Commit 4eea78e6 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Kevin Wolf
Browse files

vdi: do not create useless iovecs 



Reads and writes to the underlying file can also occur with the simple
non-vectored I/O interfaces.

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 a7a43aa1

block/vdi.c

+33 −46
Original line number Diff line number Diff line
@@ -474,8 +474,6 @@ static int vdi_co_read(BlockDriverState *bs, 
    uint32_t block_index;

    uint32_t sector_in_block;

    uint32_t n_sectors;

    struct iovec hd_iov;

    QEMUIOVector hd_qiov;

    int ret;



    logout("\n");
@@ -501,10 +499,7 @@ 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 *)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);

        ret = bdrv_read(bs->file, offset, buf, n_sectors);

    }

    logout("%u sectors read\n", n_sectors);
@@ -529,8 +524,6 @@ static int vdi_co_write(BlockDriverState *bs, 
    uint32_t n_sectors;

    uint32_t bmap_first = VDI_UNALLOCATED;

    uint32_t bmap_last = VDI_UNALLOCATED;

    struct iovec hd_iov;

    QEMUIOVector hd_qiov;

    uint8_t *block = NULL;

    int ret;
@@ -568,18 +561,12 @@ restart: 
               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;

        hd_iov.iov_len = s->block_size;

        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);

        ret = bdrv_co_writev(bs->file, offset, s->block_sectors, &hd_qiov);

        ret = bdrv_write(bs->file, offset, block, s->block_sectors);

    } 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 *)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);

        ret = bdrv_write(bs->file, offset, buf, n_sectors);

    }



    nb_sectors -= n_sectors;
@@ -592,24 +579,28 @@ restart: 
    }



    logout("finished data write\n");

    if (ret >= 0) {

        ret = 0;

    if (ret < 0) {

        return ret;

    }



    if (block) {

        /* One or more new blocks were allocated. */

        VdiHeader *header = (VdiHeader *) block;

        uint8_t *base;

        uint64_t offset;



        logout("now writing modified header\n");

        assert(VDI_IS_ALLOCATED(bmap_first));

        *header = s->header;

        vdi_header_to_le(header);

            hd_iov.iov_base = block;

            hd_iov.iov_len = SECTOR_SIZE;

            qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);

            ret = bdrv_co_writev(bs->file, 0, 1, &hd_qiov);

        }

        ret = bdrv_write(bs->file, 0, block, 1);

        g_free(block);

        block = NULL;

        if (ret >= 0 && VDI_IS_ALLOCATED(bmap_first)) {

            /* One or more new blocks were allocated. */

            uint64_t offset;



        if (ret < 0) {

            return ret;

        }



        logout("now writing modified block map entry %u...%u\n",

               bmap_first, bmap_last);

        /* Write modified sectors from block map. */
@@ -617,14 +608,10 @@ restart: 
        bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));

        n_sectors = bmap_last - bmap_first + 1;

        offset = s->bmap_sector + bmap_first;

            hd_iov.iov_base = (void *)((uint8_t *)&s->bmap[0] +

                                            bmap_first * SECTOR_SIZE);

            hd_iov.iov_len = n_sectors * SECTOR_SIZE;

            qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);

        base = ((uint8_t *)&s->bmap[0]) + bmap_first * SECTOR_SIZE;

        logout("will write %u block map sectors starting from entry %u\n",

               n_sectors, bmap_first);

            ret = bdrv_co_writev(bs->file, offset, n_sectors, &hd_qiov);

        }

        ret = bdrv_write(bs->file, offset, base, n_sectors);

    }



    return ret;