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

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

[gregkh]

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 <stable@vger.kernel.org> know about it.


>From 0c9d5b127f695818c2c5a3868c1f28ca2969e905 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.com>
Date: Thu, 6 Apr 2017 12:06:37 +1000
Subject: md/raid1: avoid reusing a resync bio after error handling.

From: NeilBrown <neilb@suse.com>

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.

Reported-and-tested-by: Michael Wang <yun.wang@profitbricks.com>
Fixes: 2e52d449bcec ("md/raid1: add failfast handling for reads.")
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -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 neilb@suse.com are

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