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authorJoe Thornber <ejt@redhat.com>2013-03-20 17:21:25 +0000
committerAlasdair G Kergon <agk@redhat.com>2013-03-20 17:21:25 +0000
commit58051b94e05a59c4d34f9f1a441af40894817c59 (patch)
tree4a4e33cac9a808805e42f0c816a4b8e5b434f28f /drivers/md/dm-thin.c
parentf046f89a99ccfd9408b94c653374ff3065c7edb3 (diff)
dm thin: fix non power of two discard granularity calc
Fix a discard granularity calculation to work for non power of 2 block sizes. In order for thinp to passdown discard bios to the underlying data device, the data device must have a discard granularity that is a factor of the thinp block size. Originally this check was done by using bitops since the block_size was known to be a power of two. Introduced by commit f13945d75730081830b6f3360266950e2b7c9067 ("dm thin: support a non power of 2 discard_granularity"). Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-thin.c')
-rw-r--r--drivers/md/dm-thin.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index ab95e5ff3758..004ad1652b73 100644
--- a/drivers/md/dm-thin.c
+++ b/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) {