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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Theodore Tso <tytso@mit.edu>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 64/70] ext4: convert BUG_ONs to WARN_ONs in mballoc.c
Date:   Fri,  1 May 2020 15:21:52 +0200
Message-Id: <20200501131532.152971895@linuxfoundation.org>
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References: <20200501131513.302599262@linuxfoundation.org>
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From: Theodore Ts'o <tytso@mit.edu>

[ Upstream commit 907ea529fc4c3296701d2bfc8b831dd2a8121a34 ]

If the in-core buddy bitmap gets corrupted (or out of sync with the
block bitmap), issue a WARN_ON and try to recover.  In most cases this
involves skipping trying to allocate out of a particular block group.
We can end up declaring the file system corrupted, which is fair,
since the file system probably should be checked before we proceed any
further.

Link: https://lore.kernel.org/r/20200414035649.293164-1-tytso@mit.edu
Google-Bug-Id: 34811296
Google-Bug-Id: 34639169
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ext4/mballoc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index fda49f4c5a8eb..04fab14e630c1 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1944,7 +1944,8 @@ void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
 	int free;
 
 	free = e4b->bd_info->bb_free;
-	BUG_ON(free <= 0);
+	if (WARN_ON(free <= 0))
+		return;
 
 	i = e4b->bd_info->bb_first_free;
 
@@ -1965,7 +1966,8 @@ void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
 		}
 
 		mb_find_extent(e4b, i, ac->ac_g_ex.fe_len, &ex);
-		BUG_ON(ex.fe_len <= 0);
+		if (WARN_ON(ex.fe_len <= 0))
+			break;
 		if (free < ex.fe_len) {
 			ext4_grp_locked_error(sb, e4b->bd_group, 0, 0,
 					"%d free clusters as per "
-- 
2.20.1