Commit a7a43aa1 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Kevin Wolf
Browse files

vdi: leave bounce buffering to block layer 



vdi.c really works as if it implemented bdrv_read and bdrv_write.  However,
because only vector I/O is supported by the asynchronous callbacks, it
went through extra pain to bounce-buffer the I/O.  This can be handled
by the block layer now that the format is coroutine-based.

Acked-by: default avatarStefan Weil <sw@weilnetz.de>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent bfc45fc1

block/vdi.c

+12 −55
Original line number Diff line number Diff line
@@ -143,12 +143,6 @@ void uuid_unparse(const uuid_t uu, char *out) 
}

#endif



typedef struct {

    BlockDriverAIOCB common;

    uint8_t *buf;

    void *orig_buf;

} VdiAIOCB;



typedef struct {

    char text[0x40];

    uint32_t signature;
@@ -472,31 +466,9 @@ static int coroutine_fn vdi_co_is_allocated(BlockDriverState *bs, 
    return VDI_IS_ALLOCATED(bmap_entry);

}



static AIOPool vdi_aio_pool = {

    .aiocb_size = sizeof(VdiAIOCB),

};



static VdiAIOCB *vdi_aio_setup(BlockDriverState *bs, QEMUIOVector *qiov)

static int vdi_co_read(BlockDriverState *bs,

        int64_t sector_num, uint8_t *buf, int nb_sectors)

{

    VdiAIOCB *acb;



    logout("%p, %p\n", bs, qiov);



    acb = qemu_aio_get(&vdi_aio_pool, bs, NULL, NULL);



    if (qiov->niov > 1) {

        acb->buf = qemu_blockalign(bs, qiov->size);

        acb->orig_buf = acb->buf;

    } else {

        acb->buf = (uint8_t *)qiov->iov->iov_base;

    }

    return acb;

}



static int vdi_co_readv(BlockDriverState *bs,

        int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)

{

    VdiAIOCB *acb;

    BDRVVdiState *s = bs->opaque;

    uint32_t bmap_entry;

    uint32_t block_index;
@@ -507,7 +479,6 @@ static int vdi_co_readv(BlockDriverState *bs, 
    int ret;



    logout("\n");

    acb = vdi_aio_setup(bs, qiov);



restart:

    block_index = sector_num / s->block_sectors;
@@ -524,13 +495,13 @@ restart: 
    bmap_entry = le32_to_cpu(s->bmap[block_index]);

    if (!VDI_IS_ALLOCATED(bmap_entry)) {

        /* Block not allocated, return zeros, no need to wait. */

        memset(acb->buf, 0, n_sectors * SECTOR_SIZE);

        memset(buf, 0, n_sectors * SECTOR_SIZE);

        ret = 0;

    } else {

        uint64_t offset = s->header.offset_data / SECTOR_SIZE +

                          (uint64_t)bmap_entry * s->block_sectors +

                          sector_in_block;

        hd_iov.iov_base = (void *)acb->buf;

        hd_iov.iov_base = (void *)buf;

        hd_iov.iov_len = n_sectors * SECTOR_SIZE;

        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);

        ret = bdrv_co_readv(bs->file, offset, n_sectors, &hd_qiov);
@@ -539,24 +510,18 @@ restart: 


    nb_sectors -= n_sectors;

    sector_num += n_sectors;

    acb->buf += n_sectors * SECTOR_SIZE;

    buf += n_sectors * SECTOR_SIZE;



    if (ret >= 0 && nb_sectors > 0) {

        goto restart;

    }



    if (acb->orig_buf) {

        qemu_iovec_from_buffer(qiov, acb->orig_buf, qiov->size);

        qemu_vfree(acb->orig_buf);

    }

    qemu_aio_release(acb);

    return ret;

}



static int vdi_co_writev(BlockDriverState *bs,

        int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)

static int vdi_co_write(BlockDriverState *bs,

        int64_t sector_num, const uint8_t *buf, int nb_sectors)

{

    VdiAIOCB *acb;

    BDRVVdiState *s = bs->opaque;

    uint32_t bmap_entry;

    uint32_t block_index;
@@ -570,10 +535,6 @@ static int vdi_co_writev(BlockDriverState *bs, 
    int ret;



    logout("\n");

    acb = vdi_aio_setup(bs, qiov);

    if (acb->orig_buf) {

        qemu_iovec_to_buffer(qiov, acb->buf);

    }



restart:

    block_index = sector_num / s->block_sectors;
@@ -604,7 +565,7 @@ restart: 
        /* Copy data to be written to new block and zero unused parts. */

        memset(block, 0, sector_in_block * SECTOR_SIZE);

        memcpy(block + sector_in_block * SECTOR_SIZE,

               acb->buf, n_sectors * SECTOR_SIZE);

               buf, n_sectors * SECTOR_SIZE);

        memset(block + (sector_in_block + n_sectors) * SECTOR_SIZE, 0,

               (s->block_sectors - n_sectors - sector_in_block) * SECTOR_SIZE);

        hd_iov.iov_base = (void *)block;
@@ -615,7 +576,7 @@ restart: 
        uint64_t offset = s->header.offset_data / SECTOR_SIZE +

                          (uint64_t)bmap_entry * s->block_sectors +

                          sector_in_block;

        hd_iov.iov_base = (void *)acb->buf;

        hd_iov.iov_base = (void *)buf;

        hd_iov.iov_len = n_sectors * SECTOR_SIZE;

        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);

        ret = bdrv_co_writev(bs->file, offset, n_sectors, &hd_qiov);
@@ -623,7 +584,7 @@ restart: 


    nb_sectors -= n_sectors;

    sector_num += n_sectors;

    acb->buf += n_sectors * SECTOR_SIZE;

    buf += n_sectors * SECTOR_SIZE;



    logout("%u sectors written\n", n_sectors);

    if (ret >= 0 && nb_sectors > 0) {
@@ -666,10 +627,6 @@ restart: 
        }

    }



    if (acb->orig_buf) {

        qemu_vfree(acb->orig_buf);

    }

    qemu_aio_release(acb);

    return ret;

}
@@ -821,9 +778,9 @@ static BlockDriver bdrv_vdi = { 
    .bdrv_co_is_allocated = vdi_co_is_allocated,

    .bdrv_make_empty = vdi_make_empty,



    .bdrv_co_readv = vdi_co_readv,

    .bdrv_read = vdi_co_read,

#if defined(CONFIG_VDI_WRITE)

    .bdrv_co_writev = vdi_co_writev,

    .bdrv_write = vdi_co_write,

#endif



    .bdrv_get_info = vdi_get_info,