From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vegard Nossum Subject: [PATCH] ext4: fix reference counting bug on block allocation error Date: Wed, 6 Jul 2016 15:57:32 +0200 Message-ID: <1467813452-26763-1-git-send-email-vegard.nossum@oracle.com> Cc: linux-ext4@vger.kernel.org, Vegard Nossum , "Aneesh Kumar K.V" To: tytso@mit.edu Return-path: Received: from userp1040.oracle.com ([156.151.31.81]:36540 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754078AbcGFN5r (ORCPT ); Wed, 6 Jul 2016 09:57:47 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: 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, handle it the same way that we handle other errors, except that we retry the allocation instead of immediately returning an error (if we were mounted with errors=continue, then ext4_mb_mark_diskspace_used() should have fixed the original error and will either succeed or give a different error; if we were mounted with errors=remount-ro, then it will not be able to fix the original error and will raise a different error). Fixes: 8556e8f3b6 ("ext4: Don't allow new groups to be added during block allocation") Cc: Aneesh Kumar K.V Signed-off-by: Vegard Nossum --- fs/ext4/mballoc.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index c1ab3ec..0370f76 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4514,11 +4514,7 @@ 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); + ext4_discard_allocated_blocks(ac); ac->ac_b_ex.fe_group = 0; ac->ac_b_ex.fe_start = 0; ac->ac_b_ex.fe_len = 0; -- 1.9.1