ext4: no need to remove extent if len is 0 in ext4_es_remove_extent()
authorEryu Guan <guaneryu@gmail.com>
Fri, 22 Feb 2013 20:27:47 +0000 (15:27 -0500)
committerTheodore Ts'o <tytso@mit.edu>
Fri, 22 Feb 2013 20:27:47 +0000 (15:27 -0500)
commitd43814721111041e26671a153e300e2054fb36fa
treecf9fd202aca4cae83989000219921ac99134f557
parent1231b3a1eb5740192aeebf5344dd6d6da000febf
ext4: no need to remove extent if len is 0 in ext4_es_remove_extent()

len is 0 means no extent needs to be removed, so return immediately.
Otherwise it could trigger the following BUG_ON() in
ext4_es_remove_extent()

end = lblk + len - 1;
BUG_ON(end < lblk);

This could be reproduced by a simple truncate(1) command by an
unprivileged user

truncate -s $(($((2**32 - 1)) * 4096)) /mnt/ext4/testfile

The same is true for __es_insert_extent().

Patched kernel passed xfstests regression test.

Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
fs/ext4/extents_status.c