Re: [Qemu-devel] [PATCH v3 11/29] block: Introduce bdrv_aligned_pwritev()

[Benoît Canet]

Le Friday 17 Jan 2014 à 15:15:01 (+0100), Kevin Wolf a écrit :
> This separates the part of bdrv_co_do_writev() 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 <address@hidden>
> Reviewed-by: Max Reitz <address@hidden>
> ---
>  block.c | 62 +++++++++++++++++++++++++++++++++++++++++---------------------
>  1 file changed, 41 insertions(+), 21 deletions(-)
> 
> diff --git a/block.c b/block.c
> index f378a10..70b72f0 100644
> --- a/block.c
> +++ b/block.c
> @@ -2964,34 +2964,20 @@ static int coroutine_fn 
> bdrv_co_do_write_zeroes(BlockDriverState *bs,
>  }
>  
>  /*
> - * Handle a write request in coroutine context
> + * Forwards an already correctly aligned write request to the BlockDriver.
>   */
> -static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
> -    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
> -    BdrvRequestFlags flags)
> +static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
> +    int64_t offset, unsigned int bytes, QEMUIOVector *qiov, int flags)
>  {
>      BlockDriver *drv = bs->drv;
>      BdrvTrackedRequest req;
>      int ret;
>  
> -    if (!bs->drv) {
> -        return -ENOMEDIUM;
> -    }
> -    if (bs->read_only) {
> -        return -EACCES;
> -    }
> -    if (bdrv_check_request(bs, sector_num, nb_sectors)) {
> -        return -EIO;
> -    }
> -
> -    if (bs->copy_on_read_in_flight) {
> -        wait_for_overlapping_requests(bs, sector_num, nb_sectors);
> -    }
> +    int64_t sector_num = offset >> BDRV_SECTOR_BITS;
> +    unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;
>  
> -    /* throttling disk I/O */
> -    if (bs->io_limits_enabled) {
> -        bdrv_io_limits_intercept(bs, nb_sectors, true);
> -    }
> +    assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
> +    assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
>  
>      tracked_request_begin(&req, bs, sector_num, nb_sectors, true);
>  
> @@ -3023,6 +3009,40 @@ static int coroutine_fn 
> bdrv_co_do_writev(BlockDriverState *bs,
>      return ret;
>  }
>  
> +/*
> + * Handle a write request in coroutine context
> + */
> +static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
> +    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
> +    BdrvRequestFlags flags)
> +{
> +    int ret;
> +
> +    if (!bs->drv) {
> +        return -ENOMEDIUM;
> +    }
> +    if (bs->read_only) {
> +        return -EACCES;
> +    }
> +    if (bdrv_check_request(bs, sector_num, nb_sectors)) {
> +        return -EIO;
> +    }
> +
> +    if (bs->copy_on_read_in_flight) {
> +        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, true);
> +    }
> +
> +    ret = bdrv_aligned_pwritev(bs, sector_num << BDRV_SECTOR_BITS,
> +                               nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
> +
> +    return ret;
> +}
> +
>  int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num,
>      int nb_sectors, QEMUIOVector *qiov)
>  {
> -- 
> 1.8.1.4
> 
> 

Reviewed-by: Benoit Canet <address@hidden>