From: Gao Xiang <gaoxiang25@huawei.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Gao Xiang <hsiangkao@aol.com>, Jan Kara <jack@suse.cz>,
Chao Yu <yuchao0@huawei.com>, Dave Chinner <david@fromorbit.com>,
LKML <linux-kernel@vger.kernel.org>,
Miao Xie <miaoxie@huawei.com>, <devel@driverdev.osuosl.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
"Darrick J . Wong" <darrick.wong@oracle.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Amir Goldstein <amir73il@gmail.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jaegeuk Kim <jaegeuk@kernel.org>, Theodore Ts'o <tytso@mit.edu>,
Pavel Machek <pavel@denx.de>, David Sterba <dsterba@suse.cz>,
Li Guifu <bluce.liguifu@huawei.com>,
Fang Wei <fangwei1@huawei.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
<linux-fsdevel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
<linux-erofs@lists.ozlabs.org>
Subject: Re: [PATCH v6 03/24] erofs: add super block operations
Date: Mon, 2 Sep 2019 23:24:52 +0800 [thread overview]
Message-ID: <20190902152451.GC179615@architecture4> (raw)
In-Reply-To: <20190902151910.GA14009@infradead.org>
Hi Christoph,
On Mon, Sep 02, 2019 at 08:19:10AM -0700, Christoph Hellwig wrote:
> On Mon, Sep 02, 2019 at 10:43:04PM +0800, Gao Xiang wrote:
> > Hi Christoph,
> > > > ...
> > > > 24 __le32 features; /* (aka. feature_compat) */
> > > > ...
> > > > 38 __le32 requirements; /* (aka. feature_incompat) */
> > > > ...
> > > > 41 };
> > >
> > > This is only cosmetic, why not stick to feature_compat and
> > > feature_incompat?
> >
> > Okay, will fix. (however, in my mind, I'm some confused why
> > "features" could be incompatible...)
>
> The feature is incompatible if it requires changes to the driver.
> An easy to understand historic example is that ext3 originally did not
> have the file types in the directory entry. Adding them means old
> file system drivers can not read a file system with this new feature,
> so an incompat flag has to be added.
Got it.
>
> > > > > > + memcpy(&sb->s_uuid, layout->uuid, sizeof(layout->uuid));
> > > > > > + memcpy(sbi->volume_name, layout->volume_name,
> > > > > > + sizeof(layout->volume_name));
> > > > >
> > > > > s_uuid should preferably be a uuid_t (assuming it is a real BE uuid,
> > > > > if it is le it should be a guid_t).
> > > >
> > > > For this case, I have no idea how to deal with...
> > > > I have little knowledge about this uuid stuff, so I just copied
> > > > from f2fs... (Could be no urgent of this field...)
> > >
> > > Who fills out this field in the on-disk format and how?
> >
> > mkfs.erofs, but this field leaves 0 for now. Is that reasonable?
> > (using libuuid can generate it easily...)
>
> If the filed is always zero for now please don't fill it out. If you
> decide it is worth adding the uuid eventually please add a compat
> feature flag that you have a valid uuid and only fill out the field
> if the file system actualy has a valid uuid.
Okay. Will do that then (as a note here).
