From: Lachlan McIlroy <[email protected]>
-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------
commit e6155736ad76b2070652745f9e54cdea3f0d8567 upstream.
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.
[[email protected]: add commit msg & comments]
Signed-off-by: Lachlan McIlroy <[email protected]>
Signed-off-by: Eric Sandeen <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>
Signed-off-by: Paul Gortmaker <[email protected]>
---
fs/ext4/mballoc.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 5e440caf82de..ac7889907361 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2068,7 +2068,11 @@ repeat:
group = ac->ac_g_ex.fe_group;
for (i = 0; i < ngroups; group++, i++) {
- if (group == ngroups)
+ /*
+ * Artificially restricted ngroups for non-extent
+ * files makes group > ngroups possible on first loop.
+ */
+ if (group >= ngroups)
group = 0;
/* This now checks without needing the buddy page */
--
1.8.5.2
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