Patchwork [v2,STABLE] monitor: allow device to be ejected if no disk is inserted

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Submitter Eduardo Habkost
Date Dec. 18, 2009, 7:07 p.m.
Message ID <1261162670-sup-2248@blackpad.lan.raisama.net>
Download mbox | patch
Permalink /patch/41425/
State New
Headers show

Comments

Eduardo Habkost - Dec. 18, 2009, 7:07 p.m.
Rebasing previous patch to latest staging tree. For the master branch and
stable-0.12.

This changes the monitor eject_device() function to not check for
bdrv_is_inserted().

Example run where the bug manifests itself:

(output of 'info block' is stripped to include only the CD-ROM device)

  QEMU 0.11.50 monitor - type 'help' for more information
  (qemu) info block
  ide1-cd0: type=cdrom removable=1 locked=0 [not inserted]
  (qemu) change ide1-cd0 /mnt/common/images/smalldisk1.img
  (qemu) info block
  ide1-cd0: type=cdrom removable=1 locked=0 file=/mnt/common/images/smalldisk1.img ro=0 drv=raw encrypted=0
  (qemu) eject ide1-cd0
  (qemu) info block
  ide1-cd0: type=cdrom removable=1 locked=0 [not inserted]

When using a file, eject works as expected. But when using a host cdrom device:

  (qemu) change ide1-cd0 /dev/cdrom
  (qemu) info block
  ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=0 drv=host_cdrom encrypted=0
  (qemu) eject ide1-cd0
  (qemu) info block
  ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=0 drv=host_cdrom encrypted=0

Eject didn't work because the is_inserted() check fails.

I have no clue why the code had the is_inserted() check, as it doesn't matter
if there is a disk present at the host drive, when the user wants the virtual
device to be disconnected from the host device.

The is_inserted() has another side effect: a memory leak if the "change"
command is used multiple times, as do_change() calls eject_device() before
re-opening the block device, but bdrv_close() is never called.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 monitor.c |   22 ++++++++++------------
 1 files changed, 10 insertions(+), 12 deletions(-)
Luiz Capitulino - Dec. 18, 2009, 8:15 p.m.
On Fri, 18 Dec 2009 17:07:43 -0200
Eduardo Habkost <ehabkost@redhat.com> wrote:

> When using a file, eject works as expected. But when using a host cdrom device:
> 
>   (qemu) change ide1-cd0 /dev/cdrom
>   (qemu) info block
>   ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=0 drv=host_cdrom encrypted=0
>   (qemu) eject ide1-cd0
>   (qemu) info block
>   ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=0 drv=host_cdrom encrypted=0

 Sorry for only taking a look at this now, but it works for me.

 Couldn't this be a bug somewhere else in the block layer?
Eduardo Habkost - Dec. 18, 2009, 8:22 p.m.
On Fri, Dec 18, 2009 at 06:15:27PM -0200, Luiz Capitulino wrote:
> On Fri, 18 Dec 2009 17:07:43 -0200
> Eduardo Habkost <ehabkost@redhat.com> wrote:
> 
> > When using a file, eject works as expected. But when using a host cdrom device:
> > 
> >   (qemu) change ide1-cd0 /dev/cdrom
> >   (qemu) info block
> >   ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=0 drv=host_cdrom encrypted=0
> >   (qemu) eject ide1-cd0
> >   (qemu) info block
> >   ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=0 drv=host_cdrom encrypted=0
> 
>  Sorry for only taking a look at this now, but it works for me.

Do you have a disk on your CD-ROM drive?
Luiz Capitulino - Dec. 18, 2009, 8:45 p.m.
On Fri, 18 Dec 2009 18:22:41 -0200
Eduardo Habkost <ehabkost@redhat.com> wrote:

> On Fri, Dec 18, 2009 at 06:15:27PM -0200, Luiz Capitulino wrote:
> > On Fri, 18 Dec 2009 17:07:43 -0200
> > Eduardo Habkost <ehabkost@redhat.com> wrote:
> > 
> > > When using a file, eject works as expected. But when using a host cdrom device:
> > > 
> > >   (qemu) change ide1-cd0 /dev/cdrom
> > >   (qemu) info block
> > >   ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=0 drv=host_cdrom encrypted=0
> > >   (qemu) eject ide1-cd0
> > >   (qemu) info block
> > >   ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=0 drv=host_cdrom encrypted=0
> > 
> >  Sorry for only taking a look at this now, but it works for me.
> 
> Do you have a disk on your CD-ROM drive?

 Yeah, I had.. Quickly tested you patch and it fixed the problem to me.

Patch

diff --git a/monitor.c b/monitor.c
index 96f7876..97fbe25 100644
--- a/monitor.c
+++ b/monitor.c
@@ -846,20 +846,18 @@  static void do_quit(Monitor *mon, const QDict *qdict, QObject **ret_data)
 
 static int eject_device(Monitor *mon, BlockDriverState *bs, int force)
 {
-    if (bdrv_is_inserted(bs)) {
-        if (!force) {
-            if (!bdrv_is_removable(bs)) {
-                qemu_error_new(QERR_DEVICE_NOT_REMOVABLE,
-                               bdrv_get_device_name(bs));
-                return -1;
-            }
-            if (bdrv_is_locked(bs)) {
-                qemu_error_new(QERR_DEVICE_LOCKED, bdrv_get_device_name(bs));
-                return -1;
-            }
+    if (!force) {
+        if (!bdrv_is_removable(bs)) {
+            qemu_error_new(QERR_DEVICE_NOT_REMOVABLE,
+                           bdrv_get_device_name(bs));
+            return -1;
+        }
+        if (bdrv_is_locked(bs)) {
+            qemu_error_new(QERR_DEVICE_LOCKED, bdrv_get_device_name(bs));
+            return -1;
         }
-        bdrv_close(bs);
     }
+    bdrv_close(bs);
     return 0;
 }