FAILED: patch "[PATCH] RAID10: ignore discard error" failed to apply to 4.4-stable tree

From 579ed34f7b751b8add233cba4cf755258dbdd60a Mon Sep 17 00:00:00 2001

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From 579ed34f7b751b8add233cba4cf755258dbdd60a Mon Sep 17 00:00:00 2001

From: Shaohua Li <[email protected]>
Date: Thu, 6 Oct 2016 14:13:52 -0700
Subject: [PATCH] RAID10: ignore discard error

This is the counterpart of raid10 fix. If a write error occurs, raid10 will try to rewrite the bio in small chunk size. If the rewrite fails, raid10 will record the error in bad block. narrow_write_error will always use WRITE for the bio, but actually it could be a discard. Since discard bio hasn't payload, write the bio will cause different issues. But discard error isn't fatal, we can safely ignore it. This is what this patch does.

This issue should exist since discard is added, but only exposed with recent arbitrary bio size feature.

Cc Sitsofe Wheeler <[email protected]>

Cc [email protected] (v3.6)

Signed-off-by Shaohua Li <[email protected]>

drivers/md/raid10.c +5 -3

index be1a9fca3b2d..39fddda2fef2 100644
@@ -447,6 +447,9 @@ static void raid10_end_write_request(struct bio *bio)
 	struct r10conf *conf = r10_bio->mddev->private;
 	int slot, repl;
 	struct md_rdev *rdev = NULL;
+	bool discard_error;
+
+	discard_error = bio->bi_error && bio_op(bio) == REQ_OP_DISCARD;
 
 	dev = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
 

@@ -460,7 +463,7 @@ static void raid10_end_write_request(struct bio *bio)
 	/*
 	 * this branch is our 'one mirror IO has finished' event handler:
 	 */
-	if (bio->bi_error) {
+	if (bio->bi_error && !discard_error) {
 		if (repl)
 			/* Never record new bad blocks to replacement,
 			 * just fail it.

@@ -503,7 +506,7 @@ static void raid10_end_write_request(struct bio *bio)
 		if (is_badblock(rdev,
 				r10_bio->devs[slot].addr,
 				r10_bio->sectors,
-				&first_bad, &bad_sectors)) {
+				&first_bad, &bad_sectors) && !discard_error) {
 			bio_put(bio);
 			if (repl)
 				r10_bio->devs[slot].repl_bio = IO_MADE_GOOD;
 
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