diff options
author | Damien Le Moal <damien.lemoal@wdc.com> | 2020-07-08 03:20:22 +0300 |
---|---|---|
committer | Mike Snitzer <snitzer@redhat.com> | 2020-07-08 19:21:53 +0300 |
commit | 174364f6a8979655f71b04b6492657aec3762703 (patch) | |
tree | 3e28277258d486c5674be621d17fc96a1a345768 /drivers/md/dm-zoned-metadata.c | |
parent | ce34c9b461b50001892b0b348e024d2275014ede (diff) | |
download | linux-174364f6a8979655f71b04b6492657aec3762703.tar.xz |
dm zoned: Fix zone reclaim trigger
Only triggering reclaim based on the percentage of unmapped cache
zones can fail to detect cases where reclaim is needed, e.g. if the
target has only 2 or 3 cache zones and only one unmapped cache zone,
the percentage of free cache zones is higher than
DMZ_RECLAIM_LOW_UNMAP_ZONES (30%) and reclaim does not trigger.
This problem, combined with the fact that dmz_schedule_reclaim() is
called from dmz_handle_bio() without the map lock held, leads to a
race between zone allocation and dmz_should_reclaim() result.
Depending on the workload applied, this race can lead to the write
path waiting forever for a free zone without reclaim being triggered.
Fix this by moving dmz_schedule_reclaim() inside dmz_alloc_zone()
under the map lock. This results in checking the need for zone reclaim
whenever a new data or buffer zone needs to be allocated.
Also fix dmz_reclaim_percentage() to always return 0 if the number of
unmapped cache (or random) zones is less than or equal to 1.
Suggested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-zoned-metadata.c')
-rw-r--r-- | drivers/md/dm-zoned-metadata.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c index 5cf6f5f552e0..b298fefb022e 100644 --- a/drivers/md/dm-zoned-metadata.c +++ b/drivers/md/dm-zoned-metadata.c @@ -2217,8 +2217,15 @@ struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned int dev_idx, { struct list_head *list; struct dm_zone *zone; - int i = 0; + int i; + + /* Schedule reclaim to ensure free zones are available */ + if (!(flags & DMZ_ALLOC_RECLAIM)) { + for (i = 0; i < zmd->nr_devs; i++) + dmz_schedule_reclaim(zmd->dev[i].reclaim); + } + i = 0; again: if (flags & DMZ_ALLOC_CACHE) list = &zmd->unmap_cache_list; |