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Message-ID: <YJlS8CldaPiT42d8@google.com>
Date: Mon, 10 May 2021 08:36:16 -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,
Yunlei He <heyunlei@...onor.com>
Subject: Re: [PATCH v2] f2fs: reduce expensive checkpoint trigger frequency
On 05/06, Chao Yu wrote:
> On 2021/5/6 12:43, Jaegeuk Kim wrote:
> > On 05/06, Chao Yu wrote:
> > > 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@...onor.com>
> > > > > > > Signed-off-by: Chao Yu <yuchao0@...wei.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
> >
> > I keep asking no encryption case where
> > 1) parent is checkpointed
> > 2) set_xattr(dir) w/ new new xnid
> > 3) create(file)
> > 4) fsync(file)
> >
> > In that case, previousely we do checkpoint, but this change does not. Yes?
>
> In this case, we won't checkpoint xnid, instead, just flushing file's data/node.
>
> So yes, actually this patch will change the policy, which looks posix compliance,
> that mean we only persist the file's meta/data after fsync(file).
>
> How about keeping original policy in FSYNC_MODE_STRICT mode, and using current
> policy in FSYNC_MODE_POSIX mode?
IIRC, it'd be much important to keep directory's xnid, so worry about stability
regression. Is that case a really performance blocker?
>
> Thanks,
>
> >
> > > 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
> > > > > > .
> > > > > >
> > > > .
> > > >
> > .
> >
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