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From: Guoqing Jiang <guoqing.jiang@linux.dev>
To: song@kernel.org
Cc: linux-raid@vger.kernel.org
Subject: [PATCH 1/6] md/raid1: only allocate write behind bio for WriteMostly device
Date: Mon,  4 Oct 2021 23:34:48 +0800	[thread overview]
Message-ID: <20211004153453.14051-2-guoqing.jiang@linux.dev> (raw)
In-Reply-To: <20211004153453.14051-1-guoqing.jiang@linux.dev>

Commit 6607cd319b6b91bff94e90f798a61c031650b514 ("raid1: ensure write
behind bio has less than BIO_MAX_VECS sectors") tried to guarantee the
size of behind bio is not bigger than BIO_MAX_VECS sectors.

Unfortunately the same calltrace still could happen since an array could
enable write-behind without write mostly device.

To match the manpage of mdadm (which says "write-behind is only attempted
on drives marked as write-mostly"), we need to check WriteMostly flag to
avoid such unexpected behavior.

[1]. https://bugzilla.kernel.org/show_bug.cgi?id=213181#c25

Cc: stable@vger.kernel.org # v5.12+
Cc: Jens Stutte <jens@chianterastutte.eu>
Reported-by: Jens Stutte <jens@chianterastutte.eu>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
---
 drivers/md/raid1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 19598bd38939..6ba12f0f0f03 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1496,7 +1496,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 		if (!r1_bio->bios[i])
 			continue;
 
-		if (first_clone) {
+		if (first_clone && test_bit(WriteMostly, &rdev->flags)) {
 			/* do behind I/O ?
 			 * Not if there are too many, or cannot
 			 * allocate memory, or a reader on WriteMostly
-- 
2.31.1


  reply	other threads:[~2021-10-04 15:40 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-04 15:34 [PATCH 0/6] Misc changes for md Guoqing Jiang
2021-10-04 15:34 ` Guoqing Jiang [this message]
2021-10-05  1:05   ` [PATCH 1/6] md/raid1: only allocate write behind bio for WriteMostly device Guoqing Jiang
2021-10-05  5:55   ` Jens Stutte
2021-10-04 15:34 ` [PATCH 2/6] md/bitmap: don't set max_write_behind if there is no write mostly device Guoqing Jiang
2021-10-07  6:25   ` Song Liu
2021-10-07 10:20     ` Guoqing Jiang
2021-10-04 15:34 ` [PATCH 3/6] md/raid1: use rdev in raid1_write_request directly Guoqing Jiang
2021-10-04 15:34 ` [PATCH 4/6] md/raid10: add 'read_err' to raid10_read_request Guoqing Jiang
2021-10-07  6:20   ` Song Liu
2021-10-07 10:16     ` Guoqing Jiang
2021-10-04 15:34 ` [PATCH 5/6] md/raid5: call roundup_pow_of_two in raid5_run Guoqing Jiang
2021-10-04 15:34 ` [PATCH 6/6] md: remove unused argument from md_new_event Guoqing Jiang
2021-10-07  6:32 ` [PATCH 0/6] Misc changes for md Song Liu

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