block: discard granularity might not be power of 2

In MD raid case, discard granularity might not be power of 2, for example, a
4-disk raid5 has 3*chunk_size discard granularity. Correct the calculation for
such cases.

Reported-by: Neil Brown <neilb@suse.de>
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 3 insertions, 3 deletions

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 779bb7646bcd..c50ecf0ea3b1 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -611,7 +611,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
                         bottom = b->discard_granularity + alignment;
 
                         /* Verify that top and bottom intervals line up */
-                        if (max(top, bottom) & (min(top, bottom) - 1))
+                        if ((max(top, bottom) % min(top, bottom)) != 0)
                                 t->discard_misaligned = 1;
                 }
 
@@ -619,8 +619,8 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
                                                       b->max_discard_sectors);
                 t->discard_granularity = max(t->discard_granularity,
                                              b->discard_granularity);
-                t->discard_alignment = lcm(t->discard_alignment, alignment) &
-                        (t->discard_granularity - 1);
+                t->discard_alignment = lcm(t->discard_alignment, alignment) %
+                        t->discard_granularity;
         }
 
         return ret;