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Commit 5a8948f8 authored by Jan Kara's avatar Jan Kara Committed by Shaohua Li
Browse files

md: Make flush bios explicitely sync 



Commit b685d3d6 "block: treat REQ_FUA and REQ_PREFLUSH as
synchronous" removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...}
definitions.  generic_make_request_checks() however strips REQ_FUA and
REQ_PREFLUSH flags from a bio when the storage doesn't report volatile
write cache and thus write effectively becomes asynchronous which can
lead to performance regressions

Fix the problem by making sure all bios which are synchronous are
properly marked with REQ_SYNC.

CC: linux-raid@vger.kernel.org
CC: Shaohua Li <shli@kernel.org>
Fixes: b685d3d6
CC: stable@vger.kernel.org
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent e1539036

drivers/md/md.c

+1 −1
Original line number Diff line number Diff line
@@ -765,7 +765,7 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev, 
	    test_bit(FailFast, &rdev->flags) &&

	    !test_bit(LastDev, &rdev->flags))

		ff = MD_FAILFAST;

	bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_FUA | ff;

	bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH | REQ_FUA | ff;



	atomic_inc(&mddev->pending_writes);

	submit_bio(bio);

drivers/md/raid5-cache.c

+2 −2
Original line number Diff line number Diff line
@@ -1782,7 +1782,7 @@ static int r5l_log_write_empty_meta_block(struct r5l_log *log, sector_t pos, 
	mb->checksum = cpu_to_le32(crc32c_le(log->uuid_checksum,

					     mb, PAGE_SIZE));

	if (!sync_page_io(log->rdev, pos, PAGE_SIZE, page, REQ_OP_WRITE,

			  REQ_FUA, false)) {

			  REQ_SYNC | REQ_FUA, false)) {

		__free_page(page);

		return -EIO;

	}
@@ -2388,7 +2388,7 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log, 
		mb->checksum = cpu_to_le32(crc32c_le(log->uuid_checksum,

						     mb, PAGE_SIZE));

		sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page,

			     REQ_OP_WRITE, REQ_FUA, false);

			     REQ_OP_WRITE, REQ_SYNC | REQ_FUA, false);

		sh->log_start = ctx->pos;

		list_add_tail(&sh->r5c, &log->stripe_in_journal_list);

		atomic_inc(&log->stripe_in_journal_count);

drivers/md/raid5-ppl.c

+2 −2
Original line number Diff line number Diff line
@@ -907,8 +907,8 @@ static int ppl_write_empty_header(struct ppl_log *log) 
	pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PAGE_SIZE));



	if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,

			  PPL_HEADER_SIZE, page, REQ_OP_WRITE | REQ_FUA, 0,

			  false)) {

			  PPL_HEADER_SIZE, page, REQ_OP_WRITE | REQ_SYNC |

			  REQ_FUA, 0, false)) {

		md_error(rdev->mddev, rdev);

		ret = -EIO;

	}