Commit 65afd211 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

block: Allow waiting for overlapping requests between begin/end 



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: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarMax Reitz <mreitz@redhat.com>
Reviewed-by: default avatarBenoit Canet <benoit@irqsave.net>
parent 793ed47a

block.c

+20 −18
Original line number Diff line number Diff line
@@ -2286,7 +2286,7 @@ 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;
@@ -2304,6 +2304,9 @@ 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
@@ -2906,10 +2909,10 @@ 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;
@@ -2924,11 +2927,9 @@ 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;
@@ -2975,8 +2976,6 @@ 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--;

    }
@@ -2992,6 +2991,8 @@ 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;
@@ -3042,9 +3043,11 @@ 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);
@@ -3163,10 +3166,10 @@ 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;
@@ -3176,12 +3179,10 @@ 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 */
@@ -3204,8 +3205,6 @@ 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;

}
@@ -3216,6 +3215,7 @@ 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) {
@@ -3234,7 +3234,9 @@ 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;

}