Thanks,
Gao Xiang
next prev parent reply other threads:[~2019-09-02 15:46 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-02 12:53 [PATCH v6 00/24] erofs: promote erofs from staging Gao Xiang
2019-08-02 12:53 ` [PATCH v6 01/24] erofs: add on-disk layout Gao Xiang
2019-08-29 9:59 ` Christoph Hellwig
2019-08-29 10:32 ` Gao Xiang
2019-08-29 10:36 ` Christoph Hellwig
2019-08-29 10:58 ` Gao Xiang
2019-08-29 15:58 ` Joe Perches
2019-08-29 17:26 ` Gao Xiang
2019-08-30 12:07 ` David Sterba
2019-08-30 12:18 ` Gao Xiang
2019-09-02 8:43 ` Pavel Machek
2019-09-02 14:07 ` David Sterba
2019-09-03 11:27 ` Pavel Machek
2019-08-29 15:41 ` Gao Xiang
2019-09-01 7:54 ` Gao Xiang
2019-09-02 12:45 ` Christoph Hellwig
2019-09-02 13:02 ` Gao Xiang
2019-09-02 8:40 ` Pavel Machek
2019-09-02 10:35 ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 02/24] erofs: add erofs in-memory stuffs Gao Xiang
2019-08-02 12:53 ` [PATCH v6 03/24] erofs: add super block operations Gao Xiang
2019-08-29 10:15 ` Christoph Hellwig
2019-08-29 10:50 ` Gao Xiang
2019-08-30 16:39 ` Christoph Hellwig
2019-08-30 17:15 ` Gao Xiang
2019-08-31 0:54 ` Gao Xiang
2019-08-31 6:34 ` Amir Goldstein
2019-08-31 6:48 ` Gao Xiang
2019-09-01 8:54 ` Gao Xiang
2019-09-02 12:51 ` Christoph Hellwig
2019-09-02 14:43 ` Gao Xiang
2019-09-02 15:19 ` Christoph Hellwig
2019-09-02 15:24 ` Gao Xiang [this message]
2019-08-02 12:53 ` [PATCH v6 04/24] erofs: add raw address_space operations Gao Xiang
2019-08-29 10:17 ` Christoph Hellwig
2019-08-29 11:46 ` Gao Xiang
2019-08-30 16:40 ` Christoph Hellwig
2019-08-30 17:23 ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 05/24] erofs: add inode operations Gao Xiang
2019-08-29 10:24 ` Christoph Hellwig
2019-08-29 11:59 ` Gao Xiang
2019-08-30 16:42 ` Christoph Hellwig
2019-08-30 18:46 ` Gao Xiang
2019-09-01 9:34 ` Gao Xiang
2019-09-02 12:53 ` Christoph Hellwig
2019-09-02 13:43 ` David Sterba
2019-09-02 13:55 ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 06/24] erofs: support special inode Gao Xiang
2019-08-29 10:25 ` Christoph Hellwig
2019-09-01 9:39 ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 07/24] erofs: add directory operations Gao Xiang
2019-08-02 12:53 ` [PATCH v6 08/24] erofs: add namei functions Gao Xiang
2019-08-29 10:28 ` Christoph Hellwig
2019-08-29 11:28 ` Gao Xiang
2019-08-02 12:53 ` [PATCH v6 09/24] erofs: support tracepoint Gao Xiang
2019-08-02 12:53 ` [PATCH v6 10/24] erofs: update Kconfig and Makefile Gao Xiang
2019-08-02 12:53 ` [PATCH v6 11/24] erofs: introduce xattr & posixacl support Gao Xiang
2019-08-02 12:53 ` [PATCH v6 12/24] erofs: introduce tagged pointer Gao Xiang
2019-08-02 12:53 ` [PATCH v6 13/24] erofs: add compression indexes support Gao Xiang
2019-08-02 12:53 ` [PATCH v6 14/24] erofs: introduce superblock registration Gao Xiang
2019-08-02 12:53 ` [PATCH v6 15/24] erofs: introduce erofs shrinker Gao Xiang
2019-08-02 12:53 ` [PATCH v6 16/24] erofs: introduce workstation for decompression Gao Xiang
2019-08-02 12:53 ` [PATCH v6 17/24] erofs: introduce per-CPU buffers implementation Gao Xiang
2019-08-02 12:53 ` [PATCH v6 18/24] erofs: introduce pagevec for decompression subsystem Gao Xiang
2019-08-02 12:53 ` [PATCH v6 19/24] erofs: add erofs_allocpage() Gao Xiang
2019-08-02 12:53 ` [PATCH v6 20/24] erofs: introduce generic decompression backend Gao Xiang
2019-08-02 12:53 ` [PATCH v6 21/24] erofs: introduce LZ4 decompression inplace Gao Xiang
2019-08-02 12:53 ` [PATCH v6 22/24] erofs: introduce the decompression frontend Gao Xiang
2019-08-02 12:53 ` [PATCH v6 23/24] erofs: introduce cached decompression Gao Xiang
2019-08-02 12:53 ` [PATCH v6 24/24] erofs: add document Gao Xiang
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