Commit 98764152 authored by Peter Lieven's avatar Peter Lieven Committed by Kevin Wolf
Browse files

block: change default for discard and write zeroes to INT_MAX 



do not trim requests if the driver does not supply a limit
through BlockLimits. For write zeroes we still keep a limit
for the unsupported path to avoid allocating a big bounce buffer.

Suggested-by: default avatarKevin Wolf <kwolf@redhat.com>
Suggested-by: default avatarDenis V. Lunev <den@openvz.org>
Signed-off-by: default avatarPeter Lieven <pl@kamp.de>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 1cdc3239

block.c

+4 −12
Original line number Diff line number Diff line
@@ -3192,10 +3192,7 @@ int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, 
                            BDRV_REQ_COPY_ON_READ);

}



/* if no limit is specified in the BlockLimits use a default

 * of 32768 512-byte sectors (16 MiB) per request.

 */

#define MAX_WRITE_ZEROES_DEFAULT 32768

#define MAX_WRITE_ZEROES_BOUNCE_BUFFER 32768



static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,

    int64_t sector_num, int nb_sectors, BdrvRequestFlags flags)
@@ -3206,7 +3203,7 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs, 
    int ret = 0;



    int max_write_zeroes = bs->bl.max_write_zeroes ?

                           bs->bl.max_write_zeroes : MAX_WRITE_ZEROES_DEFAULT;

                           bs->bl.max_write_zeroes : INT_MAX;



    while (nb_sectors > 0 && !ret) {

        int num = nb_sectors;
@@ -3242,7 +3239,7 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs, 
        if (ret == -ENOTSUP) {

            /* Fall back to bounce buffer if write zeroes is unsupported */

            int max_xfer_len = MIN_NON_ZERO(bs->bl.max_transfer_length,

                                            MAX_WRITE_ZEROES_DEFAULT);

                                            MAX_WRITE_ZEROES_BOUNCE_BUFFER);

            num = MIN(num, max_xfer_len);

            iov.iov_len = num * BDRV_SECTOR_SIZE;

            if (iov.iov_base == NULL) {
@@ -5097,11 +5094,6 @@ static void coroutine_fn bdrv_discard_co_entry(void *opaque) 
    rwco->ret = bdrv_co_discard(rwco->bs, rwco->sector_num, rwco->nb_sectors);

}



/* if no limit is specified in the BlockLimits use a default

 * of 32768 512-byte sectors (16 MiB) per request.

 */

#define MAX_DISCARD_DEFAULT 32768



int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,

                                 int nb_sectors)

{
@@ -5126,7 +5118,7 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num, 
        return 0;

    }



    max_discard = bs->bl.max_discard ?  bs->bl.max_discard : MAX_DISCARD_DEFAULT;

    max_discard = bs->bl.max_discard ?  bs->bl.max_discard : INT_MAX;

    while (nb_sectors > 0) {

        int ret;

        int num = nb_sectors;