COMPARE | + DCACHE_OP_REVALIDATE | + DCACHE_OP_DELETE )); + dentry->d_op = op; + if (!op) + return; + if (op->d_hash) + dentry->d_flags |= DCACHE_OP_HASH; + if (op->d_compare) + dentry->d_flags |= DCACHE_OP_COMPARE; + if (op->d_revalidate) + dentry->d_flags |= DCACHE_OP_REVALIDATE; + if (op->d_delete) + dentry->d_flags |= DCACHE_OP_DELETE; + +} +EXPORT_SYMBOL(d_set_d_op); + static void __d_instantiate(struct dentry *dentry, struct inode *inode) { - if (inode) + spin_lock(&dentry->d_lock); + if (inode) { + if (unlikely(IS_AUTOMOUNT(inode))) + dentry->d_flags |= DCACHE_NEED_AUTOMOUNT; list_add(&dentry->d_alias, &inode->i_dentry); + } dentry->d_inode = inode; + dentry_rcuwalk_barrier(dentry); + spin_unlock(&dentry->d_lock); fsnotify_d_instantiate(dentry, inode); } @@ -1017,9 +1395,11 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode) void d_instantiate(struct dentry *entry, struct inode * inode) { BUG_ON(!list_empty(&entry->d_alias)); - spin_lock(&dcache_lock); + if (inode) + spin_lock(&inode->i_lock); __d_instantiate(entry, inode); - spin_unlock(&dcache_lock); + if (inode) + spin_unlock(&inode->i_lock); security_d_instantiate(entry, inode); } EXPORT_SYMBOL(d_instantiate); @@ -1056,15 +1436,18 @@ static struct dentry *__d_instantiate_unique(struct dentry *entry, list_for_each_entry(alias, &inode->i_dentry, d_alias) { struct qstr *qstr = &alias->d_name; + /* + * Don't need alias->d_lock here, because aliases with + * d_parent == entry->d_parent are not subject to name or + * parent changes, because the parent inode i_mutex is held. + */ if (qstr->hash != hash) continue; if (alias->d_parent != entry->d_parent) continue; - if (qstr->len != len) + if (dentry_cmp(qstr->name, qstr->len, name, len)) continue; - if (memcmp(qstr->name, name, len)) - continue; - dget_locked(alias); + __dget(alias); return alias; } @@ -1078,9 +1461,11 @@ struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) BUG_ON(!list_empty(&entry->d_alias)); - spin_lock(&dcache_lock); + if (inode) + spin_lock(&inode->i_lock); result = __d_instantiate_unique(entry, inode); - spin_unlock(&dcache_lock); + if (inode) + spin_unlock(&inode->i_lock); if (!result) { security_d_instantiate(entry, inode); @@ -1113,6 +1498,7 @@ struct dentry * d_alloc_root(struct inode * root_inode) res = d_alloc(NULL, &name); if (res) { res->d_sb = root_inode->i_sb; + d_set_d_op(res, res->d_sb->s_d_op); res->d_parent = res; d_instantiate(res, root_inode); } @@ -1121,14 +1507,28 @@ struct dentry * d_alloc_root(struct inode * root_inode) } EXPORT_SYMBOL(d_alloc_root); -static inline struct hlist_head *d_hash(struct dentry *parent, - unsigned long hash) +static struct dentry * __d_find_any_alias(struct inode *inode) { - hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; - hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); - return dentry_hashtable + (hash & D_HASHMASK); + struct dentry *alias; + + if (list_empty(&inode->i_dentry)) + return NULL; + alias = list_first_entry(&inode->i_dentry, struct dentry, d_alias); + __dget(alias); + return alias; +} + +static struct dentry * d_find_any_alias(struct inode *inode) +{ + struct dentry *de; + + spin_lock(&inode->i_lock); + de = __d_find_any_alias(inode); + spin_unlock(&inode->i_lock); + return de; } + /** * d_obtain_alias - find or allocate a dentry for a given inode * @inode: inode to allocate the dentry for @@ -1158,7 +1558,7 @@ struct dentry *d_obtain_alias(struct inode *inode) if (IS_ERR(inode)) return ERR_CAST(inode); - res = d_find_alias(inode); + res = d_find_any_alias(inode); if (res) goto out_iput; @@ -1169,10 +1569,11 @@ struct dentry *d_obtain_alias(struct inode *inode) } tmp->d_parent = tmp; /* make sure dput doesn't croak */ - spin_lock(&dcache_lock); - res = __d_find_alias(inode, 0); + + spin_lock(&inode->i_lock); + res = __d_find_any_alias(inode); if (res) { - spin_unlock(&dcache_lock); + spin_unlock(&inode->i_lock); dput(tmp); goto out_iput; } @@ -1180,17 +1581,22 @@ struct dentry *d_obtain_alias(struct inode *inode) /* attach a disconnected dentry */ spin_lock(&tmp->d_lock); tmp->d_sb = inode->i_sb; + d_set_d_op(tmp, tmp->d_sb->s_d_op); tmp->d_inode = inode; tmp->d_flags |= DCACHE_DISCONNECTED; - tmp->d_flags &= ~DCACHE_UNHASHED; list_add(&tmp->d_alias, &inode->i_dentry); - hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon); + hlist_bl_lock(&tmp->d_sb->s_anon); + hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); + hlist_bl_unlock(&tmp->d_sb->s_anon); spin_unlock(&tmp->d_lock); + spin_unlock(&inode->i_lock); + security_d_instantiate(tmp, inode); - spin_unlock(&dcache_lock); return tmp; out_iput: + if (res && !IS_ERR(res)) + security_d_instantiate(res, inode); iput(inode); return res; } @@ -1217,18 +1623,18 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) struct dentry *new = NULL; if (inode && S_ISDIR(inode->i_mode)) { - spin_lock(&dcache_lock); + spin_lock(&inode->i_lock); new = __d_find_alias(inode, 1); if (new) { BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); - spin_unlock(&dcache_lock); + spin_unlock(&inode->i_lock); security_d_instantiate(new, inode); d_move(new, dentry); iput(inode); } else { - /* already taking dcache_lock, so d_add() by hand */ + /* already taking inode->i_lock, so d_add() by hand */ __d_instantiate(dentry, inode); - spin_unlock(&dcache_lock); + spin_unlock(&inode->i_lock); security_d_instantiate(dentry, inode); d_rehash(dentry); } @@ -1301,10 +1707,10 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, * Negative dentry: instantiate it unless the inode is a directory and * already has a dentry. */ - spin_lock(&dcache_lock); + spin_lock(&inode->i_lock); if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) { __d_instantiate(found, inode); - spin_unlock(&dcache_lock); + spin_unlock(&inode->i_lock); security_d_instantiate(found, inode); return found; } @@ -1314,8 +1720,8 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, * reference to it, move it in place and use it. */ new = list_entry(inode->i_dentry.next, struct dentry, d_alias); - dget_locked(new); - spin_unlock(&dcache_lock); + __dget(new); + spin_unlock(&inode->i_lock); security_d_instantiate(found, inode); d_move(new, found); iput(inode); @@ -1329,6 +1735,112 @@ err_out: EXPORT_SYMBOL(d_add_ci); /** + * __d_lookup_rcu - search for a dentry (racy, store-free) + * @parent: parent dentry + * @name: qstr of name we wish to find + * @seq: returns d_seq value at the point where the dentry was found + * @inode: returns dentry->d_inode when the inode was found valid. + * Returns: dentry, or NULL + * + * __d_lookup_rcu is the dcache lookup function for rcu-walk name + * resolution (store-free path walking) design described in + * Documentation/filesystems/path-lookup.txt. + * + * This is not to be used outside core vfs. + * + * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock + * held, and rcu_read_lock held. The returned dentry must not be stored into + * without taking d_lock and checking d_seq sequence count against @seq + * returned here. + * + * A refcount may be taken on the found dentry with the __d_rcu_to_refcount + * function. + * + * Alternatively, __d_lookup_rcu may be called again to look up the child of + * the returned dentry, so long as its parent's seqlock is checked after the + * child is looked up. Thus, an interlocking stepping of sequence lock checks + * is formed, giving integrity down the path walk. + */ +struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name, + unsigned *seq, struct inode **inode) +{ + unsigned int len = name->len; + unsigned int hash = name->hash; + const unsigned char *str = name->name; + struct hlist_bl_head *b = d_hash(parent, hash); + struct hlist_bl_node *node; + struct dentry *dentry; + + /* + * Note: There is significant duplication with __d_lookup_rcu which is + * required to prevent single threaded performance regressions + * especially on architectures where smp_rmb (in seqcounts) are costly. + * Keep the two functions in sync. + */ + + /* + * The hash list is protected using RCU. + * + * Carefully use d_seq when comparing a candidate dentry, to avoid + * races with d_move(). + * + * It is possible that concurrent renames can mess up our list + * walk here and result in missing our dentry, resulting in the + * false-negative result. d_lookup() protects against concurrent + * renames using rename_lock seqlock. + * + * See Documentation/filesystems/path-lookup.txt for more details. + */ + hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { + struct inode *i; + const char *tname; + int tlen; + + if (dentry->d_name.hash != hash) + continue; + +seqretry: + *seq = read_seqcount_begin(&dentry->d_seq); + if (dentry->d_parent != parent) + continue; + if (d_unhashed(dentry)) + continue; + tlen = dentry->d_name.len; + tname = dentry->d_name.name; + i = dentry->d_inode; + prefetch(tname); + if (i) + prefetch(i); + /* + * This seqcount check is required to ensure name and + * len are loaded atomically, so as not to walk off the + * edge of memory when walking. If we could load this + * atomically some other way, we could drop this check. + */ + if (read_seqcount_retry(&dentry->d_seq, *seq)) + goto seqretry; + if (parent->d_flags & DCACHE_OP_COMPARE) { + if (parent->d_op->d_compare(parent, *inode, + dentry, i, + tlen, tname, name)) + continue; + } else { + if (dentry_cmp(tname, tlen, str, len)) + continue; + } + /* + * No extra seqcount check is required after the name + * compare. The caller must perform a seqcount check in + * order to do anything useful with the returned dentry + * anyway. + */ + *inode = i; + return dentry; + } + return NULL; +} + +/** * d_lookup - search for a dentry * @parent: parent dentry * @name: qstr of name we wish to find @@ -1339,10 +1851,10 @@ EXPORT_SYMBOL(d_add_ci); * dentry is returned. The caller must use dput to free the entry when it has * finished using it. %NULL is returned if the dentry does not exist. */ -struct dentry * d_lookup(struct dentry * parent, struct qstr * name) +struct dentry *d_lookup(struct dentry *parent, struct qstr *name) { - struct dentry * dentry = NULL; - unsigned long seq; + struct dentry *dentry; + unsigned seq; do { seq = read_seqbegin(&rename_lock); @@ -1354,7 +1866,7 @@ struct dentry * d_lookup(struct dentry * parent, struct qstr * name) } EXPORT_SYMBOL(d_lookup); -/* +/** * __d_lookup - search for a dentry (racy) * @parent: parent dentry * @name: qstr of name we wish to find @@ -1369,17 +1881,24 @@ EXPORT_SYMBOL(d_lookup); * * __d_lookup callers must be commented. */ -struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) +struct dentry *__d_lookup(struct dentry *parent, struct qstr *name) { unsigned int len = name->len; unsigned int hash = name->hash; const unsigned char *str = name->name; - struct hlist_head *head = d_hash(parent,hash); + struct hlist_bl_head *b = d_hash(parent, hash); + struct hlist_bl_node *node; struct dentry *found = NULL; - struct hlist_node *node; struct dentry *dentry; /* + * Note: There is significant duplication with __d_lookup_rcu which is + * required to prevent single threaded performance regressions + * especially on architectures where smp_rmb (in seqcounts) are costly. + * Keep the two functions in sync. + */ + + /* * The hash list is protected using RCU. * * Take d_lock when comparing a candidate dentry, to avoid races @@ -1390,29 +1909,20 @@ struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) * false-negative result. d_lookup() protects against concurrent * renames using rename_lock seqlock. * - * See Documentation/vfs/dcache-locking.txt for more details. + * See Documentation/filesystems/path-lookup.txt for more details. */ rcu_read_lock(); - hlist_for_each_entry_rcu(dentry, node, head, d_hash) { - struct qstr *qstr; + hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { + const char *tname; + int tlen; if (dentry->d_name.hash != hash) continue; - if (dentry->d_parent != parent) - continue; spin_lock(&dentry->d_lock); - - /* - * Recheck the dentry after taking the lock - d_move may have - * changed things. Don't bother checking the hash because - * we're about to compare the whole name anyway. - */ if (dentry->d_parent != parent) goto next; - - /* non-existing due to RCU? */ if (d_unhashed(dentry)) goto next; @@ -1420,18 +1930,19 @@ struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) * It is safe to compare names since d_move() cannot * change the qstr (protected by d_lock). */ - qstr = &dentry->d_name; - if (parent->d_op && parent->d_op->d_compare) { - if (parent->d_op->d_compare(parent, qstr, name)) + tlen = dentry->d_name.len; + tname = dentry->d_name.name; + if (parent->d_flags & DCACHE_OP_COMPARE) { + if (parent->d_op->d_compare(parent, parent->d_inode, + dentry, dentry->d_inode, + tlen, tname, name)) goto next; } else { - if (qstr->len != len) - goto next; - if (memcmp(qstr->name, str, len)) + if (dentry_cmp(tname, tlen, str, len)) goto next; } - atomic_inc(&dentry->d_count); + dentry->d_count++; found = dentry; spin_unlock(&dentry->d_lock); break; @@ -1460,8 +1971,8 @@ struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) * routine may choose to leave the hash value unchanged. */ name->hash = full_name_hash(name->name, name->len); - if (dir->d_op && dir->d_op->d_hash) { - if (dir->d_op->d_hash(dir, name) < 0) + if (dir->d_flags & DCACHE_OP_HASH) { + if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0) goto out; } dentry = d_lookup(dir, name); @@ -1470,41 +1981,32 @@ out: } /** - * d_validate - verify dentry provided from insecure source + * d_validate - verify dentry provided from insecure source (deprecated) * @dentry: The dentry alleged to be valid child of @dparent * @dparent: The parent dentry (known to be valid) * * An insecure source has sent us a dentry, here we verify it and dget() it. * This is used by ncpfs in its readdir implementation. * Zero is returned in the dentry is invalid. + * + * This function is slow for big directories, and deprecated, do not use it. */ - int d_validate(struct dentry *dentry, struct dentry *dparent) { - struct hlist_head *base; - struct hlist_node *lhp; + struct dentry *child; - /* Check whether the ptr might be valid at all.. */ - if (!kmem_ptr_validate(dentry_cache, dentry)) - goto out; - - if (dentry->d_parent != dparent) - goto out; - - spin_lock(&dcache_lock); - base = d_hash(dparent, dentry->d_name.hash); - hlist_for_each(lhp,base) { - /* hlist_for_each_entry_rcu() not required for d_hash list - * as it is parsed under dcache_lock - */ - if (dentry == hlist_entry(lhp, struct dentry, d_hash)) { - __dget_locked(dentry); - spin_unlock(&dcache_lock); + spin_lock(&dparent->d_lock); + list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { + if (dentry == child) { + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); + __dget_dlock(dentry); + spin_unlock(&dentry->d_lock); + spin_unlock(&dparent->d_lock); return 1; } } - spin_unlock(&dcache_lock); -out: + spin_unlock(&dparent->d_lock); + return 0; } EXPORT_SYMBOL(d_validate); @@ -1532,16 +2034,23 @@ EXPORT_SYMBOL(d_validate); void d_delete(struct dentry * dentry) { + struct inode *inode; int isdir = 0; /* * Are we the only user? */ - spin_lock(&dcache_lock); +again: spin_lock(&dentry->d_lock); - isdir = S_ISDIR(dentry->d_inode->i_mode); - if (atomic_read(&dentry->d_count) == 1) { + inode = dentry->d_inode; + isdir = S_ISDIR(inode->i_mode); + if (dentry->d_count == 1) { + if (inode && !spin_trylock(&inode->i_lock)) { + spin_unlock(&dentry->d_lock); + cpu_relax(); + goto again; + } dentry->d_flags &= ~DCACHE_CANT_MOUNT; - dentry_iput(dentry); + dentry_unlink_inode(dentry); fsnotify_nameremove(dentry, isdir); return; } @@ -1550,17 +2059,18 @@ void d_delete(struct dentry * dentry) __d_drop(dentry); spin_unlock(&dentry->d_lock); - spin_unlock(&dcache_lock); fsnotify_nameremove(dentry, isdir); } EXPORT_SYMBOL(d_delete); -static void __d_rehash(struct dentry * entry, struct hlist_head *list) +static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) { - - entry->d_flags &= ~DCACHE_UNHASHED; - hlist_add_head_rcu(&entry->d_hash, list); + BUG_ON(!d_unhashed(entry)); + hlist_bl_lock(b); + entry->d_flags |= DCACHE_RCUACCESS; + hlist_bl_add_head_rcu(&entry->d_hash, b); + hlist_bl_unlock(b); } static void _d_rehash(struct dentry * entry) @@ -1577,25 +2087,39 @@ static void _d_rehash(struct dentry * entry) void d_rehash(struct dentry * entry) { - spin_lock(&dcache_lock); spin_lock(&entry->d_lock); _d_rehash(entry); spin_unlock(&entry->d_lock); - spin_unlock(&dcache_lock); } EXPORT_SYMBOL(d_rehash); -/* - * When switching names, the actual string doesn't strictly have to - * be preserved in the target - because we're dropping the target - * anyway. As such, we can just do a simple memcpy() to copy over - * the new name before we switch. +/** + * dentry_update_name_case - update case insensitive dentry with a new name + * @dentry: dentry to be updated + * @name: new name * - * Note that we have to be a lot more careful about getting the hash - * switched - we have to switch the hash value properly even if it - * then no longer matches the actual (corrupted) string of the target. - * The hash value has to match the hash queue that the dentry is on.. + * Update a case insensitive dentry with new case of name. + * + * dentry must have been returned by d_lookup with name @name. Old and new + * name