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block: ignore_bds_parents parameter for drain functions

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In the future, bdrv_drained_all_begin/end() will drain all invidiual
nodes separately rather than whole subtrees. This means that we don't
want to propagate the drain to all parents any more: If the parent is a
BDS, it will already be drained separately. Recursing to all parents is
unnecessary work and would make it an O(n²) operation.

Prepare the drain function for the changed drain_all by adding an
ignore_bds_parents parameter to the internal implementation that
prevents the propagation of the drain to BDS parents. We still (have to)
propagate it to non-BDS parents like BlockBackends or Jobs because those
are not drained separately.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2018-05-29 17:17:45 +02:00
parent c8ca33d06d
commit 6cd5c9d7b2
5 changed files with 78 additions and 44 deletions
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88
block/io.c
View file

@ -41,12 +41,13 @@
static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int bytes, BdrvRequestFlags flags);
void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore)
void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore,
bool ignore_bds_parents)
{
BdrvChild *c, *next;
QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {
if (c == ignore) {
if (c == ignore || (ignore_bds_parents && c->role->parent_is_bds)) {
continue;
}
if (c->role->drained_begin) {
@ -55,12 +56,13 @@ void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore)
}
}
void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore)
void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore,
bool ignore_bds_parents)
{
BdrvChild *c, *next;
QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {
if (c == ignore) {
if (c == ignore || (ignore_bds_parents && c->role->parent_is_bds)) {
continue;
}
if (c->role->drained_end) {
@ -69,13 +71,14 @@ void bdrv_parent_drained_end(BlockDriverState *bs, BdrvChild *ignore)
}
}
static bool bdrv_parent_drained_poll(BlockDriverState *bs, BdrvChild *ignore)
static bool bdrv_parent_drained_poll(BlockDriverState *bs, BdrvChild *ignore,
bool ignore_bds_parents)
{
BdrvChild *c, *next;
bool busy = false;
QLIST_FOREACH_SAFE(c, &bs->parents, next_parent, next) {
if (c == ignore) {
if (c == ignore || (ignore_bds_parents && c->role->parent_is_bds)) {
continue;
}
if (c->role->drained_poll) {
@ -167,6 +170,7 @@ typedef struct {
bool recursive;
bool poll;
BdrvChild *parent;
bool ignore_bds_parents;
} BdrvCoDrainData;
static void coroutine_fn bdrv_drain_invoke_entry(void *opaque)
@ -220,11 +224,11 @@ static void bdrv_drain_invoke(BlockDriverState *bs, bool begin)
/* Returns true if BDRV_POLL_WHILE() should go into a blocking aio_poll() */
bool bdrv_drain_poll(BlockDriverState *bs, bool recursive,
BdrvChild *ignore_parent)
BdrvChild *ignore_parent, bool ignore_bds_parents)
{
BdrvChild *child, *next;
if (bdrv_parent_drained_poll(bs, ignore_parent)) {
if (bdrv_parent_drained_poll(bs, ignore_parent, ignore_bds_parents)) {
return true;
}
@ -233,8 +237,9 @@ bool bdrv_drain_poll(BlockDriverState *bs, bool recursive,
}
if (recursive) {
assert(!ignore_bds_parents);
QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
if (bdrv_drain_poll(child->bs, recursive, child)) {
if (bdrv_drain_poll(child->bs, recursive, child, false)) {
return true;
}
}
@ -250,13 +255,14 @@ static bool bdrv_drain_poll_top_level(BlockDriverState *bs, bool recursive,
* have executed. */
while (aio_poll(bs->aio_context, false));
return bdrv_drain_poll(bs, recursive, ignore_parent);
return bdrv_drain_poll(bs, recursive, ignore_parent, false);
}
static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
BdrvChild *parent, bool poll);
BdrvChild *parent, bool ignore_bds_parents,
bool poll);
static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,
BdrvChild *parent);
BdrvChild *parent, bool ignore_bds_parents);
static void bdrv_co_drain_bh_cb(void *opaque)
{
@ -267,9 +273,11 @@ static void bdrv_co_drain_bh_cb(void *opaque)
if (bs) {
bdrv_dec_in_flight(bs);
if (data->begin) {
bdrv_do_drained_begin(bs, data->recursive, data->parent, data->poll);
bdrv_do_drained_begin(bs, data->recursive, data->parent,
data->ignore_bds_parents, data->poll);
} else {
bdrv_do_drained_end(bs, data->recursive, data->parent);
bdrv_do_drained_end(bs, data->recursive, data->parent,
data->ignore_bds_parents);
}
} else {
assert(data->begin);
@ -282,7 +290,9 @@ static void bdrv_co_drain_bh_cb(void *opaque)
static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
bool begin, bool recursive,
