diff options
| -rw-r--r-- | block.c | 64 |
1 files changed, 58 insertions, 6 deletions
@@ -2971,17 +2971,23 @@ out: /* * Handle a read request in coroutine context */ -static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, - int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, +static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs, + int64_t offset, unsigned int bytes, QEMUIOVector *qiov, BdrvRequestFlags flags) { BlockDriver *drv = bs->drv; + /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */ + uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment); + uint8_t *head_buf = NULL; + uint8_t *tail_buf = NULL; + QEMUIOVector local_qiov; + bool use_local_qiov = false; int ret; if (!drv) { return -ENOMEDIUM; } - if (bdrv_check_request(bs, sector_num, nb_sectors)) { + if (bdrv_check_byte_request(bs, offset, bytes)) { return -EIO; } @@ -2991,14 +2997,60 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, /* throttling disk I/O */ if (bs->io_limits_enabled) { - bdrv_io_limits_intercept(bs, nb_sectors, false); + /* TODO Switch to byte granularity */ + bdrv_io_limits_intercept(bs, bytes >> BDRV_SECTOR_BITS, false); + } + + /* Align read if necessary by padding qiov */ + if (offset & (align - 1)) { + head_buf = qemu_blockalign(bs, align); + qemu_iovec_init(&local_qiov, qiov->niov + 2); + qemu_iovec_add(&local_qiov, head_buf, offset & (align - 1)); + qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size); + use_local_qiov = true; + + bytes += offset & (align - 1); + offset = offset & ~(align - 1); + } + + if ((offset + bytes) & (align - 1)) { + if (!use_local_qiov) { + qemu_iovec_init(&local_qiov, qiov->niov + 1); + qemu_iovec_concat(&local_qiov, qiov, 0, qiov->size); + use_local_qiov = true; + } + tail_buf = qemu_blockalign(bs, align); + qemu_iovec_add(&local_qiov, tail_buf, + align - ((offset + bytes) & (align - 1))); + + bytes = ROUND_UP(bytes, align); + } + + ret = bdrv_aligned_preadv(bs, offset, bytes, + use_local_qiov ? &local_qiov : qiov, + flags); + + if (use_local_qiov) { + qemu_iovec_destroy(&local_qiov); + qemu_vfree(head_buf); + qemu_vfree(tail_buf); } - ret = bdrv_aligned_preadv(bs, sector_num << BDRV_SECTOR_BITS, - nb_sectors << BDRV_SECTOR_BITS, qiov, flags); return ret; } +static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, + BdrvRequestFlags flags) +{ + if (nb_sectors < 0 || nb_sectors > (UINT_MAX >> BDRV_SECTOR_BITS)) { + return -EINVAL; + } + + return bdrv_co_do_preadv(bs, sector_num << BDRV_SECTOR_BITS, + nb_sectors << BDRV_SECTOR_BITS, qiov, flags); +} + int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { |