From e2eca69dc6c09d968d69312b9899968a9b03a4a9 Mon Sep 17 00:00:00 2001 From: Wang Shilong Date: Thu, 17 Jul 2014 11:44:14 +0800 Subject: [PATCH] Btrfs: fix wrong extent mapping for DirectIO btrfs_next_leaf() will use current leaf's last key to search and then return a bigger one. So it may still return a file extent item that is smaller than expected value and we will get an overflow here for @em->len. This is easy to reproduce for Btrfs Direct writting, it did not cause any problem, because writting will re-insert right mapping later. However, by hacking code to make DIO support compression, wrong extent mapping is kept and it encounter merging failure(EEXIST) quickly. Fix this problem by looping to find next file extent item that is bigger than @start or we could not find anything more. Signed-off-by: Wang Shilong Reviewed-by: David Sterba Signed-off-by: Chris Mason --- fs/btrfs/inode.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 73fadc7ead0e..a3c6e76f5a4e 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6275,6 +6275,8 @@ next: goto not_found; if (start + len <= found_key.offset) goto not_found; + if (start > found_key.offset) + goto next; em->start = start; em->orig_start = start; em->len = found_key.offset - start; -- 2.39.5