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Date:   Wed, 26 May 2021 07:06:19 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 2/2 v2] f2fs: support RO feature
Message-ID: <YK5V23HDYvrrXM00@google.com>
References: <20210521190217.2484099-1-jaegeuk@kernel.org>
 <20210521190217.2484099-2-jaegeuk@kernel.org>
 <YK5UOfzwdZni7c5W@google.com>
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On 05/26, 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>
> ---
>  fs/f2fs/f2fs.h    |  2 ++
>  fs/f2fs/segment.c |  4 ++++
>  fs/f2fs/super.c   | 35 ++++++++++++++++++++++++++++++-----
>  3 files changed, 36 insertions(+), 5 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..7769ed789b38 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1162,6 +1162,12 @@ 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_info(sbi, "Allow to mount readonly mode only");
> +		err = -EINVAL;
> +		goto free_options;

Fixed:
       if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) && !f2fs_readonly(sbi->sb)) {
               f2fs_err(sbi, "Allow to mount readonly mode only");
               return EINVAL;
       }

> +	}
>  	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;
> +	}
> +
>  #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);
>  
> -- 
> 2.32.0.rc0.204.g9fa02ecfa5-goog
> 
> 
> 
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