bcachefs: Persist 64 bit io clocks

Originally, bcachefs - going back to bcache - stored, for each bucket, a
16 bit counter corresponding to how long it had been since the bucket
was read from. But, this required periodically rescaling counters on
every bucket to avoid wraparound. That wasn't an issue in bcache, where
we'd perodically rewrite the per bucket metadata all at once, but in
bcachefs we're trying to avoid having to walk every single bucket.

This patch switches to persisting 64 bit io clocks, corresponding to the
64 bit bucket timestaps introduced in the previous patch with
KEY_TYPE_alloc_v2.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/bcachefs/sysfs.c b/fs/bcachefs/sysfs.c
index 521b6d8d518f..8fdbeaf9df32 100644
--- a/fs/bcachefs/sysfs.c
+++ b/fs/bcachefs/sysfs.c
@@ -705,7 +705,7 @@ static unsigned bucket_last_io_fn(struct bch_fs *c, struct bch_dev *ca,
 {
 	int rw = (private ? 1 : 0);
 
-	return bucket_last_io(c, bucket(ca, b), rw);
+	return atomic64_read(&c->io_clock[rw].now) - bucket(ca, b)->io_time[rw];
 }
 
 static unsigned bucket_sectors_used_fn(struct bch_fs *c, struct bch_dev *ca,
@@ -718,7 +718,7 @@ static unsigned bucket_sectors_used_fn(struct bch_fs *c, struct bch_dev *ca,
 static unsigned bucket_oldest_gen_fn(struct bch_fs *c, struct bch_dev *ca,
 				     size_t b, void *private)
 {
-	return bucket_gc_gen(ca, b);
+	return bucket_gc_gen(bucket(ca, b));
 }
 
 static int unsigned_cmp(const void *_l, const void *_r)