Re: [PATCH v3 1/2] btrfs-progs: export util functions about file extent items

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2021/7/17 上午12:30, Sidong Yang wrote:
> On Thu, Jul 15, 2021 at 06:46:08AM +0800, Qu Wenruo wrote:
>>
>>
>> On 2021/7/14 下午10:54, Sidong Yang wrote:
>>> This patch export two functions that convert enum about file extents to
>>> string. It can be used in other code like inspect-internal command. And
>>> this patch also make compress_type_to_str() function more safe by using
>>> strncpy() than strcpy().
>>>
>>> Signed-off-by: Sidong Yang <realwakka@gmail.com>
>>> ---
>>> v2:
>>>    - Prints type and compression
>>>    - Use the terms from file_extents_item like disk_bytenr not like
>>>      "physical"
>>> v3:
>>>    - export util functions for removing duplication
>>>    - change the way to loop with search ioctl
>>> ---
>>>    kernel-shared/print-tree.c | 18 ++++++++++--------
>>>    kernel-shared/print-tree.h |  3 +++
>>>    2 files changed, 13 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/kernel-shared/print-tree.c b/kernel-shared/print-tree.c
>>> index e5d4b453..bfef7d26 100644
>>> --- a/kernel-shared/print-tree.c
>>> +++ b/kernel-shared/print-tree.c
>>> @@ -27,6 +27,8 @@
>>>    #include "kernel-shared/print-tree.h"
>>>    #include "common/utils.h"
>>> +#define COMPRESS_STR_LEN 5
>>
>> It's already too small to contain all the strings.
>>
>> We have a default branch:
>>
>>   	default:
>>   		sprintf(ret, "UNKNOWN.%d", compress_type);
>>
>> In that case, our minimal value should be strlen("UNKNOWN.255") + 1, which
>> is 12 bytes.
>>
>> Your old rounded up 16 bytes is in fact perfect in this case.
>>
>> Despite that, this patch looks good to me.
>
> Thanks for review.
>
> I've been thought about this. should COMPRESS_STR_LEN be exported?

I guess yes.

Thanks,
Qu

> Developer that use this function needs to know max length of string.
> Or we can choose the simple implementation that just return const char*
> like btrfs_file_extent_type_to_str(). But it will be hard to print
> unknown compress_type.
>
> Thanks,
> Sidong
>>
>> Thanks,
>> Qu
>>> +
>>>    static void print_dir_item_type(struct extent_buffer *eb,
>>>                                    struct btrfs_dir_item *di)
>>>    {
>>> @@ -338,27 +340,27 @@ static void print_uuids(struct extent_buffer *eb)
>>>    	printf("fs uuid %s\nchunk uuid %s\n", fs_uuid, chunk_uuid);
>>>    }
>>> -static void compress_type_to_str(u8 compress_type, char *ret)
>>> +void btrfs_compress_type_to_str(u8 compress_type, char *ret)
>>>    {
>>>    	switch (compress_type) {
>>>    	case BTRFS_COMPRESS_NONE:
>>> -		strcpy(ret, "none");
>>> +		strncpy(ret, "none", COMPRESS_STR_LEN);
>>>    		break;
>>>    	case BTRFS_COMPRESS_ZLIB:
>>> -		strcpy(ret, "zlib");
>>> +		strncpy(ret, "zlib", COMPRESS_STR_LEN);
>>>    		break;
>>>    	case BTRFS_COMPRESS_LZO:
>>> -		strcpy(ret, "lzo");
>>> +		strncpy(ret, "lzo", COMPRESS_STR_LEN);
>>>    		break;
>>>    	case BTRFS_COMPRESS_ZSTD:
>>> -		strcpy(ret, "zstd");
>>> +		strncpy(ret, "zstd", COMPRESS_STR_LEN);
>>>    		break;
>>>    	default:
>>>    		sprintf(ret, "UNKNOWN.%d", compress_type);
>>>    	}
>>>    }
>>> -static const char* file_extent_type_to_str(u8 type)
>>> +const char* btrfs_file_extent_type_to_str(u8 type)
>>>    {
>>>    	switch (type) {
>>>    	case BTRFS_FILE_EXTENT_INLINE: return "inline";
>>> @@ -376,12 +378,12 @@ static void print_file_extent_item(struct extent_buffer *eb,
>>>    	unsigned char extent_type = btrfs_file_extent_type(eb, fi);
>>>    	char compress_str[16];
>>> -	compress_type_to_str(btrfs_file_extent_compression(eb, fi),
>>> +	btrfs_compress_type_to_str(btrfs_file_extent_compression(eb, fi),
>>>    			     compress_str);
>>>    	printf("\t\tgeneration %llu type %hhu (%s)\n",
>>>    			btrfs_file_extent_generation(eb, fi),
>>> -			extent_type, file_extent_type_to_str(extent_type));
>>> +			extent_type, btrfs_file_extent_type_to_str(extent_type));
>>>    	if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
>>>    		printf("\t\tinline extent data size %u ram_bytes %llu compression %hhu (%s)\n",
>>> diff --git a/kernel-shared/print-tree.h b/kernel-shared/print-tree.h
>>> index 80fb6ef7..dbb2f183 100644
>>> --- a/kernel-shared/print-tree.h
>>> +++ b/kernel-shared/print-tree.h
>>> @@ -43,4 +43,7 @@ void print_objectid(FILE *stream, u64 objectid, u8 type);
>>>    void print_key_type(FILE *stream, u64 objectid, u8 type);
>>>    void btrfs_print_superblock(struct btrfs_super_block *sb, int full);
>>> +void btrfs_compress_type_to_str(u8 compress_type, char *ret);
>>> +const char* btrfs_file_extent_type_to_str(u8 type);
>>> +
>>>    #endif
>>>
>>