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bcache: gc does not work when triggering by manual command

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I try to execute the following command to trigger gc thread:
[root@localhost internal]# echo 1 > trigger_gc
But it does not work, I debug the code in gc_should_run(), It works only
if in invalidating or sectors_to_gc < 0. So set sectors_to_gc to -1 to
meet the condition when we trigger gc by manual command.

(Code comments aded by Coly Li)

Signed-off-by: Tang Junhui <tang.junhui@zte.com.cn>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tang Junhui 2017-09-06 14:25:55 +08:00 committed by Jens Axboe
parent 09b3efec81
commit 0b43f49dc4
1 changed files with 14 additions and 1 deletions
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15
drivers/md/bcache/sysfs.c
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@ -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;