diff options
author | Nick Piggin <npiggin@kernel.dk> | 2010-08-18 04:37:33 +1000 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2010-08-18 08:35:46 -0400 |
commit | 2a4419b5b2a77f3f4537c14f7ad7df95770655dd (patch) | |
tree | ad66519a92b995920ecada788e4a08e265747545 /drivers/staging | |
parent | 44672e4fbd40e2dda8bbce7d0f71d24dbfc7e00e (diff) | |
download | op-kernel-dev-2a4419b5b2a77f3f4537c14f7ad7df95770655dd.zip op-kernel-dev-2a4419b5b2a77f3f4537c14f7ad7df95770655dd.tar.gz |
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 <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'drivers/staging')
-rw-r--r-- | drivers/staging/pohmelfs/path_entry.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/staging/pohmelfs/path_entry.c b/drivers/staging/pohmelfs/path_entry.c index cdc4dd5..8ec83d2 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); |