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block: Increase BB.in_flight for coroutine and sync interfaces
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External callers of blk_co_*() and of the synchronous blk_*() functions
don't currently increase the BlockBackend.in_flight counter, but calls
from blk_aio_*() do, so there is an inconsistency whether the counter
has been increased or not.

This patch moves the actual operations to static functions that can
later know they will always be called with in_flight increased exactly
once, even for external callers using the blk_co_*() coroutine
interfaces.

If the public blk_co_*() interface is unused, remove it.

Signed-off-by: Kevin Wolf <[email protected]>
Message-Id: <[email protected]>
Reviewed-by: Max Reitz <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>
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@kevmw
kevmw committed Apr 7, 2020
1 parent 564806c commit fbb92b6
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Showing 2 changed files with 80 additions and 24 deletions.
103 changes: 80 additions & 23 deletions block/block-backend.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1147,9 +1147,10 @@ static void coroutine_fn blk_wait_while_drained(BlockBackend *blk)
}
}

int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static int coroutine_fn
blk_do_preadv(BlockBackend *blk, int64_t offset, unsigned int bytes,
QEMUIOVector *qiov, BdrvRequestFlags flags)
{
int ret;
BlockDriverState *bs;
Expand Down Expand Up @@ -1178,10 +1179,24 @@ int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
return ret;
}

int coroutine_fn blk_co_pwritev_part(BlockBackend *blk, int64_t offset,
unsigned int bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags)
int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
int ret;

blk_inc_in_flight(blk);
ret = blk_do_preadv(blk, offset, bytes, qiov, flags);
blk_dec_in_flight(blk);

return ret;
}

/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static int coroutine_fn
blk_do_pwritev_part(BlockBackend *blk, int64_t offset, unsigned int bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags)
{
int ret;
BlockDriverState *bs;
Expand Down Expand Up @@ -1214,6 +1229,20 @@ int coroutine_fn blk_co_pwritev_part(BlockBackend *blk, int64_t offset,
return ret;
}

int coroutine_fn blk_co_pwritev_part(BlockBackend *blk, int64_t offset,
unsigned int bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags)
{
int ret;

blk_inc_in_flight(blk);
ret = blk_do_pwritev_part(blk, offset, bytes, qiov, qiov_offset, flags);
blk_dec_in_flight(blk);

return ret;
}

int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
Expand All @@ -1234,7 +1263,7 @@ static void blk_read_entry(void *opaque)
BlkRwCo *rwco = opaque;
QEMUIOVector *qiov = rwco->iobuf;

rwco->ret = blk_co_preadv(rwco->blk, rwco->offset, qiov->size,
rwco->ret = blk_do_preadv(rwco->blk, rwco->offset, qiov->size,
qiov, rwco->flags);
aio_wait_kick();
}
Expand All @@ -1244,8 +1273,8 @@ static void blk_write_entry(void *opaque)
BlkRwCo *rwco = opaque;
QEMUIOVector *qiov = rwco->iobuf;

rwco->ret = blk_co_pwritev(rwco->blk, rwco->offset, qiov->size,
qiov, rwco->flags);
rwco->ret = blk_do_pwritev_part(rwco->blk, rwco->offset, qiov->size,
qiov, 0, rwco->flags);
aio_wait_kick();
}

Expand All @@ -1262,6 +1291,7 @@ static int blk_prw(BlockBackend *blk, int64_t offset, uint8_t *buf,
.ret = NOT_DONE,
};

blk_inc_in_flight(blk);
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
co_entry(&rwco);
Expand All @@ -1270,6 +1300,7 @@ static int blk_prw(BlockBackend *blk, int64_t offset, uint8_t *buf,
bdrv_coroutine_enter(blk_bs(blk), co);
BDRV_POLL_WHILE(blk_bs(blk), rwco.ret == NOT_DONE);
}
blk_dec_in_flight(blk);

return rwco.ret;
}
Expand Down Expand Up @@ -1394,7 +1425,7 @@ static void blk_aio_read_entry(void *opaque)
}

assert(qiov->size == acb->bytes);
rwco->ret = blk_co_preadv(rwco->blk, rwco->offset, acb->bytes,
rwco->ret = blk_do_preadv(rwco->blk, rwco->offset, acb->bytes,
qiov, rwco->flags);
blk_aio_complete(acb);
}
Expand All @@ -1412,8 +1443,8 @@ static void blk_aio_write_entry(void *opaque)
}

assert(!qiov || qiov->size == acb->bytes);
rwco->ret = blk_co_pwritev(rwco->blk, rwco->offset, acb->bytes,
qiov, rwco->flags);
rwco->ret = blk_do_pwritev_part(rwco->blk, rwco->offset, acb->bytes,
qiov, 0, rwco->flags);
blk_aio_complete(acb);
}

