linux-kernel - [PATCH 4.19 072/101] block: fix the return errno for direct IO

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Date:   Mon, 15 Apr 2019 20:59:10 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Christoph Hellwig <hch@....de>,
        Jens Axboe <axboe@...nel.dk>, Ming Lei <ming.lei@...hat.com>,
        Jason Yan <yanaijie@...wei.com>
Subject: [PATCH 4.19 072/101] block: fix the return errno for direct IO

From: Jason Yan <yanaijie@...wei.com>

commit a89afe58f1a74aac768a5eb77af95ef4ee15beaa upstream.

If the last bio returned is not dio->bio, the status of the bio will
not assigned to dio->bio if it is error. This will cause the whole IO
status wrong.

    ksoftirqd/21-117   [021] ..s.  4017.966090:   8,0    C   N 4883648 [0]
          <idle>-0     [018] ..s.  4017.970888:   8,0    C  WS 4924800 + 1024 [0]
          <idle>-0     [018] ..s.  4017.970909:   8,0    D  WS 4935424 + 1024 [<idle>]
          <idle>-0     [018] ..s.  4017.970924:   8,0    D  WS 4936448 + 321 [<idle>]
    ksoftirqd/21-117   [021] ..s.  4017.995033:   8,0    C   R 4883648 + 336 [65475]
    ksoftirqd/21-117   [021] d.s.  4018.001988: myprobe1: (blkdev_bio_end_io+0x0/0x168) bi_status=7
    ksoftirqd/21-117   [021] d.s.  4018.001992: myprobe: (aio_complete_rw+0x0/0x148) x0=0xffff802f2595ad80 res=0x12a000 res2=0x0

We always have to assign bio->bi_status to dio->bio.bi_status because we
will only check dio->bio.bi_status when we return the whole IO to
the upper layer.

Fixes: 542ff7bf18c6 ("block: new direct I/O implementation")
Cc: stable@...r.kernel.org
Cc: Christoph Hellwig <hch@....de>
Cc: Jens Axboe <axboe@...nel.dk>
Reviewed-by: Ming Lei <ming.lei@...hat.com>
Signed-off-by: Jason Yan <yanaijie@...wei.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/block_dev.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -296,10 +296,10 @@ static void blkdev_bio_end_io(struct bio
 	struct blkdev_dio *dio = bio->bi_private;
 	bool should_dirty = dio->should_dirty;
 
-	if (dio->multi_bio && !atomic_dec_and_test(&dio->ref)) {
-		if (bio->bi_status && !dio->bio.bi_status)
-			dio->bio.bi_status = bio->bi_status;
-	} else {
+	if (bio->bi_status && !dio->bio.bi_status)
+		dio->bio.bi_status = bio->bi_status;
+
+	if (!dio->multi_bio || atomic_dec_and_test(&dio->ref)) {
 		if (!dio->is_sync) {
 			struct kiocb *iocb = dio->iocb;
 			ssize_t ret;