block: Introduce bdrv_co_do_preadv()
Similar to bdrv_pread(), which aligns byte-aligned request to 512 byte sectors, bdrv_co_do_preadv() takes a byte-aligned request and aligns it to the alignment specified in bs->request_alignment. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net>
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block.c
64
block.c
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@ -2971,17 +2971,23 @@ out:
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/*
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/*
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* Handle a read request in coroutine context
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* Handle a read request in coroutine context
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*/
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*/
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static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
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static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
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int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
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BdrvRequestFlags flags)
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BdrvRequestFlags flags)
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{
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{
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BlockDriver *drv = bs->drv;
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BlockDriver *drv = bs->drv;
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/* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
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uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
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uint8_t *head_buf = NULL;
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uint8_t *tail_buf = NULL;
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QEMUIOVector local_qiov;
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bool use_local_qiov = false;
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int ret;
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int ret;
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if (!drv) {
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if (!drv) {
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return -ENOMEDIUM;
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return -ENOMEDIUM;
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}
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}
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if (bdrv_check_request(bs, sector_num, nb_sectors)) {
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if (bdrv_check_byte_request(bs, offset, bytes)) {
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return -EIO;
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return -EIO;
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}
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}
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@ -2991,14 +2997,60 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
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/* throttling disk I/O */
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/* throttling disk I/O */
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if (bs->io_limits_enabled) {
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if (bs->io_limits_enabled) {
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bdrv_io_limits_intercept(bs, nb_sectors, false);
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/* TODO Switch to byte granularity */
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bdrv_io_limits_intercept(bs, bytes >> BDRV_SECTOR_BITS, false);
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}
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/* Align read if necessary by padding qiov */
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if (offset & (align - 1)) {
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head_buf = qemu_blockalign(bs, align);
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qemu_iovec_init(&local_qiov, qiov->niov + 2);
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qemu_iovec_add(&local_qiov, head_buf, offset & (align - 1));
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qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
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use_local_qiov = true;
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bytes += offset & (align - 1);
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offset = offset & ~(align - 1);
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}
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if ((offset + bytes) & (align - 1)) {
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if (!use_local_qiov) {
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qemu_iovec_init(&local_qiov, qiov->niov + 1);
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qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size);
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use_local_qiov = true;
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}
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tail_buf = qemu_blockalign(bs, align);
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qemu_iovec_add(&local_qiov, tail_buf,
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align - ((offset + bytes) & (align - 1)));
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bytes = ROUND_UP(bytes, align);
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}
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ret = bdrv_aligned_preadv(bs, offset, bytes,
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use_local_qiov ? &local_qiov : qiov,
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flags);
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if (use_local_qiov) {
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qemu_iovec_destroy(&local_qiov);
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qemu_vfree(head_buf);
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qemu_vfree(tail_buf);
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}
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}
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ret = bdrv_aligned_preadv(bs, sector_num << BDRV_SECTOR_BITS,
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nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
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return ret;
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return ret;
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}
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}
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static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
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BdrvRequestFlags flags)
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{
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if (nb_sectors < 0 || nb_sectors > (UINT_MAX >> BDRV_SECTOR_BITS)) {
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return -EINVAL;
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}
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return bdrv_co_do_preadv(bs, sector_num << BDRV_SECTOR_BITS,
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nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
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}
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int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
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int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
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int nb_sectors, QEMUIOVector *qiov)
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int nb_sectors, QEMUIOVector *qiov)
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{
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{
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