Re: [PATCH 6/9] f2fs: zstd: Switch to the zstd-1.4.6 API

Chao Yu
2020-09-18T02:58:49Z

On 2020/9/18 10:56, Eric Biggers wrote:
> On Fri, Sep 18, 2020 at 09:47:32AM +0800, Chao Yu wrote:
>> Ah, I got it.
>>
>> Step of enabling compressed inode is not correct, we should touch an empty
>> file, and then use 'chattr +c' on that file to enable compression, otherwise
>> the race condition could be complicated to handle. So we need below diff to
>> disallow setting compression flag on an non-empty file:
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 8a422400e824..b462db7898fd 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -1836,6 +1836,8 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
>> if (iflags & F2FS_COMPR_FL) {
>> if (!f2fs_may_compress(inode))
>> return -EINVAL;
>> + if (get_dirty_pages(inode) || fi->i_compr_blocks)
>> + return -EINVAL;
>>
>> set_compress_context(inode);
>> }
>
> Why not:
>
> if (inode->i_size)
> return -EINVAL;

Yeah, I noticed that after replying this email, I've prepared the new patch
which including the i_size check.

Thanks for noticing this.

Thanks,

> .
>