btrfs-progs: improve error messages after failed wiping

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/utils.c b/utils.c
index 77f0f68..f22e329 100644 (file)
--- a/utils.c
+++ b/utils.c
@@ -842,8 +842,11 @@ static int btrfs_wipe_existing_sb(int fd)
 
        memset(buf, 0, len);
        ret = pwrite(fd, buf, len, offset);
-       if (ret != len) {
-               fprintf(stderr, "ERROR: cannot wipe existing superblock\n");
+       if (ret < 0) {
+               error("cannot wipe existing superblock: %s", strerror(errno));
+               ret = -1;
+       } else if (ret != len) {
+               error("cannot wipe existing superblock: wrote %d of %zd", ret, len);
                ret = -1;
        }
        fsync(fd);