NBD spec is updated, so that max_block doesn't relate to NBD_CMD_WRITE_ZEROES with NBD_CMD_FLAG_FAST_ZERO (which mirrors Qemu flag BDRV_REQ_NO_FALLBACK). To drop the restriction we need new max_pwrite_zeroes_no_fallback.
Default value of new max_pwrite_zeroes_no_fallback is zero and it means no-restriction, so we are automatically done by this commit. Note that nbd and blkdebug are the only drivers which in the same time define max_pwrite_zeroes limit and support BDRV_REQ_NO_FALLBACK, so we need to update only blkdebug. Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]> --- include/block/block_int.h | 8 ++++++++ block/blkdebug.c | 7 ++++++- block/io.c | 4 +++- 3 files changed, 17 insertions(+), 2 deletions(-) diff --git a/include/block/block_int.h b/include/block/block_int.h index 6f9fd5e20e..c167e887c6 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -618,6 +618,14 @@ typedef struct BlockLimits { * pwrite_zeroes_alignment. May be 0 if no inherent 32-bit limit */ int32_t max_pwrite_zeroes; + /* + * Maximum number of bytes that can zeroized at once if flag + * BDRV_REQ_NO_FALLBACK specified (since it is signed, it must be < 2G, if + * set). Must be multiple of pwrite_zeroes_alignment. May be 0 if no + * inherent 32-bit limit. + */ + int32_t max_pwrite_zeroes_no_fallback; + /* Optimal alignment for write zeroes requests in bytes. A power * of 2 is best but not mandatory. Must be a multiple of * bl.request_alignment, and must be less than max_pwrite_zeroes diff --git a/block/blkdebug.c b/block/blkdebug.c index af44aa973f..7627fbcb3b 100644 --- a/block/blkdebug.c +++ b/block/blkdebug.c @@ -692,7 +692,11 @@ static int coroutine_fn blkdebug_co_pwrite_zeroes(BlockDriverState *bs, } assert(QEMU_IS_ALIGNED(offset, align)); assert(QEMU_IS_ALIGNED(bytes, align)); - if (bs->bl.max_pwrite_zeroes) { + if ((flags & BDRV_REQ_NO_FALLBACK) && + bs->bl.max_pwrite_zeroes_no_fallback) + { + assert(bytes <= bs->bl.max_pwrite_zeroes_no_fallback); + } else if (bs->bl.max_pwrite_zeroes) { assert(bytes <= bs->bl.max_pwrite_zeroes); } @@ -977,6 +981,7 @@ static void blkdebug_refresh_limits(BlockDriverState *bs, Error **errp) } if (s->max_write_zero) { bs->bl.max_pwrite_zeroes = s->max_write_zero; + bs->bl.max_pwrite_zeroes_no_fallback = s->max_write_zero; } if (s->opt_discard) { bs->bl.pdiscard_alignment = s->opt_discard; diff --git a/block/io.c b/block/io.c index 7e4cb74cf4..75fd5600c2 100644 --- a/block/io.c +++ b/block/io.c @@ -1752,7 +1752,9 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, int head = 0; int tail = 0; - int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_MAX); + int max_write_zeroes = MIN_NON_ZERO((flags & BDRV_REQ_NO_FALLBACK) ? + bs->bl.max_pwrite_zeroes_no_fallback : + bs->bl.max_pwrite_zeroes, INT_MAX); int alignment = MAX(bs->bl.pwrite_zeroes_alignment, bs->bl.request_alignment); int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, MAX_BOUNCE_BUFFER); -- 2.21.0
