Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 30 Jul 2019 11:02:31 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, chao@kernel.org
Subject: Re: [PATCH v2] f2fs: separate NOCoW and pinfile semantics
Message-ID: <20190730180231.GB76478@jaegeuk-macbookpro.roam.corp.google.com>
References: <20190719073903.9138-1-yuchao0@huawei.com>
 <20190723023640.GC60778@jaegeuk-macbookpro.roam.corp.google.com>
 <d4d064a2-2b3c-3536-6488-39e7cfdb1ea4@huawei.com>
 <20190729055738.GA95664@jaegeuk-macbookpro.roam.corp.google.com>
 <07cd3aba-3516-9ba5-286e-277abb98e244@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <07cd3aba-3516-9ba5-286e-277abb98e244@huawei.com>
User-Agent: Mutt/1.8.2 (2017-04-18)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 07/29, Chao Yu wrote:
> On 2019/7/29 13:57, Jaegeuk Kim wrote:
> > On 07/23, Chao Yu wrote:
> >> On 2019/7/23 10:36, Jaegeuk Kim wrote:
> >>> On 07/19, Chao Yu wrote:
> >>>> Pinning a file is heavy, because skipping pinned files make GC
> >>>> running with heavy load or no effect.
> >>>
> >>> Pinned file is a part of NOCOW files, so I don't think we can simply drop it
> >>> for backward compatibility.
> >>
> >> Yes,
> >>
> >> But what I concerned is that pin file is too heavy, so in order to satisfy below
> >> demand, how about introducing pin_file_2 flag to triggering IPU only during
> >> flush/writeback.
> > 
> > That can be done by cold files?
> 
> Then it may inherit property of cold type file, e.g. a) goes into cold area; b)
> update with very low frequency.
> 
> Actually pin_file_2 could be used by db-wal/log file, which are updated
> frequently, and should go to hot/warm area, it does not match above two property.

How about considering another name like "IPU-only mode"?

              fallocate         write    Flag         GC
Pin_file:     preallocate       IPU      FS_NOCOW_FL  Not allowed
IPU_file:     Not preallocate   IPU      N/A          Default by temperature
Cold_file:    Not preallocate   IPU      N/A          Move in cold area
Hot_file:     Not preallocate   IPU/OPU  N/A          Move in hot area

