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Subject: Re: [f2fs-dev] [PATCH 2/2 v3] f2fs: support RO feature
To:     Jaegeuk Kim <jaegeuk@kernel.org>
CC:     <linux-kernel@vger.kernel.org>,
        <linux-f2fs-devel@lists.sourceforge.net>
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>
 <YK73nDvu1hPWr8t0@google.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <99271740-3d58-28bb-3548-0a8f27c55842@huawei.com>
Date:   Fri, 28 May 2021 10:07:19 +0800
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On 2021/5/27 9:36, Jaegeuk Kim wrote:
> 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.

Correct.

Thanks,

> 
>>
>> @@ -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);
>>>
> .
>