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From d83c96945764748dff98dbe37169ae7c65a3dac5 Mon Sep 17 00:00:00 2001
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From: Fam Zheng <famz@redhat.com>
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Date: Fri, 17 Jan 2014 03:07:52 +0100
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Subject: [PATCH 09/34] block: use BDS ref for block jobs
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RH-Author: Fam Zheng <famz@redhat.com>
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Message-id: <1389928083-8921-8-git-send-email-famz@redhat.com>
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Patchwork-id: 56769
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O-Subject: [RHEL-7 qemu-kvm PATCH 07/18] block: use BDS ref for block jobs
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Bugzilla: 1041301
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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Block jobs used drive_get_ref(drive_get_by_blockdev(bs)) to avoid BDS
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being deleted. Now we have BDS reference count, and block jobs don't
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care about dinfo, so replace them to get cleaner code. It is also the
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safe way when BDS has no drive info.
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit fa510ebffa1fd509323e2e0888e369e23adbb508)
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Conflicts:
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	blockdev.c
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Conflict because drive-backup is not backported, and downstream has
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6270aec (block: optionally disable live block jobs).
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Signed-off-by: Fam Zheng <famz@redhat.com>
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---
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 blockdev.c | 44 +++++++++++++++-----------------------------
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 blockjob.c |  1 +
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 2 files changed, 16 insertions(+), 29 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 blockdev.c |   44 +++++++++++++++-----------------------------
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 blockjob.c |    1 +
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 2 files changed, 16 insertions(+), 29 deletions(-)
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diff --git a/blockdev.c b/blockdev.c
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index 564262a..d795af2 100644
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--- a/blockdev.c
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+++ b/blockdev.c
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@@ -243,34 +243,34 @@ void drive_get_ref(DriveInfo *dinfo)
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 typedef struct {
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     QEMUBH *bh;
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-    DriveInfo *dinfo;
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-} DrivePutRefBH;
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+    BlockDriverState *bs;
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+} BDRVPutRefBH;
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 /* right now, this is only used from block_job_cb() */
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 #ifdef CONFIG_LIVE_BLOCK_OPS
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-static void drive_put_ref_bh(void *opaque)
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+static void bdrv_put_ref_bh(void *opaque)
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 {
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-    DrivePutRefBH *s = opaque;
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+    BDRVPutRefBH *s = opaque;
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-    drive_put_ref(s->dinfo);
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+    bdrv_unref(s->bs);
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     qemu_bh_delete(s->bh);
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     g_free(s);
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 }
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 /*
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- * Release a drive reference in a BH
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+ * Release a BDS reference in a BH
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  *
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- * It is not possible to use drive_put_ref() from a callback function when the
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- * callers still need the drive.  In such cases we schedule a BH to release the
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- * reference.
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+ * It is not safe to use bdrv_unref() from a callback function when the callers
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+ * still need the BlockDriverState.  In such cases we schedule a BH to release
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+ * the reference.
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  */
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-static void drive_put_ref_bh_schedule(DriveInfo *dinfo)
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+static void bdrv_put_ref_bh_schedule(BlockDriverState *bs)
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 {
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-    DrivePutRefBH *s;
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+    BDRVPutRefBH *s;
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-    s = g_new(DrivePutRefBH, 1);
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-    s->bh = qemu_bh_new(drive_put_ref_bh, s);
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-    s->dinfo = dinfo;
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+    s = g_new(BDRVPutRefBH, 1);
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+    s->bh = qemu_bh_new(bdrv_put_ref_bh, s);
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+    s->bs = bs;
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     qemu_bh_schedule(s->bh);
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 }
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 #endif
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@@ -1423,7 +1423,7 @@ static void block_job_cb(void *opaque, int ret)
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     }
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     qobject_decref(obj);
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-    drive_put_ref_bh_schedule(drive_get_by_blockdev(bs));
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+    bdrv_put_ref_bh_schedule(bs);
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 }
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 void qmp_block_stream(const char *device, bool has_base,
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@@ -1460,11 +1460,6 @@ void qmp_block_stream(const char *device, bool has_base,
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         return;
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     }
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-    /* Grab a reference so hotplug does not delete the BlockDriverState from
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-     * underneath us.
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-     */
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-    drive_get_ref(drive_get_by_blockdev(bs));
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-
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     trace_qmp_block_stream(bs, bs->job);
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 }
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@@ -1521,10 +1516,6 @@ void qmp_block_commit(const char *device,
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         error_propagate(errp, local_err);
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         return;
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     }
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-    /* Grab a reference so hotplug does not delete the BlockDriverState from
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-     * underneath us.
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-     */
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-    drive_get_ref(drive_get_by_blockdev(bs));
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 }
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 #define DEFAULT_MIRROR_BUF_SIZE   (10 << 20)
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@@ -1658,11 +1649,6 @@ void qmp_drive_mirror(const char *device, const char *target,
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         error_propagate(errp, local_err);
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         return;
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     }
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-
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-    /* Grab a reference so hotplug does not delete the BlockDriverState from
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-     * underneath us.
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-     */
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-    drive_get_ref(drive_get_by_blockdev(bs));
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 }
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 #endif
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diff --git a/blockjob.c b/blockjob.c
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index c0a22d9..6d8c3a2 100644
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--- a/blockjob.c
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+++ b/blockjob.c
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@@ -45,6 +45,7 @@ void *block_job_create(const BlockJobType *job_type, BlockDriverState *bs,
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         error_set(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bs));
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         return NULL;
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     }
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+    bdrv_ref(bs);
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     bdrv_set_in_use(bs, 1);
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     job = g_malloc0(job_type->instance_size);
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-- 
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1.7.1
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