Re: [RFC v6 02/40] vfs: Add MAY_CREATE_FILE and MAY_CREATE_DIR permission flags

From: Andreas Gruenbacher
Date: Wed Sep 02 2015 - 15:06:41 EST


2015-09-02 20:53 GMT+02:00 J. Bruce Fields <bfields@xxxxxxxxxxxx>:
>> @@ -453,7 +453,8 @@ static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
>> * this, letting us set arbitrary permissions for filesystem access without
>> * changing the "normal" UIDs which are used for other things.
>> *
>> - * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
>> + * When checking for MAY_APPEND, MAY_CREATE_FILE, MAY_CREATE_DIR,
>> + * MAY_WRITE must also be set in @mask.
>
> Why?

So that file systems that don't support MAY_APPEND can ignore the flag
and will then automatically check for MAY_WRITE instead.

> (Also: written as a simple list like that, it's a ambiguous how to
> parse that comment: I think you mean that MAY_WRITE must be set whenever
> MAY_APPEND, MAY_CREATE_FILE, or MAY_CREATE_DIR are set.)

Yes, that's better.

Thanks,
Andreas
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