linux-kernel - Re: [RFC PATCH] f2fs: reduce expensive checkpoint trigger frequency

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Message-ID: <YIS9PtDRSfmpKAJU@google.com>
Date:   Sat, 24 Apr 2021 17:52:14 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, chao@...nel.org, heyunlei@...onor.com
Subject: Re: [RFC PATCH] f2fs: reduce expensive checkpoint trigger frequency

On 04/22, Chao Yu wrote:
> On 2021/4/22 12:06, Jaegeuk Kim wrote:
> > On 04/16, 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.
> > 
> > It'll happen once? How much impact will we hit due to this?
> 
> Yunlei reports me this issue, the problems here in Honer device's specified
> environment, most fsync() on regular file triggers a checkpoint() when mkdir()
> happened concurrently, result in causing the performance issue.
> 
> Yunlei could explain more about details of this issue. @Yunlei
> 
> > 
> > > 
> > > 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().
> > > 
> > > Signed-off-by: Chao Yu <yuchao0@...wei.com>
> > > ---
> > >   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 87d734f5589d..34487e527d12 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 6284b2f4a60b..a6c38d8b1ec3 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..38796d488d15 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_is_checkpointed_node(sbi, inode->i_ino))
> > > +		f2fs_add_ino_entry(sbi, inode->i_ino, ENC_DIR_INO);
> > 
> > Is it right to say ENC_DIR_INO in this case?
> 
> Sorry, I didn't get it.

I mean, this case includes non-encrypted directory as well.

> 
> 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
> > .
> >