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Date:   Tue, 12 Jul 2022 20:51:03 +0800
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Subject: Re: [PATCH] f2fs: add some sysfs nodes for segment
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To:     Jaegeuk Kim <jaegeuk@kernel.org>, Guowei Du <duguoweisz@gmail.com>
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, duguowei <duguowei@xiaomi.com>
References: <20220706020615.29938-1-duguoweisz@gmail.com>
 <YszRrHHqLk4My3vO@google.com>
From:   Chao Yu <chao@kernel.org>
In-Reply-To: <YszRrHHqLk4My3vO@google.com>
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On 2022/7/12 9:43, Jaegeuk Kim wrote:
> On 07/06, Guowei Du wrote:
>> From: duguowei <duguowei@xiaomi.com>
>>
>> There are two ways to show meta segment information,
>> one is by dump.f2fs, another is by sysfs node. But,
>> sometimes dump needs root privilege,So adding a
>> few sysfs nodes.

If this is used for debug, how about checking /sys/kernel/debug/f2fs/status?

Thanks,

>>
>> The generic permission of node is 0444(S_IRUGO).
>>
>> $ cd /sys/fs/f2fs/DEVICE/...
>> $ ls -l
>> ...
>> -r--r--r-- 1 root root 4096 7月   5 23:21 reserved_segments
>> -r--r--r-- 1 root root 4096 7月   5 23:21 segment_count
>> -r--r--r-- 1 root root 4096 7月   5 23:21 segment_count_ckpt
>> -r--r--r-- 1 root root 4096 7月   5 23:21 segment_count_main
>> -r--r--r-- 1 root root 4096 7月   5 23:21 segment_count_nat
>> -r--r--r-- 1 root root 4096 7月   5 23:21 segment_count_sit
>> -r--r--r-- 1 root root 4096 7月   5 23:21 segment_count_ssa
>> ...
>>
>> $ sudo dump.f2fs -d 1 DEVICE
>> ...
>> Super block
>> segment_count                           [0x      26 : 38]
>> segment_count_ckpt                      [0x       2 : 2]
>> segment_count_sit                       [0x       2 : 2]
>> segment_count_nat                       [0x       2 : 2]
>> segment_count_ssa                       [0x       1 : 1]
>> segment_count_main                      [0x      1f : 31]
>> ...
>> Checkpoint
>> rsvd_segment_count                      [0x       e : 14]
>> ...
>>
>> Signed-off-by: duguowei <duguowei@xiaomi.com>
>> ---
>>   fs/f2fs/sysfs.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 63 insertions(+)
>>
>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
>> index 4c50aedd5144..05350bba2c83 100644
>> --- a/fs/f2fs/sysfs.c
>> +++ b/fs/f2fs/sysfs.c
>> @@ -697,6 +697,55 @@ static ssize_t f2fs_sb_feature_show(struct f2fs_attr *a,
>>   	return sprintf(buf, "unsupported\n");
>>   }
>>   
>> +static ssize_t segment_count_show(struct f2fs_attr *a,
>> +		struct f2fs_sb_info *sbi, char *buf)
>> +{
>> +	return sprintf(buf, "%llu\n",
>> +			(unsigned long long)(F2FS_RAW_SUPER(sbi)->segment_count));
>> +}
>> +
>> +static ssize_t segment_count_ckpt_show(struct f2fs_attr *a,
>> +		struct f2fs_sb_info *sbi, char *buf)
>> +{
>> +	return sprintf(buf, "%llu\n",
>> +			(unsigned long long)(F2FS_RAW_SUPER(sbi)->segment_count_ckpt));
>> +}
>> +
>> +static ssize_t segment_count_sit_show(struct f2fs_attr *a,
>> +		struct f2fs_sb_info *sbi, char *buf)
>> +{
>> +	return sprintf(buf, "%llu\n",
>> +			(unsigned long long)(F2FS_RAW_SUPER(sbi)->segment_count_sit));
>> +}
>> +
>> +static ssize_t segment_count_nat_show(struct f2fs_attr *a,
>> +		struct f2fs_sb_info *sbi, char *buf)
>> +{
>> +	return sprintf(buf, "%llu\n",
>> +			(unsigned long long)(F2FS_RAW_SUPER(sbi)->segment_count_nat));
>> +}
>> +
>> +static ssize_t segment_count_ssa_show(struct f2fs_attr *a,
>> +		struct f2fs_sb_info *sbi, char *buf)
>> +{
>> +	return sprintf(buf, "%llu\n",
>> +			(unsigned long long)(F2FS_RAW_SUPER(sbi)->segment_count_ssa));
>> +}
>> +
>> +static ssize_t segment_count_main_show(struct f2fs_attr *a,
>> +		struct f2fs_sb_info *sbi, char *buf)
>> +{
>> +	return sprintf(buf, "%llu\n",
>> +			(unsigned long long)(F2FS_RAW_SUPER(sbi)->segment_count_main));
>> +}
>> +
>> +static ssize_t reserved_segments_show(struct f2fs_attr *a,
>> +		struct f2fs_sb_info *sbi, char *buf)
>> +{
>> +	return sprintf(buf, "%llu\n",
>> +			(unsigned long long)(reserved_segments(sbi)));
>> +}
> 
> Can we create a macro to do the above functions?
> 
>> +
>>   #define F2FS_SB_FEATURE_RO_ATTR(_name, _feat)			\
>>   static struct f2fs_attr f2fs_attr_sb_##_name = {		\
>>   	.attr = {.name = __stringify(_name), .mode = 0444 },	\
>> @@ -801,6 +850,13 @@ F2FS_GENERAL_RO_ATTR(moved_blocks_background);
>>   F2FS_GENERAL_RO_ATTR(moved_blocks_foreground);
>>   F2FS_GENERAL_RO_ATTR(avg_vblocks);
>>   #endif
>> +F2FS_GENERAL_RO_ATTR(segment_count);
>> +F2FS_GENERAL_RO_ATTR(segment_count_ckpt);
>> +F2FS_GENERAL_RO_ATTR(segment_count_sit);
>> +F2FS_GENERAL_RO_ATTR(segment_count_nat);
>> +F2FS_GENERAL_RO_ATTR(segment_count_ssa);
>> +F2FS_GENERAL_RO_ATTR(segment_count_main);
>> +F2FS_GENERAL_RO_ATTR(reserved_segments);
>>   
>>   #ifdef CONFIG_FS_ENCRYPTION
>>   F2FS_FEATURE_RO_ATTR(encryption);
>> @@ -934,6 +990,13 @@ static struct attribute *f2fs_attrs[] = {
>>   	ATTR_LIST(gc_reclaimed_segments),
>>   	ATTR_LIST(max_fragment_chunk),
>>   	ATTR_LIST(max_fragment_hole),
>> +	ATTR_LIST(segment_count),
>> +	ATTR_LIST(segment_count_ckpt),
>> +	ATTR_LIST(segment_count_sit),
>> +	ATTR_LIST(segment_count_nat),
>> +	ATTR_LIST(segment_count_ssa),
>> +	ATTR_LIST(segment_count_main),
>> +	ATTR_LIST(reserved_segments),
>>   	NULL,
>>   };
>>   ATTRIBUTE_GROUPS(f2fs);
>> -- 
>> 2.36.1