bcachefs: Improve bch2_btree_cache_to_text()

Make the output slightly clearer, and include a counter for "nodes we
couldn't free because we would have gone under our reserve".

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

diff --git a/fs/bcachefs/btree_cache.c b/fs/bcachefs/btree_cache.c
index 9d6f78e9600e0858ac3de3d64766595d1251b83d..66f18b7cdd409fb40fc8928699ad25b3241cd3c1 100644 (file)
--- a/fs/bcachefs/btree_cache.c
+++ b/fs/bcachefs/btree_cache.c
@@ -487,7 +487,10 @@ static unsigned long bch2_btree_cache_scan(struct shrinker *shrink,
         * IO can always make forward progress:
         */
        can_free = btree_cache_can_free(list);
-       nr = min_t(unsigned long, nr, can_free);
+       if (nr > can_free) {
+               bc->not_freed[BCH_BTREE_CACHE_NOT_FREED_cache_reserve] += nr - can_free;
+               nr = can_free;
+       }
 
        i = 0;
        list_for_each_entry_safe(b, t, &bc->freeable, list) {
@@ -1489,9 +1492,10 @@ void bch2_btree_cache_to_text(struct printbuf *out, const struct btree_cache *bc
 
        prt_btree_cache_line(out, c, "live:",           bc->live[0].nr);
        prt_btree_cache_line(out, c, "pinned:",         bc->live[1].nr);
-       prt_btree_cache_line(out, c, "freeable:",       bc->nr_freeable);
+       prt_btree_cache_line(out, c, "reserve:",        bc->nr_reserve);
+       prt_btree_cache_line(out, c, "freed:",          bc->nr_freeable);
        prt_btree_cache_line(out, c, "dirty:",          atomic_long_read(&bc->nr_dirty));
-       prt_printf(out, "cannibalize lock:\t%p\n",      bc->alloc_lock);
+       prt_printf(out, "cannibalize lock:\t%s\n",      bc->alloc_lock ? "held" : "not held");
        prt_newline(out);
 
        for (unsigned i = 0; i < ARRAY_SIZE(bc->nr_by_btree); i++) {
@@ -1502,6 +1506,7 @@ void bch2_btree_cache_to_text(struct printbuf *out, const struct btree_cache *bc
        }
 
        prt_newline(out);
+       prt_printf(out, "counters since mount:\n");
        prt_printf(out, "freed:\t%zu\n", bc->nr_freed);
        prt_printf(out, "not freed:\n");
 

diff --git a/fs/bcachefs/btree_types.h b/fs/bcachefs/btree_types.h
index 81175c1344d27fc587816be12773b51787253ad5..325b9834134a4c622271ef9d4ce195d91bbee37b 100644 (file)
--- a/fs/bcachefs/btree_types.h
+++ b/fs/bcachefs/btree_types.h
@@ -139,6 +139,7 @@ struct btree {
 };
 
 #define BCH_BTREE_CACHE_NOT_FREED_REASONS()    \
+       x(cache_reserve)                        \
        x(lock_intent)                          \
        x(lock_write)                           \
        x(dirty)                                \