[Qemu-devel] [PATCH] block: Fix bdrv_commit return value

[Kevin Wolf <kwolf@redhat.com>]

bdrv_commit() could return 0 or 1 on success, depending on whether or
now the last sector was allocated in the overlay and whether the overlay
format had a .bdrv_make_empty callback.

Most callers ignored it, but qemu-img commit would print an error
message while the operation actually succeeded.

Also clean up the handling of I/O errors to return the real error code
instead of -EIO.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/block.c b/block.c
index 3e0994b..7d22ca9 100644
--- a/block.c
+++ b/block.c
@@ -2061,13 +2061,13 @@ int bdrv_commit(BlockDriverState *bs)
             goto ro_cleanup;
         }
         if (ret) {
-            if (bdrv_read(bs, sector, buf, n) != 0) {
-                ret = -EIO;
+            ret = bdrv_read(bs, sector, buf, n);
+            if (ret < 0) {
                 goto ro_cleanup;
             }
 
-            if (bdrv_write(bs->backing_hd, sector, buf, n) != 0) {
-                ret = -EIO;
+            ret = bdrv_write(bs->backing_hd, sector, buf, n);
+            if (ret < 0) {
                 goto ro_cleanup;
             }
         }
@@ -2075,6 +2075,9 @@ int bdrv_commit(BlockDriverState *bs)
 
     if (drv->bdrv_make_empty) {
         ret = drv->bdrv_make_empty(bs);
+        if (ret < 0) {
+            goto ro_cleanup;
+        }
         bdrv_flush(bs);
     }
 
@@ -2082,9 +2085,11 @@ int bdrv_commit(BlockDriverState *bs)
      * Make sure all data we wrote to the backing device is actually
      * stable on disk.
      */
-    if (bs->backing_hd)
+    if (bs->backing_hd) {
         bdrv_flush(bs->backing_hd);
+    }
 
+    ret = 0;
 ro_cleanup:
     g_free(buf);
 
-- 
1.8.1.4