Re: [f2fs-dev] [PATCH] f2fs: compress: support chksum

Chao Yu
2020-11-10T01:52:52Z

On 2020/11/10 1:06, Jaegeuk Kim wrote:
> On 11/09, Chao Yu wrote:
>> On 2020/11/7 5:12, Jaegeuk Kim wrote:
>>> On 11/03, Chao Yu wrote:
>>>> On 2020/11/3 10:02, Chao Yu wrote:
>>>>> On 2020/11/3 0:31, Jaegeuk Kim wrote:
>>>>>> On 11/02, Chao Yu wrote:
>>>>>>> This patch supports to store chksum value with compressed
>>>>>>> data, and verify the integrality of compressed data while
>>>>>>> reading the data.
>>>>>>>
>>>>>>> The feature can be enabled through specifying mount option
>>>>>>> 'compress_chksum'.
>>>>>>>
>>>>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>>>>> ---
>>>>>>> Documentation/filesystems/f2fs.rst | 1 +
>>>>>>> fs/f2fs/compress.c | 20 ++++++++++++++++++++
>>>>>>> fs/f2fs/f2fs.h | 13 ++++++++++++-
>>>>>>> fs/f2fs/inode.c | 3 +++
>>>>>>> fs/f2fs/super.c | 9 +++++++++
>>>>>>> include/linux/f2fs_fs.h | 2 +-
>>>>>>> 6 files changed, 46 insertions(+), 2 deletions(-)
>>>>>>>
>>>>>>> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
>>>>>>> index b8ee761c9922..985ae7d35066 100644
>>>>>>> --- a/Documentation/filesystems/f2fs.rst
>>>>>>> +++ b/Documentation/filesystems/f2fs.rst
>>>>>>> @@ -260,6 +260,7 @@ compress_extension=%s Support adding specified extension, so that f2fs can enab
>>>>>>> For other files, we can still enable compression via ioctl.
>>>>>>> Note that, there is one reserved special extension '*', it
>>>>>>> can be set to enable compression for all files.
>>>>>>> +compress_chksum Support verifying chksum of raw data in compressed cluster.
>>>>>>> inlinecrypt When possible, encrypt/decrypt the contents of encrypted
>>>>>>> files using the blk-crypto framework rather than
>>>>>>> filesystem-layer encryption. This allows the use of
>>>>>>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
>>>>>>> index 14262e0f1cd6..a4e0d2c745b6 100644
>>>>>>> --- a/fs/f2fs/compress.c
>>>>>>> +++ b/fs/f2fs/compress.c
>>>>>>> @@ -602,6 +602,7 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
>>>>>>> f2fs_cops[fi->i_compress_algorithm];
>>>>>>> unsigned int max_len, new_nr_cpages;
>>>>>>> struct page **new_cpages;
>>>>>>> + u32 chksum = 0;
>>>>>>> int i, ret;
>>>>>>> trace_f2fs_compress_pages_start(cc->inode, cc->cluster_idx,
>>>>>>> @@ -655,6 +656,11 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
>>>>>>> cc->cbuf->clen = cpu_to_le32(cc->clen);
>>>>>>> + if (fi->i_compress_flag & 1 << COMPRESS_CHKSUM)
>>>>>>> + chksum = f2fs_crc32(F2FS_I_SB(cc->inode),
>>>>>>> + cc->cbuf->cdata, cc->clen);
>>>>>>> + cc->cbuf->chksum = cpu_to_le32(chksum);
>>>>>>> +
>>>>>>> for (i = 0; i < COMPRESS_DATA_RESERVED_SIZE; i++)
>>>>>>> cc->cbuf->reserved[i] = cpu_to_le32(0);
>>>>>>> @@ -721,6 +727,7 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
>>>>>>> (struct decompress_io_ctx *)page_private(page);
