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Re: [Qemu-block] [Qemu-devel] [PATCH for-4.1] scsi-cd: Fix inserting rea
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH for-4.1] scsi-cd: Fix inserting read-only media in empty drive |
Date: |
Mon, 29 Jul 2019 19:17:59 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 |
On 7/29/19 6:42 PM, Kevin Wolf wrote:
> scsi-disks decides whether it has a read-only device by looking at
> whether the BlockBackend specified as drive=... is read-only. In the
> case of an anonymous BlockBackend (with a node name specified in
> drive=...), this is the read-only flag of the attached node. In the case
> of an empty anonymous BlockBackend, it's always read-write because
> nothing prevented it from being read-write.
>
> This is a problem because scsi-cd would take write permissions on the
> anonymous BlockBackend of an empty drive created without a drive=...
> option. Using blockdev-insert-medium with a read-only node fails then
> with the error message "Block node is read-only".
>
> Fix scsi_realize() so that scsi-cd devices always take read-only
> permissions on their BlockBackend instead.
>
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1733920
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
> hw/scsi/scsi-disk.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index 8e95e3e38d..af3e622dc5 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -2318,6 +2318,7 @@ static void
> scsi_disk_unit_attention_reported(SCSIDevice *dev)
> static void scsi_realize(SCSIDevice *dev, Error **errp)
> {
> SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
> + bool read_only;
>
> if (!s->qdev.conf.blk) {
> error_setg(errp, "drive property not set");
> @@ -2351,8 +2352,13 @@ static void scsi_realize(SCSIDevice *dev, Error **errp)
> return;
> }
> }
> - if (!blkconf_apply_backend_options(&dev->conf,
> - blk_is_read_only(s->qdev.conf.blk),
> +
> + read_only = blk_is_read_only(s->qdev.conf.blk);
> + if (dev->type == TYPE_ROM) {
> + read_only = true;
> + }
> +
> + if (!blkconf_apply_backend_options(&dev->conf, read_only,
> dev->type == TYPE_DISK, errp)) {
> return;
> }
>
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>