block: Print its file name if backing file opening failed

If backing file doesn't exist, the error message is confusing and
misleading:

    $ qemu /tmp/a.qcow2
    qemu: could not open disk image /tmp/a.qcow2: Could not open file: No
    such file or directory

But...

    $ ls /tmp/a.qcow2
    /tmp/a.qcow2

    $ qemu-img info /tmp/a.qcow2
    image: /tmp/a.qcow2
    file format: qcow2
    virtual size: 8.0G (8589934592 bytes)
    disk size: 196K
    cluster_size: 65536
    backing file: /tmp/b.qcow2

Because...

    $ ls /tmp/b.qcow2
    ls: cannot access /tmp/b.qcow2: No such file or directory

This is not intuitive. It's better to have the missing file's name in
the error message. With this patch:

    $ qemu-io -c 'read 0 512' /tmp/a.qcow2
    qemu-io: can't open device /tmp/a.qcow2: Could not open backing
    file: Could not open '/stor/vm/arch.raw': No such file or directory
    no file open, try 'help open'

Which is a little bit better.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/block/raw-posix.c b/block/raw-posix.c
index ace5d962e8..f836c8e745 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -310,7 +310,6 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
         if (ret == -EROFS) {
             ret = -EACCES;
         }
-        error_setg_errno(errp, -ret, "Could not open file");
         goto fail;
     }
     s->fd = fd;