dm cache: fix stacking of geometry limits
Do not blindly override the queue limits (specifically io_min and
io_opt). Allow traditional stacking of these limits if io_opt is a
factor of the cache's data block size.
Without this patch mkfs.xfs does not recognize the cache device's
provided limits as a useful geometry (e.g. raid) so these hints are
ignored. This was due to setting io_min to a useless value.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 31985ea..22ff650 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -2612,9 +2612,17 @@
static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
{
struct cache *cache = ti->private;
+ uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
- blk_limits_io_min(limits, 0);
- blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
+ /*
+ * If the system-determined stacked limits are compatible with the
+ * cache's blocksize (io_opt is a factor) do not override them.
+ */
+ if (io_opt_sectors < cache->sectors_per_block ||
+ do_div(io_opt_sectors, cache->sectors_per_block)) {
+ blk_limits_io_min(limits, 0);
+ blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
+ }
set_discard_limits(cache, limits);
}