From: Mauricio Faria de Oliveira <mfo@canonical.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Subject: [PATCH] loop: fix I/O error on fsync() in detached loop devices
Date: Thu, 31 Dec 2020 13:28:45 -0300 [thread overview]
Message-ID: <20201231162845.1853347-1-mfo@canonical.com> (raw)
There's an I/O error on fsync() in a detached loop device
if it has been previously attached.
The issue is write cache is enabled in the attach path in
loop_configure() but it isn't disabled in the detach path;
thus it remains enabled in the block device regardless of
whether it is attached or not.
Now fsync() can get an I/O request that will just be failed
later in loop_queue_rq() as device's state is not 'Lo_bound'.
So, disable write cache in the detach path.
Test-case:
# DEV=/dev/loop7
# IMG=/tmp/image
# truncate --size 1M $IMG
# losetup $DEV $IMG
# losetup -d $DEV
Before:
# strace -e fsync parted -s $DEV print 2>&1 | grep fsync
fsync(3) = -1 EIO (Input/output error)
Warning: Error fsyncing/closing /dev/loop7: Input/output error
[ 982.529929] blk_update_request: I/O error, dev loop7, sector 0 op 0x1:(WRITE) flags 0x800 phys_seg 0 prio class 0
After:
# strace -e fsync parted -s $DEV print 2>&1 | grep fsync
fsync(3) = 0
Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com>
Co-developed-by: Eric Desrochers <eric.desrochers@canonical.com>
Signed-off-by: Eric Desrochers <eric.desrochers@canonical.com>
---
drivers/block/loop.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index e5ff328f0917..49517482e061 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1212,6 +1212,9 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
goto out_unlock;
}
+ if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && filp->f_op->fsync)
+ blk_queue_write_cache(lo->lo_queue, false, false);
+
/* freeze request queue during the transition */
blk_mq_freeze_queue(lo->lo_queue);
--
2.25.1
next reply other threads:[~2020-12-31 16:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-31 16:28 Mauricio Faria de Oliveira [this message]
2021-01-02 5:13 ` [PATCH] loop: fix I/O error on fsync() in detached loop devices Gabriel Krisman Bertazi
2021-01-05 13:57 ` Mauricio Faria de Oliveira
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