Commit b2e12bc6 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Anthony Liguori
Browse files

block: add aio_flush operation 



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: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent 6f1953c4

block.c

+40 −0
Original line number Diff line number Diff line
@@ -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 */

block.h

+2 −0
Original line number Diff line number Diff line
@@ -85,6 +85,8 @@ BlockDriverAIOCB *bdrv_aio_readv(BlockDriverState *bs, int64_t sector_num, 
BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num,

                                  QEMUIOVector *iov, int nb_sectors,

                                  BlockDriverCompletionFunc *cb, void *opaque);

BlockDriverAIOCB *bdrv_aio_flush(BlockDriverState *bs,

				 BlockDriverCompletionFunc *cb, void *opaque);

void bdrv_aio_cancel(BlockDriverAIOCB *acb);



typedef struct BlockRequest {

block/raw-posix-aio.h

+2 −1
Original line number Diff line number Diff line
@@ -17,8 +17,9 @@ 
#define QEMU_AIO_READ         0x0001

#define QEMU_AIO_WRITE        0x0002

#define QEMU_AIO_IOCTL        0x0004

#define QEMU_AIO_FLUSH        0x0008

#define QEMU_AIO_TYPE_MASK \

	(QEMU_AIO_READ|QEMU_AIO_WRITE|QEMU_AIO_IOCTL)

	(QEMU_AIO_READ|QEMU_AIO_WRITE|QEMU_AIO_IOCTL|QEMU_AIO_FLUSH)



/* AIO flags */

#define QEMU_AIO_MISALIGNED   0x1000

block/raw-posix.c

+17 −0
Original line number Diff line number Diff line
@@ -574,6 +574,18 @@ static BlockDriverAIOCB *raw_aio_writev(BlockDriverState *bs, 
                          cb, opaque, QEMU_AIO_WRITE);

}



static BlockDriverAIOCB *raw_aio_flush(BlockDriverState *bs,

        BlockDriverCompletionFunc *cb, void *opaque)

{

    BDRVRawState *s = bs->opaque;



    if (fd_open(bs) < 0)

        return NULL;



    return paio_submit(bs, s->aio_ctx, s->fd, 0, NULL, 0,

    		       cb, opaque, QEMU_AIO_FLUSH);

}



static void raw_close(BlockDriverState *bs)

{

    BDRVRawState *s = bs->opaque;
@@ -749,6 +761,7 @@ static BlockDriver bdrv_raw = { 


    .bdrv_aio_readv = raw_aio_readv,

    .bdrv_aio_writev = raw_aio_writev,

    .bdrv_aio_flush = raw_aio_flush,



    .bdrv_truncate = raw_truncate,

    .bdrv_getlength = raw_getlength,
@@ -1002,6 +1015,7 @@ static BlockDriver bdrv_host_device = { 


    .bdrv_aio_readv	= raw_aio_readv,

    .bdrv_aio_writev	= raw_aio_writev,

    .bdrv_aio_flush	= raw_aio_flush,



    .bdrv_read          = raw_read,

    .bdrv_write         = raw_write,
@@ -1096,6 +1110,7 @@ static BlockDriver bdrv_host_floppy = { 


    .bdrv_aio_readv     = raw_aio_readv,

    .bdrv_aio_writev    = raw_aio_writev,

    .bdrv_aio_flush	= raw_aio_flush,



    .bdrv_read          = raw_read,

    .bdrv_write         = raw_write,
@@ -1176,6 +1191,7 @@ static BlockDriver bdrv_host_cdrom = { 


    .bdrv_aio_readv     = raw_aio_readv,

    .bdrv_aio_writev    = raw_aio_writev,

    .bdrv_aio_flush	= raw_aio_flush,



    .bdrv_read          = raw_read,

    .bdrv_write         = raw_write,
@@ -1295,6 +1311,7 @@ static BlockDriver bdrv_host_cdrom = { 


    .bdrv_aio_readv     = raw_aio_readv,

    .bdrv_aio_writev    = raw_aio_writev,

    .bdrv_aio_flush	= raw_aio_flush,



    .bdrv_read          = raw_read,

    .bdrv_write         = raw_write,

block_int.h

+2 −0
Original line number Diff line number Diff line
@@ -69,6 +69,8 @@ struct BlockDriver { 
    BlockDriverAIOCB *(*bdrv_aio_writev)(BlockDriverState *bs,

        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,

        BlockDriverCompletionFunc *cb, void *opaque);

    BlockDriverAIOCB *(*bdrv_aio_flush)(BlockDriverState *bs,

        BlockDriverCompletionFunc *cb, void *opaque);



    int (*bdrv_aio_multiwrite)(BlockDriverState *bs, BlockRequest *reqs,

        int num_reqs);