From fdfb4c8c1a9fc8dd8cf8eeb4e3ed83573b375285 Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@redhat.com>
Date: Fri, 18 Jul 2014 17:59:43 -0400
Subject: dm thin: set minimum_io_size to pool's data block size

Before, if the block layer's limit stacking didn't establish an
optimal_io_size that was compatible with the thin-pool's data block size
we'd set optimal_io_size to the data block size and minimum_io_size to 0
(which the block layer adjusts to be physical_block_size).

Update pool_io_hints() to set both minimum_io_size and optimal_io_size
to the thin-pool's data block size.  This fixes an issue reported where
mkfs.xfs would create more XFS Allocation Groups on thinp volumes than
on a normal linear LV of comparable size, see:
https://bugzilla.redhat.com/show_bug.cgi?id=1003227

Reported-by: Chris Murphy <lists@colorremedies.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
 drivers/md/dm-thin.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'drivers/md')

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 0e844a5eca8f..4843801173fe 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -3177,7 +3177,7 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
 	 */
 	if (io_opt_sectors < pool->sectors_per_block ||
 	    do_div(io_opt_sectors, pool->sectors_per_block)) {
-		blk_limits_io_min(limits, 0);
+		blk_limits_io_min(limits, pool->sectors_per_block << SECTOR_SHIFT);
 		blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
 	}
 
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