linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: compress tmp files given extension

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Message-ID: <cdeb92fd-11c1-2e3d-662d-08022dfe7e7f@kernel.org>
Date:   Tue, 13 Jun 2023 09:11:39 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: compress tmp files given extension

On 2023/6/12 23:36, Jaegeuk Kim wrote:
> On 06/12, Chao Yu wrote:
>> On 2023/6/7 4:36, Jaegeuk Kim wrote:
>>> Let's compress tmp files for the given extension list.
>>
>> Could you please check below commit? IIRC, it was introduce to avoid compressing
>> file which has unpredictable tmp file, e.g. foo.sox.
>>
>> Could you please describe the case you encounter?
> 
> I don't know what I need to describe more tho, looking at how to compress

Oh, I just like to know which case you want to cover: foo.so.tmp or foo.sotmp.

> abc.so.tmp and abc.so, given compress_extension=so.

Copied.

> 
> So, your concern is somehow abc.soa? If so, we need to fix is_extension_exist.

Yes, is_extension_exist(, true) accepts optional '.' while parsing file extension.

[filename + '.' + extension + (optional: '.' + temp extension)]

It is used to support parsing common prefix for cold file's extension, we can add
a parameter for is_extension_exist() to disable prefix parsing for compress file
extension?

const char *media_ext_lists[] = {
	/* common prefix */
	"mp", // Covers mp3, mp4, mpeg, mpg
	"wm", // Covers wma, wmb, wmv
	"og", // Covers oga, ogg, ogm, ogv
	"jp", // Covers jpg, jpeg, jp2
...
}

Thanks,

> Will check what's going on here.
> 
>>
>> commit 4a67d9b07ac8dce7f1034e0d887f2f4ee00fe118
>> Author: Chao Yu <chao@...nel.org>
>> Date:   Tue May 18 17:54:58 2021 +0800
>>
>>      f2fs: compress: fix to disallow temp extension
>>
>>      This patch restricts to configure compress extension as format of:
>>
>>       [filename + '.' + extension]
>>
>>      rather than:
>>
>>       [filename + '.' + extension + (optional: '.' + temp extension)]
>>
>>      in order to avoid to enable compression incorrectly:
>>
>>      1. compress_extension=so
>>      2. touch file.soa
>>      3. touch file.so.tmp
>>
>> Thanks,
>>
>>>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>>> ---
>>>    fs/f2fs/namei.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
>>> index 3e35eb7dbb8f..cdc94c8e60f7 100644
>>> --- a/fs/f2fs/namei.c
>>> +++ b/fs/f2fs/namei.c
>>> @@ -161,7 +161,7 @@ static void set_compress_new_inode(struct f2fs_sb_info *sbi, struct inode *dir,
>>>    	/* Compress wanting extension. */
>>>    	for (i = 0; i < ext_cnt; i++) {
>>> -		if (is_extension_exist(name, ext[i], false)) {
>>> +		if (is_extension_exist(name, ext[i], true)) {
>>>    			set_compress_context(inode);
>>>    			return;
>>>    		}