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| author | Joe Thornber <ejt@redhat.com> | 2013-03-20 21:21:25 +0400 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2013-03-20 21:21:25 +0400 |
| commit | 58051b94e05a59c4d34f9f1a441af40894817c59 (patch) | |
| tree | 4a4e33cac9a808805e42f0c816a4b8e5b434f28f | |
| parent | f046f89a99ccfd9408b94c653374ff3065c7edb3 (diff) | |
| download | linux-58051b94e05a59c4d34f9f1a441af40894817c59.tar.xz | |
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>
| -rw-r--r-- | drivers/md/dm-thin.c | 7 |
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) { |