From 7b2296afb392bc21a50f42e7c7f4b19d3fea8c6d Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Fri, 21 Jun 2013 08:58:20 -0400 Subject: locks: give the blocked_hash its own spinlock There's no reason we have to protect the blocked_hash and file_lock_list with the same spinlock. With the tests I have, breaking it in two gives a barely measurable performance benefit, but it seems reasonable to make this locking as granular as possible. Signed-off-by: Jeff Layton Signed-off-by: Al Viro --- fs/locks.c | 41 ++++++++++++++++++++++------------------- 1 file changed, 22 insertions(+), 19 deletions(-) (limited to 'fs') diff --git a/fs/locks.c b/fs/locks.c index 6242e0b1c69c..04e2c1fdb157 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -159,10 +159,11 @@ int lease_break_time = 45; * by the file_lock_lock. */ static HLIST_HEAD(file_lock_list); +static DEFINE_SPINLOCK(file_lock_lock); /* * The blocked_hash is used to find POSIX lock loops for deadlock detection. - * It is protected by file_lock_lock. + * It is protected by blocked_lock_lock. * * We hash locks by lockowner in order to optimize searching for the lock a * particular lockowner is waiting on. @@ -175,8 +176,8 @@ static HLIST_HEAD(file_lock_list); static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS); /* - * This lock protects the blocked_hash and the file_lock_list. Generally, if - * you're accessing one of those lists, you want to be holding this lock. + * This lock protects the blocked_hash. Generally, if you're accessing it, you + * want to be holding this lock. * * In addition, it also protects the fl->fl_block list, and the fl->fl_next * pointer for file_lock structures that are acting as lock requests (in @@ -191,7 +192,7 @@ static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS); * both the i_lock and the blocked_lock_lock (acquired in that order). Deleting * an entry from the list however only requires the file_lock_lock. */ -static DEFINE_SPINLOCK(file_lock_lock); +static DEFINE_SPINLOCK(blocked_lock_lock); static struct kmem_cache *filelock_cache __read_mostly; @@ -544,7 +545,7 @@ locks_delete_global_blocked(struct file_lock *waiter) /* Remove waiter from blocker's block list. * When blocker ends up pointing to itself then the list is empty. * - * Must be called with file_lock_lock held. + * Must be called with blocked_lock_lock held. */ static void __locks_delete_block(struct file_lock *waiter) { @@ -555,9 +556,9 @@ static void __locks_delete_block(struct file_lock *waiter) static void locks_delete_block(struct file_lock *waiter) { - spin_lock(&file_lock_lock); + spin_lock(&blocked_lock_lock); __locks_delete_block(waiter); - spin_unlock(&file_lock_lock); + spin_unlock(&blocked_lock_lock); } /* Insert waiter into blocker's block list. @@ -565,9 +566,9 @@ static void locks_delete_block(struct file_lock *waiter) * the order they blocked. The documentation doesn't require this but * it seems like the reasonable thing to do. * - * Must be called with both the i_lock and file_lock_lock held. The fl_block + * Must be called with both the i_lock and blocked_lock_lock held. The fl_block * list itself is protected by the file_lock_list, but by ensuring that the - * i_lock is also held on insertions we can avoid taking the file_lock_lock + * i_lock is also held on insertions we can avoid taking the blocked_lock_lock * in some cases when we see that the fl_block list is empty. */ static void __locks_insert_block(struct file_lock *blocker, @@ -584,9 +585,9 @@ static void __locks_insert_block(struct file_lock *blocker, static void locks_insert_block(struct file_lock *blocker, struct file_lock *waiter) { - spin_lock(&file_lock_lock); + spin_lock(&blocked_lock_lock); __locks_insert_block(blocker, waiter); - spin_unlock(&file_lock_lock); + spin_unlock(&blocked_lock_lock); } /* @@ -601,12 +602,12 @@ static void locks_wake_up_blocks(struct file_lock *blocker) * blocked requests are only added to the list under the i_lock, and * the i_lock is always held here. Note that removal from the fl_block * list does not require the i_lock, so we must recheck list_empty() - * after acquiring the file_lock_lock. + * after acquiring the blocked_lock_lock. */ if (list_empty(&blocker->fl_block)) return; - spin_lock(&file_lock_lock); + spin_lock(&blocked_lock_lock); while (!list_empty(&blocker->fl_block)) { struct file_lock *waiter; @@ -618,7 +619,7 @@ static void locks_wake_up_blocks(struct file_lock *blocker) else wake_up(&waiter->fl_wait); } - spin_unlock(&file_lock_lock); + spin_unlock(&blocked_lock_lock); } /* Insert file lock fl into an inode's lock list at the position indicated @@ -772,7 +773,7 @@ static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl) return NULL; } -/* Must be called with the file_lock_lock held! */ +/* Must be called with the blocked_lock_lock held! */ static int posix_locks_deadlock(struct file_lock *caller_fl, struct file_lock *block_fl) { @@ -920,12 +921,12 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str * locks list must be done while holding the same lock! */ error = -EDEADLK; - spin_lock(&file_lock_lock); + spin_lock(&blocked_lock_lock); if (likely(!posix_locks_deadlock(request, fl))) { error = FILE_LOCK_DEFERRED; __locks_insert_block(fl, request); } - spin_unlock(&file_lock_lock); + spin_unlock(&blocked_lock_lock); goto out; } } @@ -2212,12 +2213,12 @@ posix_unblock_lock(struct file_lock *waiter) { int status = 0; - spin_lock(&file_lock_lock); + spin_lock(&blocked_lock_lock); if (waiter->fl_next) __locks_delete_block(waiter); else status = -ENOENT; - spin_unlock(&file_lock_lock); + spin_unlock(&blocked_lock_lock); return status; } EXPORT_SYMBOL(posix_unblock_lock); @@ -2332,6 +2333,7 @@ static void *locks_start(struct seq_file *f, loff_t *pos) loff_t *p = f->private; spin_lock(&file_lock_lock); + spin_lock(&blocked_lock_lock); *p = (*pos + 1); return seq_hlist_start(&file_lock_list, *pos); } @@ -2345,6 +2347,7 @@ static void *locks_next(struct seq_file *f, void *v, loff_t *pos) static void locks_stop(struct seq_file *f, void *v) { + spin_unlock(&blocked_lock_lock); spin_unlock(&file_lock_lock); } -- cgit v1.2.3