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block: add BDS field to count in-flight requests

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Unlike tracked_requests, this field also counts throttled requests,
and remains non-zero if an AIO operation needs a BH to be "really"
completed.

With this change, it is no longer necessary to have a dummy
BdrvTrackedRequest for requests that are never serialising, and
it is no longer necessary to poll the AioContext once after
bdrv_requests_pending(bs) returns false.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-Id: <1477565348-5458-5-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-10-27 12:48:52 +02:00 committed by Fam Zheng
parent 9a0cec664e
commit 9972354856
3 changed files with 75 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
block/block-backend.c
View File

@ -799,20 +799,25 @@ int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
BdrvRequestFlags flags)
{
int ret;
BlockDriverState *bs = blk_bs(blk);
trace_blk_co_preadv(blk, blk_bs(blk), offset, bytes, flags);
trace_blk_co_preadv(blk, bs, offset, bytes, flags);
ret = blk_check_byte_request(blk, offset, bytes);
if (ret < 0) {
return ret;
}
bdrv_inc_in_flight(bs);
/* throttling disk I/O */
if (blk->public.throttle_state) {
throttle_group_co_io_limits_intercept(blk, bytes, false);
}
return bdrv_co_preadv(blk->root, offset, bytes, qiov, flags);
ret = bdrv_co_preadv(blk->root, offset, bytes, qiov, flags);
bdrv_dec_in_flight(bs);
return ret;
}
int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
@ -820,14 +825,17 @@ int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
BdrvRequestFlags flags)
{
int ret;
BlockDriverState *bs = blk_bs(blk);
trace_blk_co_pwritev(blk, blk_bs(blk), offset, bytes, flags);
trace_blk_co_pwritev(blk, bs, offset, bytes, flags);
ret = blk_check_byte_request(blk, offset, bytes);
if (ret < 0) {
return ret;
}
bdrv_inc_in_flight(bs);
/* throttling disk I/O */
if (blk->public.throttle_state) {
throttle_group_co_io_limits_intercept(blk, bytes, true);
@ -837,7 +845,9 @@ int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
flags |= BDRV_REQ_FUA;
}
return bdrv_co_pwritev(blk->root, offset, bytes, qiov, flags);
ret = bdrv_co_pwritev(blk->root, offset, bytes, qiov, flags);
bdrv_dec_in_flight(bs);
return ret;
}
typedef struct BlkRwCo {
@ -930,6 +940,8 @@ int blk_make_zero(BlockBackend *blk, BdrvRequestFlags flags)
static void error_callback_bh(void *opaque)
{
struct BlockBackendAIOCB *acb = opaque;
bdrv_dec_in_flight(acb->common.bs);
acb->common.cb(acb->common.opaque, acb->ret);
qemu_aio_unref(acb);
}
@ -940,6 +952,7 @@ BlockAIOCB *blk_abort_aio_request(BlockBackend *blk,
{
struct BlockBackendAIOCB *acb;
bdrv_inc_in_flight(blk_bs(blk));
acb = blk_aio_get(&block_backend_aiocb_info, blk, cb, opaque);
acb->blk = blk;
acb->ret = ret;
@ -962,6 +975,7 @@ static const AIOCBInfo blk_aio_em_aiocb_info = {
static void blk_aio_complete(BlkAioEmAIOCB *acb)
{
if (acb->has_returned) {
bdrv_dec_in_flight(acb->common.bs);
acb->common.cb(acb->common.opaque, acb->rwco.ret);
qemu_aio_unref(acb);
}
@ -983,6 +997,7 @@ static BlockAIOCB *blk_aio_prwv(BlockBackend *blk, int64_t offset, int bytes,
BlkAioEmAIOCB *acb;
Coroutine *co;
bdrv_inc_in_flight(blk_bs(blk));
acb = blk_aio_get(&blk_aio_em_aiocb_info, blk, cb, opaque);
acb->rwco = (BlkRwCo) {
.blk = blk,

