Le Friday 17 Jan 2014 à 15:15:05 (+0100), Kevin Wolf a écrit :
> Previously, it was not possible to use wait_for_overlapping_requests()
> between tracked_request_begin()/end() because it would wait for itself.
>
> Ignore the current request in the overlap check and run more of the
> bdrv_co_do_preadv/pwritev code with a BdrvTrackedRequest present.
>
> Signed-off-by: Kevin Wolf <kw...@redhat.com>
> Reviewed-by: Max Reitz <mre...@redhat.com>
> ---
> block.c | 38 ++++++++++++++++++++------------------
> 1 file changed, 20 insertions(+), 18 deletions(-)
>
> diff --git a/block.c b/block.c
> index 85f28ab..18dcd43 100644
> --- a/block.c
> +++ b/block.c
> @@ -2106,7 +2106,7 @@ static bool tracked_request_overlaps(BdrvTrackedRequest
> *req,
> }
>
> static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs,
> - int64_t offset, unsigned int bytes)
> + BdrvTrackedRequest *self, int64_t offset, unsigned int bytes)
> {
> BdrvTrackedRequest *req;
> int64_t cluster_offset;
> @@ -2124,6 +2124,9 @@ static void coroutine_fn
> wait_for_overlapping_requests(BlockDriverState *bs,
> do {
> retry = false;
> QLIST_FOREACH(req, &bs->tracked_requests, list) {
> + if (req == self) {
> + continue;
> + }
> if (tracked_request_overlaps(req, cluster_offset,
> cluster_bytes)) {
> /* Hitting this means there was a reentrant request, for
> * example, a block driver issuing nested requests. This
> must
> @@ -2726,10 +2729,10 @@ err:
> * implemented by the caller.
> */
> static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
> - int64_t offset, unsigned int bytes, QEMUIOVector *qiov, int flags)
> + BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
> + QEMUIOVector *qiov, int flags)
> {
> BlockDriver *drv = bs->drv;
> - BdrvTrackedRequest req;
> int ret;
>
> int64_t sector_num = offset >> BDRV_SECTOR_BITS;
> @@ -2744,11 +2747,9 @@ static int coroutine_fn
> bdrv_aligned_preadv(BlockDriverState *bs,
> }
>
> if (bs->copy_on_read_in_flight) {
> - wait_for_overlapping_requests(bs, offset, bytes);
> + wait_for_overlapping_requests(bs, req, offset, bytes);
> }
>
> - tracked_request_begin(&req, bs, offset, bytes, false);
> -
> if (flags & BDRV_REQ_COPY_ON_READ) {
> int pnum;
>
> @@ -2795,8 +2796,6 @@ static int coroutine_fn
> bdrv_aligned_preadv(BlockDriverState *bs,
> }
>
> out:
> - tracked_request_end(&req);
> -
> if (flags & BDRV_REQ_COPY_ON_READ) {
> bs->copy_on_read_in_flight--;
> }
> @@ -2812,6 +2811,8 @@ static int coroutine_fn
> bdrv_co_do_preadv(BlockDriverState *bs,
> BdrvRequestFlags flags)
> {
> BlockDriver *drv = bs->drv;
> + BdrvTrackedRequest req;
> +
> /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
> uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
> uint8_t *head_buf = NULL;
> @@ -2862,9 +2863,11 @@ static int coroutine_fn
> bdrv_co_do_preadv(BlockDriverState *bs,
> bytes = ROUND_UP(bytes, align);
> }
>
> - ret = bdrv_aligned_preadv(bs, offset, bytes,
> + tracked_request_begin(&req, bs, offset, bytes, false);
> + ret = bdrv_aligned_preadv(bs, &req, offset, bytes,
> use_local_qiov ? &local_qiov : qiov,
> flags);
> + tracked_request_end(&req);
>
> if (use_local_qiov) {
> qemu_iovec_destroy(&local_qiov);
> @@ -2983,10 +2986,10 @@ static int coroutine_fn
> bdrv_co_do_write_zeroes(BlockDriverState *bs,
> * Forwards an already correctly aligned write request to the BlockDriver.
> */
> static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
> - int64_t offset, unsigned int bytes, QEMUIOVector *qiov, int flags)
> + BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
> + QEMUIOVector *qiov, int flags)
> {
> BlockDriver *drv = bs->drv;
> - BdrvTrackedRequest req;
> int ret;
>
> int64_t sector_num = offset >> BDRV_SECTOR_BITS;
> @@ -2996,12 +2999,10 @@ static int coroutine_fn
> bdrv_aligned_pwritev(BlockDriverState *bs,
> assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
>
> if (bs->copy_on_read_in_flight) {
> - wait_for_overlapping_requests(bs, offset, bytes);
> + wait_for_overlapping_requests(bs, req, offset, bytes);
> }
>
> - tracked_request_begin(&req, bs, offset, bytes, true);
> -
> - ret = notifier_with_return_list_notify(&bs->before_write_notifiers,
> &req);
> + ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req);
>
> if (ret < 0) {
> /* Do nothing, write notifier decided to fail this request */
> @@ -3024,8 +3025,6 @@ static int coroutine_fn
> bdrv_aligned_pwritev(BlockDriverState *bs,
> bs->total_sectors = MAX(bs->total_sectors, sector_num + nb_sectors);
> }
>
> - tracked_request_end(&req);
> -
> return ret;
> }
>
> @@ -3036,6 +3035,7 @@ static int coroutine_fn
> bdrv_co_do_pwritev(BlockDriverState *bs,
> int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
> BdrvRequestFlags flags)
> {
> + BdrvTrackedRequest req;
> int ret;
>
> if (!bs->drv) {
> @@ -3054,7 +3054,9 @@ static int coroutine_fn
> bdrv_co_do_pwritev(BlockDriverState *bs,
> bdrv_io_limits_intercept(bs, bytes >> BDRV_SECTOR_BITS, true);
> }
>
> - ret = bdrv_aligned_pwritev(bs, offset, bytes, qiov, flags);
> + tracked_request_begin(&req, bs, offset, bytes, true);
> + ret = bdrv_aligned_pwritev(bs, &req, offset, bytes, qiov, flags);
> + tracked_request_end(&req);
>
> return ret;
> }
> --
> 1.8.1.4
>
>
Reviewed-by: Benoit Canet <ben...@irqsave.net>
