Extract the handling of io_plug "depth" from linux-aio.c and let the
main bdrv_drain loop do nothing but wait on I/O.
Like the two newly introduced functions, bdrv_io_plug and bdrv_io_unplug
now operate on all children. The visit order is now symmetrical between
plug and unplug, making it possible for formats to implement plug/unplug.
Reviewed-by: Fam Zheng <f...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
block/io.c | 72 +++++++++++++++++++++++++++++++++++------------
block/linux-aio.c | 13 ++++-----
block/raw-aio.h | 2 +-
block/raw-posix.c | 16 +----------
include/block/block.h | 3 +-
include/block/block_int.h | 5 +++-
6 files changed, 67 insertions(+), 44 deletions(-)
diff --git a/block/io.c b/block/io.c
index 272caac..d8d50b7 100644
--- a/block/io.c
+++ b/block/io.c
@@ -271,13 +271,14 @@ void bdrv_drain(BlockDriverState *bs)
bool busy = true;
bdrv_no_throttling_begin(bs);
+ bdrv_io_unplugged_begin(bs);
bdrv_drain_recurse(bs);
while (busy) {
/* Keep iterating */
- bdrv_flush_io_queue(bs);
busy = bdrv_requests_pending(bs);
busy |= aio_poll(bdrv_get_aio_context(bs), busy);
}
+ bdrv_io_unplugged_end(bs);
bdrv_no_throttling_end(bs);
}
@@ -302,6 +303,7 @@ void bdrv_drain_all(void)
block_job_pause(bs->job);
}
bdrv_no_throttling_begin(bs);
+ bdrv_io_unplugged_begin(bs);
bdrv_drain_recurse(bs);
aio_context_release(aio_context);
@@ -326,7 +328,6 @@ void bdrv_drain_all(void)
aio_context_acquire(aio_context);
while ((bs = bdrv_next(bs))) {
if (aio_context == bdrv_get_aio_context(bs)) {
- bdrv_flush_io_queue(bs);
if (bdrv_requests_pending(bs)) {
busy = true;
aio_poll(aio_context, busy);
@@ -343,6 +344,7 @@ void bdrv_drain_all(void)
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
+ bdrv_io_unplugged_end(bs);
bdrv_no_throttling_end(bs);
if (bs->job) {
block_job_resume(bs->job);
@@ -2738,31 +2740,65 @@ void bdrv_add_before_write_notifier(BlockDriverState
*bs,
void bdrv_io_plug(BlockDriverState *bs)
{
- BlockDriver *drv = bs->drv;
- if (drv && drv->bdrv_io_plug) {
- drv->bdrv_io_plug(bs);
- } else if (bs->file) {
- bdrv_io_plug(bs->file->bs);
+ BdrvChild *child;
+
+ if (bs->io_plugged++ == 0 && bs->io_plug_disabled == 0) {
+ BlockDriver *drv = bs->drv;
+ if (drv && drv->bdrv_io_plug) {
+ drv->bdrv_io_plug(bs);
+ }
+ }
+
+ QLIST_FOREACH(child, &bs->children, next) {
+ bdrv_io_plug(child->bs);
}
}
void bdrv_io_unplug(BlockDriverState *bs)
{
- BlockDriver *drv = bs->drv;
- if (drv && drv->bdrv_io_unplug) {
- drv->bdrv_io_unplug(bs);
- } else if (bs->file) {
- bdrv_io_unplug(bs->file->bs);
+ BdrvChild *child;
+
+ QLIST_FOREACH(child, &bs->children, next) {
+ bdrv_io_unplug(child->bs);
+ }
+
+ if (--bs->io_plugged == 0 && bs->io_plug_disabled == 0) {
+ BlockDriver *drv = bs->drv;
+ if (drv && drv->bdrv_io_unplug) {
+ drv->bdrv_io_unplug(bs);
+ }
}
}
-void bdrv_flush_io_queue(BlockDriverState *bs)
+void bdrv_io_unplugged_begin(BlockDriverState *bs)
{
- BlockDriver *drv = bs->drv;
- if (drv && drv->bdrv_flush_io_queue) {
- drv->bdrv_flush_io_queue(bs);
- } else if (bs->file) {
- bdrv_flush_io_queue(bs->file->bs);
+ BdrvChild *child;
+
+ if (bs->io_plug_disabled++ == 0 && bs->io_plugged > 0) {
+ BlockDriver *drv = bs->drv;
+ if (drv && drv->bdrv_io_unplug) {
+ drv->bdrv_io_unplug(bs);
+ }
+ }
+
+ QLIST_FOREACH(child, &bs->children, next) {
+ bdrv_io_unplugged_begin(child->bs);
+ }
+}
+
+void bdrv_io_unplugged_end(BlockDriverState *bs)
+{
+ BdrvChild *child;
+
+ QLIST_FOREACH(child, &bs->children, next) {
+ bdrv_io_unplugged_end(child->bs);
+ }
+
+ if (--bs->io_plug_disabled == 0 && bs->io_plugged > 0) {
+ BlockDriver *drv = bs->drv;
+ if (drv && drv->bdrv_io_plug) {
+ drv->bdrv_io_plug(bs);
+ }
}
}
diff --git a/block/linux-aio.c b/block/linux-aio.c
index 805757e..102bf92 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -220,19 +220,16 @@ void laio_io_plug(BlockDriverState *bs, void *aio_ctx)
{
