Garbage collection thread starts to work when c->sectors_to_gc is
negative value, otherwise nothing will happen even the gc thread
is woken up by wake_up_gc().
force_wake_up_gc() sets c->sectors_to_gc to -1 before calling
wake_up_gc(), then gc thread may have chance to run if no one else
sets c->sectors_to_gc to a positive value before gc_should_run().
This routine can be called where the gc thread is woken up and
required to run in force.
Signed-off-by: Coly Li <col...@suse.de>
---
drivers/md/bcache/btree.h | 18 ++++++++++++++++++
drivers/md/bcache/sysfs.c | 17 ++---------------
2 files changed, 20 insertions(+), 15 deletions(-)
diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h
index a68d6c55783b..d1c72ef64edf 100644
--- a/drivers/md/bcache/btree.h
+++ b/drivers/md/bcache/btree.h
@@ -266,6 +266,24 @@ static inline void wake_up_gc(struct cache_set *c)
wake_up(&c->gc_wait);
}
+static inline void force_wake_up_gc(struct cache_set *c)
+{
+ /*
+ * Garbage collection thread only works when sectors_to_gc < 0,
+ * calling wake_up_gc() won't start gc thread if sectors_to_gc is
+ * not a nagetive value.
+ * Therefore sectors_to_gc is set to -1 here, before waking up
+ * gc thread by calling wake_up_gc(). Then gc_should_run() will
+ * give a chance to permit gc thread to run. "Give a chance" means
+ * before going into gc_should_run(), there is still possibility
+ * that c->sectors_to_gc being set to other positive value. So
+ * this routine won't 100% make sure gc thread will be woken up
+ * to run.
+ */
+ atomic_set(&c->sectors_to_gc, -1);
+ wake_up_gc(c);
+}
+
#define MAP_DONE 0
#define MAP_CONTINUE 1
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index d2e5c9892d4d..7351ee4940f3 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -725,21 +725,8 @@ STORE(__bch_cache_set)
bch_cache_accounting_clear(&c->accounting);
}
- 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_trigger_gc)
+ force_wake_up_gc(c);
if (attr == &sysfs_prune_cache) {
struct shrink_control sc;
--
2.16.4