BdrvChild *parent, bool poll)
BdrvChild *parent,
bool ignore_bds_parents,
bool poll)
{
BdrvCoDrainData data;
@ -297,6 +307,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
.begin = begin,
.recursive = recursive,
.parent = parent,
.ignore_bds_parents = ignore_bds_parents,
.poll = poll,
};
if (bs) {
@ -312,7 +323,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
}
void bdrv_do_drained_begin_quiesce(BlockDriverState *bs,
BdrvChild *parent)
BdrvChild *parent, bool ignore_bds_parents)
{
assert(!qemu_in_coroutine());
@ -321,26 +332,30 @@ void bdrv_do_drained_begin_quiesce(BlockDriverState *bs,
aio_disable_external(bdrv_get_aio_context(bs));
}
bdrv_parent_drained_begin(bs, parent);
bdrv_parent_drained_begin(bs, parent, ignore_bds_parents);
bdrv_drain_invoke(bs, true);
}
static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
BdrvChild *parent, bool poll)
BdrvChild *parent, bool ignore_bds_parents,
bool poll)
{
BdrvChild *child, *next;
if (qemu_in_coroutine()) {
bdrv_co_yield_to_drain(bs, true, recursive, parent, poll);
bdrv_co_yield_to_drain(bs, true, recursive, parent, ignore_bds_parents,
poll);
return;
}
bdrv_do_drained_begin_quiesce(bs, parent);
bdrv_do_drained_begin_quiesce(bs, parent, ignore_bds_parents);
if (recursive) {
assert(!ignore_bds_parents);
bs->recursive_quiesce_counter++;
QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
bdrv_do_drained_begin(child->bs, true, child, false);
bdrv_do_drained_begin(child->bs, true, child, ignore_bds_parents,
false);
}
}
@ -354,28 +369,30 @@ static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive,
* nodes.
*/
if (poll) {
assert(!ignore_bds_parents);
BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, recursive, parent));
}
}
void bdrv_drained_begin(BlockDriverState *bs)
{
bdrv_do_drained_begin(bs, false, NULL, true);
bdrv_do_drained_begin(bs, false, NULL, false, true);
}
void bdrv_subtree_drained_begin(BlockDriverState *bs)
{
bdrv_do_drained_begin(bs, true, NULL, true);
bdrv_do_drained_begin(bs, true, NULL, false, true);
}
void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,
BdrvChild *parent)
static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,
BdrvChild *parent, bool ignore_bds_parents)
{
BdrvChild *child, *next;
int old_quiesce_counter;
if (qemu_in_coroutine()) {
bdrv_co_yield_to_drain(bs, false, recursive, parent, false);
bdrv_co_yield_to_drain(bs, false, recursive, parent, ignore_bds_parents,
false);
return;
}
assert(bs->quiesce_counter > 0);
@ -383,27 +400,28 @@ void bdrv_do_drained_end(BlockDriverState *bs, bool recursive,
/* Re-enable things in child-to-parent order */
bdrv_drain_invoke(bs, false);
bdrv_parent_drained_end(bs, parent);
bdrv_parent_drained_end(bs, parent, ignore_bds_parents);
if (old_quiesce_counter == 1) {
aio_enable_external(bdrv_get_aio_context(bs));
}
if (recursive) {
assert(!ignore_bds_parents);
bs->recursive_quiesce_counter--;
QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
bdrv_do_drained_end(child->bs, true, child);
bdrv_do_drained_end(child->bs, true, child, ignore_bds_parents);
}
}
}
void bdrv_drained_end(BlockDriverState *bs)
{
bdrv_do_drained_end(bs, false, NULL);
bdrv_do_drained_end(bs, false, NULL, false);
}
void bdrv_subtree_drained_end(BlockDriverState *bs)
{
bdrv_do_drained_end(bs, true, NULL);
bdrv_do_drained_end(bs, true, NULL, false);
}
void bdrv_apply_subtree_drain(BdrvChild *child, BlockDriverState *new_parent)
@ -411,7 +429,7 @@ void bdrv_apply_subtree_drain(BdrvChild *child, BlockDriverState *new_parent)
int i;
for (i = 0; i < new_parent->recursive_quiesce_counter; i++) {
bdrv_do_drained_begin(child->bs, true, child, true);
bdrv_do_drained_begin(child->bs, true, child, false, true);
}
}
@ -420,7 +438,7 @@ void bdrv_unapply_subtree_drain(BdrvChild *child, BlockDriverState *old_parent)
int i;
for (i = 0; i < old_parent->recursive_quiesce_counter; i++) {
bdrv_do_drained_end(child->bs, true, child);
bdrv_do_drained_end(child->bs, true, child, false);
}
}
@ -472,7 +490,7 @@ void bdrv_drain_all_begin(void)
BdrvNextIterator it;
if (qemu_in_coroutine()) {
bdrv_co_yield_to_drain(NULL, true, false, NULL, true);
bdrv_co_yield_to_drain(NULL, true, false, NULL, false, true);
return;
}
@ -486,7 +504,7 @@ void bdrv_drain_all_begin(void)
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
bdrv_do_drained_begin(bs, true, NULL, true);
bdrv_do_drained_begin(bs, true, NULL, false, true);
aio_context_release(aio_context);
}
@ -504,7 +522,7 @@ void bdrv_drain_all_end(void)
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
bdrv_do_drained_end(bs, true, NULL);
bdrv_do_drained_end(bs, true, NULL, false);
aio_context_release(aio_context);
}
}