[dm-devel] [PATCH 3/3] dm-thin: fix discard_granularity

Mikulas Patocka mpatocka at redhat.com
Mon Jul 16 18:35:45 UTC 2012


dm-thin: fix discard_granularity

The kernel expects that limits->discard_granularity is a power of two.
Set this limit only if we use a power of two block size.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>

---
 drivers/md/dm-thin.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-3.5-rc6-fast/drivers/md/dm-thin.c
===================================================================
--- linux-3.5-rc6-fast.orig/drivers/md/dm-thin.c	2012-07-16 20:07:49.000000000 +0200
+++ linux-3.5-rc6-fast/drivers/md/dm-thin.c	2012-07-16 20:08:01.000000000 +0200
@@ -2502,7 +2502,8 @@ static void set_discard_limits(struct po
 	 * bios cover a block partially.  A discard that spans a block boundary
 	 * is not sent to this target.
 	 */
-	limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
+	if (pool->sectors_per_block_shift >= 0)
+		limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
 	limits->discard_zeroes_data = pool->pf.zero_new_blocks;
 }
 




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