bcache: Fix sysfs splat on shutdown with flash only devs

Whoops.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>

drivers/md/bcache/bcache.h

@@ -266,12 +266,10 @@ struct bcache_device {
 
 	struct gendisk		*disk;
 
-	/* If nonzero, we're closing */
-	atomic_t		closing;
-
-	/* If nonzero, we're detaching/unregistering from cache set */
-	atomic_t		detaching;
-	int			flush_done;
+	unsigned long		flags;
+#define BCACHE_DEV_CLOSING	0
+#define BCACHE_DEV_DETACHING	1
+#define BCACHE_DEV_UNLINK_DONE	2
 
 	unsigned		nr_stripes;
 	unsigned		stripe_size;

drivers/md/bcache/request.c

@@ -512,7 +512,7 @@ static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)
 	struct task_struct *task = current;
 	struct io *i;
 
-	if (atomic_read(&dc->disk.detaching) ||
+	if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
 	    c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
 	    (bio->bi_rw & REQ_DISCARD))
 		goto skip;

drivers/md/bcache/super.c

@@ -621,7 +621,7 @@ static void prio_read(struct cache *ca, uint64_t bucket)
 static int open_dev(struct block_device *b, fmode_t mode)
 {
 	struct bcache_device *d = b->bd_disk->private_data;
-	if (atomic_read(&d->closing))
+	if (test_bit(BCACHE_DEV_CLOSING, &d->flags))
 		return -ENXIO;
 
 	closure_get(&d->cl);
@@ -650,12 +650,15 @@ static const struct block_device_operations bcache_ops = {
 
 void bcache_device_stop(struct bcache_device *d)
 {
-	if (!atomic_xchg(&d->closing, 1))
+	if (!test_and_set_bit(BCACHE_DEV_CLOSING, &d->flags))
 		closure_queue(&d->cl);
 }
 
 static void bcache_device_unlink(struct bcache_device *d)
 {
+	lockdep_assert_held(&bch_register_lock);
+
+	if (d->c && !test_and_set_bit(BCACHE_DEV_UNLINK_DONE, &d->flags)) {
 		unsigned i;
 		struct cache *ca;
 
@@ -664,6 +667,7 @@ static void bcache_device_unlink(struct bcache_device *d)
 
 		for_each_cache(ca, d->c, i)
 			bd_unlink_disk_holder(ca->bdev, d->disk);
+	}
 }
 
 static void bcache_device_link(struct bcache_device *d, struct cache_set *c,
@@ -687,18 +691,15 @@ static void bcache_device_detach(struct bcache_device *d)
 {
 	lockdep_assert_held(&bch_register_lock);
 
-	if (atomic_read(&d->detaching)) {
+	if (test_bit(BCACHE_DEV_DETACHING, &d->flags)) {
 		struct uuid_entry *u = d->c->uuids + d->id;
 
 		SET_UUID_FLASH_ONLY(u, 0);
 		memcpy(u->uuid, invalid_uuid, 16);
 		u->invalidated = cpu_to_le32(get_seconds());
 		bch_uuid_write(d->c);
-
-		atomic_set(&d->detaching, 0);
 	}
 
-	if (!d->flush_done)
 	bcache_device_unlink(d);
 
 	d->c->devices[d->id] = NULL;
@@ -879,7 +880,7 @@ static void cached_dev_detach_finish(struct work_struct *w)
 	struct closure cl;
 	closure_init_stack(&cl);
 
-	BUG_ON(!atomic_read(&dc->disk.detaching));
+	BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags));
 	BUG_ON(atomic_read(&dc->count));
 
 	mutex_lock(&bch_register_lock);
@@ -893,6 +894,8 @@ static void cached_dev_detach_finish(struct work_struct *w)
 	bcache_device_detach(&dc->disk);
 	list_move(&dc->list, &uncached_devices);
 
+	clear_bit(BCACHE_DEV_DETACHING, &dc->disk.flags);
+
 	mutex_unlock(&bch_register_lock);
 
 	pr_info("Caching disabled for %s", bdevname(dc->bdev, buf));
@@ -905,10 +908,10 @@ void bch_cached_dev_detach(struct cached_dev *dc)
 {
 	lockdep_assert_held(&bch_register_lock);
 
-	if (atomic_read(&dc->disk.closing))
+	if (test_bit(BCACHE_DEV_CLOSING, &dc->disk.flags))
 		return;
 
-	if (atomic_xchg(&dc->disk.detaching, 1))
+	if (test_and_set_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
 		return;
 
 	/*
@@ -1064,11 +1067,7 @@ static void cached_dev_flush(struct closure *cl)
 	struct bcache_device *d = &dc->disk;
 
 	mutex_lock(&bch_register_lock);
-	d->flush_done = 1;
-
-	if (d->c)
 	bcache_device_unlink(d);
-
 	mutex_unlock(&bch_register_lock);
 
 	bch_cache_accounting_destroy(&dc->accounting);

drivers/md/bcache/sysfs.c

@@ -370,7 +370,7 @@ STORE(__bch_flash_dev)
 	}
 
 	if (attr == &sysfs_unregister) {
-		atomic_set(&d->detaching, 1);
+		set_bit(BCACHE_DEV_DETACHING, &d->flags);
 		bcache_device_stop(d);
 	}
 

drivers/md/bcache/writeback.c

@@ -89,7 +89,7 @@ static unsigned writeback_delay(struct cached_dev *dc, unsigned sectors)
 {
 	uint64_t ret;
 
-	if (atomic_read(&dc->disk.detaching) ||
+	if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
 	    !dc->writeback_percent)
 		return 0;
 
@@ -404,7 +404,7 @@ static int bch_writeback_thread(void *arg)
 	while (!kthread_should_stop()) {
 		down_write(&dc->writeback_lock);
 		if (!atomic_read(&dc->has_dirty) ||
-		    (!atomic_read(&dc->disk.detaching) &&
+		    (!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) &&
 		     !dc->writeback_running)) {
 			up_write(&dc->writeback_lock);
 			set_current_state(TASK_INTERRUPTIBLE);
@@ -437,7 +437,7 @@ static int bch_writeback_thread(void *arg)
 
 			while (delay &&
 			       !kthread_should_stop() &&
-			       !atomic_read(&dc->disk.detaching))
+			       !test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
 				delay = schedule_timeout_interruptible(delay);
 		}
 	}

drivers/md/bcache/writeback.h

@@ -45,7 +45,7 @@ static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
 	unsigned in_use = dc->disk.c->gc_stats.in_use;
 
 	if (cache_mode != CACHE_MODE_WRITEBACK ||
-	    atomic_read(&dc->disk.detaching) ||
+	    test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
 	    in_use > CUTOFF_WRITEBACK_SYNC)
 		return false;