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bcache: introduce force_wake_up_gc() 

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 <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Coly Li 2018-12-13 22:53:52 +08:00 committed by Jens Axboe
parent f383ae300c
commit cb07ad6368
2 changed files with 20 additions and 15 deletions
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18
drivers/md/bcache/btree.h
View File

@ -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

17
drivers/md/bcache/sysfs.c
View File

@ -742,21 +742,8 @@ 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;