[3.16.y-ckt stable] Patch "md/raid0: apply base queue limits *before* disk_stack_limits" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    md/raid0: apply base queue limits *before* disk_stack_limits

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt21.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From ba03dfc5846df79bf6ca6d0dd99a508ae1cd9171 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb at suse.com>
Date: Thu, 24 Sep 2015 15:47:47 +1000
Subject: md/raid0: apply base queue limits *before* disk_stack_limits

commit 66eefe5de11db1e0d8f2edc3880d50e7c36a9d43 upstream.

Calling e.g. blk_queue_max_hw_sectors() after calls to
disk_stack_limits() discards the settings determined by
disk_stack_limits().
So we need to make those calls first.

Fixes: 199dc6ed5179 ("md/raid0: update queue parameter in a safer location.")
Reported-by: Jes Sorensen <Jes.Sorensen at redhat.com>
Signed-off-by: NeilBrown <neilb at suse.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/md/raid0.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 3d6b97b6dc6f..8f7dfc58f965 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -437,12 +437,6 @@ static int raid0_run(struct mddev *mddev)
 		mddev->private = conf;
 	}
 	conf = mddev->private;
-	rdev_for_each(rdev, mddev) {
-		disk_stack_limits(mddev->gendisk, rdev->bdev,
-				  rdev->data_offset << 9);
-		if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
-			discard_supported = true;
-	}
 	blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 	blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
 	blk_queue_max_discard_sectors(mddev->queue, mddev->chunk_sectors);
@@ -451,6 +445,13 @@ static int raid0_run(struct mddev *mddev)
 	blk_queue_io_opt(mddev->queue,
 			 (mddev->chunk_sectors << 9) * mddev->raid_disks);

+	rdev_for_each(rdev, mddev) {
+		disk_stack_limits(mddev->gendisk, rdev->bdev,
+				  rdev->data_offset << 9);
+		if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
+			discard_supported = true;
+	}
+
 	if (!discard_supported)
 		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
 	else