From: Jan Kara <jack@suse.cz>
To: Kim Jaegeuk <jaegeuk.kim@gmail.com>
Cc: Jan Kara <jack@suse.cz>,
Linus Torvalds <torvalds@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>, Christoph Hellwig <hch@lst.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Jaegeuk Kim <jaegeuk.kim@samsung.com>
Subject: Re: [git pull] vfs pile 1
Date: Thu, 30 Jan 2014 16:26:36 +0100 [thread overview]
Message-ID: <20140130152636.GB12687@quack.suse.cz> (raw)
In-Reply-To: <CAOtxgyd_T8eXpQ89KhMCLRhy6ebO55dXscVikhuX2a9HCdGTQA@mail.gmail.com>
On Thu 30-01-14 11:02:49, Kim Jaegeuk wrote:
> 2014-01-29 Jan Kara <jack@suse.cz>:
> > On Tue 28-01-14 19:26:08, Linus Torvalds wrote:
> >> On Mon, Jan 27, 2014 at 6:25 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> >> > Assorted stuff; the biggest pile here is Christoph's ACL series.
> >> > Plus assorted cleanups and fixes all over the place... There will be
> >> > another pile later this week.
> >>
> >> The posix_acl_chmod() code looks wrong.
> >>
> >> Not that it looked right before either, but whatever. The code
> >> basically looks like some variation of this in most setattr()
> >> implementations:
> >>
> >> if (ia_valid & ATTR_MODE)
> >> rc = posix_acl_chmod(inode, inode->i_mode);
> >>
> >> but the mode we're changing to (and what ATTR_MODE guards) is actually
> >> attr->ia_mode, not inode->i_mode.
> > Yes, but posix_acl_chmod() is called after setattr_copy() was done so
> > inode->i_mode should be the same as attr->ia_mode. Whether i_mode or
> > ia_mode is mode logical depends on whether you view posix_acl_chmod() as
> > "sync current i_mode into acls" or "reflect this i_mode change in acls".
> > I agree the function name suggests more the latter semantics.
> >
> >> And quite frankly, passing in inode->i_mode looks stupid, since we're
> >> already passing in the inode pointer, so that's just redundant and
> >> pointless information.
> > Yes, it looks stupid. We could almost drop that argument, except that f2fs
> > tries to play some tricks with i_mode and stores i_mode in a different
> > place when acls are enabled. Huh? Jaegeuk, can you explain why are you
> > doing that?
>
> As described to Christoph before, the reason is for acl consistency
> between on-disk xattr->mode and on-disk inode->mode.
>
> Previously, there are three i_modes managed by:
> inode->mode on-disk xattr->mode on-disk->i_mode
> f2fs_setattr [x] y y
> [update_inode] x y [x]
> [checkpoint] x [y] x
> __f2fs_setxattr x [x] x
>
> In this flow, f2fs is able to break the consistency between on-disk
> xattr->mode and on-disk->i_mode after checkpoint followed by
> sudden-power-off.
>
> So, fi->i_mode was introduced to address the problem.
> The new f2fs_setattr triggers:
> inode->mode fi->i_mode on-disk xattr->mode on-disk->i_mode
> f2fs_setattr y [x] y
> y
> [update_inode] y x y
> y
> [checkpoint] y x y
> y
> __f2fs_setxattr [x] x [x]
> [x]
>
> Finally, __f2fs_setxattr synchronizes inode->mode, on-disk xattr->mode,
> and on-disk inode->i_mode all together.
>
> Am I missing something?
OK, I see. Thanks for explanation.
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2014-01-30 15:26 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-27 14:25 [git pull] vfs pile 1 Al Viro
2014-01-27 23:05 ` Stephen Rothwell
2014-01-29 3:26 ` Linus Torvalds
2014-01-29 13:37 ` Jan Kara
2014-01-30 2:02 ` Kim Jaegeuk
2014-01-30 15:26 ` Jan Kara [this message]
2014-01-30 13:07 ` Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2018-06-04 0:59 [git pull] vfs, " Al Viro
2016-12-16 13:30 [git pull] vfs " Al Viro
2015-09-06 2:55 Al Viro
2015-06-22 6:47 Al Viro
2013-02-27 3:24 Al Viro
2012-03-21 3:31 Al Viro
2012-01-05 2:23 Al Viro
2012-01-08 23:04 ` Linus Torvalds
2012-01-08 23:50 ` Al Viro
2012-01-08 23:53 ` Al Viro
2012-01-09 0:11 ` Linus Torvalds
2012-01-09 0:25 ` Al Viro
2012-01-09 0:39 ` Linus Torvalds
2012-01-09 2:12 ` Al Viro
2012-01-09 15:11 ` Ted Ts'o
2012-01-11 11:58 ` Christoph Hellwig
2012-01-11 12:36 ` Miklos Szeredi
2012-01-11 12:40 ` Christoph Hellwig
2012-01-11 13:12 ` Miklos Szeredi
2012-01-11 15:23 ` Ted Ts'o
2012-01-11 16:19 ` Al Viro
2012-01-12 11:41 ` Miklos Szeredi
2011-05-26 11:53 Al Viro
2011-01-13 5:35 Al Viro
2011-01-13 6:25 ` Stephen Rothwell
2011-01-13 8:55 ` Christoph Hellwig
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