From f0deecff827c838a71f83539b0572094aefe3d5e Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Fri, 11 Dec 2020 21:39:22 +0300 Subject: block/io: refactor bdrv_pad_request(): move bdrv_pad_request() up Prepare for the following patch when bdrv_pad_request() will be able to fail. Update the comments. Signed-off-by: Vladimir Sementsov-Ogievskiy Message-Id: <20201211183934.169161-5-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake [eblake: grammar tweak] Signed-off-by: Eric Blake --- block/io.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) diff --git a/block/io.c b/block/io.c index c8c9dea554..3b1aec366e 100644 --- a/block/io.c +++ b/block/io.c @@ -2135,6 +2135,7 @@ int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child, uint64_t align = bs->bl.request_alignment; BdrvRequestPadding pad; int ret; + bool padded = false; trace_bdrv_co_pwritev(child->bs, offset, bytes, flags); @@ -2166,20 +2167,32 @@ int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child, return 0; } + if (!(flags & BDRV_REQ_ZERO_WRITE)) { + /* + * Pad request for following read-modify-write cycle. + * bdrv_co_do_zero_pwritev() does aligning by itself, so, we do + * alignment only if there is no ZERO flag. + */ + padded = bdrv_pad_request(bs, &qiov, &qiov_offset, &offset, &bytes, + &pad); + } + bdrv_inc_in_flight(bs); - /* - * Align write if necessary by performing a read-modify-write cycle. - * Pad qiov with the read parts and be sure to have a tracked request not - * only for bdrv_aligned_pwritev, but also for the reads of the RMW cycle. - */ tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_WRITE); if (flags & BDRV_REQ_ZERO_WRITE) { + assert(!padded); ret = bdrv_co_do_zero_pwritev(child, offset, bytes, flags, &req); goto out; } - if (bdrv_pad_request(bs, &qiov, &qiov_offset, &offset, &bytes, &pad)) { + if (padded) { + /* + * Request was unaligned to request_alignment and therefore + * padded. We are going to do read-modify-write, and must + * serialize the request to prevent interactions of the + * widened region with other transactions. + */ bdrv_make_request_serialising(&req, align); bdrv_padding_rmw_read(child, &req, &pad, false); } -- cgit v1.2.3-55-g7522