md/raid1,raid10: don't ignore IO flags

JIRA: https://issues.redhat.com/browse/RHEL-83988

commit e879a0d
Author: Yu Kuai <yukuai3@huawei.com>
Date:   Thu Feb 27 20:16:57 2025 +0800

    md/raid1,raid10: don't ignore IO flags

    If blk-wbt is enabled by default, it's found that raid write performance
    is quite bad because all IO are throttled by wbt of underlying disks,
    due to flag REQ_IDLE is ignored. And turns out this behaviour exist since
    blk-wbt is introduced.

    Other than REQ_IDLE, other flags should not be ignored as well, for
    example REQ_META can be set for filesystems, clearing it can cause priority
    reverse problems; And REQ_NOWAIT should not be cleared as well, because
    io will wait instead of failing directly in underlying disks.

    Fix those problems by keep IO flags from master bio.

    Fises: f51d46d ("md: add support for REQ_NOWAIT")
    Fixes: e34cbd3 ("blk-wbt: add general throttling mechanism")
    Fixes: 5404bc7 ("[PATCH] Allow file systems to differentiate between data and meta reads")
    Link: https://lore.kernel.org/linux-raid/20250227121657.832356-1-yukuai1@huaweicloud.com
    Signed-off-by: Yu Kuai <yukuai3@huawei.com>

Signed-off-by: Nigel Croxon <ncroxon@redhat.com>

Author: ncroxon

drivers/md/raid1.c

@@ -1316,8 +1316,6 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
 	struct r1conf *conf = mddev->private;
 	struct raid1_info *mirror;
 	struct bio *read_bio;
-	const enum req_op op = bio_op(bio);
-	const blk_opf_t do_sync = bio->bi_opf & REQ_SYNC;
 	int max_sectors;
 	int rdisk, error;
 	bool r1bio_existed = !!r1_bio;
@@ -1405,7 +1403,6 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
 	read_bio->bi_iter.bi_sector = r1_bio->sector +
 		mirror->rdev->data_offset;
 	read_bio->bi_end_io = raid1_end_read_request;
-	read_bio->bi_opf = op | do_sync;
 	if (test_bit(FailFast, &mirror->rdev->flags) &&
 	    test_bit(R1BIO_FailFast, &r1_bio->state))
 	        read_bio->bi_opf |= MD_FAILFAST;
@@ -1654,8 +1651,6 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 
 		mbio->bi_iter.bi_sector	= (r1_bio->sector + rdev->data_offset);
 		mbio->bi_end_io	= raid1_end_write_request;
-		mbio->bi_opf = bio_op(bio) |
-			(bio->bi_opf & (REQ_SYNC | REQ_FUA | REQ_ATOMIC));
 		if (test_bit(FailFast, &rdev->flags) &&
 		    !test_bit(WriteMostly, &rdev->flags) &&
 		    conf->raid_disks - mddev->degraded > 1)

drivers/md/raid10.c

@@ -1147,8 +1147,6 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
 {
 	struct r10conf *conf = mddev->private;
 	struct bio *read_bio;
-	const enum req_op op = bio_op(bio);
-	const blk_opf_t do_sync = bio->bi_opf & REQ_SYNC;
 	int max_sectors;
 	struct md_rdev *rdev;
 	char b[BDEVNAME_SIZE];
@@ -1229,7 +1227,6 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
 	read_bio->bi_iter.bi_sector = r10_bio->devs[slot].addr +
 		choose_data_offset(r10_bio, rdev);
 	read_bio->bi_end_io = raid10_end_read_request;
-	read_bio->bi_opf = op | do_sync;
 	if (test_bit(FailFast, &rdev->flags) &&
 	    test_bit(R10BIO_FailFast, &r10_bio->state))
 	        read_bio->bi_opf |= MD_FAILFAST;
@@ -1248,10 +1245,6 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
 				  struct bio *bio, bool replacement,
 				  int n_copy)
 {
-	const enum req_op op = bio_op(bio);
-	const blk_opf_t do_sync = bio->bi_opf & REQ_SYNC;
-	const blk_opf_t do_fua = bio->bi_opf & REQ_FUA;
-	const blk_opf_t do_atomic = bio->bi_opf & REQ_ATOMIC;
 	unsigned long flags;
 	struct r10conf *conf = mddev->private;
 	struct md_rdev *rdev;
@@ -1270,7 +1263,6 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
 	mbio->bi_iter.bi_sector	= (r10_bio->devs[n_copy].addr +
 				   choose_data_offset(r10_bio, rdev));
 	mbio->bi_end_io	= raid10_end_write_request;
-	mbio->bi_opf = op | do_sync | do_fua | do_atomic;
 	if (!replacement && test_bit(FailFast,
 				     &conf->mirrors[devnum].rdev->flags)
 			 && enough(conf, devnum))