Le Friday 17 Jan 2014 à 15:14:59 (+0100), Kevin Wolf a écrit :
> This separates the part of bdrv_co_do_readv() that needs to happen
> before the request is modified to match the backend alignment, and a
> part that needs to be executed afterwards and passes the request to the
> BlockDriver.
>
> Signed-off-by: Kevin Wolf <kw...@redhat.com>
> Reviewed-by: Wenchao Xia <xiaw...@linux.vnet.ibm.com>
> Reviewed-by: Max Reitz <mre...@redhat.com>
> ---
> block.c | 61 +++++++++++++++++++++++++++++++++++++++++++------------------
> 1 file changed, 43 insertions(+), 18 deletions(-)
>
> diff --git a/block.c b/block.c
> index 25ae896..0c2baf5 100644
> --- a/block.c
> +++ b/block.c
> @@ -2705,26 +2705,24 @@ err:
> }
>
> /*
> - * Handle a read request in coroutine context
> + * Forwards an already correctly aligned request to the BlockDriver. This
> + * handles copy on read and zeroing after EOF; any other features must be
> + * implemented by the caller.
> */
> -static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
> - int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
> - BdrvRequestFlags flags)
> +static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
> + int64_t offset, unsigned int bytes, QEMUIOVector *qiov, int flags)
unsigned int bytes <- Would it worth it to make this int64_t or size_t for the
not so far future where 4GB will be the new 4MB ?
Best regards
Benoît
> {
> BlockDriver *drv = bs->drv;
> BdrvTrackedRequest req;
> int ret;
>
> - if (!drv) {
> - return -ENOMEDIUM;
> - }
> - if (bdrv_check_request(bs, sector_num, nb_sectors)) {
> - return -EIO;
> - }
> + int64_t sector_num = offset >> BDRV_SECTOR_BITS;
> + unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;
>
> - if (bs->copy_on_read) {
> - flags |= BDRV_REQ_COPY_ON_READ;
> - }
> + assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
> + assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
> +
> + /* Handle Copy on Read and associated serialisation */
> if (flags & BDRV_REQ_COPY_ON_READ) {
> bs->copy_on_read_in_flight++;
> }
> @@ -2733,11 +2731,6 @@ static int coroutine_fn
> bdrv_co_do_readv(BlockDriverState *bs,
> wait_for_overlapping_requests(bs, sector_num, nb_sectors);
> }
>
> - /* throttling disk I/O */
> - if (bs->io_limits_enabled) {
> - bdrv_io_limits_intercept(bs, nb_sectors, false);
> - }
> -
> tracked_request_begin(&req, bs, sector_num, nb_sectors, false);
>
> if (flags & BDRV_REQ_COPY_ON_READ) {
> @@ -2754,6 +2747,7 @@ static int coroutine_fn
> bdrv_co_do_readv(BlockDriverState *bs,
> }
> }
>
> + /* Forward the request to the BlockDriver */
> if (!(bs->zero_beyond_eof && bs->growable)) {
> ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
> } else {
> @@ -2794,6 +2788,37 @@ out:
> return ret;
> }
>
> +/*
> + * 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,
> + BdrvRequestFlags flags)
> +{
> + BlockDriver *drv = bs->drv;
> + int ret;
> +
> + if (!drv) {
> + return -ENOMEDIUM;
> + }
> + if (bdrv_check_request(bs, sector_num, nb_sectors)) {
> + return -EIO;
> + }
> +
> + if (bs->copy_on_read) {
> + flags |= BDRV_REQ_COPY_ON_READ;
> + }
> +
> + /* throttling disk I/O */
> + if (bs->io_limits_enabled) {
> + bdrv_io_limits_intercept(bs, nb_sectors, false);
> + }
> +
> + ret = bdrv_aligned_preadv(bs, sector_num << BDRV_SECTOR_BITS,
> + nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
> + return ret;
> +}
> +
> int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
> int nb_sectors, QEMUIOVector *qiov)
> {
> --
> 1.8.1.4
>
>