75
block/io.c
View File

@ -143,7 +143,7 @@ bool bdrv_requests_pending(BlockDriverState *bs)
{
BdrvChild *child;
if (!QLIST_EMPTY(&bs->tracked_requests)) {
if (atomic_read(&bs->in_flight)) {
return true;
}
@ -176,12 +176,9 @@ typedef struct {
static void bdrv_drain_poll(BlockDriverState *bs)
{
bool busy = true;
while (busy) {
while (bdrv_requests_pending(bs)) {
/* Keep iterating */
busy = bdrv_requests_pending(bs);
busy |= aio_poll(bdrv_get_aio_context(bs), busy);
aio_poll(bdrv_get_aio_context(bs), true);
}
}
@ -189,8 +186,10 @@ static void bdrv_co_drain_bh_cb(void *opaque)
{
BdrvCoDrainData *data = opaque;
Coroutine *co = data->co;
BlockDriverState *bs = data->bs;
bdrv_drain_poll(data->bs);
bdrv_dec_in_flight(bs);
bdrv_drain_poll(bs);
data->done = true;
qemu_coroutine_enter(co);
}
@ -209,6 +208,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs)
.bs = bs,
.done = false,
};
bdrv_inc_in_flight(bs);
aio_bh_schedule_oneshot(bdrv_get_aio_context(bs),
bdrv_co_drain_bh_cb, &data);
@ -279,7 +279,7 @@ void bdrv_drain(BlockDriverState *bs)
void bdrv_drain_all(void)
{
/* Always run first iteration so any pending completion BHs run */
bool busy = true;
bool waited = true;
BlockDriverState *bs;
BdrvNextIterator it;
BlockJob *job = NULL;
@ -313,8 +313,8 @@ void bdrv_drain_all(void)
* request completion. Therefore we must keep looping until there was no
* more activity rather than simply draining each device independently.
*/
while (busy) {
busy = false;
while (waited) {
waited = false;
for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
AioContext *aio_context = ctx->data;
@ -323,12 +323,11 @@ void bdrv_drain_all(void)
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
if (aio_context == bdrv_get_aio_context(bs)) {
if (bdrv_requests_pending(bs)) {
busy = true;
aio_poll(aio_context, busy);
aio_poll(aio_context, true);
waited = true;
}
}
}
busy |= aio_poll(aio_context, false);
aio_context_release(aio_context);
}
}
@ -476,6 +475,16 @@ static bool tracked_request_overlaps(BdrvTrackedRequest *req,
return true;
}
void bdrv_inc_in_flight(BlockDriverState *bs)
{
atomic_inc(&bs->in_flight);
}
void bdrv_dec_in_flight(BlockDriverState *bs)
{
atomic_dec(&bs->in_flight);
}
static bool coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self)
{
BlockDriverState *bs = self->bs;
@ -1097,6 +1106,8 @@ int coroutine_fn bdrv_co_preadv(BdrvChild *child,
return ret;
}
bdrv_inc_in_flight(bs);
/* Don't do copy-on-read if we read data before write operation */
if (bs->copy_on_read && !(flags & BDRV_REQ_NO_SERIALISING)) {
flags |= BDRV_REQ_COPY_ON_READ;
@ -1132,6 +1143,7 @@ int coroutine_fn bdrv_co_preadv(BdrvChild *child,
use_local_qiov ? &local_qiov : qiov,
flags);
tracked_request_end(&req);
bdrv_dec_in_flight(bs);
if (use_local_qiov) {
qemu_iovec_destroy(&local_qiov);
@ -1480,6 +1492,7 @@ int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
return ret;
}
bdrv_inc_in_flight(bs);
/*
* Align write if necessary by performing a read-modify-write cycle.
* Pad qiov with the read parts and be sure to have a tracked request not
@ -1581,6 +1594,7 @@ fail:
qemu_vfree(tail_buf);
out:
tracked_request_end(&req);
bdrv_dec_in_flight(bs);
return ret;
}
@ -1705,17 +1719,19 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
}
*file = NULL;
bdrv_inc_in_flight(bs);
ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum,
file);
if (ret < 0) {
*pnum = 0;
return ret;
goto out;
}
if (ret & BDRV_BLOCK_RAW) {
assert(ret & BDRV_BLOCK_OFFSET_VALID);
return bdrv_get_block_status(bs->file->bs, ret >> BDRV_SECTOR_BITS,
*pnum, pnum, file);
ret = bdrv_get_block_status(bs->file->bs, ret >> BDRV_SECTOR_BITS,
*pnum, pnum, file);
goto out;
}
if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) {
@ -1757,6 +1773,8 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
}
}
out:
bdrv_dec_in_flight(bs);
return ret;
}
@ -2102,6 +2120,7 @@ static const AIOCBInfo bdrv_em_co_aiocb_info = {
static void bdrv_co_complete(BlockAIOCBCoroutine *acb)
{
if (!acb->need_bh) {
bdrv_dec_in_flight(acb->common.bs);
acb->common.cb(acb->common.opaque, acb->req.error);
qemu_aio_unref(acb);
}
@ -2152,6 +2171,9 @@ static BlockAIOCB *bdrv_co_aio_prw_vector(BdrvChild *child,
Coroutine *co;
BlockAIOCBCoroutine *acb;
/* Matched by bdrv_co_complete's bdrv_dec_in_flight. */
bdrv_inc_in_flight(child->bs);
acb = qemu_aio_get(&bdrv_em_co_aiocb_info, child->bs, cb, opaque);
acb->child = child;
acb->need_bh = true;
@ -2185,6 +2207,9 @@ BlockAIOCB *bdrv_aio_flush(BlockDriverState *bs,
Coroutine *co;
BlockAIOCBCoroutine *acb;
/* Matched by bdrv_co_complete's bdrv_dec_in_flight. */
bdrv_inc_in_flight(bs);
acb = qemu_aio_get(&bdrv_em_co_aiocb_info, bs, cb, opaque);
acb->need_bh = true;
acb->req.error = -EINPROGRESS;
@ -2244,23 +2269,22 @@ static void coroutine_fn bdrv_flush_co_entry(void *opaque)
int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
{
int ret;
BdrvTrackedRequest req;
if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs) ||
bdrv_is_sg(bs)) {
return 0;
}
tracked_request_begin(&req, bs, 0, 0, BDRV_TRACKED_FLUSH);
bdrv_inc_in_flight(bs);
int current_gen = bs->write_gen;
/* Wait until any previous flushes are completed */
while (bs->active_flush_req != NULL) {
while (bs->active_flush_req) {
qemu_co_queue_wait(&bs->flush_queue);
}
bs->active_flush_req = &req;
bs->active_flush_req = true;
/* Write back all layers by calling one driver function */
if (bs->drv->bdrv_co_flush) {
@ -2330,11 +2354,11 @@ flush_parent:
out:
/* Notify any pending flushes that we have completed */
bs->flushed_gen = current_gen;
bs->active_flush_req = NULL;
bs->active_flush_req = false;
/* Return value is ignored - it's ok if wait queue is empty */
qemu_co_queue_next(&bs->flush_queue);
tracked_request_end(&req);
bdrv_dec_in_flight(bs);
return ret;
}
@ -2417,6 +2441,7 @@ int coroutine_fn bdrv_co_pdiscard(BlockDriverState *bs, int64_t offset,
return 0;
}
bdrv_inc_in_flight(bs);
tracked_request_begin(&req, bs, offset, count, BDRV_TRACKED_DISCARD);
ret = notifier_with_return_list_notify(&bs->before_write_notifiers, &req);
@ -2463,6 +2488,7 @@ out:
bdrv_set_dirty(bs, req.offset >> BDRV_SECTOR_BITS,
req.bytes >> BDRV_SECTOR_BITS);
tracked_request_end(&req);
bdrv_dec_in_flight(bs);
return ret;
}
@ -2495,13 +2521,12 @@ int bdrv_pdiscard(BlockDriverState *bs, int64_t offset, int count)
int bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf)
{
BlockDriver *drv = bs->drv;
BdrvTrackedRequest tracked_req;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
BlockAIOCB *acb;
tracked_request_begin(&tracked_req, bs, 0, 0, BDRV_TRACKED_IOCTL);
bdrv_inc_in_flight(bs);
if (!drv || (!drv->bdrv_aio_ioctl && !drv->bdrv_co_ioctl)) {
co.ret = -ENOTSUP;
goto out;
@ -2518,7 +2543,7 @@ int bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf)
qemu_coroutine_yield();
}
out:
tracked_request_end(&tracked_req);
bdrv_dec_in_flight(bs);
return co.ret;
}

