Re: [f2fs-dev] [PATCH v3] f2fs: reduce expensive checkpoint trigger frequency

[Chao Yu <chao@kernel.org>]

On 2024/6/25 10:14, wangzijie wrote:
>> We may trigger high frequent checkpoint for below case:
>> 1. mkdir /mnt/dir1; set dir1 encrypted
>> 2. touch /mnt/file1; fsync /mnt/file1
>> 3. mkdir /mnt/dir2; set dir2 encrypted
>> 4. touch /mnt/file2; fsync /mnt/file2
>> ...
>>
>> Although, newly created dir and file are not related, due to
>> commit bbf156f7afa7 ("f2fs: fix lost xattrs of directories"), we will
>> trigger checkpoint whenever fsync() comes after a new encrypted dir
>> created.
>>
>> In order to avoid such condition, let's record an entry including
>> directory's ino into global cache when we initialize encryption policy
>> in a checkpointed directory, and then only trigger checkpoint() when
>> target file's parent has non-persisted encryption policy, for the case
>> its parent is not checkpointed, need_do_checkpoint() has cover that
>> by verifying it with f2fs_is_checkpointed_node().
>>
>> Reported-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
>> Tested-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
>> Reported-by: Yunlei He <heyunlei@hihonor.com>
>> Signed-off-by: Chao Yu <chao@kernel.org>
>> ---
>> v3:
>> - Recently, Zhiguo Niu reported the same issue, so I repost this
>> patch for comments.
>>   fs/f2fs/f2fs.h              |  2 ++
>>   fs/f2fs/file.c              |  3 +++
>>   fs/f2fs/xattr.c             | 16 ++++++++++++++--
>>   include/trace/events/f2fs.h |  3 ++-
>>   4 files changed, 21 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index e2e0ca45f881..0094a8c85f4a 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -279,6 +279,7 @@ enum {
>>   	APPEND_INO,		/* for append ino list */
>>   	UPDATE_INO,		/* for update ino list */
>>   	TRANS_DIR_INO,		/* for transactions dir ino list */
>> +	ENC_DIR_INO,		/* for encrypted dir ino list */
>>   	FLUSH_INO,		/* for multiple device flushing */
>>   	MAX_INO_ENTRY,		/* max. list */
>>   };
>> @@ -1147,6 +1148,7 @@ enum cp_reason_type {
>>   	CP_FASTBOOT_MODE,
>>   	CP_SPEC_LOG_NUM,
>>   	CP_RECOVER_DIR,
>> +	CP_ENC_DIR,
>>   };
>>   
>>   enum iostat_type {
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 8198afb5fb9c..18b33b1f0c83 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -218,6 +218,9 @@ static inline enum cp_reason_type need_do_checkpoint(struct inode *inode)
>>   		f2fs_exist_written_data(sbi, F2FS_I(inode)->i_pino,
>>   							TRANS_DIR_INO))
>>   		cp_reason = CP_RECOVER_DIR;
>> +	else if (f2fs_exist_written_data(sbi, F2FS_I(inode)->i_pino,
>> +							ENC_DIR_INO))
>> +		cp_reason = CP_ENC_DIR;
>>   
>>   	return cp_reason;
>>   }
>> diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
>> index f290fe9327c4..cbd1b88297fe 100644
>> --- a/fs/f2fs/xattr.c
>> +++ b/fs/f2fs/xattr.c
>> @@ -629,6 +629,7 @@ static int __f2fs_setxattr(struct inode *inode, int index,
>>   			const char *name, const void *value, size_t size,
>>   			struct page *ipage, int flags)
>>   {
>> +	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>   	struct f2fs_xattr_entry *here, *last;
>>   	void *base_addr, *last_base_addr;
>>   	int found, newsize;
>> @@ -772,8 +773,19 @@ static int __f2fs_setxattr(struct inode *inode, int index,
>>   	if (index == F2FS_XATTR_INDEX_ENCRYPTION &&
>>   			!strcmp(name, F2FS_XATTR_NAME_ENCRYPTION_CONTEXT))
>>   		f2fs_set_encrypted_inode(inode);
>> -	if (S_ISDIR(inode->i_mode))
>> -		set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_CP);
>> +
>> +	if (S_ISDIR(inode->i_mode)) {
>> +		/*
>> +		 * In restrict mode, fsync() always tries triggering checkpoint
>> +		 * for all metadata consistency, in other mode, it only triggers
>> +		 * checkpoint when parent's encryption metadata updates.
>> +		 */
>> +		if (F2FS_OPTION(sbi).fsync_mode == FSYNC_MODE_STRICT)
>> +			set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_CP);
>> +		else if (IS_ENCRYPTED(inode) &&
>> +			f2fs_is_checkpointed_node(sbi, inode->i_ino))
>> +			f2fs_add_ino_entry(sbi, inode->i_ino, ENC_DIR_INO);
>> +	}
>>   
>>   same:
>>   	if (is_inode_flag_set(inode, FI_ACL_MODE)) {
>> diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h
>> index 7ed0fc430dc6..48f2e399e184 100644
>> --- a/include/trace/events/f2fs.h
>> +++ b/include/trace/events/f2fs.h
>> @@ -139,7 +139,8 @@ TRACE_DEFINE_ENUM(EX_BLOCK_AGE);
>>   		{ CP_NODE_NEED_CP,	"node needs cp" },		\
>>   		{ CP_FASTBOOT_MODE,	"fastboot mode" },		\
>>   		{ CP_SPEC_LOG_NUM,	"log type is 2" },		\
>> -		{ CP_RECOVER_DIR,	"dir needs recovery" })
>> +		{ CP_RECOVER_DIR,	"dir needs recovery" },		\
>> +		{ CP_ENC_DIR,		"persist encryption policy" })
>>   
>>   #define show_shutdown_mode(type)					\
>>   	__print_symbolic(type,						\
>> -- 
>> 2.40.1
> 
> Hi, Chao
> I noticed the discussion about patch v2, Jaegeuk mentioned no encryption case:
> 1) parent is checkpointed
> 2) set_xattr(dir) w/ new xnid
> 3) create(file)
> 4) fsync(file)
> We will not trigger checkpoint() after this change.
> So, how about adding a rule in need_do_checkpoint? We can judge if the parent has xnid
> being checkpointed or not, if not we can still trigger checkpoint() and keep the same
> behavior before this change.

Hi wangzijie,

It may cause performance overhead to get parent's xnid by parent ino,
so I prefer to tag ENC_DIR_INO for the inode if its parent's xnid is
not checkpointed, it that fine to you?

Thanks,

> 
> 
> 
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