dm: store only first barrier error

With the following patches, more than one error can occur during
processing.  Change md->barrier_error so that only the first one is
recorded and returned to the caller.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 910bce8..7797209 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -555,7 +555,8 @@ static void dec_pending(struct dm_io *io, int error)
                         * a per-device variable for error reporting.
                         * Note that you can't touch the bio after end_io_acct
                         */
-                       md->barrier_error = io_error;
+                       if (!md->barrier_error)
+                               md->barrier_error = io_error;
                        end_io_acct(io);
                } else {
                        end_io_acct(io);
@@ -867,7 +868,8 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
                if (!bio_barrier(bio))
                        bio_io_error(bio);
                else
-                       md->barrier_error = -EIO;
+                       if (!md->barrier_error)
+                               md->barrier_error = -EIO;
                return;
        }
 
@@ -1448,16 +1450,15 @@ static void dm_flush(struct mapped_device *md)
 
 static void process_barrier(struct mapped_device *md, struct bio *bio)
 {
+       md->barrier_error = 0;
+
        dm_flush(md);
 
-       if (bio_empty_barrier(bio)) {
-               bio_endio(bio, 0);
-               return;
+       if (!bio_empty_barrier(bio)) {
+               __split_and_process_bio(md, bio);
+               dm_flush(md);
        }
 
-       __split_and_process_bio(md, bio);
-       dm_flush(md);
-
        if (md->barrier_error != DM_ENDIO_REQUEUE)
                bio_endio(bio, md->barrier_error);
        else {