From: Lars Ellenberg lars.ellenberg@linbit.com
stable inclusion from stable-v5.10.110 commit fde8c5cad0881fb899a104a187c80fb8cfc8af97 bugzilla: https://gitee.com/openeuler/kernel/issues/I574AL
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit f4329d1f848ac35757d9cc5487669d19dfc5979c upstream.
Scenario: ---------
bio chain generated by blk_queue_split(). Some split bio fails and propagates its error status to the "parent" bio. But then the (last part of the) parent bio itself completes without error.
We would clobber the already recorded error status with BLK_STS_OK, causing silent data corruption.
Reproducer: -----------
How to trigger this in the real world within seconds:
DRBD on top of degraded parity raid, small stripe_cache_size, large read_ahead setting. Drop page cache (sysctl vm.drop_caches=1, fadvise "DONTNEED", umount and mount again, "reboot").
Cause significant read ahead.
Large read ahead request is split by blk_queue_split(). Parts of the read ahead that are already in the stripe cache, or find an available stripe cache to use, can be serviced. Parts of the read ahead that would need "too much work", would need to wait for a "stripe_head" to become available, are rejected immediately.
For larger read ahead requests that are split in many pieces, it is very likely that some "splits" will be serviced, but then the stripe cache is exhausted/busy, and the remaining ones will be rejected.
Signed-off-by: Lars Ellenberg lars.ellenberg@linbit.com Signed-off-by: Christoph Böhmwalder christoph.boehmwalder@linbit.com Cc: stable@vger.kernel.org # 4.13.x Link: https://lore.kernel.org/r/20220330185551.3553196-1-christoph.boehmwalder@lin... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yu Liao liaoyu15@huawei.com Reviewed-by: Wei Li liwei391@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- drivers/block/drbd/drbd_req.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index 330f851cb8f0..69638146f949 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -177,7 +177,8 @@ void start_new_tl_epoch(struct drbd_connection *connection) void complete_master_bio(struct drbd_device *device, struct bio_and_error *m) { - m->bio->bi_status = errno_to_blk_status(m->error); + if (unlikely(m->error)) + m->bio->bi_status = errno_to_blk_status(m->error); bio_endio(m->bio); dec_ap_bio(device); }