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Date:   Wed, 26 May 2021 18:36:28 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 2/2 v3] f2fs: support RO feature
Message-ID: <YK73nDvu1hPWr8t0@google.com>
References: <20210521190217.2484099-1-jaegeuk@kernel.org>
 <20210521190217.2484099-2-jaegeuk@kernel.org>
 <YK5UOfzwdZni7c5W@google.com>
 <YK5edM0igwfd47LV@google.com>
 <9070633e-39ef-6e13-6467-534541d917b7@huawei.com>
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In-Reply-To: <9070633e-39ef-6e13-6467-534541d917b7@huawei.com>
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On 05/27, Chao Yu wrote:
> On 2021/5/26 22:43, Jaegeuk Kim wrote:
> > Given RO feature in superblock, we don't need to check provisioning/reserve
> > spaces and SSA area.
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> > ---
> > Change log from v2:
> >   - allow curseg updates
> >   - fix some bugs
> > 
> >   fs/f2fs/f2fs.h    |  2 ++
> >   fs/f2fs/segment.c |  4 ++++
> >   fs/f2fs/super.c   | 37 +++++++++++++++++++++++++++++++------
> >   3 files changed, 37 insertions(+), 6 deletions(-)
> > 
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index eaf57b5f3c4b..9ad502f92529 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -168,6 +168,7 @@ struct f2fs_mount_info {
> >   #define F2FS_FEATURE_SB_CHKSUM		0x0800
> >   #define F2FS_FEATURE_CASEFOLD		0x1000
> >   #define F2FS_FEATURE_COMPRESSION	0x2000
> > +#define F2FS_FEATURE_RO			0x4000
> >   #define __F2FS_HAS_FEATURE(raw_super, mask)				\
> >   	((raw_super->feature & cpu_to_le32(mask)) != 0)
> > @@ -940,6 +941,7 @@ static inline void set_new_dnode(struct dnode_of_data *dn, struct inode *inode,
> >   #define	NR_CURSEG_DATA_TYPE	(3)
> >   #define NR_CURSEG_NODE_TYPE	(3)
> >   #define NR_CURSEG_INMEM_TYPE	(2)
> > +#define NR_CURSEG_RO_TYPE	(2)
> >   #define NR_CURSEG_PERSIST_TYPE	(NR_CURSEG_DATA_TYPE + NR_CURSEG_NODE_TYPE)
> >   #define NR_CURSEG_TYPE		(NR_CURSEG_INMEM_TYPE + NR_CURSEG_PERSIST_TYPE)
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 8668df7870d0..02e0c38be7eb 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -4683,6 +4683,10 @@ static int sanity_check_curseg(struct f2fs_sb_info *sbi)
> >   		struct seg_entry *se = get_seg_entry(sbi, curseg->segno);
> >   		unsigned int blkofs = curseg->next_blkoff;
> > +		if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) &&
> > +			i != CURSEG_HOT_DATA && i != CURSEG_HOT_NODE)
> > +			continue;
> > +
> >   		sanity_check_seg_type(sbi, curseg->seg_type);
> >   		if (f2fs_test_bit(blkofs, se->cur_valid_map))
> > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > index e70aca8f97bd..6788e7b71e27 100644
> > --- a/fs/f2fs/super.c
> > +++ b/fs/f2fs/super.c
> > @@ -555,7 +555,7 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
> >   	int ret;
> >   	if (!options)
> > -		return 0;
> > +		goto default_check;
> >   	while ((p = strsep(&options, ",")) != NULL) {
> >   		int token;
> > @@ -1090,6 +1090,7 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
> >   			return -EINVAL;
> >   		}
> >   	}
> > +default_check:
> >   #ifdef CONFIG_QUOTA
> >   	if (f2fs_check_quota_options(sbi))
> >   		return -EINVAL;
> > @@ -1162,6 +1163,11 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
> >   	 */
> >   	if (F2FS_OPTION(sbi).active_logs != NR_CURSEG_TYPE)
> >   		F2FS_OPTION(sbi).whint_mode = WHINT_MODE_OFF;
> > +
> > +	if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) && !f2fs_readonly(sbi->sb)) {
> > +		f2fs_err(sbi, "Allow to mount readonly mode only");
> > +		return -EROFS;
> > +	}
> >   	return 0;
> >   }
> > @@ -1819,7 +1825,11 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
> >   static void default_options(struct f2fs_sb_info *sbi)
> >   {
> >   	/* init some FS parameters */
> > -	F2FS_OPTION(sbi).active_logs = NR_CURSEG_PERSIST_TYPE;
> > +	if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO))
> > +		F2FS_OPTION(sbi).active_logs = NR_CURSEG_RO_TYPE;
> > +	else
> > +		F2FS_OPTION(sbi).active_logs = NR_CURSEG_PERSIST_TYPE;
> > +
> >   	F2FS_OPTION(sbi).inline_xattr_size = DEFAULT_INLINE_XATTR_ADDRS;
> >   	F2FS_OPTION(sbi).whint_mode = WHINT_MODE_OFF;
> >   	F2FS_OPTION(sbi).alloc_mode = ALLOC_MODE_DEFAULT;
> > @@ -2001,6 +2011,11 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
> >   	if (f2fs_readonly(sb) && (*flags & SB_RDONLY))
> >   		goto skip;
> > +	if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) && !(*flags & SB_RDONLY)) {
> > +		err = -EROFS;
> > +		goto restore_opts;
> > +	}
> 
> remount() -> parse_options() will fail due to below check, so it doesn't need
> to check again? Am I missing something?

