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From: "Pali Rohár" <pali.rohar@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Namjae Jeon <linkinjeon@gmail.com>,
	Namjae Jeon <namjae.jeon@samsung.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
	gregkh <gregkh@linuxfoundation.org>,
	Valdis Kletnieks <valdis.kletnieks@vt.edu>,
	Christoph Hellwig <hch@lst.de>,
	sj1557.seo@samsung.com
Subject: Re: [PATCH v10 09/14] exfat: add misc operations
Date: Wed, 15 Jan 2020 15:24:28 +0100
Message-ID: <20200115142428.ugsp3binf2vuiarq@pali> (raw)
In-Reply-To: <CAK8P3a1ozgLYpDtveU0CtLj5fEFG8i=_QrnEAtoVFt-yC=Dc0g@mail.gmail.com>

On Wednesday 15 January 2020 14:50:10 Arnd Bergmann wrote:
> On Wed, Jan 15, 2020 at 2:38 PM Pali Rohár <pali.rohar@gmail.com> wrote:
> > On Wednesday 15 January 2020 22:30:59 Namjae Jeon wrote:
> > > 2020-01-15 19:10 GMT+09:00, Arnd Bergmann <arnd@arndb.de>:
> 
> > > It is not described in the specification. I don't know exactly what
> > > the problem is because sys_tz.tz_minuteswest seems to work fine to me.
> > > It can be random garbage value ?
> > >
> > > > so if there is a choice, falling back to UTC would
> > > > be nicer.
> > >
> > > Okay.
> >
> > Arnd, what is the default value of sys_tz.tz_minuteswest? What is the
> > benefit of not using it?
> >
> > I though that timezone mount option is just an old hack when userspace
> > does not correctly set kernel's timezone and that this timezone mount
> > option should be in most cases avoided.
> 
> The main problem is that it is system-wide and initialized at boot
> time through settimeofday() to a timezone picked by the system
> administrator.
> 
> However, in user space, every user may set their own timezone with
> the 'TZ' variable, and the default timezone may be different inside of a
> container based on the contents of /etc/timezone in its root directory.

So kernel timezone is shared across all containers, right?

> > So also another question, what is benefit of having fs specific timezone
> > mount option? As it is fs specific it means that it would be used so
> > much.
> 
> You can use it to access removable media that were written in
> a different timezone or a partition that is shared with another OS
> running on the same machine but with different timezone settings.

So... basically all userspace <--> kernel API which works with timestamp
do not have information about timezone right? creat(), utime() or
utimensat() just pass timestamp without timezone information. Is this
timestamp mean to be in UTC or in local user time zone (as specified by
user's TZ= env variable)?