10
include/block/block_int.h
View File

@ -62,8 +62,6 @@
enum BdrvTrackedRequestType {
BDRV_TRACKED_READ,
BDRV_TRACKED_WRITE,
BDRV_TRACKED_FLUSH,
BDRV_TRACKED_IOCTL,
BDRV_TRACKED_DISCARD,
};
@ -445,7 +443,7 @@ struct BlockDriverState {
note this is a reference count */
CoQueue flush_queue; /* Serializing flush queue */
BdrvTrackedRequest *active_flush_req; /* Flush request in flight */
bool active_flush_req; /* Flush request in flight? */
unsigned int write_gen; /* Current data generation */
unsigned int flushed_gen; /* Flushed write generation */
@ -473,7 +471,8 @@ struct BlockDriverState {
/* Callback before write request is processed */
NotifierWithReturnList before_write_notifiers;
/* number of in-flight serialising requests */
/* number of in-flight requests; overall and serialising */
unsigned int in_flight;
unsigned int serialising_in_flight;
/* Offset after the highest byte written to */
@ -787,6 +786,9 @@ bool bdrv_requests_pending(BlockDriverState *bs);
void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap **out);
void bdrv_undo_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap *in);
void bdrv_inc_in_flight(BlockDriverState *bs);
void bdrv_dec_in_flight(BlockDriverState *bs);
void blockdev_close_all_bdrv_states(void);
#endif /* BLOCK_INT_H */