From: Gao Xiang <gaoxiang25@huawei.com> To: Christoph Hellwig <hch@infradead.org> Cc: Jan Kara <jack@suse.cz>, Amir Goldstein <amir73il@gmail.com>, Dave Chinner <david@fromorbit.com>, David Sterba <dsterba@suse.cz>, Miao Xie <miaoxie@huawei.com>, devel@driverdev.osuosl.org, Stephen Rothwell <sfr@canb.auug.org.au>, "Darrick J . Wong" <darrick.wong@oracle.com>, Alexander Viro <viro@zeniv.linux.org.uk>, Jaegeuk Kim <jaegeuk@kernel.org>, Theodore Ts'o <tytso@mit.edu>, Pavel Machek <pavel@denx.de>, Linus Torvalds <torvalds@linux-foundation.org>, LKML <linux-kernel@vger.kernel.org>, 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 22:43:04 +0800 Message-ID: <20190902144303.GF2664@architecture4> (raw) In-Reply-To: <20190902125109.GA9826@infradead.org> Hi Christoph, On Mon, Sep 02, 2019 at 05:51:09AM -0700, Christoph Hellwig wrote: > On Sun, Sep 01, 2019 at 04:54:55PM +0800, Gao Xiang wrote: > > No modification at this... (some comments already right here...) > > > 20 /* 128-byte erofs on-disk super block */ > > 21 struct erofs_super_block { > > ... > > 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...) > > > > > + bh = sb_bread(sb, 0); > > > > > > Is there any good reasons to use buffer heads like this in new code > > > vs directly using bios? > > > > As you said, I want it in the page cache. > > > > The reason "why not use read_mapping_page or similar?" is simply > > read_mapping_page -> .readpage -> (for bdev inode) block_read_full_page > > -> create_page_buffers anyway... > > > > sb_bread haven't obsoleted... It has similar function though... > > With the different that it keeps you isolated from the buffer_head > internals. This seems to be your only direct use of buffer heads, > which while not deprecated are a bit of an ugly step child. So if > you can easily avoid creating a buffer_head dependency in a new > filesystem I think you should avoid it. OK, let's use read_mapping_page instead. > > > > > + sbi->build_time = le64_to_cpu(layout->build_time); > > > > + sbi->build_time_nsec = le32_to_cpu(layout->build_time_nsec); > > > > + > > > > + 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...) > > > The background is Al's comments in erofs v2.... > > (which simplify erofs_fill_super logic) > > https://lore.kernel.org/r/20190720224955.GD17978@ZenIV.linux.org.uk/ > > > > with a specific notation... > > https://lore.kernel.org/r/20190721040547.GF17978@ZenIV.linux.org.uk/ > > > > " > > > OTOH, for the case of NULL ->s_root ->put_super() won't be called > > > at all, so in that case you need it directly in ->kill_sb(). > > " > > Yes. Although none of that is relevant for this initial version, > just after more features are added. This patch uses it actually... since no failure path in erofs_fill_super() and s_root will be filled nearly at the end of the function... Thanks, Gao Xiang
next prev parent reply index Thread overview: 159+ 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 via Linux-erofs 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 via Linux-erofs 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 via Linux-erofs 2019-09-02 12:51 ` Christoph Hellwig 2019-09-02 14:43 ` Gao Xiang [this message] 2019-09-02 15:19 ` Christoph Hellwig 2019-09-02 15:24 ` Gao Xiang 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 via Linux-erofs 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 via Linux-erofs 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 2019-09-01 5:51 ` [PATCH 00/21] erofs: patchset addressing Christoph's comments Gao Xiang via Linux-erofs 2019-09-01 5:51 ` [PATCH 01/21] erofs: remove all the byte offset comments Gao Xiang via Linux-erofs 2019-09-02 12:05 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 02/21] erofs: on-disk format should have explicitly assigned numbers Gao Xiang via Linux-erofs 2019-09-02 12:05 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 03/21] erofs: some macros are much more readable as a function Gao Xiang via Linux-erofs 2019-09-02 12:06 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 04/21] erofs: kill __packed for on-disk structures Gao Xiang via Linux-erofs 2019-09-02 12:06 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 05/21] erofs: update erofs_inode_is_data_compressed helper Gao Xiang via Linux-erofs 2019-09-02 12:07 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 06/21] erofs: kill erofs_{init,exit}_inode_cache Gao Xiang via Linux-erofs 2019-09-02 12:09 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 07/21] erofs: use erofs_inode naming Gao Xiang via Linux-erofs 2019-09-02 12:10 ` Christoph Hellwig 2019-09-02 12:13 ` Gao Xiang 2019-09-02 