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-rw-r--r--drivers/md/bcache/sysfs.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index f90f13616980..09295c07ea88 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -615,8 +615,21 @@ STORE(__bch_cache_set)
bch_cache_accounting_clear(&c->accounting);
}
- if (attr == &sysfs_trigger_gc)
+ if (attr == &sysfs_trigger_gc) {
+ /*
+ * Garbage collection thread only works when sectors_to_gc < 0,
+ * when users write to sysfs entry trigger_gc, most of time
+ * they want to forcibly triger gargage collection. Here -1 is
+ * set to c->sectors_to_gc, to make gc_should_run() give a
+ * chance to permit gc thread to run. "give a chance" means
+ * before going into gc_should_run(), there is still chance
+ * that c->sectors_to_gc being set to other positive value. So
+ * writing sysfs entry trigger_gc won't always make sure gc
+ * thread takes effect.
+ */
+ atomic_set(&c->sectors_to_gc, -1);
wake_up_gc(c);
+ }
if (attr == &sysfs_prune_cache) {
struct shrink_control sc;