Re: [f2fs-dev] [PATCH 2/3] f2fs: move release of block devices to after kill_block_super()

[Chao Yu <chao@kernel.org>]

On 2023/12/13 12:00, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Call destroy_device_list() and free the f2fs_sb_info from
> kill_f2fs_super(), after the call to kill_block_super().  This is
> necessary to order it after the call to fscrypt_destroy_keyring() once
> generic_shutdown_super() starts calling fscrypt_destroy_keyring() just
> after calling ->put_super.  This is because fscrypt_destroy_keyring()
> may call into f2fs_get_devices() via the fscrypt_operations.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>   fs/f2fs/super.c | 12 +++++++-----
>   1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 033af907c3b1d..ba95a341a9a36 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1710,42 +1710,39 @@ static void f2fs_put_super(struct super_block *sb)
>   	f2fs_destroy_node_manager(sbi);
>   	f2fs_destroy_segment_manager(sbi);
>   
>   	/* flush s_error_work before sbi destroy */
>   	flush_work(&sbi->s_error_work);
>   
>   	f2fs_destroy_post_read_wq(sbi);
>   
>   	kvfree(sbi->ckpt);
>   
> -	sb->s_fs_info = NULL;
>   	if (sbi->s_chksum_driver)
>   		crypto_free_shash(sbi->s_chksum_driver);
>   	kfree(sbi->raw_super);
>   
> -	destroy_device_list(sbi);
>   	f2fs_destroy_page_array_cache(sbi);
>   	f2fs_destroy_xattr_caches(sbi);
>   	mempool_destroy(sbi->write_io_dummy);
>   #ifdef CONFIG_QUOTA
>   	for (i = 0; i < MAXQUOTAS; i++)
>   		kfree(F2FS_OPTION(sbi).s_qf_names[i]);
>   #endif
>   	fscrypt_free_dummy_policy(&F2FS_OPTION(sbi).dummy_enc_policy);
>   	destroy_percpu_info(sbi);
>   	f2fs_destroy_iostat(sbi);
>   	for (i = 0; i < NR_PAGE_TYPE; i++)
>   		kvfree(sbi->write_io[i]);
>   #if IS_ENABLED(CONFIG_UNICODE)
>   	utf8_unload(sb->s_encoding);
>   #endif
> -	kfree(sbi);
>   }
>   
>   int f2fs_sync_fs(struct super_block *sb, int sync)
>   {
>   	struct f2fs_sb_info *sbi = F2FS_SB(sb);
>   	int err = 0;
>   
>   	if (unlikely(f2fs_cp_error(sbi)))
>   		return 0;
>   	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
> @@ -4895,23 +4892,23 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>   }
>   
>   static struct dentry *f2fs_mount(struct file_system_type *fs_type, int flags,
>   			const char *dev_name, void *data)
>   {
>   	return mount_bdev(fs_type, flags, dev_name, data, f2fs_fill_super);
>   }
>   
>   static void kill_f2fs_super(struct super_block *sb)
>   {
> -	if (sb->s_root) {
> -		struct f2fs_sb_info *sbi = F2FS_SB(sb);
> +	struct f2fs_sb_info *sbi = F2FS_SB(sb);
>   
> +	if (sb->s_root) {
>   		set_sbi_flag(sbi, SBI_IS_CLOSE);
>   		f2fs_stop_gc_thread(sbi);
>   		f2fs_stop_discard_thread(sbi);
>   
>   #ifdef CONFIG_F2FS_FS_COMPRESSION
>   		/*
>   		 * latter evict_inode() can bypass checking and invalidating
>   		 * compress inode cache.
>   		 */
>   		if (test_opt(sbi, COMPRESS_CACHE))
> @@ -4924,20 +4921,25 @@ static void kill_f2fs_super(struct super_block *sb)
>   				.reason = CP_UMOUNT,
>   			};
>   			stat_inc_cp_call_count(sbi, TOTAL_CALL);
>   			f2fs_write_checkpoint(sbi, &cpc);
>   		}
>   
>   		if (is_sbi_flag_set(sbi, SBI_IS_RECOVERED) && f2fs_readonly(sb))
>   			sb->s_flags &= ~SB_RDONLY;
>   	}
>   	kill_block_super(sb);
> +	if (sbi) {

Can you please add one single line comment here to expand why we
need to delay destroying device_list?

Other code part looks good to me.

Thanks,

> +		destroy_device_list(sbi);
> +		kfree(sbi);
> +		sb->s_fs_info = NULL;
> +	}
>   }
>   
>   static struct file_system_type f2fs_fs_type = {
>   	.owner		= THIS_MODULE,
>   	.name		= "f2fs",
>   	.mount		= f2fs_mount,
>   	.kill_sb	= kill_f2fs_super,
>   	.fs_flags	= FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
>   };
>   MODULE_ALIAS_FS("f2fs");