ext4: limit group search loop for non-extent files
authorLachlan McIlroy <lmcilroy@redhat.com>
Mon, 6 May 2013 03:10:00 +0000 (23:10 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Mon, 6 May 2013 03:10:00 +0000 (23:10 -0400)
commite6155736ad76b2070652745f9e54cdea3f0d8567
treefe6efdb379eb2f09c2f2356f1f8d27e1cb4073cb
parente30b5dca15dea86aa697f9d58ff646294fe80d3d
ext4: limit group search loop for non-extent files

In the case where we are allocating for a non-extent file,
we must limit the groups we allocate from to those below
2^32 blocks, and ext4_mb_regular_allocator() attempts to
do this initially by putting a cap on ngroups for the
subsequent search loop.

However, the initial target group comes in from the
allocation context (ac), and it may already be beyond
the artificially limited ngroups.  In this case,
the limit

if (group == ngroups)
group = 0;

at the top of the loop is never true, and the loop will
run away.

Catch this case inside the loop and reset the search to
start at group 0.

[sandeen@redhat.com: add commit msg & comments]

Signed-off-by: Lachlan McIlroy <lmcilroy@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
fs/ext4/mballoc.c