linux-kernel - [PATCH] bcache: move calc_cached_dev_sectors to proper place on backing device detach

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Date:   Fri, 15 Oct 2021 18:16:00 +0800
From:   Lin Feng <linf@...gsu.com>
To:     colyli@...e.de, kent.overstreet@...il.com
Cc:     linux-bcache@...r.kernel.org, linux-kernel@...r.kernel.org,
        linf@...gsu.com
Subject: [PATCH] bcache: move calc_cached_dev_sectors to proper place on backing device detach

Calculation of cache_set's cached sectors is done by travelling
cached_devs list as shown below:

static void calc_cached_dev_sectors(struct cache_set *c)
{
...
        list_for_each_entry(dc, &c->cached_devs, list)
                sectors += bdev_sectors(dc->bdev);

        c->cached_dev_sectors = sectors;
}

But cached_dev won't be unlinked from c->cached_devs list until we call
following list_move(&dc->list, &uncached_devices),
so previous fix in 'commit 46010141da6677b81cc77f9b47f8ac62bd1cbfd3
("bcache: recal cached_dev_sectors on detach")' is wrong, now we move 
it to its right palce.

Signed-off-by: Lin Feng <linf@...gsu.com>
---
 drivers/md/bcache/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index f2874c77ff79..8543e6997770 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1154,9 +1154,9 @@ static void cached_dev_detach_finish(struct work_struct *w)
 
 	mutex_lock(&bch_register_lock);
 
-	calc_cached_dev_sectors(dc->disk.c);
 	bcache_device_detach(&dc->disk);
 	list_move(&dc->list, &uncached_devices);
+	calc_cached_dev_sectors(dc->disk.c);
 
 	clear_bit(BCACHE_DEV_DETACHING, &dc->disk.flags);
 	clear_bit(BCACHE_DEV_UNLINK_DONE, &dc->disk.flags);
-- 
2.31.1