Commit 1bf1cbc9 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

block: Use blk_co_preadv() for blk_read() 



This patch introduces blk_co_preadv() as a central function on the
BlockBackend level that is supposed to handle all read requests from the
BB to its root BDS eventually.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent f21d96d0

block/block-backend.c

+60 −4
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ 
/* Number of coroutines to reserve per attached device model */

#define COROUTINE_POOL_RESERVATION 64



#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */



static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb);



struct BlockBackend {
@@ -693,15 +695,69 @@ static int blk_check_request(BlockBackend *blk, int64_t sector_num, 
                                  nb_sectors * BDRV_SECTOR_SIZE);

}



int blk_read(BlockBackend *blk, int64_t sector_num, uint8_t *buf,

             int nb_sectors)

static int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,

                                      unsigned int bytes, QEMUIOVector *qiov,

                                      BdrvRequestFlags flags)

{

    int ret = blk_check_request(blk, sector_num, nb_sectors);

    int ret = blk_check_byte_request(blk, offset, bytes);

    if (ret < 0) {

        return ret;

    }



    return bdrv_read(blk_bs(blk), sector_num, buf, nb_sectors);

    return bdrv_co_do_preadv(blk_bs(blk), offset, bytes, qiov, flags);

}



typedef struct BlkRwCo {

    BlockBackend *blk;

    int64_t offset;

    QEMUIOVector *qiov;

    int ret;

    BdrvRequestFlags flags;

} BlkRwCo;



static void blk_read_entry(void *opaque)

{

    BlkRwCo *rwco = opaque;



    rwco->ret = blk_co_preadv(rwco->blk, rwco->offset, rwco->qiov->size,

                              rwco->qiov, rwco->flags);

}



int blk_read(BlockBackend *blk, int64_t sector_num, uint8_t *buf,

             int nb_sectors)

{

    AioContext *aio_context;

    QEMUIOVector qiov;

    struct iovec iov;

    Coroutine *co;

    BlkRwCo rwco;



    if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {

        return -EINVAL;

    }



    iov = (struct iovec) {

        .iov_base = buf,

        .iov_len = nb_sectors * BDRV_SECTOR_SIZE,

    };

    qemu_iovec_init_external(&qiov, &iov, 1);



    rwco = (BlkRwCo) {

        .blk    = blk,

        .offset = sector_num << BDRV_SECTOR_BITS,

        .qiov   = &qiov,

        .ret    = NOT_DONE,

    };



    co = qemu_coroutine_create(blk_read_entry);

    qemu_coroutine_enter(co, &rwco);



    aio_context = blk_get_aio_context(blk);

    while (rwco.ret == NOT_DONE) {

        aio_poll(aio_context, true);

    }



    return rwco.ret;

}



int blk_read_unthrottled(BlockBackend *blk, int64_t sector_num, uint8_t *buf,

block/io.c

+1 −4
Original line number Diff line number Diff line
@@ -44,9 +44,6 @@ static int coroutine_fn bdrv_co_readv_em(BlockDriverState *bs, 
static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,

                                         int64_t sector_num, int nb_sectors,

                                         QEMUIOVector *iov);

static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,

    int64_t offset, unsigned int bytes, QEMUIOVector *qiov,

    BdrvRequestFlags flags);

static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,

    int64_t offset, unsigned int bytes, QEMUIOVector *qiov,

    BdrvRequestFlags flags);
@@ -939,7 +936,7 @@ out: 
/*

 * Handle a read request in coroutine context

 */

static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,

int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,

    int64_t offset, unsigned int bytes, QEMUIOVector *qiov,

    BdrvRequestFlags flags)

{

include/block/block_int.h

+4 −0
Original line number Diff line number Diff line
@@ -508,6 +508,10 @@ extern BlockDriver bdrv_qcow2; 
 */

void bdrv_setup_io_funcs(BlockDriver *bdrv);



int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,

    int64_t offset, unsigned int bytes, QEMUIOVector *qiov,

    BdrvRequestFlags flags);



int get_tmp_filename(char *filename, int size);

BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,

                            const char *filename);