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-rw-r--r--drivers/md/dm-thin.c21
1 files changed, 7 insertions, 14 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index e9e9584fe769..8735543eacdb 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -3587,27 +3587,20 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
sector_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
/*
- * Adjust max_sectors_kb to highest possible power-of-2
- * factor of pool->sectors_per_block.
+ * If max_sectors is smaller than pool->sectors_per_block adjust it
+ * to the highest possible power-of-2 factor of pool->sectors_per_block.
+ * This is especially beneficial when the pool's data device is a RAID
+ * device that has a full stripe width that matches pool->sectors_per_block
+ * -- because even though partial RAID stripe-sized IOs will be issued to a
+ * single RAID stripe; when aggregated they will end on a full RAID stripe
+ * boundary.. which avoids additional partial RAID stripe writes cascading
*/
- if (limits->max_hw_sectors & (limits->max_hw_sectors - 1))
- limits->max_sectors = rounddown_pow_of_two(limits->max_hw_sectors);
- else
- limits->max_sectors = limits->max_hw_sectors;
-
if (limits->max_sectors < pool->sectors_per_block) {
while (!is_factor(pool->sectors_per_block, limits->max_sectors)) {
if ((limits->max_sectors & (limits->max_sectors - 1)) == 0)
limits->max_sectors--;
limits->max_sectors = rounddown_pow_of_two(limits->max_sectors);
}
- } else if (block_size_is_power_of_two(pool)) {
- /* max_sectors_kb is >= power-of-2 thinp blocksize */
- while (!is_factor(limits->max_sectors, pool->sectors_per_block)) {
- if ((limits->max_sectors & (limits->max_sectors - 1)) == 0)
- limits->max_sectors--;
- limits->max_sectors = rounddown_pow_of_two(limits->max_sectors);
- }
}
/*