Patch "md/raid1: avoid reusing a resync bio after error handling." has been added to the 4.11-stable tree

This is a note to let you know that I've just added the patch titled

md/raid1: avoid reusing a resync bio after error handling.

to the 4.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
md-raid1-avoid-reusing-a-resync-bio-after-error-handling.patch
and it can be found in the queue-4.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: NeilBrown <[email protected]>
Date: Thu, 6 Apr 2017 12:06:37 +1000
Subject: md/raid1: avoid reusing a resync bio after error handling.

From: NeilBrown <[email protected]>

commit 0c9d5b127f695818c2c5a3868c1f28ca2969e905 upstream.

fix_sync_read_error() modifies a bio on a newly faulty device by setting bi_end_io to end_sync_write.
This ensure that put_buf() will still call rdev_dec_pending() as required, but makes sure that subsequent code in fix_sync_read_error() doesn't try to read from the device.

Unfortunately this interacts badly with sync_request_write() which assumes that any bio with bi_end_io set to non-NULL other than end_sync_read is safe to write to.

As the device is now faulty it doesn't make sense to write. As the bio was recently used for a read, it is "dirty" and not suitable for immediate submission.
In particular, ->bi_next might be non-NULL, which will cause generic_make_request() to complain.

Break this interaction by refusing to write to devices which are marked as Faulty.

---
 drivers/md/raid1.c |    2 ++
 1 file changed, 2 insertions(+)

@@ -2222,6 +2222,8 @@ static void sync_request_write(struct md
 		     (i == r1_bio->read_disk ||
 		      !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
 			continue;
+		if (test_bit(Faulty, &conf->mirrors[i].rdev->flags))
+			continue;
 
 		bio_set_op_attrs(wbio, REQ_OP_WRITE, 0);
 		if (test_bit(FailFast, &conf->mirrors[i].rdev->flags))

Patches currently in stable-queue which might be from [email protected] are

queue-4.11/md-raid1-avoid-reusing-a-resync-bio-after-error-handling.patch