Expand Down Expand Up @@ -1498,7 +1529,9 @@ void blk_aio_cancel_async(BlockAIOCB *acb)
bdrv_aio_cancel_async(acb);
}

int blk_co_ioctl(BlockBackend *blk, unsigned long int req, void *buf)
/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static int coroutine_fn
blk_do_ioctl(BlockBackend *blk, unsigned long int req, void *buf)
{
blk_wait_while_drained(blk);

Expand All @@ -1514,8 +1547,7 @@ static void blk_ioctl_entry(void *opaque)
BlkRwCo *rwco = opaque;
QEMUIOVector *qiov = rwco->iobuf;

rwco->ret = blk_co_ioctl(rwco->blk, rwco->offset,
qiov->iov[0].iov_base);
rwco->ret = blk_do_ioctl(rwco->blk, rwco->offset, qiov->iov[0].iov_base);
aio_wait_kick();
}

Expand All @@ -1529,7 +1561,7 @@ static void blk_aio_ioctl_entry(void *opaque)
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;

rwco->ret = blk_co_ioctl(rwco->blk, rwco->offset, rwco->iobuf);
rwco->ret = blk_do_ioctl(rwco->blk, rwco->offset, rwco->iobuf);

blk_aio_complete(acb);
}
Expand All @@ -1540,7 +1572,9 @@ BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
return blk_aio_prwv(blk, req, 0, buf, blk_aio_ioctl_entry, 0, cb, opaque);
}

int blk_co_pdiscard(BlockBackend *blk, int64_t offset, int bytes)
/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static int coroutine_fn
blk_do_pdiscard(BlockBackend *blk, int64_t offset, int bytes)
{
int ret;

Expand All @@ -1559,7 +1593,7 @@ static void blk_aio_pdiscard_entry(void *opaque)
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;

rwco->ret = blk_co_pdiscard(rwco->blk, rwco->offset, acb->bytes);
rwco->ret = blk_do_pdiscard(rwco->blk, rwco->offset, acb->bytes);
blk_aio_complete(acb);
}

Expand All @@ -1571,12 +1605,23 @@ BlockAIOCB *blk_aio_pdiscard(BlockBackend *blk,
cb, opaque);
}

int coroutine_fn blk_co_pdiscard(BlockBackend *blk, int64_t offset, int bytes)
{
int ret;

blk_inc_in_flight(blk);
ret = blk_do_pdiscard(blk, offset, bytes);
blk_dec_in_flight(blk);

return ret;
}

static void blk_pdiscard_entry(void *opaque)
{
BlkRwCo *rwco = opaque;
QEMUIOVector *qiov = rwco->iobuf;

rwco->ret = blk_co_pdiscard(rwco->blk, rwco->offset, qiov->size);
rwco->ret = blk_do_pdiscard(rwco->blk, rwco->offset, qiov->size);
aio_wait_kick();
}

Expand All @@ -1585,7 +1630,8 @@ int blk_pdiscard(BlockBackend *blk, int64_t offset, int bytes)
return blk_prw(blk, offset, NULL, bytes, blk_pdiscard_entry, 0);
}

int blk_co_flush(BlockBackend *blk)
/* To be called between exactly one pair of blk_inc/dec_in_flight() */
static int coroutine_fn blk_do_flush(BlockBackend *blk)
{
blk_wait_while_drained(blk);

Expand All @@ -1601,7 +1647,7 @@ static void blk_aio_flush_entry(void *opaque)
BlkAioEmAIOCB *acb = opaque;
BlkRwCo *rwco = &acb->rwco;

rwco->ret = blk_co_flush(rwco->blk);
rwco->ret = blk_do_flush(rwco->blk);
blk_aio_complete(acb);
}

Expand All @@ -1611,10 +1657,21 @@ BlockAIOCB *blk_aio_flush(BlockBackend *blk,
return blk_aio_prwv(blk, 0, 0, NULL, blk_aio_flush_entry, 0, cb, opaque);
}

int coroutine_fn blk_co_flush(BlockBackend *blk)
{
int ret;

blk_inc_in_flight(blk);
ret = blk_do_flush(blk);
blk_dec_in_flight(blk);

return ret;
}

static void blk_flush_entry(void *opaque)
{
BlkRwCo *rwco = opaque;
rwco->ret = blk_co_flush(rwco->blk);
rwco->ret = blk_do_flush(rwco->blk);
aio_wait_kick();
}

Expand Down
1 change: 0 additions & 1 deletion include/sysemu/block-backend.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -171,7 +171,6 @@ BlockAIOCB *blk_aio_pdiscard(BlockBackend *blk, int64_t offset, int bytes,
BlockCompletionFunc *cb, void *opaque);
void blk_aio_cancel(BlockAIOCB *acb);
void blk_aio_cancel_async(BlockAIOCB *acb);
int blk_co_ioctl(BlockBackend *blk, unsigned long int req, void *buf);
int blk_ioctl(BlockBackend *blk, unsigned long int req, void *buf);
BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
BlockCompletionFunc *cb, void *opaque);
Expand Down

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