From 11ef160fda9c150cd75db77194bcc66839709662 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 23 Sep 2009 20:28:46 -0400 Subject: [PATCH] Btrfs: fix releasepage to avoid unlocking extents we haven't locked During releasepage, we try to drop any extent_state structs for the bye offsets of the page we're releaseing. But the code was incorrectly telling clear_extent_bit to delete the state struct unconditionallly. Normally this would be fine because we have the page locked, but other parts of btrfs will lock down an entire extent, the most common place being IO completion. releasepage was deleting the extent state without first locking the extent, which may result in removing a state struct that another process had locked down. The fix here is to leave the NODATASUM and EXTENT_LOCKED bits alone in releasepage. Signed-off-by: Chris Mason --- fs/btrfs/extent_io.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index dcce98d0ec4f..0cb88f8146ea 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2809,8 +2809,13 @@ int try_release_extent_state(struct extent_map_tree *map, else { if ((mask & GFP_NOFS) == GFP_NOFS) mask = GFP_NOFS; - clear_extent_bit(tree, start, end, EXTENT_UPTODATE, - 1, 1, NULL, mask); + /* + * at this point we can safely clear everything except the + * locked bit and the nodatasum bit + */ + clear_extent_bit(tree, start, end, + ~(EXTENT_LOCKED | EXTENT_NODATASUM), + 0, 0, NULL, mask); } return ret; } -- GitLab