On 2017/2/20 下午10:06, Greg KH wrote:
> On Mon, Feb 20, 2017 at 04:12:58AM -0900, Kent Overstreet wrote:
>> On Mon, Feb 20, 2017 at 01:31:37PM +0100, Greg KH wrote:
>>> On Mon, Jan 23, 2017 at 03:54:07PM +0100, Greg KH wrote:
>>>> Kent, any hints?
>>>
>>> Without a response from the maintainer, I can't apply this...
>>>
>>> greg k-h
>>
>> Sorry I missed this - yes, this patch should be safe to apply and it does fix
>> that crash. The relevant code hasn't been changed in ages, 4.4 is definitely
>> fine.
>
> Ok, I've queued this up for 4.9, but for 4.4 it does not apply. Coly,
> can you provide a working backport for 4.4-stable?
Greg,
It is because the 'commit 29e6c57cc78e ("bcache: bch_gc_thread() is not
freezable")' remove a "try_to_freeze()" in bch_gc_thread(), which
happens in v4.7.
I just rebase Kent's fix to v4.4 kernel, solve the conflict. Could you
please check and try the attached patch ?
Thanks.
Coly
Subject: [PATCH] bcache: Make gc wakeup sane, remove set_task_state()
Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
---
drivers/md/bcache/bcache.h | 4 ++--
drivers/md/bcache/btree.c | 40 ++++++++++++++++++++--------------------
drivers/md/bcache/btree.h | 3 +--
drivers/md/bcache/request.c | 4 +---
drivers/md/bcache/super.c | 2 ++
5 files changed, 26 insertions(+), 27 deletions(-)
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 6b420a5..c3ea03c 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -425,7 +425,7 @@ struct cache {
* until a gc finishes - otherwise we could pointlessly burn a ton of
* cpu
*/
- unsigned invalidate_needs_gc:1;
+ unsigned invalidate_needs_gc;
bool discard; /* Get rid of? */
@@ -593,8 +593,8 @@ struct cache_set {
/* Counts how many sectors bio_insert has added to the cache */
atomic_t sectors_to_gc;
+ wait_queue_head_t gc_wait;
- wait_queue_head_t moving_gc_wait;
struct keybuf moving_gc_keys;
/* Number of moving GC bios in flight */
struct semaphore moving_in_flight;
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 83392f8..b5eccb5 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -1761,33 +1761,34 @@ static void bch_btree_gc(struct cache_set *c)
bch_moving_gc(c);
}
-static int bch_gc_thread(void *arg)
+static bool gc_should_run(struct cache_set *c)
{
- struct cache_set *c = arg;
struct cache *ca;
unsigned i;
- while (1) {
-again:
- bch_btree_gc(c);
+ for_each_cache(ca, c, i)
+ if (ca->invalidate_needs_gc)
+ return true;
- set_current_state(TASK_INTERRUPTIBLE);
- if (kthread_should_stop())
- break;
+ if (atomic_read(&c->sectors_to_gc) < 0)
+ return true;
- mutex_lock(&c->bucket_lock);
+ return false;
+}
- for_each_cache(ca, c, i)
- if (ca->invalidate_needs_gc) {
- mutex_unlock(&c->bucket_lock);
- set_current_state(TASK_RUNNING);
- goto again;
- }
+static int bch_gc_thread(void *arg)
+{
+ struct cache_set *c = arg;
- mutex_unlock(&c->bucket_lock);
+ while (1) {
+ wait_event_interruptible(c->gc_wait,
+ kthread_should_stop() || gc_should_run(c));
- try_to_freeze();
- schedule();
+ if (kthread_should_stop())
+ break;
+
+ set_gc_sectors(c);
+ bch_btree_gc(c);
}
return 0;
@@ -1795,11 +1796,10 @@ again:
int bch_gc_thread_start(struct cache_set *c)
{
- c->gc_thread = kthread_create(bch_gc_thread, c, "bcache_gc");
+ c->gc_thread = kthread_run(bch_gc_thread, c, "bcache_gc");
if (IS_ERR(c->gc_thread))
return PTR_ERR(c->gc_thread);
- set_task_state(c->gc_thread, TASK_INTERRUPTIBLE);
return 0;
}
diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h
index 5c391fa..9b80417 100644
--- a/drivers/md/bcache/btree.h
+++ b/drivers/md/bcache/btree.h
@@ -260,8 +260,7 @@ void bch_initial_mark_key(struct cache_set *, int, struct bkey *);
static inline void wake_up_gc(struct cache_set *c)
{
- if (c->gc_thread)
- wake_up_process(c->gc_thread);
+ wake_up(&c->gc_wait);
}
#define MAP_DONE 0
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 25fa844..2410df1 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -196,10 +196,8 @@ static void bch_data_insert_start(struct closure *cl)
struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
struct bio *bio = op->bio, *n;
- if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) {
- set_gc_sectors(op->c);
+ if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0)
wake_up_gc(op->c);
- }
if (op->bypass)
return bch_data_invalidate(cl);
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 679a093..81fef23 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1474,6 +1474,7 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
mutex_init(&c->bucket_lock);
init_waitqueue_head(&c->btree_cache_wait);
init_waitqueue_head(&c->bucket_wait);
+ init_waitqueue_head(&c->gc_wait);
sema_init(&c->uuid_write_mutex, 1);
spin_lock_init(&c->btree_gc_time.lock);
@@ -1532,6 +1533,7 @@ static void run_cache_set(struct cache_set *c)
for_each_cache(ca, c, i)
c->nbuckets += ca->sb.nbuckets;
+ set_gc_sectors(c);
if (CACHE_SYNC(&c->sb)) {
LIST_HEAD(journal);
--
2.10.2