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authorDamien Le Moal <damien.lemoal@wdc.com>2020-06-19 16:49:55 +0900
committerMike Snitzer <snitzer@redhat.com>2020-06-19 12:28:23 -0400
commit3ee39573e567eded4f73e1e22216034bc29f3813 (patch)
tree3dc8a86b745cf670e8d6f0ea97117756b93fe4ee /drivers/md
parent415c79e13b17ce5f0a0815bab4d584f75f4d1171 (diff)
downloadlinux-3ee39573e567eded4f73e1e22216034bc29f3813.tar.bz2
dm zoned: Fix random zone reclaim selection
Commit 2094045fe5b5 ("dm zoned: prefer full zones for reclaim") modified dmz_get_rnd_zone_for_reclaim() to add a search for the buffer zone with the heaviest weight as an optimal candidate for reclaim. This modification uses the zone pointer variabl "last" which is set only once and never modified as zones are scanned, resulting in the search being inefective. Furthermore, if the selected buffer zone at the end of the search loop is active or already locked for reclaim, dmz_get_rnd_zone_for_reclaim() returns NULL even if other random zones with a lesser weight can be reclaimed. To fix the search and to guarantee that reclaim can make forward progress, fix dmz_get_rnd_zone_for_reclaim() loop to correctly find the buffer zone with the heaviest weight using the variable maxw_z. Also make sure to fallback to finding the first random zone that can be reclaimed if this best candidate zone cannot be reclaimed. While at it, also fix the device index check to consider only random zones, ignoring cache zones belonging to the cache device if one is used as that device does not have a reclaim process. Fixes: 2094045fe5b5 ("dm zoned: prefer full zones for reclaim") 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')
-rw-r--r--drivers/md/dm-zoned-metadata.c35
1 files changed, 27 insertions, 8 deletions
diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c
index fc1329ca3e70..b40e643ddf73 100644
--- a/drivers/md/dm-zoned-metadata.c
+++ b/drivers/md/dm-zoned-metadata.c
@@ -1950,7 +1950,7 @@ static struct dm_zone *dmz_get_rnd_zone_for_reclaim(struct dmz_metadata *zmd,
unsigned int idx, bool idle)
{
struct dm_zone *dzone = NULL;
- struct dm_zone *zone, *last = NULL;
+ struct dm_zone *zone, *maxw_z = NULL;
struct list_head *zone_list;
/* If we have cache zones select from the cache zone list */
@@ -1962,18 +1962,37 @@ static struct dm_zone *dmz_get_rnd_zone_for_reclaim(struct dmz_metadata *zmd,
} else
zone_list = &zmd->dev[idx].map_rnd_list;
+ /*
+ * Find the buffer zone with the heaviest weight or the first (oldest)
+ * data zone that can be reclaimed.
+ */
list_for_each_entry(zone, zone_list, link) {
if (dmz_is_buf(zone)) {
dzone = zone->bzone;
- if (dzone->dev->dev_idx != idx)
+ if (dmz_is_rnd(dzone) && dzone->dev->dev_idx != idx)
continue;
- if (!last) {
- last = dzone;
- continue;
- }
- if (last->weight < dzone->weight)
+ if (!maxw_z || maxw_z->weight < dzone->weight)
+ maxw_z = dzone;
+ } else {
+ dzone = zone;
+ if (dmz_lock_zone_reclaim(dzone))
+ return dzone;
+ }
+ }
+
+ if (maxw_z && dmz_lock_zone_reclaim(maxw_z))
+ return maxw_z;
+
+ /*
+ * If we come here, none of the zones inspected could be locked for
+ * reclaim. Try again, being more aggressive, that is, find the
+ * first zone that can be reclaimed regardless of its weitght.
+ */
+ list_for_each_entry(zone, zone_list, link) {
+ if (dmz_is_buf(zone)) {
+ dzone = zone->bzone;
+ if (dmz_is_rnd(dzone) && dzone->dev->dev_idx != idx)
continue;
- dzone = last;
} else
dzone = zone;
if (dmz_lock_zone_reclaim(dzone))