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From: Al Viro <[email protected]>
To: Christian Brauner <[email protected]>
Cc: [email protected], Jan Kara <[email protected]>,
	Christoph Hellwig <[email protected]>, Jens Axboe <[email protected]>,
	Dave Chinner <[email protected]>,
	[email protected]
Subject: Re: [PATCH v2] fs: claw back a few FMODE_* bits
Date: Sat, 6 Apr 2024 07:16:04 +0100	[thread overview]
Message-ID: <20240406061604.GA538574@ZenIV> (raw)
In-Reply-To: <20240406061002.GZ538574@ZenIV>

On Sat, Apr 06, 2024 at 07:10:02AM +0100, Al Viro wrote:
> On Thu, Mar 28, 2024 at 01:27:24PM +0100, Christian Brauner wrote:
> > There's a bunch of flags that are purely based on what the file
> > operations support while also never being conditionally set or unset.
> > IOW, they're not subject to change for individual files. Imho, such
> > flags don't need to live in f_mode they might as well live in the fops
> > structs itself. And the fops struct already has that lonely
> > mmap_supported_flags member. We might as well turn that into a generic
> > fop_flags member and move a few flags from FMODE_* space into FOP_*
> > space. That gets us four FMODE_* bits back and the ability for new
> > static flags that are about file ops to not have to live in FMODE_*
> > space but in their own FOP_* space. It's not the most beautiful thing
> > ever but it gets the job done. Yes, there'll be an additional pointer
> > chase but hopefully that won't matter for these flags.
> > 
> > I suspect there's a few more we can move into there and that we can also
> > redirect a bunch of new flag suggestions that follow this pattern into
> > the fop_flags field instead of f_mode.
> 
> Looks sane; one suggestion, though - if we are going to try and free
> bits, etc., it might be a good idea to use e.g.
> #define FMODE_NOACCOUNT         ((__force fmode_t)BIT(29))
> instead of hex constants.  IME it's easier to keep track of, especially
> if we have comments between the definitions.

... or (1u << 29), for that matter; the point is that counting zeroes
visually is error-prone, so seeing the binary logarithm of the value
somewhere would be a good idea.


  reply	other threads:[~2024-04-06  6:16 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-28 12:27 [PATCH v2] fs: claw back a few FMODE_* bits Christian Brauner
2024-03-28 13:08 ` Christoph Hellwig
2024-04-02 10:51 ` Jan Kara
2024-04-02 12:59 ` Jens Axboe
2024-04-03 21:12 ` Mark Brown
2024-04-04  9:12   ` Jan Kara
2024-04-04 11:43     ` Mark Brown
2024-04-05 10:27       ` Christian Brauner
2024-04-05 11:12         ` Mark Brown
2024-04-04  0:18 ` Al Viro
2024-04-05 10:06   ` Christian Brauner
2024-04-06  6:10 ` Al Viro
2024-04-06  6:16   ` Al Viro [this message]
2024-04-09  9:12     ` Christian Brauner

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