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From: Hanna Reitz <hreitz@redhat.com>
To: qemu-block@nongnu.org
Subject: [PULL 32/56] block/copy-before-write: use file child instead of
backing
Date: Wed, 1 Sep 2021 17:15:55 +0200
Message-Id: <20210901151619.689075-33-hreitz@redhat.com>
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From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
We are going to publish copy-before-write filter, and there no public
backing-child-based filter in Qemu. No reason to create a precedent, so
let's refactor copy-before-write filter instead.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-13-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
---
block/copy-before-write.c | 39 ++++++++++++++++++++++-----------------
1 file changed, 22 insertions(+), 17 deletions(-)
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index 945d9340f4..7a6c15f141 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -43,7 +43,7 @@ static coroutine_fn int cbw_co_preadv(
BlockDriverState *bs, uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
- return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags);
+ return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
}
=20
static coroutine_fn int cbw_do_copy_before_write(BlockDriverState *bs,
@@ -71,7 +71,7 @@ static int coroutine_fn cbw_co_pdiscard(BlockDriverState =
*bs,
return ret;
}
=20
- return bdrv_co_pdiscard(bs->backing, offset, bytes);
+ return bdrv_co_pdiscard(bs->file, offset, bytes);
}
=20
static int coroutine_fn cbw_co_pwrite_zeroes(BlockDriverState *bs,
@@ -82,7 +82,7 @@ static int coroutine_fn cbw_co_pwrite_zeroes(BlockDriverS=
tate *bs,
return ret;
}
=20
- return bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags);
+ return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
}
=20
static coroutine_fn int cbw_co_pwritev(BlockDriverState *bs,
@@ -95,29 +95,22 @@ static coroutine_fn int cbw_co_pwritev(BlockDriverState=
*bs,
return ret;
}
=20
- return bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags);
+ return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
}
=20
static int coroutine_fn cbw_co_flush(BlockDriverState *bs)
{
- if (!bs->backing) {
+ if (!bs->file) {
return 0;
}
=20
- return bdrv_co_flush(bs->backing->bs);
+ return bdrv_co_flush(bs->file->bs);
}
=20
static void cbw_refresh_filename(BlockDriverState *bs)
{
- if (bs->backing =3D=3D NULL) {
- /*
- * we can be here after failed bdrv_attach_child in
- * bdrv_set_backing_hd
- */
- return;
- }
pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
- bs->backing->bs->filename);
+ bs->file->bs->filename);
}
=20
static void cbw_child_perm(BlockDriverState *bs, BdrvChild *c,
@@ -186,6 +179,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *sou=
rce,
top =3D bdrv_new_open_driver(&bdrv_cbw_filter, filter_node_name,
BDRV_O_RDWR, errp);
if (!top) {
+ error_prepend(errp, "Cannot open driver: ");
return NULL;
}
=20
@@ -201,21 +195,32 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *s=
ource,
state->target =3D bdrv_attach_child(top, target, "target", &child_of_b=
ds,
BDRV_CHILD_DATA, errp);
if (!state->target) {
+ error_prepend(errp, "Cannot attach target child: ");
+ bdrv_unref(top);
+ return NULL;
+ }
+
+ bdrv_ref(source);
+ top->file =3D bdrv_attach_child(top, source, "file", &child_of_bds,
+ BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
+ errp);
+ if (!top->file) {
+ error_prepend(errp, "Cannot attach file child: ");
bdrv_unref(top);
return NULL;
}
=20
bdrv_drained_begin(source);
=20
- ret =3D bdrv_append(top, source, errp);
+ ret =3D bdrv_replace_node(source, top, errp);
if (ret < 0) {
error_prepend(errp, "Cannot append copy-before-write filter: ");
goto fail;
}
appended =3D true;
=20
- state->bcs =3D block_copy_state_new(top->backing, state->target,
- false, compress, errp);
+ state->bcs =3D block_copy_state_new(top->file, state->target, false, c=
ompress,
+ errp);
if (!state->bcs) {
error_prepend(errp, "Cannot create block-copy-state: ");
goto fail;
--=20
2.31.1