>>>>>>> struct f2fs_sb_info *sbi = F2FS_I_SB(dic->inode);
>>>>>>> struct f2fs_inode_info *fi= F2FS_I(dic->inode);
>>>>>>> + struct f2fs_sb_info *sbi = F2FS_I_SB(dic->inode);
>>>>>>> const struct f2fs_compress_ops *cops =
>>>>>>> f2fs_cops[fi->i_compress_algorithm];
>>>>>>> int ret;
>>>>>>> @@ -790,6 +797,19 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
>>>>>>> ret = cops->decompress_pages(dic);
>>>>>>> + if (!ret && fi->i_compress_flag & 1 << COMPRESS_CHKSUM) {
>>>>>>> + u32 provided = le32_to_cpu(dic->cbuf->chksum);
>>>>>>> + u32 calculated = f2fs_crc32(sbi, dic->cbuf->cdata, dic->clen);
>>>>>>> +
>>>>>>> + if (provided != calculated) {
>>>>>>> + printk_ratelimited(
>>>>>>> + "%sF2FS-fs (%s): checksum invalid, nid = %lu, %x vs %x",
>>>>>>> + KERN_INFO, sbi->sb->s_id, dic->inode->i_ino,
>>>>>>> + provided, calculated);
>>>>>>> + ret = -EFSCORRUPTED;
>>>>>>
>>>>>> Do we need to change fsck.f2fs to recover this?
>>>>
>>>> However, we don't know which one is correct, compressed data or chksum value?
>>>> if compressed data was corrupted, repairing chksum value doesn't help.
>>>>
>>>> Or how about adding chksum values for both raw data and compressed data.
>>>>
>>>> #define COMPRESS_DATA_RESERVED_SIZE 3
>>>> struct compress_data {
>>>> __le32 clen; /* compressed data size */
>>>> + __le32 raw_chksum; /* raw data chksum */
>>>> + __le32 compress_chksum; /* compressed data chksum */
>>>> __le32 reserved[COMPRESS_DATA_RESERVED_SIZE]; /* reserved */
>>>> u8 cdata[]; /* compressed data */
>>>> };
>>>>
>>>> raw_chksum compress_chksum
>>>> match match -> data is verified, pass
>>>> not match match -> repair raw_chksum
>>>> matcth not match -> repair compress_chksum
>>>
>>> I think only compress_chksum would be enough. BTW, can we give WARN_ON and
>>> marking a FSCK flag without returning EFSCORRUPTED, since we don't really
>>> know who was corrupted. If data was corrupted, we should be able to see app
>>> corruption. In that case, we can check the kernel log. If checksum was simply
>>
>> I don't think that app will always corrupt once data was corrupted, I doubt its
>> behavior could be slightly abnormal in some cases, e.g. it can just cause apps to
>> show wrong number in interaction interface.
>
> I didn't say we can always get it. But, it's likely to happen with something
> like that.
>
>>
>> In this case, if we fix chksum in fsck, the wrong data will never be found due to
>> data's chksum matches data itself after repair.
>
> At least, we should see that log as a hint.
>
>>
>> IMO, the chksum and data was a whole dataset, once they are mismatch, we can
>> not trust either of them, fsck should do nothing on them unless we store parity
>> bits or replica.
>
> Yeah, the point is those are not written as a transaction. Three concerns to me:

