[PATCH 4.19 156/220] bcache: account size of buckets used in uuid write to ca->meta_sectors_written

From: Greg Kroah-Hartman
Date: Fri Nov 22 2019 - 06:09:32 EST

From: Shenghui Wang <shhuiw@xxxxxxxxxxx>

[ Upstream commit 7a55948d38eb9b274cbbdd56dc1dd4b96ebfbe04 ]

UUIDs are considered as metadata. __uuid_write should add the number
of buckets (in sectors) written to disk to ca->meta_sectors_written.
Currently only 1 bucket is used in uuid write.

Steps to test:
1) create a fresh backing device and a fresh cache device separately.
The backing device didn't attach to any cache set.
2) cd /sys/block/<cache device>/bcache
cat metadata_written // record the output value
cat bucket_size
3) attach the backing device to cache set
4) cat metadata_written
The output value is almost the same as the value in step 2
before the change.
After the change, the value is bigger about 1 bucket size.

Signed-off-by: Shenghui Wang <shhuiw@xxxxxxxxxxx>
Reviewed-by: Tang Junhui <tang.junhui.linux@xxxxxxxxx>
Signed-off-by: Coly Li <colyli@xxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/md/bcache/super.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 2321643974dab..c4da2fe623e9e 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -418,6 +418,7 @@ static int __uuid_write(struct cache_set *c)
struct closure cl;
+ struct cache *ca;

@@ -429,6 +430,10 @@ static int __uuid_write(struct cache_set *c)
uuid_io(c, REQ_OP_WRITE, 0, &k.key, &cl);

+ /* Only one bucket used for uuid write */
+ ca = PTR_CACHE(c, &k.key, 0);
+ atomic_long_add(ca->sb.bucket_size, &ca->meta_sectors_written);
bkey_copy(&c->uuid_bucket, &k.key);
bkey_put(c, &k.key);
return 0;