bcachefs: Tweak threshold for allocator triggering discards

The allocator path has a "if we're really low on free buckets, check if
we should issue discards" - tweak this to also trigger discards if more
than 1/128th of the device is in need_discard state.

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

diff --git a/fs/bcachefs/alloc_foreground.c b/fs/bcachefs/alloc_foreground.c
index b375ad610acdbaef6ac0dd55b60103e1f3dd7ebd..b58525ec7b4d3caa6221b213b619e7f209c23c62 100644 (file)
--- a/fs/bcachefs/alloc_foreground.c
+++ b/fs/bcachefs/alloc_foreground.c
@@ -511,7 +511,8 @@ again:
        bch2_dev_usage_read_fast(ca, &req->usage);
        avail = dev_buckets_free(ca, req->usage, req->watermark);
 
-       if (req->usage.buckets[BCH_DATA_need_discard] > avail)
+       if (req->usage.buckets[BCH_DATA_need_discard] >
+           min(avail, ca->mi.nbuckets >> 7))
                bch2_dev_do_discards(ca);
 
        if (req->usage.buckets[BCH_DATA_need_gc_gens] > avail)