linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: fix to do sanity with enabled features in image

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Message-ID: <20190723013546.GA60778@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Mon, 22 Jul 2019 18:35:46 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     Chao Yu <chao@...nel.org>, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: fix to do sanity with enabled features
 in image

On 07/16, Chao Yu wrote:
> Hi Jaegeuk,
> 
> On 2019/5/9 9:15, Chao Yu wrote:
> > On 2019/5/5 10:51, Chao Yu wrote:
> >> On 2019/5/1 11:22, Jaegeuk Kim wrote:
> >>> On 04/29, Chao Yu wrote:
> >>>> On 2019-4-28 21:38, Jaegeuk Kim wrote:
> >>>>> On 04/24, Chao Yu wrote:
> >>>>>> This patch fixes to do sanity with enabled features in image, if
> >>>>>> there are features kernel can not recognize, just fail the mount.
> >>>>>
> >>>>> We need to figure out per-feature-based rejection, since some of them can
> >>>>> be set without layout change.
> 
> What about adding one field in superblock for compatible features in future?
> 
> sb.feature(F2FS_FEATURE_LAST, max] stores uncompatible features
> sb.compatible_feature stores compatible features
> 
> If we follow above rule when adding one feature, then, we can fail the mount if
> sb.feature(F2FS_FEATURE_LAST, max] is valid.

How about adding required_features flag in sb to check part of features only?

> 
> Thanks,
> 
> >>>>
> >>>> So any suggestion on how to implement this?
> >>>
> >>> Which features do we need to disallow? When we introduce new features, they
> >>
> >> I guess it should be the new features.
> >>
> >>> didn't hurt the previous flow by checking f2fs_sb_has_###().
> >>
> >> Yes, but new features may use new disk layout, if old kernel handled it with old
> >> disk layout, there must be problematic.
> >>
> >> e.g. format image with -O extra_attr, and mount it with kernel who don't
> >> recognize new inode layout.
> > 
> > Jaegeuk,
> > 
> > Any thoughts?
> > 
> > Thanks,
> > 
> >>
> >> Thanks,
> >>
> >>>
> >>>>
> >>>> Maybe:
> >>>>
> >>>> if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 14, 0))
> >>>> 	check 4.14+ features
> >>>> else if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 9, 0))
> >>>> 	check 4.9+ features
> >>>> else if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 4, 0))
> >>>> 	check 4.4+ features
> >>>>
> >>>> Thanks,
> >>>>
> >>>>>
> >>>>>>
> >>>>>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> >>>>>> ---
> >>>>>>  fs/f2fs/f2fs.h  | 13 +++++++++++++
> >>>>>>  fs/f2fs/super.c |  9 +++++++++
> >>>>>>  2 files changed, 22 insertions(+)
> >>>>>>
> >>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >>>>>> index f5ffc09705eb..15b640967e12 100644
> >>>>>> --- a/fs/f2fs/f2fs.h
> >>>>>> +++ b/fs/f2fs/f2fs.h
> >>>>>> @@ -151,6 +151,19 @@ struct f2fs_mount_info {
> >>>>>>  #define F2FS_FEATURE_VERITY		0x0400	/* reserved */
> >>>>>>  #define F2FS_FEATURE_SB_CHKSUM		0x0800
> >>>>>>  
> >>>>>> +#define F2FS_ALL_FEATURES	(F2FS_FEATURE_ENCRYPT |			\
> >>>>>> +				F2FS_FEATURE_BLKZONED |			\
> >>>>>> +				F2FS_FEATURE_ATOMIC_WRITE |		\
> >>>>>> +				F2FS_FEATURE_EXTRA_ATTR |		\
> >>>>>> +				F2FS_FEATURE_PRJQUOTA |			\
> >>>>>> +				F2FS_FEATURE_INODE_CHKSUM |		\
> >>>>>> +				F2FS_FEATURE_FLEXIBLE_INLINE_XATTR |	\
> >>>>>> +				F2FS_FEATURE_QUOTA_INO |		\
> >>>>>> +				F2FS_FEATURE_INODE_CRTIME |		\
> >>>>>> +				F2FS_FEATURE_LOST_FOUND |		\
> >>>>>> +				F2FS_FEATURE_VERITY |			\
> >>>>>> +				F2FS_FEATURE_SB_CHKSUM)
> >>>>>> +
> >>>>>>  #define __F2FS_HAS_FEATURE(raw_super, mask)				\
> >>>>>>  	((raw_super->feature & cpu_to_le32(mask)) != 0)
> >>>>>>  #define F2FS_HAS_FEATURE(sbi, mask)	__F2FS_HAS_FEATURE(sbi->raw_super, mask)
> >>>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> >>>>>> index 4f8e9ab48b26..57f2fc6d14ba 100644
> >>>>>> --- a/fs/f2fs/super.c
> >>>>>> +++ b/fs/f2fs/super.c
> >>>>>> @@ -2573,6 +2573,15 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
> >>>>>>  		return 1;
> >>>>>>  	}
> >>>>>>  
> >>>>>> +	/* check whether kernel supports all features */
> >>>>>> +	if (le32_to_cpu(raw_super->feature) & (~F2FS_ALL_FEATURES)) {
> >>>>>> +		f2fs_msg(sb, KERN_INFO,
> >>>>>> +			"Unsupported feature:%u: supported:%u",
> >>>>>> +			le32_to_cpu(raw_super->feature),
> >>>>>> +			F2FS_ALL_FEATURES);
> >>>>>> +		return 1;
> >>>>>> +	}
> >>>>>> +
> >>>>>>  	/* check CP/SIT/NAT/SSA/MAIN_AREA area boundary */
> >>>>>>  	if (sanity_check_area_boundary(sbi, bh))
> >>>>>>  		return 1;
> >>>>>> -- 
> >>>>>> 2.18.0.rc1
> >>> .
> >>>
> >>
> >>
> >> _______________________________________________
> >> Linux-f2fs-devel mailing list
> >> Linux-f2fs-devel@...ts.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> >> .
> >>
> > 
> > 
> > _______________________________________________
> > Linux-f2fs-devel mailing list
> > Linux-f2fs-devel@...ts.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> > .
> >