Just to confirm:

> 1) agreed to see compressed data corruption by checksum

return EFSBADCRC always like we did as inode chksum feature.

2) I don't want to see the error messages all the time

Something like below?

if (provided != calculated) {
if (!is_inode_flag_set(,FI_DATA_CORRUPTED)) {
printk_ratelimited();
WARN_ON()
set_inode_flag(, FI_DATA_CORRUPTED);
}
return EFSBADCRC;
}

3) don't touch the data, even if it was corrupted, since there's no way to fix it.

It seems that we don't need to change fsck.f2fs finally...

Thanks,

>
>>
>> Thanks,
>>
>>> corrupted, next fsck will fix the checksum. So, in general, I hope to keep
>>> the data as is and raise a flag by the checksum.
>>>
>>>> not match not match -> corrupted, can not repair
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>> Yes, prepared to update inode layout in fsck.f2fs w/ kernel side change. >
>>>>> Thanks,
>>>>>
>>>>>>
>>>>>>> + }
>>>>>>> + }
>>>>>>> +
>>>>>>> out_vunmap_cbuf:
>>>>>>> vm_unmap_ram(dic->cbuf, dic->nr_cpages);
>>>>>>> out_vunmap_rbuf:
>>>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>>>>> index 99bcf4b44a9c..2ae254ab7b7d 100644
>>>>>>> --- a/fs/f2fs/f2fs.h
>>>>>>> +++ b/fs/f2fs/f2fs.h
>>>>>>> @@ -147,7 +147,8 @@ struct f2fs_mount_info {
>>>>>>> /* For compression */
>>>>>>> unsigned char compress_algorithm; /* algorithm type */
>>>>>>> - unsigned compress_log_size; /* cluster log size */
>>>>>>> + unsigned char compress_log_size; /* cluster log size */
>>>>>>> + bool compress_chksum; /* compressed data chksum */
>>>>>>> unsigned char compress_ext_cnt; /* extension count */
>>>>>>> unsigned char extensions[COMPRESS_EXT_NUM][F2FS_EXTENSION_LEN]; /* extensions */
>>>>>>> };
>>>>>>> @@ -731,6 +732,7 @@ struct f2fs_inode_info {
>>>>>>> atomic_t i_compr_blocks; /* # of compressed blocks */
>>>>>>> unsigned char i_compress_algorithm; /* algorithm type */
>>>>>>> unsigned char i_log_cluster_size; /* log of cluster size */
>>>>>>> + unsigned short i_compress_flag; /* compress flag */
>>>>>>> unsigned int i_cluster_size; /* cluster size */
>>>>>>> };
>>>>>>> @@ -1270,9 +1272,15 @@ enum compress_algorithm_type {
>>>>>>> COMPRESS_MAX,
>>>>>>> };
>>>>>>> +enum compress_flag {
>>>>>>> + COMPRESS_CHKSUM,
>>>>>>> + COMPRESS_MAX_FLAG,
>>>>>>> +};
>>>>>>> +
>>>>>>> #define COMPRESS_DATA_RESERVED_SIZE 5
>>>>>>> struct compress_data {
>>>>>>> __le32 clen; /* compressed data size */
>>>>>>> + __le32 chksum; /* compressed data chksum */
>>>>>>> __le32 reserved[COMPRESS_DATA_RESERVED_SIZE]; /* reserved */
>>>>>>> u8 cdata[]; /* compressed data */
>>>>>>> };
>>>>>>> @@ -3882,6 +3890,9 @@ static inline void set_compress_context(struct inode *inode)
>>>>>>> F2FS_OPTION(sbi).compress_algorithm;
>>>>>>> F2FS_I(inode)->i_log_cluster_size =
>>>>>>> F2FS_OPTION(sbi).compress_log_size;
>>>>>>> + F2FS_I(inode)->i_compress_flag =
>>>>>>> + F2FS_OPTION(sbi).compress_chksum ?
>>>>>>> + 1 << COMPRESS_CHKSUM : 0;
>>>>>>> F2FS_I(inode)->i_cluster_size =
>>>>>>> 1 << F2FS_I(inode)->i_log_cluster_size;
>>>>>>> F2FS_I(inode)->i_flags |= F2FS_COMPR_FL;
>>>>>>> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
>>>>>>> index 657db2fb6739..de8f7fc89efa 100644
>>>>>>> --- a/fs/f2fs/inode.c
>>>>>>> +++ b/fs/f2fs/inode.c
>>>>>>> @@ -456,6 +456,7 @@ static int do_read_inode(struct inode *inode)
