[Qemu-devel] [PATCH 04/14] monitor: allow device to be ejected if no disk is inserted

[Kevin Wolf <kwolf@redhat.com>]

From: Eduardo Habkost <ehabkost@redhat.com>

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) info block
  ide1-cd0: type=cdrom removable=1 locked=0 [not inserted]
  (qemu) change ide1-cd0 /dev/cdrom host_cdrom
  (qemu) info block
  ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=1 drv=host_cdrom encrypted=0
  (qemu) eject ide1-cd0
  (qemu) info block
  ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=1 drv=host_cdrom encrypted=0

  # at this point, a disk was inserted on the host CD-ROM drive

  (qemu) info block
  ide1-cd0: type=cdrom removable=1 locked=0 file=/dev/cdrom ro=1 drv=host_cdrom encrypted=0
  (qemu) eject ide1-cd0
  (qemu) info block
  ide1-cd0: type=cdrom removable=1 locked=0 [not inserted]
  (qemu)

The first eject command didn't work because the is_inserted() check
failed.

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() check 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>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 blockdev.c |   22 ++++++++++------------
 1 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index b376884..3b8c606 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -503,20 +503,18 @@ void do_commit(Monitor *mon, const QDict *qdict)
 
 static int eject_device(Monitor *mon, BlockDriverState *bs, int force)
 {
-    if (bdrv_is_inserted(bs)) {
-        if (!force) {
-            if (!bdrv_is_removable(bs)) {
-                qerror_report(QERR_DEVICE_NOT_REMOVABLE,
-                               bdrv_get_device_name(bs));
-                return -1;
-            }
-            if (bdrv_is_locked(bs)) {
-                qerror_report(QERR_DEVICE_LOCKED, bdrv_get_device_name(bs));
-                return -1;
-            }
+    if (!force) {
+        if (!bdrv_is_removable(bs)) {
+            qerror_report(QERR_DEVICE_NOT_REMOVABLE,
+                           bdrv_get_device_name(bs));
+            return -1;
+        }
+        if (bdrv_is_locked(bs)) {
+            qerror_report(QERR_DEVICE_LOCKED, bdrv_get_device_name(bs));
+            return -1;
         }
-        bdrv_close(bs);
     }
+    bdrv_close(bs);
     return 0;
 }
 
-- 
1.6.6.1