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dm cache: fix stacking of geometry limits

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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>
This commit is contained in:
Mike Snitzer 2013-08-20 15:02:41 -04:00
parent 0cc67cd9c5
commit f610937214
1 changed files with 10 additions and 2 deletions
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12
drivers/md/dm-cache-target.c
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@ -2612,9 +2612,17 @@ static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
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);
}