From 2a4419b5b2a77f3f4537c14f7ad7df95770655dd Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:33 +1000 Subject: fs: fs_struct rwlock to spinlock fs: fs_struct rwlock to spinlock struct fs_struct.lock is an rwlock with the read-side used to protect root and pwd members while taking references to them. Taking a reference to a path typically requires just 2 atomic ops, so the critical section is very small. Parallel read-side operations would have cacheline contention on the lock, the dentry, and the vfsmount cachelines, so the rwlock is unlikely to ever give a real parallelism increase. Replace it with a spinlock to avoid one or two atomic operations in typical path lookup fastpath. Signed-off-by: Nick Piggin Signed-off-by: Al Viro --- drivers/staging/pohmelfs/path_entry.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers') diff --git a/drivers/staging/pohmelfs/path_entry.c b/drivers/staging/pohmelfs/path_entry.c index cdc4dd50d63..8ec83d2dffb 100644 --- a/drivers/staging/pohmelfs/path_entry.c +++ b/drivers/staging/pohmelfs/path_entry.c @@ -44,9 +44,9 @@ int pohmelfs_construct_path_string(struct pohmelfs_inode *pi, void *data, int le return -ENOENT; } - read_lock(¤t->fs->lock); + spin_lock(¤t->fs->lock); path.mnt = mntget(current->fs->root.mnt); - read_unlock(¤t->fs->lock); + spin_unlock(¤t->fs->lock); path.dentry = d; @@ -91,9 +91,9 @@ int pohmelfs_path_length(struct pohmelfs_inode *pi) return -ENOENT; } - read_lock(¤t->fs->lock); + spin_lock(¤t->fs->lock); root = dget(current->fs->root.dentry); - read_unlock(¤t->fs->lock); + spin_unlock(¤t->fs->lock); spin_lock(&dcache_lock); -- cgit v1.2.3-70-g09d2