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From: Petr Vorel <pvorel@suse.cz>
To: Cyril Hrubis <chrubis@suse.cz>
Cc: ltp@lists.linux.it, Chen Hanxiao <chenhx.fnst@cn.fujitsu.com>
Subject: Re: [LTP] [PATCH v2] syscalls/mount_setattr01: Add basic functional test
Date: Thu, 21 Apr 2022 11:14:02 +0200	[thread overview]
Message-ID: <YmEgWnz8Sr1jiYPT@pevik> (raw)
In-Reply-To: <YmEgVS3DBARBkYOx@yuki>

> Hi!
> > > +struct mount_attr {
> > > +	uint64_t attr_set;
> > > +	uint64_t attr_clr;
> > > +	uint64_t propagation;
> > > +	uint64_t userns_fd;
> > > +};
> > Interesting enough: in kernel tools/testing/selftests/mount_setattr/mount_setattr_test.c
> > defines it as __u64 (IMHO should be really uint64_t as that test is userspace as
> > Cyril pointed out) but real kernel code in fs/namespace.c happily uses "unsigned
> > int" :).

> You are just confused by the fact that there are two different
> structures there is mount_attr and mount_kattr, the mount_setattr()
> syscall gets the mount_attr from userspace and then fills in mount_kattr
> based on that. See the function build_mount_kattr() in fs/namespace.c

> I guess that this is simply done so that there is enough space for flags
> to be added in the future without a need to change the structure.

Ah, thx for info.

Kind regards,
Petr

-- 
Mailing list info: https://lists.linux.it/listinfo/ltp

  reply	other threads:[~2022-04-21  9:14 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-20 10:29 [LTP] [PATCH v2] syscalls/mount_setattr01: Add basic functional test Chen Hanxiao
2022-04-20 20:43 ` Petr Vorel
2022-04-21  9:13   ` Cyril Hrubis
2022-04-21  9:14     ` Petr Vorel [this message]
2022-04-22 11:05   ` [LTP] 回复: " chenhx.fnst
2022-04-22 14:11     ` Petr Vorel

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