From 09084a94d2b176e33ee52a0bb41409988e6ff744 Mon Sep 17 00:00:00 2001
From: Vegard Nossum <vegard.nossum@oracle.com>
Date: Wed, 6 Jul 2016 15:01:36 +0200
Subject: [PATCH] ext4: fix reference counting bug on block allocation error
If we hit this error when mounted with errors=continue or
errors=remount-ro:
EXT4-fs error (device loop0): ext4_mb_mark_diskspace_used:2940: comm ext4.exe: Allocating blocks 5090-6081 which overlap fs metadata
then ext4_mb_new_blocks() will call ext4_mb_release_context() and try to
continue. However, ext4_mb_release_context() is the wrong thing to call
here since we are still actually using the allocation context.
Instead, just error out. We could retry the allocation, but there is a
possibility of getting stuck in an infinite loop instead, so this seems
safer.
Fixes: 8556e8f3b6 ("ext4: Don't allow new groups to be added during block allocation")
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
---
fs/ext4/mballoc.c | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)
@@ -4513,18 +4513,7 @@ repeat:
}
if (likely(ac->ac_status == AC_STATUS_FOUND)) {
*errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_clstrs);
- if (*errp == -EAGAIN) {
- /*
- * drop the reference that we took
- * in ext4_mb_use_best_found
- */
- ext4_mb_release_context(ac);
- ac->ac_b_ex.fe_group = 0;
- ac->ac_b_ex.fe_start = 0;
- ac->ac_b_ex.fe_len = 0;
- ac->ac_status = AC_STATUS_CONTINUE;
- goto repeat;
- } else if (*errp) {
+ if (*errp) {
ext4_discard_allocated_blocks(ac);
goto errout;
} else {
--
1.9.1