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Subject: Re: [f2fs-dev] [PATCH v4 2/2] f2fs: add F2FS_IOC_SET_COMPRESS_OPTION
 ioctl
To:     Daeho Jeong <daeho43@gmail.com>
CC:     <linux-kernel@vger.kernel.org>,
        <linux-f2fs-devel@lists.sourceforge.net>,
        <kernel-team@android.com>, Daeho Jeong <daehojeong@google.com>
References: <20201027053818.3291747-1-daeho43@gmail.com>
 <20201027053818.3291747-2-daeho43@gmail.com>
 <290cd375-704e-9315-a035-ab4c1ce1f6f2@huawei.com>
 <CACOAw_ycvV9_O_tb=axgT2Pu9ySvdKfVjBv+Fe90+XObKGjjTg@mail.gmail.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <f81da3dc-aa9d-a186-f078-512bbf4ce8d4@huawei.com>
Date:   Thu, 29 Oct 2020 09:41:33 +0800
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Daeho,

On 2020/10/29 9:21, Daeho Jeong wrote:
> Chao,
> 
> Do you want to print out a kernel warning message in this case? like
> "XX compression algorithm is set for this inode, but current mount
> option doesn't support this algorithm."?

Yup, something like that,

Change 'current mount option' to 'current kernel' or 'current f2fs module' would be
better?

