bcachefs: Fix incorrect gfp check

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

fs/bcachefs/btree_cache.c

@@ -310,7 +310,7 @@ static unsigned long bch2_btree_cache_scan(struct shrinker *shrink,
 			if (freed >= nr)
 				goto out;
 
-			if (sc->gfp_mask & __GFP_IO)
+			if (sc->gfp_mask & __GFP_FS)
 				mutex_lock(&bc->lock);
 			else if (!mutex_trylock(&bc->lock))
 				goto out;