From 6dd834effc12ba71092d9d1e4944530234b58ab1 Mon Sep 17 00:00:00 2001 From: Lukas Czerner Date: Fri, 18 Apr 2014 10:55:24 -0400 Subject: [PATCH] ext4: fix extent merging in ext4_ext_shift_path_extents() There is a bug in ext4_ext_shift_path_extents() where if we actually manage to merge a extent we would skip shifting the next extent. This will result in in one extent in the extent tree not being properly shifted. This is causing failure in various xfstests tests using fsx or fsstress with collapse range support. It will also cause file system corruption which looks something like: e2fsck 1.42.9 (4-Feb-2014) Pass 1: Checking inodes, blocks, and sizes Inode 20 has out of order extents (invalid logical block 3, physical block 492938, len 2) Clear? yes ... when running e2fsck. It's also very easily reproducible just by running fsx without any parameters. I can usually hit the problem within a minute. Fix it by increasing ex_start only if we're not merging the extent. Signed-off-by: Lukas Czerner Signed-off-by: "Theodore Ts'o" Reviewed-by: Namjae Jeon --- fs/ext4/extents.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index eb7be8f08e10..d0860f2d36d0 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -5245,13 +5245,14 @@ ext4_ext_shift_path_extents(struct ext4_ext_path *path, ext4_lblk_t shift, while (ex_start <= ex_last) { le32_add_cpu(&ex_start->ee_block, -shift); - if (ex_start > - EXT_FIRST_EXTENT(path[depth].p_hdr)) { - if (ext4_ext_try_to_merge_right(inode, - path, ex_start - 1)) - ex_last--; - } - ex_start++; + /* Try to merge to the left. */ + if ((ex_start > + EXT_FIRST_EXTENT(path[depth].p_hdr)) && + ext4_ext_try_to_merge_right(inode, + path, ex_start - 1)) + ex_last--; + else + ex_start++; } err = ext4_ext_dirty(handle, inode, path + depth); if (err) -- 2.20.1