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Commit 0cc67cd9 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm thin: 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 thin-pool's data block size.

Without this patch mkfs.xfs does not recognize the thin 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: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
Acked-by: default avatarJoe Thornber <ejt@redhat.com>
parent a561ddbe

drivers/md/dm-thin.c

+10 −2
Original line number Diff line number Diff line
@@ -2648,9 +2648,17 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits) 
{

	struct pool_c *pt = ti->private;

	struct pool *pool = pt->pool;

	uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;



	/*

	 * If the system-determined stacked limits are compatible with the

	 * pool's blocksize (io_opt is a factor) do not override them.

	 */

	if (io_opt_sectors < pool->sectors_per_block ||

	    do_div(io_opt_sectors, pool->sectors_per_block)) {

		blk_limits_io_min(limits, 0);

		blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);

	}



	/*

	 * pt->adjusted_pf is a staging area for the actual features to use.