This is a note to let you know that I've just added the patch titled
ext4: limit group search loop for non-extent files
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-limit-group-search-loop-for-non-extent-files.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e6155736ad76b2070652745f9e54cdea3f0d8567 Mon Sep 17 00:00:00 2001
From: Lachlan McIlroy <lmcilroy@xxxxxxxxxx>
Date: Sun, 5 May 2013 23:10:00 -0400
Subject: ext4: limit group search loop for non-extent files
From: Lachlan McIlroy <lmcilroy@xxxxxxxxxx>
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.
[sandeen@xxxxxxxxxx: add commit msg & comments]
Signed-off-by: Lachlan McIlroy <lmcilroy@xxxxxxxxxx>
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/mballoc.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1980,7 +1980,11 @@ 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 */
Patches currently in stable-queue which might be from lmcilroy@xxxxxxxxxx are
queue-3.4/ext4-limit-group-search-loop-for-non-extent-files.patch
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