We are gradually moving away from sector-based interfaces, towards byte-based. Make the change for the last few sector-based callbacks in the null-co and null-aio drivers.
Note that since the null driver does nothing on writes, it trivially supports the BDRV_REQ_FUA flag (all writes have already landed to the same bit-bucket without needing an extra flush call). Furthermore, bdrv_refresh_limits() defaults the block size to 512 for any driver that does not support coroutines; while this is still correct for the other aio-based drivers, the null driver does just as well with byte-based requests, and being explicit means we can avoid cycles wasted on read-modify-write. Signed-off-by: Eric Blake <ebl...@redhat.com> --- block/null.c | 66 ++++++++++++++++++++++++++++++++++-------------------------- 1 file changed, 37 insertions(+), 29 deletions(-) diff --git a/block/null.c b/block/null.c index 806a8631e4d..2381090dfcf 100644 --- a/block/null.c +++ b/block/null.c @@ -93,6 +93,7 @@ static int null_file_open(BlockDriverState *bs, QDict *options, int flags, } s->read_zeroes = qemu_opt_get_bool(opts, NULL_OPT_ZEROES, false); qemu_opts_del(opts); + bs->supported_write_flags = BDRV_REQ_FUA; return ret; } @@ -116,22 +117,22 @@ static coroutine_fn int null_co_common(BlockDriverState *bs) return 0; } -static coroutine_fn int null_co_readv(BlockDriverState *bs, - int64_t sector_num, int nb_sectors, - QEMUIOVector *qiov) +static coroutine_fn int null_co_preadv(BlockDriverState *bs, + uint64_t offset, uint64_t bytes, + QEMUIOVector *qiov, int flags) { BDRVNullState *s = bs->opaque; if (s->read_zeroes) { - qemu_iovec_memset(qiov, 0, 0, nb_sectors * BDRV_SECTOR_SIZE); + qemu_iovec_memset(qiov, 0, 0, bytes); } return null_co_common(bs); } -static coroutine_fn int null_co_writev(BlockDriverState *bs, - int64_t sector_num, int nb_sectors, - QEMUIOVector *qiov) +static coroutine_fn int null_co_pwritev(BlockDriverState *bs, + uint64_t offset, uint64_t bytes, + QEMUIOVector *qiov, int flags) { return null_co_common(bs); } @@ -186,26 +187,26 @@ static inline BlockAIOCB *null_aio_common(BlockDriverState *bs, return &acb->common; } -static BlockAIOCB *null_aio_readv(BlockDriverState *bs, - int64_t sector_num, QEMUIOVector *qiov, - int nb_sectors, - BlockCompletionFunc *cb, - void *opaque) -{ - BDRVNullState *s = bs->opaque; - - if (s->read_zeroes) { - qemu_iovec_memset(qiov, 0, 0, nb_sectors * BDRV_SECTOR_SIZE); - } - - return null_aio_common(bs, cb, opaque); -} - -static BlockAIOCB *null_aio_writev(BlockDriverState *bs, - int64_t sector_num, QEMUIOVector *qiov, - int nb_sectors, +static BlockAIOCB *null_aio_preadv(BlockDriverState *bs, + uint64_t offset, uint64_t bytes, + QEMUIOVector *qiov, int flags, BlockCompletionFunc *cb, void *opaque) +{ + BDRVNullState *s = bs->opaque; + + if (s->read_zeroes) { + qemu_iovec_memset(qiov, 0, 0, bytes); + } + + return null_aio_common(bs, cb, opaque); +} + +static BlockAIOCB *null_aio_pwritev(BlockDriverState *bs, + uint64_t offset, uint64_t bytes, + QEMUIOVector *qiov, int flags, + BlockCompletionFunc *cb, + void *opaque) { return null_aio_common(bs, cb, opaque); } @@ -256,6 +257,11 @@ static void null_refresh_filename(BlockDriverState *bs, QDict *opts) bs->full_open_options = opts; } +static void null_refresh_limits(BlockDriverState *bs, Error **errp) +{ + bs->bl.request_alignment = 1; +} + static BlockDriver bdrv_null_co = { .format_name = "null-co", .protocol_name = "null-co", @@ -266,14 +272,15 @@ static BlockDriver bdrv_null_co = { .bdrv_close = null_close, .bdrv_getlength = null_getlength, - .bdrv_co_readv = null_co_readv, - .bdrv_co_writev = null_co_writev, + .bdrv_co_preadv = null_co_preadv, + .bdrv_co_pwritev = null_co_pwritev, .bdrv_co_flush_to_disk = null_co_flush, .bdrv_reopen_prepare = null_reopen_prepare, .bdrv_co_block_status = null_co_block_status, .bdrv_refresh_filename = null_refresh_filename, + .bdrv_refresh_limits = null_refresh_limits, }; static BlockDriver bdrv_null_aio = { @@ -286,14 +293,15 @@ static BlockDriver bdrv_null_aio = { .bdrv_close = null_close, .bdrv_getlength = null_getlength, - .bdrv_aio_readv = null_aio_readv, - .bdrv_aio_writev = null_aio_writev, + .bdrv_aio_preadv = null_aio_preadv, + .bdrv_aio_pwritev = null_aio_pwritev, .bdrv_aio_flush = null_aio_flush, .bdrv_reopen_prepare = null_reopen_prepare, .bdrv_co_block_status = null_co_block_status, .bdrv_refresh_filename = null_refresh_filename, + .bdrv_refresh_limits = null_refresh_limits, }; static void bdrv_null_init(void) -- 2.14.3