> 
> Thank,
> 
> > 
> >>
> >>>
> >>>>
> >>>> So that this patch propose to separate nocow and pinfile semantics:
> >>>> - NOCoW flag can only be set on regular file.
> >>>> - NOCoW file will only trigger IPU at common writeback/flush.
> >>>> - NOCow file will do OPU during GC.
> >>>>
> >>>> For the demand of 1) avoid fragment of file's physical block and
> >>>> 2) userspace don't care about file's specific physical address,
> >>>> tagging file as NOCoW will be cheaper than pinned one.
> >>
> >> ^^^
> >>
> >> Thanks,
> >>
> >>>>
> >>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> >>>> ---
> >>>> v2:
> >>>> - rebase code to fix compile error.
> >>>>  fs/f2fs/data.c |  3 ++-
> >>>>  fs/f2fs/f2fs.h |  1 +
> >>>>  fs/f2fs/file.c | 22 +++++++++++++++++++---
> >>>>  3 files changed, 22 insertions(+), 4 deletions(-)
> >>>>
> >>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> >>>> index a2a28bb269bf..15fb8954c363 100644
> >>>> --- a/fs/f2fs/data.c
> >>>> +++ b/fs/f2fs/data.c
> >>>> @@ -1884,7 +1884,8 @@ static inline bool check_inplace_update_policy(struct inode *inode,
> >>>>  
> >>>>  bool f2fs_should_update_inplace(struct inode *inode, struct f2fs_io_info *fio)
> >>>>  {
> >>>> -	if (f2fs_is_pinned_file(inode))
> >>>> +	if (f2fs_is_pinned_file(inode) ||
> >>>> +			F2FS_I(inode)->i_flags & F2FS_NOCOW_FL)
> >>>>  		return true;
> >>>>  
> >>>>  	/* if this is cold file, we should overwrite to avoid fragmentation */
> >>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >>>> index 596ab3e1dd7b..f6c5a3d2e659 100644
> >>>> --- a/fs/f2fs/f2fs.h
> >>>> +++ b/fs/f2fs/f2fs.h
> >>>> @@ -2374,6 +2374,7 @@ static inline void f2fs_change_bit(unsigned int nr, char *addr)
> >>>>  #define F2FS_NOATIME_FL			0x00000080 /* do not update atime */
> >>>>  #define F2FS_INDEX_FL			0x00001000 /* hash-indexed directory */
> >>>>  #define F2FS_DIRSYNC_FL			0x00010000 /* dirsync behaviour (directories only) */
> >>>> +#define F2FS_NOCOW_FL			0x00800000 /* Do not cow file */
> >>>>  #define F2FS_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
> >>>>  
> >>>>  /* Flags that should be inherited by new inodes from their parent. */
> >>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> >>>> index 7ca545874060..ae0fec54cac6 100644
> >>>> --- a/fs/f2fs/file.c
> >>>> +++ b/fs/f2fs/file.c
> >>>> @@ -1692,6 +1692,7 @@ static const struct {
> >>>>  	{ F2FS_NOATIME_FL,	FS_NOATIME_FL },
> >>>>  	{ F2FS_INDEX_FL,	FS_INDEX_FL },
> >>>>  	{ F2FS_DIRSYNC_FL,	FS_DIRSYNC_FL },
> >>>> +	{ F2FS_NOCOW_FL,	FS_NOCOW_FL },
> >>>>  	{ F2FS_PROJINHERIT_FL,	FS_PROJINHERIT_FL },
> >>>>  };
> >>>>  
> >>>> @@ -1715,7 +1716,8 @@ static const struct {
> >>>>  		FS_NODUMP_FL |		\
> >>>>  		FS_NOATIME_FL |		\
> >>>>  		FS_DIRSYNC_FL |		\
> >>>> -		FS_PROJINHERIT_FL)
> >>>> +		FS_PROJINHERIT_FL |	\
> >>>> +		FS_NOCOW_FL)
> >>>>  
> >>>>  /* Convert f2fs on-disk i_flags to FS_IOC_{GET,SET}FLAGS flags */
> >>>>  static inline u32 f2fs_iflags_to_fsflags(u32 iflags)
> >>>> @@ -1753,8 +1755,6 @@ static int f2fs_ioc_getflags(struct file *filp, unsigned long arg)
> >>>>  		fsflags |= FS_ENCRYPT_FL;
> >>>>  	if (f2fs_has_inline_data(inode) || f2fs_has_inline_dentry(inode))
> >>>>  		fsflags |= FS_INLINE_DATA_FL;
> >>>> -	if (is_inode_flag_set(inode, FI_PIN_FILE))
> >>>> -		fsflags |= FS_NOCOW_FL;
> >>>>  
> >>>>  	fsflags &= F2FS_GETTABLE_FS_FL;
> >>>>  
> >>>> @@ -1794,6 +1794,22 @@ static int f2fs_ioc_setflags(struct file *filp, unsigned long arg)
> >>>>  	if (ret)
> >>>>  		goto out;
> >>>>  
> >>>> +	if ((fsflags ^ old_fsflags) & FS_NOCOW_FL) {
> >>>> +		if (!S_ISREG(inode->i_mode)) {
> >>>> +			ret = -EINVAL;
> >>>> +			goto out;
> >>>> +		}
> >>>> +
> >>>> +		if (f2fs_should_update_outplace(inode, NULL)) {
> >>>> +			ret = -EINVAL;
> >>>> +			goto out;
> >>>> +		}
> >>>> +
> >>>> +		ret = f2fs_convert_inline_inode(inode);
> >>>> +		if (ret)
> >>>> +			goto out;
> >>>> +	}
> >>>> +
> >>>>  	ret = f2fs_setflags_common(inode, iflags,
> >>>>  			f2fs_fsflags_to_iflags(F2FS_SETTABLE_FS_FL));
> >>>>  out:
> >>>> -- 
> >>>> 2.18.0.rc1
> >>> .
> >>>
> > .
> >