Re: [PATCH v2] f2fs: reduce expensive checkpoint trigger frequency

Chao Yu
2021-05-06T02:15:27Z

On 2021/5/4 22:36, Jaegeuk Kim wrote:
> On 04/27, Chao Yu wrote:
>> On 2021/4/27 1:09, Jaegeuk Kim wrote:
>>> On 04/25, Chao Yu 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: Yunlei He <heyunlei@hihonor.com>
>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>> ---
>>>> v2:
>>>> - fix to set ENC_DIR_INO only for encrypted directory
>>>> fs/f2fs/f2fs.h | 2 ++
>>>> fs/f2fs/file.c | 3 +++
>>>> fs/f2fs/xattr.c | 6 ++++--
>>>> include/trace/events/f2fs.h | 3 ++-
>>>> 4 files changed, 11 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>> index b9d5317db0a7..0fe881309a20 100644
>>>> --- a/fs/f2fs/f2fs.h
>>>> +++ b/fs/f2fs/f2fs.h
>>>> @@ -246,6 +246,7 @@ enum {
>>>> APPEND_INO, /* for append ino list */
>>>> UPDATE_INO, /* for update ino list */
>>>> TRANS_DIR_INO, /* for trasactions dir ino list */
>>>> + ENC_DIR_INO, /* for encrypted dir ino list */
>>>> FLUSH_INO, /* for multiple device flushing */
>>>> MAX_INO_ENTRY, /* max. list */
>>>> };
>>>> @@ -1090,6 +1091,7 @@ 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 a595050c56d3..62af29ec0879 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 c8f34decbf8e..70615d504f7e 100644
>>>> --- a/fs/f2fs/xattr.c
>>>> +++ b/fs/f2fs/xattr.c
>>>> @@ -630,6 +630,7 @@ 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;
>>>> @@ -745,8 +746,9 @@ static int __f2fs_setxattr(struct inode *inode, int index,
>>>> !strcmp(name, F2FS_XATTR_NAME_ENCRYPTION_CONTEXT))
>>>> f2fs_set_encrypted_inode(inode);
>>>> f2fs_mark_inode_dirty_sync(inode, true);
>>>> - if (!error && S_ISDIR(inode->i_mode))
>>>> - set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_CP);
>>>> + if (!error && S_ISDIR(inode->i_mode) && f2fs_encrypted_file(inode) &&
>>>> + f2fs_is_checkpointed_node(sbi, inode->i_ino))
>>>> + f2fs_add_ino_entry(sbi, inode->i_ino, ENC_DIR_INO);
>>>
>>> What will happen, if we need to checkpoint xattr_nid on this directory?
>>
>> need_do_checkpoint()
>>
>> a) else if (!f2fs_is_checkpointed_node(sbi, F2FS_I(inode)->i_pino))
>> cp_reason = CP_NODE_NEED_CP;
>
> This will change the current behavior which does checkpoint regardless of the
> parent being checkpointed. If i_pino was checkpointed but xnid wasn't, can we
> get xnid being checkpointed?

Yes,

>> If parent is checkpointed, after converting parent to encrypted directory
>> and create the file in parent, fsync this file will trigger checkpoint() due
>> to b)

If i_pino was checkpointed, but xnid wasn't due to enable encryption on this
directory, fsync() this file will trigger checkpoint() to make sure xnid
checkpointed due to b) case.

Thanks,

>
>>
>> b) else if (f2fs_exist_written_data(sbi, F2FS_I(inode)->i_pino,
>> ENC_DIR_INO))
>> cp_reason = CP_ENC_DIR;
>>
>> If parent is not checkpointed, after converting parent to encrypted directory
>> and create the file in parent, fsync this file will trigger checkpoint() due
>> to a)
>>
>> If parent is checkpointed, after converting parent to encrypted directory
>> and create the file in parent, fsync this file will trigger checkpoint() due
>> to b)
>>
>> Am I missing any cases?
>>
>> Thanks,
>>
>>>
>>>> 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 56b113e3cd6a..ca0cf12226e9 100644
>>>> --- a/include/trace/events/f2fs.h
>>>> +++ b/include/trace/events/f2fs.h
>>>> @@ -145,7 +145,8 @@ TRACE_DEFINE_ENUM(CP_RESIZE);
>>>> { 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, \
>>>> --
>>>> 2.29.2
>>> .
>>>
> .
>