lengths must match (ie. no d_compare which allows mismatched name + * lengths). + * + * Parent inode i_mutex must be held over d_lookup and into this call (to + * keep renames and concurrent inserts, and readdir(2) away). */ +void dentry_update_name_case(struct dentry *dentry, struct qstr *name) +{ + BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex)); + BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ + + spin_lock(&dentry->d_lock); + write_seqcount_begin(&dentry->d_seq); + memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); + write_seqcount_end(&dentry->d_seq); + spin_unlock(&dentry->d_lock); +} +EXPORT_SYMBOL(dentry_update_name_case); + static void switch_names(struct dentry *dentry, struct dentry *target) { if (dname_external(target)) { @@ -1637,54 +2161,84 @@ static void switch_names(struct dentry *dentry, struct dentry *target) swap(dentry->d_name.len, target->d_name.len); } +static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) +{ + /* + * XXXX: do we really need to take target->d_lock? + */ + if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) + spin_lock(&target->d_parent->d_lock); + else { + if (d_ancestor(dentry->d_parent, target->d_parent)) { + spin_lock(&dentry->d_parent->d_lock); + spin_lock_nested(&target->d_parent->d_lock, + DENTRY_D_LOCK_NESTED); + } else { + spin_lock(&target->d_parent->d_lock); + spin_lock_nested(&dentry->d_parent->d_lock, + DENTRY_D_LOCK_NESTED); + } + } + if (target < dentry) { + spin_lock_nested(&target->d_lock, 2); + spin_lock_nested(&dentry->d_lock, 3); + } else { + spin_lock_nested(&dentry->d_lock, 2); + spin_lock_nested(&target->d_lock, 3); + } +} + +static void dentry_unlock_parents_for_move(struct dentry *dentry, + struct dentry *target) +{ + if (target->d_parent != dentry->d_parent) + spin_unlock(&dentry->d_parent->d_lock); + if (target->d_parent != target) + spin_unlock(&target->d_parent->d_lock); +} + /* - * We cannibalize "target" when moving dentry on top of it, - * because it's going to be thrown away anyway. We could be more - * polite about it, though. - * - * This forceful removal will result in ugly /proc output if - * somebody holds a file open that got deleted due to a rename. - * We could be nicer about the deleted file, and let it show - * up under the name it had before it was deleted rather than - * under the original name of the file that was moved on top of it. + * When switching names, the actual string doesn't strictly have to + * be preserved in the target - because we're dropping the target + * anyway. As such, we can just do a simple memcpy() to copy over + * the new name before we switch. + * + * Note that we have to be a lot more careful about getting the hash + * switched - we have to switch the hash value properly even if it + * then no longer matches the actual (corrupted) string of the target. + * The hash value has to match the hash queue that the dentry is on.. */ - /* - * d_move_locked - move a dentry + * d_move - move a dentry * @dentry: entry to move * @target: new dentry * * Update the dcache to reflect the move of a file name. Negative * dcache entries should not be moved in this way. */ -static void d_move_locked(struct dentry * dentry, struct dentry * target) +void d_move(struct dentry * dentry, struct dentry * target) { - struct hlist_head *list; - if (!dentry->d_inode) printk(KERN_WARNING "VFS: moving negative dcache entry\n"); + BUG_ON(d_ancestor(dentry, target)); + BUG_ON(d_ancestor(target, dentry)); + write_seqlock(&rename_lock); - /* - * XXXX: do we really need to take target->d_lock? - */ - if (target < dentry) { - spin_lock(&target->d_lock); - spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); - } else { - spin_lock(&dentry->d_lock); - spin_lock_nested(&target->d_lock, DENTRY_D_LOCK_NESTED); - } - /* Move the dentry to the target hash queue, if on different bucket */ - if (d_unhashed(dentry)) - goto already_unhashed; + dentry_lock_for_move(dentry, target); - hlist_del_rcu(&dentry->d_hash); + write_seqcount_begin(&dentry->d_seq); + write_seqcount_begin(&target->d_seq); -already_unhashed: - list = d_hash(target->d_parent, target->d_name.hash); - __d_rehash(dentry, list); + /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ + + /* + * Move the dentry to the target hash queue. Don't bother checking + * for the same hash