>>>>>>> le64_to_cpu(ri->i_compr_blocks));
>>>>>>> fi->i_compress_algorithm = ri->i_compress_algorithm;
>>>>>>> fi->i_log_cluster_size = ri->i_log_cluster_size;
>>>>>>> + fi->i_compress_flag = ri->i_compress_flag;
>>>>>>> fi->i_cluster_size = 1 << fi->i_log_cluster_size;
>>>>>>> set_inode_flag(inode, FI_COMPRESSED_FILE);
>>>>>>> }
>>>>>>> @@ -634,6 +635,8 @@ void f2fs_update_inode(struct inode *inode, struct page *node_page)
>>>>>>> &F2FS_I(inode)->i_compr_blocks));
>>>>>>> ri->i_compress_algorithm =
>>>>>>> F2FS_I(inode)->i_compress_algorithm;
>>>>>>> + ri->i_compress_flag =
>>>>>>> + cpu_to_le16(F2FS_I(inode)->i_compress_flag);
>>>>>>> ri->i_log_cluster_size =
>>>>>>> F2FS_I(inode)->i_log_cluster_size;
>>>>>>> }
>>>>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>>>>>> index 00eff2f51807..f8de4d83a5be 100644
>>>>>>> --- a/fs/f2fs/super.c
>>>>>>> +++ b/fs/f2fs/super.c
>>>>>>> @@ -146,6 +146,7 @@ enum {
>>>>>>> Opt_compress_algorithm,
>>>>>>> Opt_compress_log_size,
>>>>>>> Opt_compress_extension,
>>>>>>> + Opt_compress_chksum,
>>>>>>> Opt_atgc,
>>>>>>> Opt_err,
>>>>>>> };
>>>>>>> @@ -214,6 +215,7 @@ static match_table_t f2fs_tokens = {
>>>>>>> {Opt_compress_algorithm, "compress_algorithm=%s"},
>>>>>>> {Opt_compress_log_size, "compress_log_size=%u"},
>>>>>>> {Opt_compress_extension, "compress_extension=%s"},
>>>>>>> + {Opt_compress_chksum, "compress_chksum"},
>>>>>>> {Opt_atgc, "atgc"},
>>>>>>> {Opt_err, NULL},
>>>>>>> };
>>>>>>> @@ -934,10 +936,14 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
>>>>>>> F2FS_OPTION(sbi).compress_ext_cnt++;
>>>>>>> kfree(name);
>>>>>>> break;
>>>>>>> + case Opt_compress_chksum:
>>>>>>> + F2FS_OPTION(sbi).compress_chksum = true;
>>>>>>> + break;
>>>>>>> #else
>>>>>>> case Opt_compress_algorithm:
>>>>>>> case Opt_compress_log_size:
>>>>>>> case Opt_compress_extension:
>>>>>>> + case Opt_compress_chksum:
>>>>>>> f2fs_info(sbi, "compression options not supported");
>>>>>>> break;
>>>>>>> #endif
>>>>>>> @@ -1523,6 +1529,9 @@ static inline void f2fs_show_compress_options(struct seq_file *seq,
>>>>>>> seq_printf(seq, ",compress_extension=%s",
>>>>>>> F2FS_OPTION(sbi).extensions[i]);
>>>>>>> }
>>>>>>> +
>>>>>>> + if (F2FS_OPTION(sbi).compress_chksum)
>>>>>>> + seq_puts(seq, ",compress_chksum");
>>>>>>> }
>>>>>>> static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
>>>>>>> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
>>>>>>> index a5dbb57a687f..7dc2a06cf19a 100644
>>>>>>> --- a/include/linux/f2fs_fs.h
>>>>>>> +++ b/include/linux/f2fs_fs.h
>>>>>>> @@ -273,7 +273,7 @@ struct f2fs_inode {
>>>>>>> __le64 i_compr_blocks; /* # of compressed blocks */
>>>>>>> __u8 i_compress_algorithm; /* compress algorithm */
>>>>>>> __u8 i_log_cluster_size; /* log of cluster size */
>>>>>>> - __le16 i_padding; /* padding */
>>>>>>> + __le16 i_compress_flag; /* compress flag */
>>>>>>> __le32 i_extra_end[0]; /* for attribute size calculation */
>>>>>>> } __packed;
>>>>>>> __le32 i_addr[DEF_ADDRS_PER_INODE]; /* Pointers to data blocks */
>>>>>>> --
>>>>>>> 2.26.2
>>>>>> .
>>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Linux-f2fs-devel mailing list
>>>>> Linux-f2fs-devel@lists.sourceforge.net
>>>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>>>>> .
>>>>>
>>> .
>>>
> .
>