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From:   linan666@huaweicloud.com
To:     song@kernel.org, neilb@suse.de
Cc:     linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org,
        linan122@huawei.com, yukuai3@huawei.com, yi.zhang@huawei.com,
        houtao1@huawei.com, yangerkun@huawei.com
Subject: [PATCH 3/3] md/raid10: improve raid10_end_write_request()
Date:   Wed, 14 Jun 2023 16:47:40 +0800
Message-Id: <20230614084740.1493969-4-linan666@huaweicloud.com>
In-Reply-To: <20230614084740.1493969-1-linan666@huaweicloud.com>
References: <20230614084740.1493969-1-linan666@huaweicloud.com>
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From: Li Nan <linan122@huawei.com>

Improving the code to prevent excessive nesting by repeated checks of
'repl'. And putting bio after it has been set to IO_MADE_GOOD is more
reasonable.

Signed-off-by: Li Nan <linan122@huawei.com>
---
 drivers/md/raid10.c | 74 ++++++++++++++++++++++++---------------------
 1 file changed, 39 insertions(+), 35 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 56206cbd169d..b9f2c841dd9f 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -467,48 +467,51 @@ static void raid10_end_write_request(struct bio *bio)
 
 	dev = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
 
-	if (repl)
+	if (repl) {
 		rdev = r10_bio->devs[slot].replacement;
-	else
+		/* replacement may have replaced rdev */
+		if (rdev == conf->mirrors[dev].replacement) {
+			if (bio->bi_status && !discard_error) {
+				/*
+				 * Never record new bad blocks to replacement,
+				 * just fail it.
+				 */
+				md_error(rdev->mddev, rdev);
+				goto out;
+			}
+		}
+	} else {
 		rdev = r10_bio->devs[slot].rdev;
+	}
 	/*
 	 * this branch is our 'one mirror IO has finished' event handler:
 	 */
 	if (bio->bi_status && !discard_error) {
-		/* replacement may have replaced rdev */
-		if (repl && rdev == conf->mirrors[dev].replacement)
-			/* Never record new bad blocks to replacement,
-			 * just fail it.
-			 */
-			md_error(rdev->mddev, rdev);
-		else {
-			set_bit(WriteErrorSeen,	&rdev->flags);
-			if (!test_and_set_bit(WantReplacement, &rdev->flags))
-				set_bit(MD_RECOVERY_NEEDED,
-					&rdev->mddev->recovery);
+		set_bit(WriteErrorSeen,	&rdev->flags);
+		if (!test_and_set_bit(WantReplacement, &rdev->flags))
+			set_bit(MD_RECOVERY_NEEDED,
+				&rdev->mddev->recovery);
 
-			dec_rdev = 0;
-			if (test_bit(FailFast, &rdev->flags) &&
-			    (bio->bi_opf & MD_FAILFAST)) {
-				md_error(rdev->mddev, rdev);
-			}
+		dec_rdev = 0;
+		if (test_bit(FailFast, &rdev->flags) &&
+		    (bio->bi_opf & MD_FAILFAST))
+			md_error(rdev->mddev, rdev);
 
-			/*
-			 * When the device is faulty, it is not necessary to
-			 * handle write error.
-			 */
-			if (!test_bit(Faulty, &rdev->flags))
-				set_bit(R10BIO_WriteError, &r10_bio->state);
-			else {
-				/* Fail the request */
-				set_bit(R10BIO_Degraded, &r10_bio->state);
-				if (repl)
-					r10_bio->devs[slot].repl_bio = NULL;
-				else
-					r10_bio->devs[slot].bio = NULL;
-				to_put = bio;
-				dec_rdev = 1;
-			}
+		/*
+		 * When the device is faulty, it is not necessary to
+		 * handle write error.
+		 */
+		if (!test_bit(Faulty, &rdev->flags)) {
+			set_bit(R10BIO_WriteError, &r10_bio->state);
+		} else {
+			/* Fail the request */
+			set_bit(R10BIO_Degraded, &r10_bio->state);
+			if (repl)
+				r10_bio->devs[slot].repl_bio = NULL;
+			else
+				r10_bio->devs[slot].bio = NULL;
+			to_put = bio;
+			dec_rdev = 1;
 		}
 	} else {
 		/*
@@ -540,16 +543,17 @@ static void raid10_end_write_request(struct bio *bio)
 				r10_bio->devs[slot].addr,
 				r10_bio->sectors,
 				&first_bad, &bad_sectors) && !discard_error) {
-			bio_put(bio);
 			if (repl)
 				r10_bio->devs[slot].repl_bio = IO_MADE_GOOD;
 			else
 				r10_bio->devs[slot].bio = IO_MADE_GOOD;
+			bio_put(bio);
 			dec_rdev = 0;
 			set_bit(R10BIO_MadeGood, &r10_bio->state);
 		}
 	}
 
+out:
 	/*
 	 *
 	 * Let's see if all mirrored write operations have finished
-- 
2.39.2