From d83c96945764748dff98dbe37169ae7c65a3dac5 Mon Sep 17 00:00:00 2001
From: Fam Zheng <famz@redhat.com>
Date: Fri, 17 Jan 2014 03:07:52 +0100
Subject: [PATCH 09/34] block: use BDS ref for block jobs

RH-Author: Fam Zheng <famz@redhat.com>
Message-id: <1389928083-8921-8-git-send-email-famz@redhat.com>
Patchwork-id: 56769
O-Subject: [RHEL-7 qemu-kvm PATCH 07/18] block: use BDS ref for block jobs
Bugzilla: 1041301
RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

Block jobs used drive_get_ref(drive_get_by_blockdev(bs)) to avoid BDS
being deleted. Now we have BDS reference count, and block jobs don't
care about dinfo, so replace them to get cleaner code. It is also the
safe way when BDS has no drive info.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit fa510ebffa1fd509323e2e0888e369e23adbb508)
Signed-off-by: Fam Zheng <famz@redhat.com>

Conflicts:
	blockdev.c

Conflict because drive-backup is not backported, and downstream has
6270aec (block: optionally disable live block jobs).

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 blockdev.c | 44 +++++++++++++++-----------------------------
 blockjob.c |  1 +
 2 files changed, 16 insertions(+), 29 deletions(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 blockdev.c |   44 +++++++++++++++-----------------------------
 blockjob.c |    1 +
 2 files changed, 16 insertions(+), 29 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 564262a..d795af2 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -243,34 +243,34 @@ void drive_get_ref(DriveInfo *dinfo)
 
 typedef struct {
     QEMUBH *bh;
-    DriveInfo *dinfo;
-} DrivePutRefBH;
+    BlockDriverState *bs;
+} BDRVPutRefBH;
 
 /* right now, this is only used from block_job_cb() */
 #ifdef CONFIG_LIVE_BLOCK_OPS
-static void drive_put_ref_bh(void *opaque)
+static void bdrv_put_ref_bh(void *opaque)
 {
-    DrivePutRefBH *s = opaque;
+    BDRVPutRefBH *s = opaque;
 
-    drive_put_ref(s->dinfo);
+    bdrv_unref(s->bs);
     qemu_bh_delete(s->bh);
     g_free(s);
 }
 
 /*
- * Release a drive reference in a BH
+ * Release a BDS reference in a BH
  *
- * It is not possible to use drive_put_ref() from a callback function when the
- * callers still need the drive.  In such cases we schedule a BH to release the
- * reference.
+ * It is not safe to use bdrv_unref() from a callback function when the callers
+ * still need the BlockDriverState.  In such cases we schedule a BH to release
+ * the reference.
  */
-static void drive_put_ref_bh_schedule(DriveInfo *dinfo)
+static void bdrv_put_ref_bh_schedule(BlockDriverState *bs)
 {
-    DrivePutRefBH *s;
+    BDRVPutRefBH *s;
 
-    s = g_new(DrivePutRefBH, 1);
-    s->bh = qemu_bh_new(drive_put_ref_bh, s);
-    s->dinfo = dinfo;
+    s = g_new(BDRVPutRefBH, 1);
+    s->bh = qemu_bh_new(bdrv_put_ref_bh, s);
+    s->bs = bs;
     qemu_bh_schedule(s->bh);
 }
 #endif
@@ -1423,7 +1423,7 @@ static void block_job_cb(void *opaque, int ret)
     }
     qobject_decref(obj);
 
-    drive_put_ref_bh_schedule(drive_get_by_blockdev(bs));
+    bdrv_put_ref_bh_schedule(bs);
 }
 
 void qmp_block_stream(const char *device, bool has_base,
@@ -1460,11 +1460,6 @@ void qmp_block_stream(const char *device, bool has_base,
         return;
     }
 
-    /* Grab a reference so hotplug does not delete the BlockDriverState from
-     * underneath us.
-     */
-    drive_get_ref(drive_get_by_blockdev(bs));
-
     trace_qmp_block_stream(bs, bs->job);
 }
 
@@ -1521,10 +1516,6 @@ void qmp_block_commit(const char *device,
         error_propagate(errp, local_err);
         return;
     }
-    /* Grab a reference so hotplug does not delete the BlockDriverState from
-     * underneath us.
-     */
-    drive_get_ref(drive_get_by_blockdev(bs));
 }
 
 #define DEFAULT_MIRROR_BUF_SIZE   (10 << 20)
@@ -1658,11 +1649,6 @@ void qmp_drive_mirror(const char *device, const char *target,
         error_propagate(errp, local_err);
         return;
     }
-
-    /* Grab a reference so hotplug does not delete the BlockDriverState from
-     * underneath us.
-     */
-    drive_get_ref(drive_get_by_blockdev(bs));
 }
 #endif
 
diff --git a/blockjob.c b/blockjob.c
index c0a22d9..6d8c3a2 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -45,6 +45,7 @@ void *block_job_create(const BlockJobType *job_type, BlockDriverState *bs,
         error_set(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bs));
         return NULL;
     }
+    bdrv_ref(bs);
     bdrv_set_in_use(bs, 1);
 
     job = g_malloc0(job_type->instance_size);
-- 
1.7.1