linux-kernel - [PATCH AUTOSEL 5.2 194/249] bcache: check CACHE_SET_IO_DISABLE bit in bch

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Date:   Mon, 15 Jul 2019 09:45:59 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Coly Li <colyli@...e.de>, Jens Axboe <axboe@...nel.dk>,
        Sasha Levin <sashal@...nel.org>, linux-bcache@...r.kernel.org
Subject: [PATCH AUTOSEL 5.2 194/249] bcache: check CACHE_SET_IO_DISABLE bit in bch_journal()

From: Coly Li <colyli@...e.de>

[ Upstream commit 383ff2183ad16a8842d1fbd9dd3e1cbd66813e64 ]

When too many I/O errors happen on cache set and CACHE_SET_IO_DISABLE
bit is set, bch_journal() may continue to work because the journaling
bkey might be still in write set yet. The caller of bch_journal() may
believe the journal still work but the truth is in-memory journal write
set won't be written into cache device any more. This behavior may
introduce potential inconsistent metadata status.

This patch checks CACHE_SET_IO_DISABLE bit at the head of bch_journal(),
if the bit is set, bch_journal() returns NULL immediately to notice
caller to know journal does not work.

Signed-off-by: Coly Li <colyli@...e.de>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/md/bcache/journal.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index 4e5fc05720fc..54f8886b6177 100644
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -811,6 +811,10 @@ atomic_t *bch_journal(struct cache_set *c,
 	struct journal_write *w;
 	atomic_t *ret;

+	/* No journaling if CACHE_SET_IO_DISABLE set already */
+	if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags)))
+		return NULL;
+
 	if (!CACHE_SYNC(&c->sb))
 		return NULL;

-- 
2.20.1