From 98ebc4e55985747726bbcbedecbe06fed8d7ea0a Mon Sep 17 00:00:00 2001

From: Max Reitz <mreitz@redhat.com>

Date: Mon, 27 Nov 2017 16:19:58 +0100

Subject: [PATCH 03/21] qcow2: Always execute preallocate() in a coroutine

RH-Author: Max Reitz <mreitz@redhat.com>

Message-id: <20171127161959.13234-4-mreitz@redhat.com>

Patchwork-id: 77913

O-Subject: [RHV-7.5 qemu-kvm-rhev PATCH 3/4] qcow2: Always execute preallocate() in a coroutine

Bugzilla: 1414049

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Jeffrey Cody <jcody@redhat.com>

RH-Acked-by: Fam Zheng <famz@redhat.com>

RH-Acked-by: John Snow <jsnow@redhat.com>

Some qcow2 functions (at least perform_cow()) expect s->lock to be

taken.  Therefore, if we want to make use of them, we should execute

preallocate() (as "preallocate_co") in a coroutine so that we can use

the qemu_co_mutex_* functions.

Signed-off-by: Max Reitz <mreitz@redhat.com>

Message-id: 20171009215533.12530-3-mreitz@redhat.com

Cc: qemu-stable@nongnu.org

Reviewed-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Jeff Cody <jcody@redhat.com>

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>

(cherry picked from commit 572b07bea1d1a0f7726fd95c2613c76002a379bc)

Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 block/qcow2.c | 41 ++++++++++++++++++++++++++++++++++-------

 1 file changed, 34 insertions(+), 7 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c

index 2cfe706..b26cbbf 100644

--- a/block/qcow2.c

+++ b/block/qcow2.c

@@ -2476,6 +2476,14 @@ static int qcow2_set_up_encryption(BlockDriverState *bs, const char *encryptfmt,

 }

+typedef struct PreallocCo {

+    BlockDriverState *bs;

+    uint64_t offset;

+    uint64_t new_length;

+

+    int ret;

+} PreallocCo;

+

 /**

  * Preallocates metadata structures for data clusters between @offset (in the

  * guest disk) and @new_length (which is thus generally the new guest disk

@@ -2483,9 +2491,12 @@ static int qcow2_set_up_encryption(BlockDriverState *bs, const char *encryptfmt,

  *

  * Returns: 0 on success, -errno on failure.

  */

-static int preallocate(BlockDriverState *bs,

-                       uint64_t offset, uint64_t new_length)

+static void coroutine_fn preallocate_co(void *opaque)

 {

+    PreallocCo *params = opaque;

+    BlockDriverState *bs = params->bs;

+    uint64_t offset = params->offset;

+    uint64_t new_length = params->new_length;

     BDRVQcow2State *s = bs->opaque;

     uint64_t bytes;

     uint64_t host_offset = 0;

@@ -2493,9 +2504,7 @@ static int preallocate(BlockDriverState *bs,

     int ret;

     QCowL2Meta *meta;

-    if (qemu_in_coroutine()) {

-        qemu_co_mutex_lock(&s->lock);

-    }

+    qemu_co_mutex_lock(&s->lock);

     assert(offset <= new_length);

     bytes = new_length - offset;

@@ -2549,10 +2558,28 @@ static int preallocate(BlockDriverState *bs,

     ret = 0;

 done:

+    qemu_co_mutex_unlock(&s->lock);

+    params->ret = ret;

+}

+

+static int preallocate(BlockDriverState *bs,

+                       uint64_t offset, uint64_t new_length)

+{

+    PreallocCo params = {

+        .bs         = bs,

+        .offset     = offset,

+        .new_length = new_length,

+        .ret        = -EINPROGRESS,

+    };

+

     if (qemu_in_coroutine()) {

-        qemu_co_mutex_unlock(&s->lock);

+        preallocate_co(&params);

+    } else {

+        Coroutine *co = qemu_coroutine_create(preallocate_co, &params);

+        bdrv_coroutine_enter(bs, co);

+        BDRV_POLL_WHILE(bs, params.ret == -EINPROGRESS);

     }

-    return ret;

+    return params.ret;

 }

 /* qcow2_refcount_metadata_size:

-- 

1.8.3.1