From d099a41a7ab30d0fe15098f52cbb6506bdc0cdb3 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@redhat.com>
Date: Wed, 20 Mar 2013 17:21:25 +0000
Subject: [PATCH] --- yaml --- r: 361512 b: refs/heads/master c:
 58051b94e05a59c4d34f9f1a441af40894817c59 h: refs/heads/master v: v3

---
 [refs]                     | 2 +-
 trunk/drivers/md/dm-thin.c | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index abc0058c9d2c..d390e7dcaa88 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f046f89a99ccfd9408b94c653374ff3065c7edb3
+refs/heads/master: 58051b94e05a59c4d34f9f1a441af40894817c59
diff --git a/trunk/drivers/md/dm-thin.c b/trunk/drivers/md/dm-thin.c
index ab95e5ff3758..004ad1652b73 100644
--- a/trunk/drivers/md/dm-thin.c
+++ b/trunk/drivers/md/dm-thin.c
@@ -1577,6 +1577,11 @@ static bool data_dev_supports_discard(struct pool_c *pt)
 	return q && blk_queue_discard(q);
 }
 
+static bool is_factor(sector_t block_size, uint32_t n)
+{
+	return !sector_div(block_size, n);
+}
+
 /*
  * If discard_passdown was enabled verify that the data device
  * supports discards.  Disable discard_passdown if not.
@@ -1602,7 +1607,7 @@ static void disable_passdown_if_not_supported(struct pool_c *pt)
 	else if (data_limits->discard_granularity > block_size)
 		reason = "discard granularity larger than a block";
 
-	else if (block_size & (data_limits->discard_granularity - 1))
+	else if (!is_factor(block_size, data_limits->discard_granularity))
 		reason = "discard granularity not a factor of block size";
 
 	if (reason) {