diff options
| -rw-r--r-- | fs/dcache.c | 112 |
1 files changed, 84 insertions, 28 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 1e124d4..3d3c843 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -37,11 +37,19 @@ /* * Usage: - * dcache_hash_lock protects dcache hash table, s_anon lists + * dcache_hash_lock protects: + * - the dcache hash table, s_anon lists + * dcache_lru_lock protects: + * - the dcache lru lists and counters + * d_lock protects: + * - d_flags + * - d_name + * - d_lru * * Ordering: * dcache_lock * dentry->d_lock + * dcache_lru_lock * dcache_hash_lock * * if (dentry1 < dentry2) @@ -52,6 +60,7 @@ int sysctl_vfs_cache_pressure __read_mostly = 100; EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_hash_lock); +static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock); __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock); __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); @@ -154,28 +163,38 @@ static void dentry_iput(struct dentry * dentry) } /* - * dentry_lru_(add|del|move_tail) must be called with dcache_lock held. + * dentry_lru_(add|del|move_tail) must be called with d_lock held. */ static void dentry_lru_add(struct dentry *dentry) { 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_del(struct dentry *dentry) +{ + 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_init(&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_move_tail(struct dentry *dentry) { + 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++; @@ -183,6 +202,7 @@ static void dentry_lru_move_tail(struct dentry *dentry) } else { list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); } + spin_unlock(&dcache_lru_lock); } /** @@ -192,6 +212,8 @@ static void dentry_lru_move_tail(struct dentry *dentry) * The dentry must already be unhashed and removed from the LRU. * * If this is the root of the dentry tree, return NULL. + * + * dcache_lock and d_lock must be held by caller, are dropped by d_kill. */ static struct dentry *d_kill(struct dentry *dentry) __releases(dentry->d_lock) @@ -383,10 +405,19 @@ int d_invalidate(struct dentry * dentry) EXPORT_SYMBOL(d_invalidate); /* This should be called _only_ with dcache_lock held */ +static inline struct dentry * __dget_locked_dlock(struct dentry *dentry) +{ + atomic_inc(&dentry->d_count); + dentry_lru_del(dentry); + return dentry; +} + static inline struct dentry * __dget_locked(struct dentry *dentry) { atomic_inc(&dentry->d_count); + spin_lock(&dentry->d_lock); dentry_lru_del(dentry); + spin_unlock(&dentry->d_lock); return dentry; } @@ -465,7 +496,7 @@ restart: list_for_each_entry(dentry, &inode->i_dentry, d_alias) { spin_lock(&dentry->d_lock); if (!atomic_read(&dentry->d_count)) { - __dget_locked(dentry); + __dget_locked_dlock(dentry); __d_drop(dentry); spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); @@ -489,7 +520,6 @@ EXPORT_SYMBOL(d_prune_aliases); static void prune_one_dentry(struct dentry * dentry) __releases(dentry->d_lock) __releases(dcache_lock) - __acquires(dcache_lock) { __d_drop(dentry); dentry = d_kill(dentry); @@ -498,15 +528,16 @@ static void prune_one_dentry(struct dentry * dentry) * Prune ancestors. Locking is simpler than in dput(), * because dcache_lock needs to be taken anyway. */ - spin_lock(&dcache_lock); while (dentry) { - if (!atomic_dec_and_lock(&dentry->d_count, &dentry->d_lock)) + spin_lock(&dcache_lock); + if (!atomic_dec_and_lock(&dentry->d_count, &dentry->d_lock)) { + spin_unlock(&dcache_lock); return; + } dentry_lru_del(dentry); __d_drop(dentry); dentry = d_kill(dentry); - spin_lock(&dcache_lock); } } @@ -516,21 +547,31 @@ static void shrink_dentry_list(struct list_head *list) while (!list_empty(list)) { dentry = list_entry(list->prev, struct dentry, d_lru); - dentry_lru_del(dentry); + + if (!spin_trylock(&dentry->d_lock)) { + spin_unlock(&dcache_lru_lock); + cpu_relax(); + spin_lock(&dcache_lru_lock); + continue; + } + + __dentry_lru_del(dentry); /* * 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. */ - spin_lock(&dentry->d_lock); if (atomic_read(&dentry->d_count)) { spin_unlock(&dentry->d_lock); continue; } + spin_unlock(&dcache_lru_lock); + prune_one_dentry(dentry); - /* dentry->d_lock was dropped in prune_one_dentry() */ - cond_resched_lock(&dcache_lock); + /* dcache_lock and dentry->d_lock dropped */ + spin_lock(&dcache_lock); + spin_lock(&dcache_lru_lock); } } @@ -551,32 +592,36 @@ static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) int cnt = *count; spin_lock(&dcache_lock); +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) { - spin_lock(&dentry->d_lock); - if (dentry->d_flags & DCACHE_REFERENCED) { - dentry->d_flags &= ~DCACHE_REFERENCED; - list_move(&dentry->d_lru, &referenced); - spin_unlock(&dentry->d_lock); - cond_resched_lock(&dcache_lock); - continue; - } + 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; } - - list_move_tail(&dentry->d_lru, &tmp); - if (!--cnt) - break; - cond_resched_lock(&dcache_lock); + /* XXX: re-add cond_resched_lock when dcache_lock goes away */ } *count = cnt; @@ -584,6 +629,7 @@ static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) if (!list_empty(&referenced)) list_splice(&referenced, &sb->s_dentry_lru); + spin_unlock(&dcache_lru_lock); spin_unlock(&dcache_lock); } @@ -679,10 +725,12 @@ void shrink_dcache_sb(struct super_block *sb) LIST_HEAD(tmp); spin_lock(&dcache_lock); + spin_lock(&dcache_lru_lock); while (!list_empty(&sb->s_dentry_lru)) { list_splice_init(&sb->s_dentry_lru, &tmp); shrink_dentry_list(&tmp); } + spin_unlock(&dcache_lru_lock); spin_unlock(&dcache_lock); } EXPORT_SYMBOL(shrink_dcache_sb); @@ -701,7 +749,9 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) /* detach this root from the system */ spin_lock(&dcache_lock); + spin_lock(&dentry->d_lock); dentry_lru_del(dentry); + spin_unlock(&dentry->d_lock); __d_drop(dentry); spin_unlock(&dcache_lock); @@ -715,7 +765,9 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) spin_lock(&dcache_lock); list_for_each_entry(loop, &dentry->d_subdirs, d_u.d_child) { + spin_lock(&loop->d_lock); dentry_lru_del(loop); + spin_unlock(&loop->d_lock); __d_drop(loop); cond_resched_lock(&dcache_lock); } @@ -892,6 +944,8 @@ resume: struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); next = tmp->next; + spin_lock(&dentry->d_lock); + /* * move only zero ref count dentries to the end * of the unused list for prune_dcache @@ -903,6 +957,8 @@ resume: dentry_lru_del(dentry); } + spin_unlock(&dentry->d_lock); + /* * We can return to the caller if we have found some (this * ensures forward progress). We'll be coming back to find |