linux-kernel - Re: [PATCH v3 1/2] fs: New zonefs file system

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Date:   Wed, 25 Dec 2019 08:21:58 +0000
From:   Damien Le Moal <Damien.LeMoal@....com>
To:     "Darrick J. Wong" <darrick.wong@...cle.com>
CC:     "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Johannes Thumshirn <jth@...nel.org>,
        Naohiro Aota <Naohiro.Aota@....com>,
        Hannes Reinecke <hare@...e.de>
Subject: Re: [PATCH v3 1/2] fs: New zonefs file system

On 2019/12/25 16:20, Damien Le Moal wrote:
> On 2019/12/25 15:05, Damien Le Moal wrote:
>>>> +		inode->i_mode = S_IFREG;
>>>
>>> i_mode &= ~S_IRWXUGO; ?
>>
>> Yes, indeed that is better. checkpatch.pl does spit out a warning if one
>> uses the S_Ixxx macros though. See below.
> 
> Please disregard this comment. checkpatch is fine. For some reasons I
> had warnings in the past but they are now gone. So using the macros
> instead of the harder to read hard-coded values.

Retracting this... My apologies for the noise.

Checkpatch does complain about the use of symbolic permissions:

WARNING: Symbolic permissions 'S_IRWXUGO' are not preferred. Consider
using octal permissions '0777'.
#657: FILE: fs/zonefs/super.c:400:
+               inode->i_mode &= ~S_IRWXUGO;

I do not understand why this would be a problem. I still went ahead and
used the macros as I find the code more readable using them. Please let
me know if that is not recommended (checking the code, not surprisingly,
many FS use these macros).

> 
>>
>>>
>>> Note that clearing the mode flags won't prevent programs with an
>>> existing writable fd from being able to call write().  I'd imagine that
>>> they'd hit EIO pretty fast though, so that might not matter.
>>>
>>>> +		zone->wp = zone->start;
>>>> +	} else if (zone->cond == BLK_ZONE_COND_READONLY) {
>>>> +		inode->i_flags |= S_IMMUTABLE;
>>>> +		inode->i_mode &= ~(0222); /* S_IWUGO */
>>>
>>> Might as well just use S_IWUGO directly here?
> 
> Yes, I did in v4.
> 
>> Because checkpatch spits out a warning if I do. I would prefer using the
>> macro as I find it much easier to read. Should I just ignore checkpatch
>> warning ?
> 
> My mistake. No warnings :)
> 
> 


-- 
Damien Le Moal
Western Digital Research