ext4: no need to generate from free list in mballoc

Commit 7a2fcbf7 ("ext4: don't use blocks freed but not yet committed in
buddy cache init") added a code to mark as used blocks in the list of not yet
committed freed blocks during initialization of a buddy page. However
ext4_mb_free_metadata() makes sure buddy page is already loaded and takes a
reference to it so it cannot happen that ext4_mb_init_cache() is called
when efd list is non-empty. Just remove the
ext4_mb_generate_from_freelist() call.

Fixes: 7a2fcbf7('ext4: don't use blocks freed but not yet committed in buddy cache init')
Signed-off-by: Wang Jianjian <wangjianjian0@foxmail.com>
Link: https://lore.kernel.org/r/tencent_53CBCB1668358AE862684E453DF37B722008@qq.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

fs/ext4/mballoc.c

@@ -417,8 +417,6 @@ static const char * const ext4_groupinfo_slab_names[NR_GRPINFO_CACHES] = {
 
 static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
 					ext4_group_t group);
-static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
-						ext4_group_t group);
 static void ext4_mb_new_preallocation(struct ext4_allocation_context *ac);
 
 static bool ext4_mb_good_group(struct ext4_allocation_context *ac,
@@ -1361,17 +1359,17 @@ static int ext4_mb_init_cache(struct page *page, char *incore, gfp_t gfp)
 		 * We place the buddy block and bitmap block
 		 * close together
 		 */
+		grinfo = ext4_get_group_info(sb, group);
+		if (!grinfo) {
+			err = -EFSCORRUPTED;
+		        goto out;
+		}
 		if ((first_block + i) & 1) {
 			/* this is block of buddy */
 			BUG_ON(incore == NULL);
 			mb_debug(sb, "put buddy for group %u in page %lu/%x\n",
 				group, page->index, i * blocksize);
 			trace_ext4_mb_buddy_bitmap_load(sb, group);
-			grinfo = ext4_get_group_info(sb, group);
-			if (!grinfo) {
-				err = -EFSCORRUPTED;
-				goto out;
-			}
 			grinfo->bb_fragments = 0;
 			memset(grinfo->bb_counters, 0,
 			       sizeof(*grinfo->bb_counters) *
@@ -1398,7 +1396,7 @@ static int ext4_mb_init_cache(struct page *page, char *incore, gfp_t gfp)
 
 			/* mark all preallocated blks used in in-core bitmap */
 			ext4_mb_generate_from_pa(sb, data, group);
-			ext4_mb_generate_from_freelist(sb, data, group);
+			WARN_ON_ONCE(!RB_EMPTY_ROOT(&grinfo->bb_free_root));
 			ext4_unlock_group(sb, group);
 
 			/* set incore so that the buddy information can be
@@ -4950,31 +4948,6 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 	return false;
 }
 
-/*
- * the function goes through all block freed in the group
- * but not yet committed and marks them used in in-core bitmap.
- * buddy must be generated from this bitmap
- * Need to be called with the ext4 group lock held
- */
-static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
-						ext4_group_t group)
-{
-	struct rb_node *n;
-	struct ext4_group_info *grp;
-	struct ext4_free_data *entry;
-
-	grp = ext4_get_group_info(sb, group);
-	if (!grp)
-		return;
-	n = rb_first(&(grp->bb_free_root));
-
-	while (n) {
-		entry = rb_entry(n, struct ext4_free_data, efd_node);
-		mb_set_bits(bitmap, entry->efd_start_cluster, entry->efd_count);
-		n = rb_next(n);
-	}
-}
-
 /*
  * the function goes through all preallocation in this group and marks them
  * used in in-core bitmap. buddy must be generated from this bitmap