f2fs: fix sbi->extent_list corruption issue

When there is a failure in f2fs_fill_super() after/during
the recovery of fsync'd nodes, it frees the current sbi and
retries again. This time the mount is successful, but the files
that got recovered before retry, still holds the extent tree,
whose extent nodes list is corrupted since sbi and sbi->extent_list
is freed up. The list_del corruption issue is observed when the
file system is getting unmounted and when those recoverd files extent
node is being freed up in the below context.

list_del corruption. prev->next should be fffffff1e1ef5480, but was (null)
<...>
kernel BUG at kernel/msm-4.14/lib/list_debug.c:53!
task: fffffff1f46f2280 task.stack: ffffff8008068000
lr : __list_del_entry_valid+0x94/0xb4
pc : __list_del_entry_valid+0x94/0xb4
<...>
Call trace:
__list_del_entry_valid+0x94/0xb4
__release_extent_node+0xb0/0x114
__free_extent_tree+0x58/0x7c
f2fs_shrink_extent_tree+0xdc/0x3b0
f2fs_leave_shrinker+0x28/0x7c
f2fs_put_super+0xfc/0x1e0
generic_shutdown_super+0x70/0xf4
kill_block_super+0x2c/0x5c
kill_f2fs_super+0x44/0x50
deactivate_locked_super+0x60/0x8c
deactivate_super+0x68/0x74
cleanup_mnt+0x40/0x78
__cleanup_mnt+0x1c/0x28
task_work_run+0x48/0xd0
do_notify_resume+0x678/0xe98
work_pending+0x8/0x14

Fix this by cleaning up inodes, extent tree and nodes of those
recovered files before freeing up sbi and before next retry.

Change-Id: Ib7c9d055250faad25774d3113f2bc003c854839b
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>

fs/f2fs/f2fs.h

@@ -3172,6 +3172,7 @@ struct rb_entry *__lookup_rb_tree_ret(struct rb_root *root,
 bool __check_rb_tree_consistence(struct f2fs_sb_info *sbi,
 						struct rb_root *root);
 unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink);
+unsigned long __count_extent_cache(struct f2fs_sb_info *sbi);
 bool f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext);
 void f2fs_drop_extent_tree(struct inode *inode);
 unsigned int f2fs_destroy_extent_node(struct inode *inode);

fs/f2fs/shrinker.c

@@ -33,7 +33,7 @@ static unsigned long __count_free_nids(struct f2fs_sb_info *sbi)
 	return count > 0 ? count : 0;
 }
 
-static unsigned long __count_extent_cache(struct f2fs_sb_info *sbi)
+unsigned long __count_extent_cache(struct f2fs_sb_info *sbi)
 {
 	return atomic_read(&sbi->total_zombie_tree) +
 				atomic_read(&sbi->total_ext_node);

fs/f2fs/super.c

@@ -2637,6 +2637,16 @@ static void f2fs_tuning_parameters(struct f2fs_sb_info *sbi)
 	}
 }
 
+static void f2fs_cleanup_inodes(struct f2fs_sb_info *sbi)
+{
+	struct super_block *sb = sbi->sb;
+
+	sync_filesystem(sb);
+	shrink_dcache_sb(sb);
+	evict_inodes(sb);
+	f2fs_shrink_extent_tree(sbi, __count_extent_cache(sbi));
+}
+
 static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct f2fs_sb_info *sbi;
@@ -3011,6 +3021,8 @@ free_meta:
 	 * falls into an infinite loop in sync_meta_pages().
 	 */
 	truncate_inode_pages_final(META_MAPPING(sbi));
+	/* cleanup recovery and quota inodes */
+	f2fs_cleanup_inodes(sbi);
 #ifdef CONFIG_QUOTA
 free_sysfs:
 #endif
@@ -3057,7 +3069,6 @@ free_sbi:
 	/* give only one another chance */
 	if (retry) {
 		retry = false;
-		shrink_dcache_sb(sb);
 		goto try_onemore;
 	}
 	return err;