This is a note to let you know that I've just added the patch titled
ext4: fix ext4_discard_allocated_blocks() if we can't allocate the pa struct
to the 3.10-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-fix-ext4_discard_allocated_blocks-if-we-can-t-allocate-the-pa-struct.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 86f0afd463215fc3e58020493482faa4ac3a4d69 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@xxxxxxx>
Date: Wed, 30 Jul 2014 22:17:17 -0400
Subject: ext4: fix ext4_discard_allocated_blocks() if we can't allocate the pa struct
From: Theodore Ts'o <tytso@xxxxxxx>
commit 86f0afd463215fc3e58020493482faa4ac3a4d69 upstream.
If there is a failure while allocating the preallocation structure, a
number of blocks can end up getting marked in the in-memory buddy
bitmap, and then not getting released. This can result in the
following corruption getting reported by the kernel:
EXT4-fs error (device sda3): ext4_mb_generate_buddy:758: group 1126,
12793 clusters in bitmap, 12729 in gd
In that case, we need to release the blocks using mb_free_blocks().
Tested: fs smoke test; also demonstrated that with injected errors,
the file system is no longer getting corrupted
Google-Bug-Id: 16657874
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/mballoc.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3177,8 +3177,27 @@ static void ext4_mb_collect_stats(struct
static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac)
{
struct ext4_prealloc_space *pa = ac->ac_pa;
+ struct ext4_buddy e4b;
+ int err;
- if (pa && pa->pa_type == MB_INODE_PA)
+ if (pa == NULL) {
+ err = ext4_mb_load_buddy(ac->ac_sb, ac->ac_f_ex.fe_group, &e4b);
+ if (err) {
+ /*
+ * This should never happen since we pin the
+ * pages in the ext4_allocation_context so
+ * ext4_mb_load_buddy() should never fail.
+ */
+ WARN(1, "mb_load_buddy failed (%d)", err);
+ return;
+ }
+ ext4_lock_group(ac->ac_sb, ac->ac_f_ex.fe_group);
+ mb_free_blocks(ac->ac_inode, &e4b, ac->ac_f_ex.fe_start,
+ ac->ac_f_ex.fe_len);
+ ext4_unlock_group(ac->ac_sb, ac->ac_f_ex.fe_group);
+ return;
+ }
+ if (pa->pa_type == MB_INODE_PA)
pa->pa_free += ac->ac_b_ex.fe_len;
}
Patches currently in stable-queue which might be from tytso@xxxxxxx are
queue-3.10/ext4-fix-ext4_discard_allocated_blocks-if-we-can-t-allocate-the-pa-struct.patch
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