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From: Alberto Garcia <berto@igalia.com>
To: qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Alberto Garcia <berto@igalia.com>,
	qemu-block@nongnu.org, Max Reitz <mreitz@redhat.com>
Subject: [Qemu-devel] [PATCH 1/3] block: Allow x-blockdev-del on a BB with a monitor-owned BDS
Date: Mon,  8 Feb 2016 16:14:03 +0200	[thread overview]
Message-ID: <7bfce913f68d95284746e7cf3693703f5361b26f.1454940776.git.berto@igalia.com> (raw)

When x-blockdev-del is performed on a BlockBackend that has inserted
media it will only succeed if the BDS doesn't have any additional
references.

The only problem with this is that if the BDS was created separately
using blockdev-add then the backend won't be able to be destroyed
unless the BDS is ejected first. This is an unnecessary restriction.

Now that we have a list of monitor-owned BDSs we can allow
x-blockdev-del to work in this scenario if the BDS has exactly one
extra reference and that reference is from the monitor.

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 blockdev.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index e1b6b0f..847058d 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3966,9 +3966,16 @@ void qmp_x_blockdev_del(bool has_id, const char *id,
         }
 
         if (bs->refcnt > 1) {
-            error_setg(errp, "Block device %s is in use",
-                       bdrv_get_device_or_node_name(bs));
-            goto out;
+            /* We allow deleting a BlockBackend that has a BDS with an
+             * extra reference if that extra reference is from the
+             * monitor. */
+            bool bs_has_only_monitor_ref =
+                blk && bs->monitor_list.tqe_prev && bs->refcnt == 2;
+            if (!bs_has_only_monitor_ref) {
+                error_setg(errp, "Block device %s is in use",
+                           bdrv_get_device_or_node_name(bs));
+                goto out;
+            }
         }
     }
 
-- 
2.7.0

             reply	other threads:[~2016-02-08 14:14 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-08 14:14 Alberto Garcia [this message]
2016-02-08 14:14 ` [Qemu-devel] [PATCH 2/3] iotests: Update test 139 after the changes in x-blockdev-del Alberto Garcia
2016-02-09 15:36   ` Eric Blake
2016-02-09 15:44     ` Alberto Garcia
2016-02-08 14:14 ` [Qemu-devel] [PATCH 3/3] block: Update the x-blockdev-del documentation Alberto Garcia
2016-02-09 15:38   ` Eric Blake
2016-02-09 10:32 ` [Qemu-devel] [PATCH 1/3] block: Allow x-blockdev-del on a BB with a monitor-owned BDS Kevin Wolf
2016-02-09 10:47   ` Alberto Garcia
2016-02-09 15:34 ` Eric Blake
2016-02-09 15:39   ` Alberto Garcia

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