[PATCH] Btrfs: avoid unnecessarily locking inode when clearing a range

[fdmanana@kernel.org]

From: Filipe Manana <fdmanana@suse.com>

If the range being cleared was not marked for defrag and we are not
about to clear the range from the defrag status, we don't need to
lock and unlock the inode.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/inode.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index eb495e956d53..51c45c0a8553 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1797,10 +1797,11 @@ static void btrfs_clear_bit_hook(void *private_data,
 	u64 len = state->end + 1 - state->start;
 	u32 num_extents = count_max_extents(len);
 
-	spin_lock(&inode->lock);
-	if ((state->state & EXTENT_DEFRAG) && (*bits & EXTENT_DEFRAG))
+	if ((state->state & EXTENT_DEFRAG) && (*bits & EXTENT_DEFRAG)) {
+		spin_lock(&inode->lock);
 		inode->defrag_bytes -= len;
-	spin_unlock(&inode->lock);
+		spin_unlock(&inode->lock);
+	}
 
 	/*
 	 * set_bit and clear bit hooks normally require _irqsave/restore
-- 
2.11.0