From 19156840e33a23eeb1a749c0f991dab6588b077d Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Wed, 28 Aug 2013 10:17:55 +1000 Subject: [PATCH] dentry: move to per-sb LRU locks MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit With the dentry LRUs being per-sb structures, there is no real need for a global dentry_lru_lock. The locking can be made more fine-grained by moving to a per-sb LRU lock, isolating the LRU operations of different filesytsems completely from each other. The need for this is independent of any performance consideration that may arise: in the interest of abstracting the lru operations away, it is mandatory that each lru works around its own lock instead of a global lock for all of them. [glommer@openvz.org: updated changelog ] Signed-off-by: Dave Chinner Signed-off-by: Glauber Costa Reviewed-by: Christoph Hellwig Acked-by: Mel Gorman Cc: "Theodore Ts'o" Cc: Adrian Hunter Cc: Al Viro Cc: Artem Bityutskiy Cc: Arve Hjønnevåg Cc: Carlos Maiolino Cc: Christoph Hellwig Cc: Chuck Lever Cc: Daniel Vetter Cc: David Rientjes Cc: Gleb Natapov Cc: Greg Thelen Cc: J. Bruce Fields Cc: Jan Kara Cc: Jerome Glisse Cc: John Stultz Cc: KAMEZAWA Hiroyuki Cc: Kent Overstreet Cc: Kirill A. Shutemov Cc: Marcelo Tosatti Cc: Mel Gorman Cc: Steven Whitehouse Cc: Thomas Hellstrom Cc: Trond Myklebust Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/dcache.c | 33 ++++++++++++++++----------------- fs/super.c | 1 + include/linux/fs.h | 4 +++- 3 files changed, 20 insertions(+), 18 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 03161240e744..e989ecb44a65 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -48,7 +48,7 @@ * - the dcache hash table * s_anon bl list spinlock protects: * - the s_anon list (see __d_drop) - * dcache_lru_lock protects: + * dentry->d_sb->s_dentry_lru_lock protects: * - the dcache lru lists and counters * d_lock protects: * - d_flags @@ -63,7 +63,7 @@ * Ordering: * dentry->d_inode->i_lock * dentry->d_lock - * dcache_lru_lock + * dentry->d_sb->s_dentry_lru_lock * dcache_hash_bucket lock * s_anon lock * @@ -81,7 +81,6 @@ int sysctl_vfs_cache_pressure __read_mostly = 100; EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); -static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock); __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); EXPORT_SYMBOL(rename_lock); @@ -362,12 +361,12 @@ static void dentry_unlink_inode(struct dentry * dentry) static void dentry_lru_add(struct dentry *dentry) { if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) { - spin_lock(&dcache_lru_lock); + spin_lock(&dentry->d_sb->s_dentry_lru_lock); dentry->d_flags |= DCACHE_LRU_LIST; list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); dentry->d_sb->s_nr_dentry_unused++; this_cpu_inc(nr_dentry_unused); - spin_unlock(&dcache_lru_lock); + spin_unlock(&dentry->d_sb->s_dentry_lru_lock); } } @@ -385,15 +384,15 @@ static void __dentry_lru_del(struct dentry *dentry) static void dentry_lru_del(struct dentry *dentry) { if (!list_empty(&dentry->d_lru)) { - spin_lock(&dcache_lru_lock); + spin_lock(&dentry->d_sb->s_dentry_lru_lock); __dentry_lru_del(dentry); - spin_unlock(&dcache_lru_lock); + spin_unlock(&dentry->d_sb->s_dentry_lru_lock); } } static void dentry_lru_move_list(struct dentry *dentry, struct list_head *list) { - spin_lock(&dcache_lru_lock); + spin_lock(&dentry->d_sb->s_dentry_lru_lock); if (list_empty(&dentry->d_lru)) { dentry->d_flags |= DCACHE_LRU_LIST; list_add_tail(&dentry->d_lru, list); @@ -402,7 +401,7 @@ static void dentry_lru_move_list(struct dentry *dentry, struct list_head *list) } else { list_move_tail(&dentry->d_lru, list); } - spin_unlock(&dcache_lru_lock); + spin_unlock(&dentry->d_sb->s_dentry_lru_lock); } /** @@ -895,14 +894,14 @@ void prune_dcache_sb(struct super_block *sb, int count) LIST_HEAD(tmp); relock: - spin_lock(&dcache_lru_lock); + spin_lock(&sb->s_dentry_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); + spin_unlock(&sb->s_dentry_lru_lock); cpu_relax(); goto relock; } @@ -918,11 +917,11 @@ relock: if (!--count) break; } - cond_resched_lock(&dcache_lru_lock); + cond_resched_lock(&sb->s_dentry_lru_lock); } if (!list_empty(&referenced)) list_splice(&referenced, &sb->s_dentry_lru); - spin_unlock(&dcache_lru_lock); + spin_unlock(&sb->s_dentry_lru_lock); shrink_dentry_list(&tmp); } @@ -938,14 +937,14 @@ void shrink_dcache_sb(struct super_block *sb) { LIST_HEAD(tmp); - spin_lock(&dcache_lru_lock); + spin_lock(&sb->s_dentry_lru_lock); while (!list_empty(&sb->s_dentry_lru)) { list_splice_init(&sb->s_dentry_lru, &tmp); - spin_unlock(&dcache_lru_lock); + spin_unlock(&sb->s_dentry_lru_lock); shrink_dentry_list(&tmp); - spin_lock(&dcache_lru_lock); + spin_lock(&sb->s_dentry_lru_lock); } - spin_unlock(&dcache_lru_lock); + spin_unlock(&sb->s_dentry_lru_lock); } EXPORT_SYMBOL(shrink_dcache_sb); diff --git a/fs/super.c b/fs/super.c index 63b6863bac7b..3c5318694ccd 100644 --- a/fs/super.c +++ b/fs/super.c @@ -176,6 +176,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags) INIT_HLIST_BL_HEAD(&s->s_anon); INIT_LIST_HEAD(&s->s_inodes); INIT_LIST_HEAD(&s->s_dentry_lru); + spin_lock_init(&s->s_dentry_lru_lock); INIT_LIST_HEAD(&s->s_inode_lru); spin_lock_init(&s->s_inode_lru_lock); INIT_LIST_HEAD(&s->s_mounts); diff --git a/include/linux/fs.h b/include/linux/fs.h index 3b3edac75df2..14a90f6886fa 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1269,7 +1269,9 @@ struct super_block { struct list_head s_files; #endif struct list_head s_mounts; /* list of mounts; _not_ for fs use */ - /* s_dentry_lru, s_nr_dentry_unused protected by dcache.c lru locks */ + + /* s_dentry_lru_lock protects s_dentry_lru and s_nr_dentry_unused */ + spinlock_t s_dentry_lru_lock ____cacheline_aligned_in_smp; struct list_head s_dentry_lru; /* unused dentry lru */ long s_nr_dentry_unused; /* # of dentry on lru */ -- 2.20.1