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From: Al Viro <viro@zeniv.linux.org.uk>
To: Lukas Czerner <lczerner@redhat.com>
Cc: linux-ext4@vger.kernel.org, Theodore Ts'o <tytso@mit.edu>,
	David Howells <dhowells@redhat.com>
Subject: Re: [PATCH 02/17] ext4: Add fs parameter description
Date: Tue, 24 Dec 2019 17:18:18 +0000	[thread overview]
Message-ID: <20191224171818.GO4203@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20191217163432.diborehdrfkmfqxp@work>

On Tue, Dec 17, 2019 at 05:34:32PM +0100, Lukas Czerner wrote:

> > If so, I would prefer
> > 	fsparam_flag_no("barrier", Opt_barrier),	// barrier | nobarrier
> > 	fsparam_u32("barrier", Opt_barrier),		// barrier=<number>
> > as the solution, with fs_parse() having been taught to allow argument-bearing
> > and argument-less options with the same name, picking the right one.  That
> > way Opt_nobarrier gets removed as well...
> > 
> > I'll push a branch with that stuff later today; will post when it's out...
> 
> That would be great, thanks.

It took longer than I hoped, sorry ;-/  The current patchset is in
#untested.fs_parse; the really interesting part is up to
"turn fs_param_is_... into functions".

One surprising source of PITA around your patchset is ext4_show_options().
It pretty much forces you into keeping "no..." forms separate, even though
normally you could just say
	fsparam_flag_no("quota",               Opt_quota),
and get rid of Opt_noquota, etc.

If you keep that dependency, it'll need to be documented - right in
fs/ext4/super.c, to make sure we don't get "optimizing" followups breaking
the hell out of things.

Said that, I really doubt that token2str() is a good idea.  It might make
more sense to start with separating _ext4_show_options() from that
machinery.

Another thing is that all fsparam_bool() users are modifying user-visible
ABI; use fparam_flag_no() + fsparam_u32() with the same name and same
opt - that'll give you the existing behaviour.

  reply	other threads:[~2019-12-24 17:18 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06 10:14 ext4: new mount API conversion Lukas Czerner
2019-11-06 10:14 ` [PATCH 01/17] vfs: Handle fs_param_neg_with_empty Lukas Czerner
2019-11-06 10:14 ` [PATCH 02/17] ext4: Add fs parameter description Lukas Czerner
2019-12-17  0:44   ` Al Viro
2019-12-17 12:19     ` Lukas Czerner
2019-12-17 15:20       ` Al Viro
2019-12-17 16:34         ` Lukas Czerner
2019-12-24 17:18           ` Al Viro [this message]
2019-11-06 10:14 ` [PATCH 03/17] ext4: move option validation to a separate function Lukas Czerner
2019-11-06 10:14 ` [PATCH 04/17] ext4: Change handle_mount_opt() to use fs_parameter Lukas Czerner
2019-11-06 10:14 ` [PATCH 05/17] ext4: Allow sb to be NULL in ext4_msg() Lukas Czerner
2019-11-06 10:14 ` [PATCH 06/17] ext4: move quota configuration out of handle_mount_opt() Lukas Czerner
2019-11-06 10:14 ` [PATCH 07/17] ext4: check ext2/3 compatibility outside handle_mount_opt() Lukas Czerner
2019-11-06 10:14 ` [PATCH 08/17] ext4: get rid of super block and sbi from handle_mount_ops() Lukas Czerner
2019-11-06 10:14 ` [PATCH 09/17] ext4: parse Opt_sb in handle_mount_opt() Lukas Czerner
2019-11-06 10:14 ` [PATCH 10/17] ext4: clean up return values " Lukas Czerner
2019-11-06 10:14 ` [PATCH 11/17] ext4: add ext4_get_tree for the new mount API Lukas Czerner
2019-11-06 10:14 ` [PATCH 12/17] ext4: refactor ext4_remount() Lukas Czerner
2019-11-06 10:14 ` [PATCH 13/17] ext4: add ext4_reconfigure for the new mount API Lukas Czerner
2019-11-06 10:14 ` [PATCH 14/17] ext4: add ext4_fc_free " Lukas Czerner
2019-11-06 10:14 ` [PATCH 15/17] ext4: switch to " Lukas Czerner
2019-11-06 10:14 ` [PATCH 16/17] ext4: change token2str() to use ext4_param_specs Lukas Czerner
2019-11-06 10:14 ` [PATCH 17/17] ext4: Remove unused code from old mount api Lukas Czerner

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