struct qemu_laio_state *s = aio_ctx;
- s->io_q.plugged++;
+ assert(!s->io_q.plugged);
+ s->io_q.plugged = 1;
}
-void laio_io_unplug(BlockDriverState *bs, void *aio_ctx, bool unplug)
+void laio_io_unplug(BlockDriverState *bs, void *aio_ctx)
{
struct qemu_laio_state *s = aio_ctx;
- assert(s->io_q.plugged > 0 || !unplug);
-
- if (unplug && --s->io_q.plugged > 0) {
- return;
- }
-
+ assert(s->io_q.plugged);
+ s->io_q.plugged = 0;
if (!s->io_q.blocked && !QSIMPLEQ_EMPTY(&s->io_q.pending)) {
ioq_submit(s);
}
diff --git a/block/raw-aio.h b/block/raw-aio.h
index 31d791f..7600060 100644
--- a/block/raw-aio.h
+++ b/block/raw-aio.h
@@ -41,7 +41,7 @@ BlockAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx,
int fd,
void laio_detach_aio_context(void *s, AioContext *old_context);
void laio_attach_aio_context(void *s, AioContext *new_context);
void laio_io_plug(BlockDriverState *bs, void *aio_ctx);
-void laio_io_unplug(BlockDriverState *bs, void *aio_ctx, bool unplug);
+void laio_io_unplug(BlockDriverState *bs, void *aio_ctx);
#endif
#ifdef _WIN32
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 8866121..7ecbee3 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1343,17 +1343,7 @@ static void raw_aio_unplug(BlockDriverState *bs)
#ifdef CONFIG_LINUX_AIO
BDRVRawState *s = bs->opaque;
if (s->use_aio) {
- laio_io_unplug(bs, s->aio_ctx, true);
- }
-#endif
-}
-
-static void raw_aio_flush_io_queue(BlockDriverState *bs)
-{
-#ifdef CONFIG_LINUX_AIO
- BDRVRawState *s = bs->opaque;
- if (s->use_aio) {
- laio_io_unplug(bs, s->aio_ctx, false);
+ laio_io_unplug(bs, s->aio_ctx);
}
#endif
}
@@ -1947,7 +1937,6 @@ BlockDriver bdrv_file = {
.bdrv_refresh_limits = raw_refresh_limits,
.bdrv_io_plug = raw_aio_plug,
.bdrv_io_unplug = raw_aio_unplug,
- .bdrv_flush_io_queue = raw_aio_flush_io_queue,
.bdrv_truncate = raw_truncate,
.bdrv_getlength = raw_getlength,
@@ -2310,7 +2299,6 @@ static BlockDriver bdrv_host_device = {
.bdrv_refresh_limits = raw_refresh_limits,
.bdrv_io_plug = raw_aio_plug,
.bdrv_io_unplug = raw_aio_unplug,
- .bdrv_flush_io_queue = raw_aio_flush_io_queue,
.bdrv_truncate = raw_truncate,
.bdrv_getlength = raw_getlength,
@@ -2440,7 +2428,6 @@ static BlockDriver bdrv_host_cdrom = {
.bdrv_refresh_limits = raw_refresh_limits,
.bdrv_io_plug = raw_aio_plug,
.bdrv_io_unplug = raw_aio_unplug,
- .bdrv_flush_io_queue = raw_aio_flush_io_queue,
.bdrv_truncate = raw_truncate,
.bdrv_getlength = raw_getlength,
@@ -2576,7 +2563,6 @@ static BlockDriver bdrv_host_cdrom = {
.bdrv_refresh_limits = raw_refresh_limits,
.bdrv_io_plug = raw_aio_plug,
.bdrv_io_unplug = raw_aio_unplug,
- .bdrv_flush_io_queue = raw_aio_flush_io_queue,
.bdrv_truncate = raw_truncate,
.bdrv_getlength = raw_getlength,
diff --git a/include/block/block.h b/include/block/block.h
index eaa6426..527b691 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -524,7 +524,8 @@ int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry
*geo);
void bdrv_io_plug(BlockDriverState *bs);
void bdrv_io_unplug(BlockDriverState *bs);
-void bdrv_flush_io_queue(BlockDriverState *bs);
+void bdrv_io_unplugged_begin(BlockDriverState *bs);
+void bdrv_io_unplugged_end(BlockDriverState *bs);
/**
* bdrv_drained_begin:
diff --git a/include/block/block_int.h b/include/block/block_int.h
index dac6d43..13136a3 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -282,7 +282,6 @@ struct BlockDriver {
/* io queue for linux-aio */
void (*bdrv_io_plug)(BlockDriverState *bs);
void (*bdrv_io_unplug)(BlockDriverState *bs);
- void (*bdrv_flush_io_queue)(BlockDriverState *bs);
/**
* Try to get @bs's logical and physical block size.
@@ -477,6 +476,10 @@ struct BlockDriverState {
uint64_t write_threshold_offset;
NotifierWithReturn write_threshold_notifier;
+ /* counters for nested bdrv_io_plug and bdrv_io_unplugged_begin */
+ unsigned io_plugged;
+ unsigned io_plug_disabled;
+
int quiesce_counter;
};
--
1.8.3.1