We haven't changed sb->ro at this point yet.

> 
> @@ -1162,6 +1163,11 @@
> 
>  static int parse_options(struct super_block *sb, char *options, bool is_remount)
> 
>  	 */
>  	if (F2FS_OPTION(sbi).active_logs != NR_CURSEG_TYPE)
>  		F2FS_OPTION(sbi).whint_mode = WHINT_MODE_OFF;
> +
> +	if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) && !f2fs_readonly(sbi->sb)) {
> +		f2fs_err(sbi, "Allow to mount readonly mode only");
> +		return -EROFS;
> +	}
>  	return 0;
>  }
> 
> Thanks,
> 
> > +
> >   #ifdef CONFIG_QUOTA
> >   	if (!f2fs_readonly(sb) && (*flags & SB_RDONLY)) {
> >   		err = dquot_suspend(sb, -1);
> > @@ -3134,14 +3149,15 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
> >   	ovp_segments = le32_to_cpu(ckpt->overprov_segment_count);
> >   	reserved_segments = le32_to_cpu(ckpt->rsvd_segment_count);
> > -	if (unlikely(fsmeta < F2FS_MIN_META_SEGMENTS ||
> > +	if (!F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) &&
> > +			unlikely(fsmeta < F2FS_MIN_META_SEGMENTS ||
> >   			ovp_segments == 0 || reserved_segments == 0)) {
> >   		f2fs_err(sbi, "Wrong layout: check mkfs.f2fs version");
> >   		return 1;
> >   	}
> > -
> >   	user_block_count = le64_to_cpu(ckpt->user_block_count);
> > -	segment_count_main = le32_to_cpu(raw_super->segment_count_main);
> > +	segment_count_main = le32_to_cpu(raw_super->segment_count_main) +
> > +			(F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) ? 1 : 0);
> >   	log_blocks_per_seg = le32_to_cpu(raw_super->log_blocks_per_seg);
> >   	if (!user_block_count || user_block_count >=
> >   			segment_count_main << log_blocks_per_seg) {
> > @@ -3172,6 +3188,10 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
> >   		if (le32_to_cpu(ckpt->cur_node_segno[i]) >= main_segs ||
> >   			le16_to_cpu(ckpt->cur_node_blkoff[i]) >= blocks_per_seg)
> >   			return 1;
> > +
> > +		if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO))
> > +			goto check_data;
> > +
> >   		for (j = i + 1; j < NR_CURSEG_NODE_TYPE; j++) {
> >   			if (le32_to_cpu(ckpt->cur_node_segno[i]) ==
> >   				le32_to_cpu(ckpt->cur_node_segno[j])) {
> > @@ -3182,10 +3202,15 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
> >   			}
> >   		}
> >   	}
> > +check_data:
> >   	for (i = 0; i < NR_CURSEG_DATA_TYPE; i++) {
> >   		if (le32_to_cpu(ckpt->cur_data_segno[i]) >= main_segs ||
> >   			le16_to_cpu(ckpt->cur_data_blkoff[i]) >= blocks_per_seg)
> >   			return 1;
> > +
> > +		if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO))
> > +			goto skip_cross;
> > +
> >   		for (j = i + 1; j < NR_CURSEG_DATA_TYPE; j++) {
> >   			if (le32_to_cpu(ckpt->cur_data_segno[i]) ==
> >   				le32_to_cpu(ckpt->cur_data_segno[j])) {
> > @@ -3207,7 +3232,7 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
> >   			}
> >   		}
> >   	}
> > -
> > +skip_cross:
> >   	sit_bitmap_size = le32_to_cpu(ckpt->sit_ver_bitmap_bytesize);
> >   	nat_bitmap_size = le32_to_cpu(ckpt->nat_ver_bitmap_bytesize);
> >