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>
---
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 94c756c66bd7..448e531e8c2d 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -417,6 +417,7 @@ static int __uuid_write(struct cache_set *c)
{
BKEY_PADDED(key) k;
struct closure cl;
+ struct cache *ca;
closure_init_stack(&cl);
lockdep_assert_held(&bch_register_lock);
@@ -428,6 +429,10 @@ static int __uuid_write(struct cache_set *c)
uuid_io(c, REQ_OP_WRITE, 0, &k.key, &cl);
closure_sync(&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;
--
2.18.0
