bcachefs: Improve "copygc requested to run" error message

This improves the "copygc requested to run but no buckets found" to show
the device that requires copygc to be run on - we'll definitely need to
improve this more.

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

diff --git a/fs/bcachefs/movinggc.c b/fs/bcachefs/movinggc.c
index 6209cb51efcb375d1afe520c286c90b548abc445..1e2de1e818c1c9a33e707bcf5172ee913913ea9d 100644 (file)
--- a/fs/bcachefs/movinggc.c
+++ b/fs/bcachefs/movinggc.c
@@ -255,7 +255,28 @@ static int bch2_copygc(struct bch_fs *c)
        }
 
        if (!h->used) {
-               bch_err_ratelimited(c, "copygc requested to run but found no buckets to move!");
+               s64 wait = S64_MAX, dev_wait;
+               u64 dev_min_wait_fragmented = 0;
+               u64 dev_min_wait_allowed = 0;
+               int dev_min_wait = -1;
+
+               for_each_rw_member(ca, c, dev_idx) {
+                       struct bch_dev_usage usage = bch2_dev_usage_read(ca);
+                       s64 allowed = ((__dev_buckets_available(ca, usage, RESERVE_none) *
+                                              ca->mi.bucket_size) >> 1);
+                       s64 fragmented = usage.d[BCH_DATA_user].fragmented;
+
+                       dev_wait = max(0LL, allowed - fragmented);
+
+                       if (dev_min_wait < 0 || dev_wait < wait) {
+                               dev_min_wait = dev_idx;
+                               dev_min_wait_fragmented = fragmented;
+                               dev_min_wait_allowed    = allowed;
+                       }
+               }
+
+               bch_err_ratelimited(c, "copygc requested to run but found no buckets to move! dev %u fragmented %llu allowed %llu",
+                                   dev_min_wait, dev_min_wait_fragmented, dev_min_wait_allowed);
                return 0;
        }