block: fix the return errno for direct IO

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: a35c10ce2415 ("block: new direct I/O implementation")
Cc: stable@vger.kernel.org
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 78d3257435c00b76633ee6168a2586ccfa70118c..24615c76c1d0e20739db509d3ddde0e111994e2b 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -307,10 +307,10 @@ static void blkdev_bio_end_io(struct bio *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;