From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41937) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wlyfe-0003gB-5x for qemu-devel@nongnu.org; Sun, 18 May 2014 06:50:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WlyfY-0007KB-7U for qemu-devel@nongnu.org; Sun, 18 May 2014 06:50:22 -0400 From: Hani Benhabiles Date: Sun, 18 May 2014 11:50:04 +0100 Message-Id: <1400410205-26152-1-git-send-email-kroosec@gmail.com> Subject: [Qemu-devel] [PATCH 1/2] nbd: Don't export a block device with no medium. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-trivial@nongnu.org, pbonzini@redhat.com, kwolf@redhat.com, stefanha@redhat.com The device is exported with erroneous values and can't be read. Before the patch: $ sudo nbd-client localhost -p 10809 /dev/nbd0 -name floppy0 Negotiation: ..size = 17592186044415MB bs=1024, sz=18446744073709547520 bytes $ sudo mount /dev/nbd0 /mnt/tmp/ mount: block device /dev/nbd0 is write-protected, mounting read-only mount: /dev/nbd0: can't read superblock After the patch: (qemu) nbd_server_add ide0-hd0 (qemu) nbd_server_add floppy0 Device 'floppy0' has no medium Signed-off-by: Hani Benhabiles --- blockdev-nbd.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/blockdev-nbd.c b/blockdev-nbd.c index 922cf56..a700d52 100644 --- a/blockdev-nbd.c +++ b/blockdev-nbd.c @@ -91,6 +91,10 @@ void qmp_nbd_server_add(const char *device, bool has_writable, bool writable, error_set(errp, QERR_DEVICE_NOT_FOUND, device); return; } + if (!bdrv_is_inserted(bs)) { + error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, device); + return; + } if (!has_writable) { writable = false; -- 1.8.3.2