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From: Kevin Wolf <kwolf@redhat.com>
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Date: Fri, 22 Dec 2017 16:18:39 +0100
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Subject: [Qemu-devel] [PULL v3 28/35] block: Add
bdrv_subtree_drained_begin/end()
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bdrv_drained_begin() waits for the completion of requests in the whole
subtree, but it only actually keeps its immediate bs parameter quiesced
until bdrv_drained_end().
Add a version that keeps the whole subtree drained. As of this commit,
graph changes cannot be allowed during a subtree drained section, but
this will be fixed soon.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/block.h | 13 +++++++++++++
block/io.c | 54 ++++++++++++++++++++++++++++++++++++++++-------=
----
2 files changed, 56 insertions(+), 11 deletions(-)
diff --git a/include/block/block.h b/include/block/block.h
index 60c5d11029..de9c5a2b9b 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -608,12 +608,25 @@ void bdrv_parent_drained_end(BlockDriverState *bs, Bd=
rvChild *ignore);
void bdrv_drained_begin(BlockDriverState *bs);
=20
/**
+ * Like bdrv_drained_begin, but recursively begins a quiesced section for
+ * exclusive access to all child nodes as well.
+ *
+ * Graph changes are not allowed during a subtree drain section.
+ */
+void bdrv_subtree_drained_begin(BlockDriverState *bs);
+
+/**
* bdrv_drained_end:
*
* End a quiescent section started by bdrv_drained_begin().
*/
void bdrv_drained_end(BlockDriverState *bs);
=20
+/**
+ * End a quiescent section started by bdrv_subtree_drained_begin().
+ */
+void bdrv_subtree_drained_end(BlockDriverState *bs);
+
void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
Error **errp);
void bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **er=
rp);
diff --git a/block/io.c b/block/io.c
index 09de0a9070..6befef166d 100644
--- a/block/io.c
+++ b/block/io.c
@@ -145,6 +145,7 @@ typedef struct {
BlockDriverState *bs;
bool done;
bool begin;
+ bool recursive;
BdrvChild *parent;
} BdrvCoDrainData;
=20
@@ -218,8 +219,10 @@ static bool bdrv_drain_recurse(BlockDriverState *bs)
return waited;
}
=20
-static void bdrv_do_drained_begin(BlockDriverState *bs, BdrvChild *parent);
-static void bdrv_do_drained_end(BlockDriverState *bs, BdrvChild *parent);
+static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
+ BdrvChild *parent);
+static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,
+ BdrvChild *parent);
=20
static void bdrv_co_drain_bh_cb(void *opaque)
{
@@ -229,9 +232,9 @@ static void bdrv_co_drain_bh_cb(void *opaque)
=20
bdrv_dec_in_flight(bs);
if (data->begin) {
- bdrv_do_drained_begin(bs, data->parent);
+ bdrv_do_drained_begin(bs, data->recursive, data->parent);
} else {
- bdrv_do_drained_end(bs, data->parent);
+ bdrv_do_drained_end(bs, data->recursive, data->parent);
}
=20
data->done =3D true;
@@ -239,7 +242,8 @@ static void bdrv_co_drain_bh_cb(void *opaque)
}
=20
static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
- bool begin, BdrvChild *par=
ent)
+ bool begin, bool recursive,
+ BdrvChild *parent)
{
BdrvCoDrainData data;
=20
@@ -253,6 +257,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDr=
iverState *bs,
.bs =3D bs,
.done =3D false,
.begin =3D begin,
+ .recursive =3D recursive,
.parent =3D parent,
};
bdrv_inc_in_flight(bs);
@@ -265,10 +270,13 @@ static void coroutine_fn bdrv_co_yield_to_drain(Block=
DriverState *bs,
assert(data.done);
}
=20
-static void bdrv_do_drained_begin(BlockDriverState *bs, BdrvChild *parent)
+static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
+ BdrvChild *parent)
{
+ BdrvChild *child, *next;
+
if (qemu_in_coroutine()) {
- bdrv_co_yield_to_drain(bs, true, parent);
+ bdrv_co_yield_to_drain(bs, true, recursive, parent);
return;
}
=20
@@ -280,19 +288,32 @@ static void bdrv_do_drained_begin(BlockDriverState *b=
s, BdrvChild *parent)
bdrv_parent_drained_begin(bs, parent);
bdrv_drain_invoke(bs, true, false);
bdrv_drain_recurse(bs);
+
+ if (recursive) {
+ QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
+ bdrv_do_drained_begin(child->bs, true, child);
+ }
+ }
}
=20
void bdrv_drained_begin(BlockDriverState *bs)
{
- bdrv_do_drained_begin(bs, NULL);
+ bdrv_do_drained_begin(bs, false, NULL);
+}
+
+void bdrv_subtree_drained_begin(BlockDriverState *bs)
+{
+ bdrv_do_drained_begin(bs, true, NULL);
}
=20
-static void bdrv_do_drained_end(BlockDriverState *bs, BdrvChild *parent)
+static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,
+ BdrvChild *parent)
{
+ BdrvChild *child, *next;
int old_quiesce_counter;
=20
if (qemu_in_coroutine()) {
- bdrv_co_yield_to_drain(bs, false, parent);
+ bdrv_co_yield_to_drain(bs, false, recursive, parent);
return;
}
assert(bs->quiesce_counter > 0);
@@ -304,11 +325,22 @@ static void bdrv_do_drained_end(BlockDriverState *bs,=
BdrvChild *parent)
if (old_quiesce_counter =3D=3D 1) {
aio_enable_external(bdrv_get_aio_context(bs));
}
+
+ if (recursive) {
+ QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
+ bdrv_do_drained_end(child->bs, true, child);
+ }
+ }
}
=20
void bdrv_drained_end(BlockDriverState *bs)
{
- bdrv_do_drained_end(bs, NULL);
+ bdrv_do_drained_end(bs, false, NULL);
+}
+
+void bdrv_subtree_drained_end(BlockDriverState *bs)
+{
+ bdrv_do_drained_end(bs, true, NULL);
}
=20
/*
--=20
2.13.6