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>

1 files changed, 9 insertions, 8 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 910bce85f443..77972090abe5 100644
--- 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 {