queue because of how unlikely it is. + */ + __d_drop(dentry); + __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); /* Unhash the target: dput() will then get rid of it */ __d_drop(target); @@ -1709,27 +2263,16 @@ already_unhashed: } list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); + + write_seqcount_end(&target->d_seq); + write_seqcount_end(&dentry->d_seq); + + dentry_unlock_parents_for_move(dentry, target); spin_unlock(&target->d_lock); fsnotify_d_move(dentry); spin_unlock(&dentry->d_lock); write_sequnlock(&rename_lock); } - -/** - * d_move - move a dentry - * @dentry: entry to move - * @target: new dentry - * - * Update the dcache to reflect the move of a file name. Negative - * dcache entries should not be moved in this way. - */ - -void d_move(struct dentry * dentry, struct dentry * target) -{ - spin_lock(&dcache_lock); - d_move_locked(dentry, target); - spin_unlock(&dcache_lock); -} EXPORT_SYMBOL(d_move); /** @@ -1755,13 +2298,13 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) * This helper attempts to cope with remotely renamed directories * * It assumes that the caller is already holding - * dentry->d_parent->d_inode->i_mutex and the dcache_lock + * dentry->d_parent->d_inode->i_mutex and the inode->i_lock * * Note: If ever the locking in lock_rename() changes, then please * remember to update this too... */ -static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) - __releases(dcache_lock) +static struct dentry *__d_unalias(struct inode *inode, + struct dentry *dentry, struct dentry *alias) { struct mutex *m1 = NULL, *m2 = NULL; struct dentry *ret; @@ -1784,10 +2327,10 @@ static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) goto out_err; m2 = &alias->d_parent->d_inode->i_mutex; out_unalias: - d_move_locked(alias, dentry); + d_move(alias, dentry); ret = alias; out_err: - spin_unlock(&dcache_lock); + spin_unlock(&inode->i_lock); if (m2) mutex_unlock(m2); if (m1) @@ -1798,17 +2341,23 @@ out_err: /* * Prepare an anonymous dentry for life in the superblock's dentry tree as a * named dentry in place of the dentry to be replaced. + * returns with anon->d_lock held! */ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) { struct dentry *dparent, *aparent; - switch_names(dentry, anon); - swap(dentry->d_name.hash, anon->d_name.hash); + dentry_lock_for_move(anon, dentry); + + write_seqcount_begin(&dentry->d_seq); + write_seqcount_begin(&anon->d_seq); dparent = dentry->d_parent; aparent = anon->d_parent; + switch_names(dentry, anon); + swap(dentry->d_name.hash, anon->d_name.hash); + dentry->d_parent = (aparent == anon) ? dentry : aparent; list_del(&dentry->d_u.d_child); if (!IS_ROOT(dentry)) @@ -1823,6 +2372,13 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) else INIT_LIST_HEAD(&anon->d_u.d_child); + write_seqcount_end(&dentry->d_seq); + write_seqcount_end(&anon->d_seq); + + dentry_unlock_parents_for_move(anon, dentry); + spin_unlock(&dentry->d_lock); + + /* anon->d_lock still locked, returns locked */ anon->d_flags &= ~DCACHE_DISCONNECTED; } @@ -1840,14 +2396,15 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) BUG_ON(!d_unhashed(dentry)); - spin_lock(&dcache_lock); - if (!inode) { actual = dentry; __d_instantiate(dentry, NULL); - goto found_lock; + d_rehash(actual); + goto out_nolock; } + spin_lock(&inode->i_lock); + if (S_ISDIR(inode->i_mode)) { struct dentry *alias; @@ -1858,13 +2415,12 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) /* Is this an anonymous mountpoint that we could splice * into our tree? */ if (IS_ROOT(alias)) { - spin_lock(&alias->d_lock); __d_materialise_dentry(dentry, alias); __d_drop(alias); goto found; } /* Nope, but we must(!) avoid directory aliasing */ - actual = __d_unalias(dentry, alias); + actual = __d_unalias(inode, dentry, alias); if (IS_ERR(actual)) dput(alias); goto out_nolock; @@ -1875,15 +2431,14 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) actual = __d_instantiate_unique(dentry, inode); if (!actual) actual = dentry; - else if (unlikely(!d_unhashed(actual))) - goto shouldnt_be_hashed; + else + BUG_ON(!d_unhashed(actual)); -found_lock: spin_lock(&actual->d_lock); found: _d_rehash(actual); spin_unlock(&actual->d_lock); - spin_unlock(&dcache_lock); + spin_unlock(&inode->i_lock); out_nolock: if (actual == dentry) { security_d_instantiate(dentry, inode); @@ -1892,10 +2447,6 @@ out_nolock: iput(inode); return actual; - -shouldnt_be_hashed: - spin_unlock(&dcache_lock); - BUG(); } EXPORT_SYMBOL_GPL(d_materialise_unique); @@ -1915,14 +2466,13 @@ static int prepend_name(char **buffer, int *buflen, struct qstr *name) } /** - * Prepend path string to a buffer - * + * prepend_path - Prepend path string to a buffer * @path: the dentry/vfsmount to report * @root: root vfsmnt/dentry (may be modified by this function) * @buffer: pointer to the end of the buffer * @buflen: pointer to buffer length * - * Caller holds the dcache_lock. + * Caller holds the rename_lock. * * If path is not reachable from the supplied root, then the value of * root is changed (without modifying refcounts). @@ -1950,7 +2500,9 @@ static int prepend_path(const struct path *path, struct path *root, } parent = dentry->d_parent; prefetch(parent); + spin_lock(&dentry->d_lock); error = prepend_name(buffer, buflen, &dentry->d_name); + spin_unlock(&dentry->d_lock); if (!error) error = prepend(buffer, buflen, "/", 1); if (error) @@ -1994,7 +2546,7 @@ global_root: * Returns a pointer into the buffer or an error code if the * path was too long. * - * "buflen" should be positive. Caller holds the dcache_lock. + * "buflen" should be positive. * * If path is not reachable from the supplied root, then the value of * root is changed (without modifying refcounts). @@ -2006,10 +2558,12 @@ char *__d_path(const struct path *path, struct path *root, int error; prepend(&res, &buflen, "\0", 1); + write_seqlock(&rename_lock); error = prepend_path(path, root, &res, &buflen); + write_sequnlock(&rename_lock); + if (error) return ERR_PTR(error); - return res; } @@ -2068,12 +2622,12 @@ char *d_path(const struct path *path, char *buf, int buflen) return path->dentry->d_op->d_dname(path->dentry, buf, buflen); get_fs_root(current->fs, &root); - spin_lock(&dcache_lock); + write_seqlock(&rename_lock); tmp = root; error = path_with_deleted(path, &tmp, &res, &buflen); if (error) res = ERR_PTR(error); - spin_unlock(&dcache_lock); + write_sequnlock(&rename_lock); path_put(&root); return res; } @@ -2099,12 +2653,12 @@ char *d_path_with_unreachable(const struct path *path, char *buf, int buflen) return path->dentry->d_op->d_dname(path->dentry, buf, buflen); get_fs_root(current->fs, &root); - spin_lock(&dcache_lock); + write_seqlock(&rename_lock); tmp = root; error = path_with_deleted(path, &tmp, &res, &buflen); if (!error && !path_equal(&tmp, &root)) error = prepend_unreachable(&res, &buflen); - spin_unlock(&dcache_lock); + write_sequnlock(&rename_lock); path_put(&root); if (error) res = ERR_PTR(error); @@ -2136,7 +2690,7 @@ char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, /* * Write full pathname from the root of the filesystem into the buffer. */ -char *__dentry_path(struct dentry *dentry, char *buf, int buflen) +static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) { char *end = buf + buflen; char *retval; @@ -2150,10 +2704,13 @@ char *__dentry_path(struct dentry *dentry, char *buf, int buflen) while (!IS_ROOT(dentry)) { struct dentry *parent = dentry->d_parent; + int error; prefetch(parent); - if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) || - (prepend(&end, &buflen, "/", 1) != 0)) + spin_lock(&dentry->d_lock); + error = prepend_name(&end, &buflen, &dentry->d_name); + spin_unlock(&dentry->d_lock); + if (error != 0 || prepend(&end, &buflen, "/", 1) != 0) goto Elong; retval = end; @@ -2163,14 +2720,25 @@ char *__dentry_path(struct dentry *dentry, char *buf, int buflen) Elong: return ERR_PTR(-ENAMETOOLONG); } -EXPORT_SYMBOL(__dentry_path); + +char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) +{ + char *retval; + + write_seqlock(&rename_lock); + retval = __dentry_path(dentry, buf, buflen); + write_sequnlock(&rename_lock); + + return retval; +} +EXPORT_SYMBOL(dentry_path_raw); char *dentry_path(struct dentry *dentry, char *buf, int buflen) { char *p = NULL; char *retval; - spin_lock(&dcache_lock); + write_seqlock(&rename_lock); if (d_unlinked(dentry)) { p = buf + buflen; if (prepend(&p, &buflen, "//deleted", 10) != 0) @@ -2178,12 +2746,11 @@ char *dentry_path(struct dentry *dentry, char *buf, int buflen) buflen++; } retval = __dentry_path(dentry, buf, buflen); - spin_unlock(&dcache_lock); + write_sequnlock(&rename_lock); if (!IS_ERR(retval) && p) *p = '/'; /* restore '/' overriden with '\0' */ return retval; Elong: - spin_unlock(&dcache_lock); return ERR_PTR(-ENAMETOOLONG); } @@ -2217,7 +2784,7 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) get_fs_root_and_pwd(current->fs, &root, &pwd); error = -ENOENT; - spin_lock(&dcache_lock); + write_seqlock(&rename_lock); if (!d_unlinked(pwd.dentry)) { unsigned long len; struct path tmp = root; @@ -2226,7 +2793,7 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) prepend(&cwd, &buflen, "\0", 1); error = prepend_path(&pwd, &tmp, &cwd, &buflen); - spin_unlock(&dcache_lock); + write_sequnlock(&rename_lock); if (error) goto out; @@ -2245,8 +2812,9 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) if (copy_to_user(buf, cwd, len)) error = -EFAULT; } - } else - spin_unlock(&dcache_lock); + } else { + write_sequnlock(&rename_lock); + } out: path_put(&pwd); @@ -2274,25 +2842,25 @@ out: int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) { int result; - unsigned long seq; + unsigned seq; if (new_dentry == old_dentry) return 1; - /* - * Need rcu_readlock to protect against the d_parent trashing - * due to d_move - */ - rcu_read_lock(); do { /* for restarting inner loop in case of seq retry */ seq = read_seqbegin(&rename_lock); + /* + * Need rcu_readlock to protect against the d_parent trashing + * due to d_move + */ + rcu_read_lock(); if (d_ancestor(old_dentry, new_dentry)) result = 1; else result = 0; + rcu_read_unlock(); } while (read_seqretry(&rename_lock, seq)); - rcu_read_unlock(); return result; } @@ -2324,10 +2892,15 @@ EXPORT_SYMBOL(path_is_under); void d_genocide(struct dentry *root) { - struct dentry *this_parent = root; + struct dentry *this_parent; struct list_head *next; + unsigned seq; + int locked = 0; - spin_lock(&dcache_lock); + seq = read_seqbegin(&rename_lock); +again: + this_parent = root; + spin_lock(&this_parent->d_lock); repeat: next = this_parent->d_subdirs.next; resume: @@ -2335,21 +2908,48 @@ resume: struct list_head *tmp = next; struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); next = tmp->next; - if (d_unhashed(dentry)||!dentry->d_inode) + + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); + if (d_unhashed(dentry) || !dentry->d_inode) { + spin_unlock(&dentry->d_lock); continue; + } if (!list_empty(&dentry->d_subdirs)) { + spin_unlock(&this_parent->d_lock); + spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); this_parent = dentry; + spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); goto repeat; } - atomic_dec(&dentry->d_count); + if (!(dentry->d_flags & DCACHE_GENOCIDE)) { + dentry->d_flags |= DCACHE_GENOCIDE; + dentry->d_count--; + } + spin_unlock(&dentry->d_lock); } if (this_parent != root) { - next = this_parent->d_u.d_child.next; - atomic_dec(&this_parent->d_count); - this_parent = this_parent->d_parent; + struct dentry *child = this_parent; + if (!(this_parent->d_flags & DCACHE_GENOCIDE)) { + this_parent->d_flags |= DCACHE_GENOCIDE; + this_parent->d_count--; + } + this_parent = try_to_ascend(this_parent, locked, seq); + if (!this_parent) + goto rename_retry; + next = child->d_u.d_child.next; goto resume; } - spin_unlock(&dcache_lock); + spin_unlock(&this_parent->d_lock); + if (!locked && read_seqretry(&rename_lock, seq)) + goto rename_retry; + if (locked) + write_sequnlock(&rename_lock); + return; + +rename_retry: + locked = 1; + write_seqlock(&rename_lock); + goto again; } /** @@ -2403,7 +3003,7 @@ static void __init dcache_init_early(void) dentry_hashtable = alloc_large_system_hash("Dentry cache", - sizeof(struct hlist_head), + sizeof(struct hlist_bl_head), dhash_entries, 13, HASH_EARLY, @@ -2412,7 +3012,7 @@ static void __init dcache_init_early(void) 0); for (loop = 0; loop < (1 << d_hash_shift); loop++) - INIT_HLIST_HEAD(&dentry_hashtable[loop]); + INIT_HLIST_BL_HEAD(dentry_hashtable + loop); } static void __init dcache_init(void) @@ -2435,7 +3035,7 @@ static void __init dcache_init(void) dentry_hashtable = alloc_large_system_hash("Dentry cache", - sizeof(struct hlist_head), + sizeof(struct hlist_bl_head), dhash_entries, 13, 0, @@ -2444,7 +3044,7 @@ static void __init dcache_init(void) 0); for (loop = 0; loop < (1 << d_hash_shift); loop++) - INIT_HLIST_HEAD(&dentry_hashtable[loop]); + INIT_HLIST_BL_HEAD(dentry_hashtable + loop); } /* SLAB cache for __getname() consumers */ |