-- 
Pali Rohár
pali.rohar@gmail.com

  reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200115082818epcas1p4892a99345626188afd111ee263132458@epcas1p4.samsung.com>
2020-01-15  8:24 ` [PATCH v10 00/14] add the latest exfat driver Namjae Jeon
     [not found]   ` <CGME20200115082819epcas1p3303009557f8bf670b47991530f380ef7@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 01/14] exfat: add in-memory and on-disk structures and headers Namjae Jeon
     [not found]   ` <CGME20200115082819epcas1p3825d5bed592a8378ad26254d07d59b18@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 02/14] exfat: add super block operations Namjae Jeon
     [not found]   ` <CGME20200115082820epcas1p34ebebebaf610fd61c4e9882fca8ddbd5@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 03/14] exfat: add inode operations Namjae Jeon
2020-01-15 10:25       ` Arnd Bergmann
2020-01-15 13:39         ` Namjae Jeon
2020-01-17  9:25       ` Pali Rohár
2020-01-17 11:17       ` Pali Rohár
     [not found]   ` <CGME20200115082821epcas1p3db1f70cf53185c40934c3a754c65e648@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 04/14] exfat: add directory operations Namjae Jeon
2020-01-17 11:13       ` Pali Rohár
     [not found]   ` <CGME20200115082821epcas1p4d76d8668dfac70ae3e3889d4ccb6c3ee@epcas1p4.samsung.com>
2020-01-15  8:24     ` [PATCH v10 05/14] exfat: add file operations Namjae Jeon
2020-01-15  9:56       ` Arnd Bergmann
2020-01-15 13:07         ` Namjae Jeon
2020-01-17  9:18       ` Pali Rohár
2020-01-17 12:12         ` Namjae Jeon
     [not found]   ` <CGME20200115082822epcas1p37aca37dad0aa9159d7eddde01edfeec2@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 06/14] exfat: add fat entry operations Namjae Jeon
     [not found]   ` <CGME20200115082822epcas1p384d080724d8bb0a8cd4c3e3015a0895c@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 07/14] exfat: add bitmap operations Namjae Jeon
     [not found]   ` <CGME20200115082823epcas1p27ec5ff6d384f148d826529f573173b04@epcas1p2.samsung.com>
2020-01-15  8:24     ` [PATCH v10 08/14] exfat: add exfat cache Namjae Jeon
     [not found]   ` <CGME20200115082824epcas1p4eb45d088c2f88149acb94563c4a9b276@epcas1p4.samsung.com>
2020-01-15  8:24     ` [PATCH v10 09/14] exfat: add misc operations Namjae Jeon
2020-01-15 10:10       ` Arnd Bergmann
2020-01-15 13:30         ` Namjae Jeon
2020-01-15 13:38           ` Pali Rohár
2020-01-15 13:50             ` Arnd Bergmann
2020-01-15 14:24               ` Pali Rohár [this message]
2020-01-15 15:03                 ` Arnd Bergmann
2020-01-15 15:39                   ` Pali Rohár
2020-01-15 15:52                     ` Arnd Bergmann
2020-01-16 10:19                       ` Pali Rohár
2020-01-16 10:23                         ` Christoph Hellwig
2020-01-16 16:00                           ` Pali Rohár
2020-01-17  2:59                       ` Namjae Jeon
2020-01-17 10:13                         ` Arnd Bergmann
2020-01-17 12:13                           ` Namjae Jeon
     [not found]   ` <CGME20200115082824epcas1p23a0fa255a5833c6dcd2479b384f37740@epcas1p2.samsung.com>
2020-01-15  8:24     ` [PATCH v10 10/14] exfat: add nls operations Namjae Jeon
     [not found]   ` <CGME20200115082825epcas1p1f22ddca6dbf5d70e65d3b0e3c25c3a59@epcas1p1.samsung.com>
2020-01-15  8:24     ` [PATCH v10 11/14] exfat: add Kconfig and Makefile Namjae Jeon
2020-01-15  9:39       ` Pali Rohár
2020-01-17  4:22         ` Namjae Jeon
2020-01-17  9:12           ` Pali Rohár
2020-01-17 11:59             ` Namjae Jeon
     [not found]   ` <CGME20200115082825epcas1p4a0d63d53d8737a84fe8867bc1e63811e@epcas1p4.samsung.com>
2020-01-15  8:24     ` [PATCH v10 12/14] exfat: add exfat in fs/Kconfig and fs/Makefile Namjae Jeon
     [not found]   ` <CGME20200115082826epcas1p117191a39ecccaef5a9b5cbe77b05c5a5@epcas1p1.samsung.com>
2020-01-15  8:24     ` [PATCH v10 13/14] MAINTAINERS: add exfat filesystem Namjae Jeon
     [not found]   ` <CGME20200115082826epcas1p3475ce2b4d03234dc96ced428be582eb3@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 14/14] staging: exfat: make staging/exfat and fs/exfat mutually exclusive Namjae Jeon
2020-01-15  8:56       ` Greg KH
2020-01-15 13:06         ` Namjae Jeon
2020-01-15  9:47   ` [PATCH v10 00/14] add the latest exfat driver Pali Rohár
2020-01-15 13:05     ` Namjae Jeon
2020-01-16 10:51     ` Christoph Hellwig
2020-01-16 11:32       ` Pali Rohár
2020-01-16 13:01       ` Greg KH

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