bcachefs: btree_gc no longer uses main in-memory bucket array

This changes the btree_gc code to only use the second bucket array, the
one dedicated to GC. On completion, it compares what's in its in memory
bucket array to the allocation information in the btree and writes it
directly, instead of updating the main in-memory bucket array and
writing that.

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

1 files changed, 5 insertions, 18 deletions

diff --git a/fs/bcachefs/recovery.c b/fs/bcachefs/recovery.c
index 383838d66edf..feafb7296ddf 100644
--- a/fs/bcachefs/recovery.c
+++ b/fs/bcachefs/recovery.c
@@ -1113,7 +1113,11 @@ use_clean:
 
 	bch_verbose(c, "starting alloc read");
 	err = "error reading allocation information";
-	ret = bch2_alloc_read(c);
+
+	down_read(&c->gc_lock);
+	ret = bch2_alloc_read(c, false, false);
+	up_read(&c->gc_lock);
+
 	if (ret)
 		goto err;
 	bch_verbose(c, "alloc read done");
@@ -1171,23 +1175,6 @@ use_clean:
 	if (c->opts.verbose || !c->sb.clean)
 		bch_info(c, "journal replay done");
 
-	if (test_bit(BCH_FS_NEED_ALLOC_WRITE, &c->flags) &&
-	    !c->opts.nochanges) {
-		/*
-		 * note that even when filesystem was clean there might be work
-		 * to do here, if we ran gc (because of fsck) which recalculated
-		 * oldest_gen:
-		 */
-		bch_verbose(c, "writing allocation info");
-		err = "error writing out alloc info";
-		ret = bch2_alloc_write_all(c, BTREE_INSERT_LAZY_RW);
-		if (ret) {
-			bch_err(c, "error writing alloc info");
-			goto err;
-		}
-		bch_verbose(c, "alloc write done");
-	}
-
 	if (c->sb.version < bcachefs_metadata_version_snapshot_2) {
 		bch2_fs_lazy_rw(c);