From: Jan Kara <jack@suse.cz>
To: Luis Henriques <lhenriques@suse.de>
Cc: Christian Brauner <brauner@kernel.org>,
Theodore Ts'o <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
Miklos Szeredi <miklos@szeredi.hu>,
Amir Goldstein <amir73il@gmail.com>,
linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] fs_parser: handle parameters that can be empty and don't have a value
Date: Thu, 7 Mar 2024 16:13:56 +0100 [thread overview]
Message-ID: <20240307151356.ishrtxrsge2i5mjn@quack3> (raw)
In-Reply-To: <87il269crs.fsf@suse.de>
On Fri 01-03-24 15:45:27, Luis Henriques wrote:
> Christian Brauner <brauner@kernel.org> writes:
>
> > On Thu, Feb 29, 2024 at 04:30:08PM +0000, Luis Henriques wrote:
> >> Currently, only parameters that have the fs_parameter_spec 'type' set to
> >> NULL are handled as 'flag' types. However, parameters that have the
> >> 'fs_param_can_be_empty' flag set and their value is NULL should also be
> >> handled as 'flag' type, as their type is set to 'fs_value_is_flag'.
> >>
> >> Signed-off-by: Luis Henriques <lhenriques@suse.de>
> >> ---
> >> fs/fs_parser.c | 3 ++-
> >> 1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/fs/fs_parser.c b/fs/fs_parser.c
> >> index edb3712dcfa5..53f6cb98a3e0 100644
> >> --- a/fs/fs_parser.c
> >> +++ b/fs/fs_parser.c
> >> @@ -119,7 +119,8 @@ int __fs_parse(struct p_log *log,
> >> /* Try to turn the type we were given into the type desired by the
> >> * parameter and give an error if we can't.
> >> */
> >> - if (is_flag(p)) {
> >> + if (is_flag(p) ||
> >> + (!param->string && (p->flags & fs_param_can_be_empty))) {
> >> if (param->type != fs_value_is_flag)
> >> return inval_plog(log, "Unexpected value for '%s'",
> >> param->key);
> >
> > If the parameter was derived from FSCONFIG_SET_STRING in fsconfig() then
> > param->string is guaranteed to not be NULL. So really this is only
> > about:
> >
> > FSCONFIG_SET_FD
> > FSCONFIG_SET_BINARY
> > FSCONFIG_SET_PATH
> > FSCONFIG_SET_PATH_EMPTY
> >
> > and those values being used without a value. What filesystem does this?
> > I don't see any.
> >
> > The tempting thing to do here is to to just remove fs_param_can_be_empty
> > from every helper that isn't fs_param_is_string() until we actually have
> > a filesystem that wants to use any of the above as flags. Will lose a
> > lot of code that isn't currently used.
>
> Right, I find it quite confusing and I may be fixing the issue in the
> wrong place. What I'm seeing with ext4 when I mount a filesystem using
> the option '-o usrjquota' is that fs_parse() will get:
>
> * p->type is set to fs_param_is_string
> ('p' is a struct fs_parameter_spec, ->type is a function)
> * param->type is set to fs_value_is_flag
> ('param' is a struct fs_parameter, ->type is an enum)
>
> This is because ext4 will use the __fsparam macro to set define a
> fs_param_spec as a fs_param_is_string but will also set the
> fs_param_can_be_empty; and the fsconfig() syscall will get that parameter
> as a flag. That's why param->string will be NULL in this case.
So I'm a bit confused here. Valid variants of these quota options are like
"usrjquota=<filename>" (to set quota file name) or "usrjquota=" (to clear
quota file name). The variant "usrjquota" should ideally be rejected
because it doesn't make a good sense and only adds to confusion. Now as far
as I'm reading fs/ext4/super.c: parse_options() (and as far as my testing
shows) this is what is happening so what is exactly the problem you're
trying to fix?
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2024-03-07 23:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-29 16:30 [PATCH 0/3] fs_parser: handle parameters that can be empty and don't have a value Luis Henriques
2024-02-29 16:30 ` [PATCH 1/3] " Luis Henriques
2024-03-01 13:31 ` Christian Brauner
2024-03-01 15:45 ` Luis Henriques
2024-03-02 11:46 ` Christian Brauner
2024-03-02 17:56 ` Christian Brauner
2024-03-03 21:31 ` Luis Henriques
2024-03-04 9:04 ` Christian Brauner
2024-03-03 21:17 ` Luis Henriques
2024-03-07 15:13 ` Jan Kara [this message]
2024-03-08 9:53 ` Christian Brauner
2024-03-08 10:12 ` Luis Henriques
2024-03-08 23:09 ` Jan Kara
2024-03-11 10:26 ` Luis Henriques
2024-03-11 16:01 ` Jan Kara
2024-02-29 16:30 ` [PATCH 2/3] ext4: fix mount parameters check for empty values Luis Henriques
2024-03-01 13:36 ` Christian Brauner
2024-03-01 15:47 ` Luis Henriques
2024-02-29 16:30 ` [PATCH 3/3] overlay: " Luis Henriques
2024-03-01 13:37 ` Christian Brauner
2024-03-01 13:12 ` [PATCH 0/3] fs_parser: handle parameters that can be empty and don't have a value Christian Brauner
2024-03-01 14:54 ` Eric Sandeen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240307151356.ishrtxrsge2i5mjn@quack3 \
--to=jack@suse.cz \
--cc=adilger.kernel@dilger.ca \
--cc=amir73il@gmail.com \
--cc=brauner@kernel.org \
--cc=lhenriques@suse.de \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-unionfs@vger.kernel.org \
--cc=miklos@szeredi.hu \
--cc=tytso@mit.edu \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).