Commit 68485420 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

block: Emulate AIO functions with bdrv_co_readv/writev 



Use the bdrv_co_readv/writev callbacks to implement bdrv_aio_readv/writev and
bdrv_read/write if a driver provides the coroutine version instead of the
synchronous or AIO version.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent da1fa91d

block.c

+97 −1
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include "block_int.h"

#include "module.h"

#include "qemu-objects.h"

#include "qemu-coroutine.h"



#ifdef CONFIG_BSD

#include <sys/types.h>
@@ -57,6 +58,12 @@ 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,

                         const uint8_t *buf, int nb_sectors);

static BlockDriverAIOCB *bdrv_co_aio_readv_em(BlockDriverState *bs,

        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,

        BlockDriverCompletionFunc *cb, void *opaque);

static BlockDriverAIOCB *bdrv_co_aio_writev_em(BlockDriverState *bs,

        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,

        BlockDriverCompletionFunc *cb, void *opaque);



static QTAILQ_HEAD(, BlockDriverState) bdrv_states =

    QTAILQ_HEAD_INITIALIZER(bdrv_states);
@@ -169,7 +176,13 @@ void path_combine(char *dest, int dest_size, 


void bdrv_register(BlockDriver *bdrv)

{

    if (!bdrv->bdrv_aio_readv) {

    if (bdrv->bdrv_co_readv) {

        /* Emulate AIO by coroutines, and sync by AIO */

        bdrv->bdrv_aio_readv = bdrv_co_aio_readv_em;

        bdrv->bdrv_aio_writev = bdrv_co_aio_writev_em;

        bdrv->bdrv_read = bdrv_read_em;

        bdrv->bdrv_write = bdrv_write_em;

     } else if (!bdrv->bdrv_aio_readv) {

        /* add AIO emulation layer */

        bdrv->bdrv_aio_readv = bdrv_aio_readv_em;

        bdrv->bdrv_aio_writev = bdrv_aio_writev_em;
@@ -2614,6 +2627,89 @@ static BlockDriverAIOCB *bdrv_aio_writev_em(BlockDriverState *bs, 
    return bdrv_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);

}





typedef struct BlockDriverAIOCBCoroutine {

    BlockDriverAIOCB common;

    BlockRequest req;

    bool is_write;

    QEMUBH* bh;

} BlockDriverAIOCBCoroutine;



static void bdrv_aio_co_cancel_em(BlockDriverAIOCB *blockacb)

{

    qemu_aio_flush();

}



static AIOPool bdrv_em_co_aio_pool = {

    .aiocb_size         = sizeof(BlockDriverAIOCBCoroutine),

    .cancel             = bdrv_aio_co_cancel_em,

};



static void bdrv_co_rw_bh(void *opaque)

{

    BlockDriverAIOCBCoroutine *acb = opaque;



    acb->common.cb(acb->common.opaque, acb->req.error);

    qemu_bh_delete(acb->bh);

    qemu_aio_release(acb);

}



static void coroutine_fn bdrv_co_rw(void *opaque)

{

    BlockDriverAIOCBCoroutine *acb = opaque;

    BlockDriverState *bs = acb->common.bs;



    if (!acb->is_write) {

        acb->req.error = bs->drv->bdrv_co_readv(bs, acb->req.sector,

            acb->req.nb_sectors, acb->req.qiov);

    } else {

        acb->req.error = bs->drv->bdrv_co_writev(bs, acb->req.sector,

            acb->req.nb_sectors, acb->req.qiov);

    }



    acb->bh = qemu_bh_new(bdrv_co_rw_bh, acb);

    qemu_bh_schedule(acb->bh);

}



static BlockDriverAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,

                                               int64_t sector_num,

                                               QEMUIOVector *qiov,

                                               int nb_sectors,

                                               BlockDriverCompletionFunc *cb,

                                               void *opaque,

                                               bool is_write)

{

    Coroutine *co;

    BlockDriverAIOCBCoroutine *acb;



    acb = qemu_aio_get(&bdrv_em_co_aio_pool, bs, cb, opaque);

    acb->req.sector = sector_num;

    acb->req.nb_sectors = nb_sectors;

    acb->req.qiov = qiov;

    acb->is_write = is_write;



    co = qemu_coroutine_create(bdrv_co_rw);

    qemu_coroutine_enter(co, acb);



    return &acb->common;

}



static BlockDriverAIOCB *bdrv_co_aio_readv_em(BlockDriverState *bs,

        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,

        BlockDriverCompletionFunc *cb, void *opaque)

{

    return bdrv_co_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque,

                                 false);

}



static BlockDriverAIOCB *bdrv_co_aio_writev_em(BlockDriverState *bs,

        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,

        BlockDriverCompletionFunc *cb, void *opaque)

{

    return bdrv_co_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque,

                                 true);

}



static BlockDriverAIOCB *bdrv_aio_flush_em(BlockDriverState *bs,

        BlockDriverCompletionFunc *cb, void *opaque)

{