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block: add aio_flush operation

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Instead stalling the VCPU while serving a cache flush try to do it
asynchronously.  Use our good old helper thread pool to issue an
asynchronous fdatasync for raw-posix.  Note that while Linux AIO
implements a fdatasync operation it is not useful for us because
it isn't actually implement in asynchronous fashion.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Christoph Hellwig 2009-09-04 19:01:49 +02:00 • committed by Anthony Liguori
parent 6f1953c4c1
commit b2e12bc6e3
6 changed files with 80 additions and 3 deletions
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40
block.c
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@ -54,6 +54,8 @@ static BlockDriverAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
static BlockDriverAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
static BlockDriverAIOCB *bdrv_aio_flush_em(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
static int bdrv_read_em(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors);
static int bdrv_write_em(BlockDriverState *bs, int64_t sector_num,
@ -138,6 +140,10 @@ void bdrv_register(BlockDriver *bdrv)
bdrv->bdrv_read = bdrv_read_em;
bdrv->bdrv_write = bdrv_write_em;
}
if (!bdrv->bdrv_aio_flush)
bdrv->bdrv_aio_flush = bdrv_aio_flush_em;
bdrv->next = first_drv;
first_drv = bdrv;
}
@ -1552,6 +1558,21 @@ fail:
return -1;
}
BlockDriverAIOCB *bdrv_aio_flush(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque)
{
BlockDriver *drv = bs->drv;
if (!drv)
return NULL;
/*
* Note that unlike bdrv_flush the driver is reponsible for flushing a
* backing image if it exists.
*/
return drv->bdrv_aio_flush(bs, cb, opaque);
}
void bdrv_aio_cancel(BlockDriverAIOCB *acb)
{
acb->pool->cancel(acb);
@ -1642,6 +1663,25 @@ static BlockDriverAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
return bdrv_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
}
static BlockDriverAIOCB *bdrv_aio_flush_em(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque)
{
BlockDriverAIOCBSync *acb;
acb = qemu_aio_get(&bdrv_em_aio_pool, bs, cb, opaque);
acb->is_write = 1; /* don't bounce in the completion hadler */
acb->qiov = NULL;
acb->bounce = NULL;
acb->ret = 0;
if (!acb->bh)
acb->bh = qemu_bh_new(bdrv_aio_bh_cb, acb);
bdrv_flush(bs);
qemu_bh_schedule(acb->bh);
return &acb->common;
}
/**************************************************************/
/* sync block device emulation */