> 
> 2020년 10월 28일 (수) 오후 3:47, Chao Yu <yuchao0@huawei.com>님이 작성:
>>
>> On 2020/10/27 13:38, Daeho Jeong wrote:
>>> From: Daeho Jeong <daehojeong@google.com>
>>>
>>> Added a new F2FS_IOC_SET_COMPRESS_OPTION ioctl to change file
>>> compression option of a file.
>>>
>>> struct f2fs_comp_option {
>>>       u8 algorithm;         => compression algorithm
>>>                             => 0:lzo, 1:lz4, 2:zstd, 3:lzorle
>>>       u8 log_cluster_size;  => log scale cluster size
>>>                             => 2 ~ 8
>>> };
>>>
>>> struct f2fs_comp_option option;
>>>
>>> option.algorithm = 1;
>>> option.log_cluster_size = 7;
>>>
>>> ioctl(fd, F2FS_IOC_SET_COMPRESS_OPTION, &option);
>>>
>>> Signed-off-by: Daeho Jeong <daehojeong@google.com>
>>> ---
>>>
>>> v4: changed commit message.
>>> v3: changed the error number more specific.
>>>       folded in fix for build breakage reported by kernel test robot
>>>       <lkp@intel.com> and Dan Carpenter <dan.carpenter@oracle.com>.
>>> v2: added ioctl description.
>>> ---
>>>    fs/f2fs/compress.c |  5 +++++
>>>    fs/f2fs/f2fs.h     |  7 +++++++
>>>    fs/f2fs/file.c     | 52 ++++++++++++++++++++++++++++++++++++++++++++++
>>>    3 files changed, 64 insertions(+)
>>>
>>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
>>> index 7895186cc765..816d7adc914c 100644
>>> --- a/fs/f2fs/compress.c
>>> +++ b/fs/f2fs/compress.c
>>> @@ -514,6 +514,11 @@ bool f2fs_is_compress_backend_ready(struct inode *inode)
>>>        return f2fs_cops[F2FS_I(inode)->i_compress_algorithm];
>>>    }
>>>
>>> +bool f2fs_is_compress_algorithm_ready(unsigned char algorithm)
>>> +{
>>> +     return algorithm < COMPRESS_MAX && f2fs_cops[algorithm] != NULL;
>>> +}
>>> +
>>>    static mempool_t *compress_page_pool;
>>>    static int num_compress_pages = 512;
>>>    module_param(num_compress_pages, uint, 0444);
>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>> index a33c90cf979b..cc38afde6c04 100644
>>> --- a/fs/f2fs/f2fs.h
>>> +++ b/fs/f2fs/f2fs.h
>>> @@ -435,6 +435,8 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
>>>                                                struct f2fs_sectrim_range)
>>>    #define F2FS_IOC_GET_COMPRESS_OPTION        _IOR(F2FS_IOCTL_MAGIC, 21,      \
>>>                                                struct f2fs_comp_option)
>>> +#define F2FS_IOC_SET_COMPRESS_OPTION _IOW(F2FS_IOCTL_MAGIC, 22,      \
>>> +                                             struct f2fs_comp_option)
>>>
>>>    /*
>>>     * should be same as XFS_IOC_GOINGDOWN.
>>> @@ -3915,6 +3917,7 @@ bool f2fs_compress_write_end(struct inode *inode, void *fsdata,
>>>    int f2fs_truncate_partial_cluster(struct inode *inode, u64 from, bool lock);
>>>    void f2fs_compress_write_end_io(struct bio *bio, struct page *page);
>>>    bool f2fs_is_compress_backend_ready(struct inode *inode);
>>> +bool f2fs_is_compress_algorithm_ready(unsigned char algorithm);
>>>    int f2fs_init_compress_mempool(void);
>>>    void f2fs_destroy_compress_mempool(void);
>>>    void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity);
>>> @@ -3945,6 +3948,10 @@ static inline bool f2fs_is_compress_backend_ready(struct inode *inode)
>>>        /* not support compression */
>>>        return false;
>>>    }
>>> +static inline bool f2fs_is_compress_algorithm_ready(unsigned char algorithm)
>>> +{
>>> +     return false;
>>> +}
>>>    static inline struct page *f2fs_compress_control_page(struct page *page)
>>>    {
>>>        WARN_ON_ONCE(1);
>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>> index 8922ab191a9d..8048b150e43b 100644
>>> --- a/fs/f2fs/file.c
>>> +++ b/fs/f2fs/file.c
>>> @@ -3963,6 +3963,55 @@ static int f2fs_ioc_get_compress_option(struct file *filp, unsigned long arg)
>>>        return 0;
>>>    }
>>>
>>> +static int f2fs_ioc_set_compress_option(struct file *filp, unsigned long arg)
>>> +{
>>> +     struct inode *inode = file_inode(filp);
>>> +     struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>> +     struct f2fs_comp_option option;
>>> +     int ret = 0;
>>> +
>>> +     if (!f2fs_sb_has_compression(sbi))
>>> +             return -EOPNOTSUPP;
>>> +
>>> +     if (!(filp->f_mode & FMODE_WRITE))
>>> +             return -EBADF;
>>> +
>>> +     if (copy_from_user(&option, (struct f2fs_comp_option __user *)arg,
>>> +                             sizeof(option)))
>>> +             return -EFAULT;
>>> +
>>> +     if (!f2fs_compressed_file(inode) ||
>>> +                     option.log_cluster_size < MIN_COMPRESS_LOG_SIZE ||
>>> +                     option.log_cluster_size > MAX_COMPRESS_LOG_SIZE)
>>> +             return -EINVAL;
>>> +
>>> +     if (!f2fs_is_compress_algorithm_ready(option.algorithm))
>>> +             return -ENOPKG;
>>
>> As we allow to mount image with different kernel which supports different compress
>> algorithms, so I guess we can support to change algorithm to one other which current
>> kernel doesn't support, since we have add f2fs_is_compress_backend_ready() in all
>> foreground operations to disallow user to operate such inode's data.
>>
>> IMO, just add to print one warnning message is fine.
>>
>> Thanks,
>>
>>> +
>>> +     file_start_write(filp);
>>> +     inode_lock(inode);
>>> +
>>> +     if (f2fs_is_mmap_file(inode) || get_dirty_pages(inode)) {
>>> +             ret = -EBUSY;
>>> +             goto out;
>>> +     }
>>> +
>>> +     if (inode->i_size != 0) {
>>> +             ret = -EFBIG;
>>> +             goto out;
>>> +     }
>>> +
>>> +     F2FS_I(inode)->i_compress_algorithm = option.algorithm;
>>> +     F2FS_I(inode)->i_log_cluster_size = option.log_cluster_size;
>>> +     F2FS_I(inode)->i_cluster_size = 1 << option.log_cluster_size;
>>> +     f2fs_mark_inode_dirty_sync(inode, true);
>>> +out:
>>> +     inode_unlock(inode);
>>> +     file_end_write(filp);
>>> +
>>> +     return ret;
>>> +}
>>> +
>>>    long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>>    {
>>>        if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(filp)))))
>>> @@ -4053,6 +4102,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>>                return f2fs_sec_trim_file(filp, arg);
>>>        case F2FS_IOC_GET_COMPRESS_OPTION:
>>>                return f2fs_ioc_get_compress_option(filp, arg);
>>> +     case F2FS_IOC_SET_COMPRESS_OPTION:
>>> +             return f2fs_ioc_set_compress_option(filp, arg);
>>>        default:
>>>                return -ENOTTY;
>>>        }
>>> @@ -4224,6 +4275,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>>>        case F2FS_IOC_RESERVE_COMPRESS_BLOCKS:
>>>        case F2FS_IOC_SEC_TRIM_FILE:
>>>        case F2FS_IOC_GET_COMPRESS_OPTION:
>>> +     case F2FS_IOC_SET_COMPRESS_OPTION:
>>>                break;
>>>        default:
>>>                return -ENOIOCTLCMD;
>>>
> .
>