diff mbox

Btrfs: fix double range unlock of hole region when reading page

Message ID 1444751508-23571-1-git-send-email-fdmanana@kernel.org (mailing list archive)
State Accepted
Headers show

Commit Message

Filipe Manana Oct. 13, 2015, 3:51 p.m. UTC 
From: Filipe Manana <fdmanana@suse.com>

If when reading a page we find a hole and our caller had already locked
the range (bio flags has the bit EXTENT_BIO_PARENT_LOCKED set), we end
up unlocking the hole's range and then later our caller unlocks it
again, which might have already been locked by some other task once
the first unlock happened.

Currently this can only happen during a call to the extent_same ioctl,
as it's the only caller of __do_readpage() that sets the bit
EXTENT_BIO_PARENT_LOCKED for bio flags.

Fix this by leaving the unlock exclusively to the caller.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/extent_io.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index ecb1204..6e6df34 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3070,8 +3070,12 @@  static int __do_readpage(struct extent_io_tree *tree,
 
 			set_extent_uptodate(tree, cur, cur + iosize - 1,
 					    &cached, GFP_NOFS);
-			unlock_extent_cached(tree, cur, cur + iosize - 1,
-			                     &cached, GFP_NOFS);
+			if (parent_locked)
+				free_extent_state(cached);
+			else
+				unlock_extent_cached(tree, cur,
+						     cur + iosize - 1,
+						     &cached, GFP_NOFS);
 			cur = cur + iosize;
 			pg_offset += iosize;
 			continue;