12:47 ` Christoph Hellwig 2019-09-02 13:33 ` Gao Xiang 2019-09-01 5:51 ` [PATCH 08/21] erofs: update comments in inode.c Gao Xiang via Linux-erofs 2019-09-01 5:51 ` [PATCH 09/21] erofs: update erofs symlink stuffs Gao Xiang via Linux-erofs 2019-09-02 12:11 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 10/21] erofs: kill is_inode_layout_compression() Gao Xiang via Linux-erofs 2019-09-02 12:11 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 11/21] erofs: use dsb instead of layout for ondisk super_block Gao Xiang via Linux-erofs 2019-09-02 12:12 ` Christoph Hellwig 2019-09-02 12:15 ` Gao Xiang 2019-09-01 5:51 ` [PATCH 12/21] erofs: kill verbose debug info in erofs_fill_super Gao Xiang via Linux-erofs 2019-09-02 12:14 ` Christoph Hellwig 2019-09-02 12:18 ` Gao Xiang 2019-09-01 5:51 ` [PATCH 13/21] erofs: simplify erofs_grab_bio() since bio_alloc() never fail Gao Xiang via Linux-erofs 2019-09-02 12:20 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 14/21] erofs: kill prio and nofail of erofs_get_meta_page() Gao Xiang via Linux-erofs 2019-09-02 12:21 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 15/21] erofs: kill __submit_bio() Gao Xiang via Linux-erofs 2019-09-01 5:51 ` [PATCH 16/21] erofs: kill magic underscores Gao Xiang via Linux-erofs 2019-09-02 12:26 ` Christoph Hellwig 2019-09-02 12:39 ` Gao Xiang 2019-09-02 12:54 ` Christoph Hellwig 2019-09-02 13:38 ` Gao Xiang 2019-09-01 5:51 ` [PATCH 17/21] erofs: use a switch statement when dealing with the file modes Gao Xiang via Linux-erofs 2019-09-02 12:27 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 18/21] erofs: add "erofs_" prefix for common and short functions Gao Xiang via Linux-erofs 2019-09-02 12:28 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 19/21] erofs: kill all erofs specific fault injection Gao Xiang via Linux-erofs 2019-09-02 12:28 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 20/21] erofs: kill use_vmap module parameter Gao Xiang via Linux-erofs 2019-09-02 12:31 ` Christoph Hellwig 2019-09-02 12:43 ` Gao Xiang 2019-09-01 5:51 ` [PATCH 21/21] erofs: save one level of indentation Gao Xiang via Linux-erofs 2019-09-02 12:31 ` Christoph Hellwig 2019-09-02 12:46 ` [PATCH 00/21] erofs: patchset addressing Christoph's comments Christoph Hellwig 2019-09-02 14:24 ` Gao Xiang 2019-09-02 15:23 ` Christoph Hellwig 2019-09-02 15:50 ` Gao Xiang 2019-09-03 6:58 ` Christoph Hellwig 2019-09-03 8:17 ` Gao Xiang 2019-09-03 15:37 ` Christoph Hellwig 2019-09-03 15:43 ` Gao Xiang via Linux-erofs 2019-09-04 2:08 ` [PATCH v2 00/25] " Gao Xiang 2019-09-04 2:08 ` [PATCH v2 01/25] erofs: remove all the byte offset comments Gao Xiang 2019-09-04 2:08 ` [PATCH v2 02/25] erofs: on-disk format should have explicitly assigned numbers Gao Xiang 2019-09-04 2:08 ` [PATCH v2 03/25] erofs: some macros are much more readable as a function Gao Xiang 2019-09-04 2:08 ` [PATCH v2 04/25] erofs: kill __packed for on-disk structures Gao Xiang 2019-09-04 2:08 ` [PATCH v2 05/25] erofs: update erofs_inode_is_data_compressed helper Gao Xiang 2019-09-04 2:08 ` [PATCH v2 06/25] erofs: use feature_incompat rather than requirements Gao Xiang 2019-09-04 2:08 ` [PATCH v2 07/25] erofs: better naming for erofs inode related stuffs Gao Xiang 2019-09-04 2:08 ` [PATCH v2 08/25] erofs: kill erofs_{init,exit}_inode_cache Gao Xiang 2019-09-04 2:08 ` [PATCH v2 09/25] erofs: use erofs_inode naming Gao Xiang 2019-09-04 2:08 ` [PATCH v2 10/25] erofs: update erofs_fs.h comments Gao Xiang 2019-09-04 2:08 ` [PATCH v2 11/25] erofs: update comments in inode.c Gao Xiang 2019-09-04 2:08 ` [PATCH v2 12/25] erofs: better erofs symlink stuffs Gao Xiang 2019-09-04 2:09 ` [PATCH v2 13/25] erofs: use dsb instead of layout for ondisk super_block Gao Xiang 2019-09-04 2:09 ` [PATCH v2 14/25] erofs: kill verbose debug info in erofs_fill_super Gao Xiang 2019-09-04 2:09 ` [PATCH v2 15/25] erofs: localize erofs_grab_bio() Gao Xiang 2019-09-04 2:09 ` [PATCH v2 16/25] erofs: kill prio and nofail of erofs_get_meta_page() Gao Xiang 2019-09-04 2:09 ` [PATCH v2 17/25] erofs: kill __submit_bio() Gao Xiang 2019-09-04 2:09 ` [PATCH v2 18/25] erofs: add "erofs_" prefix for common and short functions Gao Xiang 2019-09-04 2:09 ` [PATCH v2 19/25] erofs: kill all erofs specific fault injection Gao Xiang 2019-09-04 2:09 ` [PATCH v2 20/25] erofs: kill use_vmap module parameter Gao Xiang 2019-09-04 2:09 ` [PATCH v2 21/25] erofs: save one level of indentation Gao Xiang 2019-09-04 2:09 ` [PATCH v2 22/25] erofs: rename errln/infoln/debugln to erofs_{err, info, dbg} Gao Xiang 2019-09-04 2:09 ` [PATCH v2 23/25] erofs: use read_mapping_page instead of sb_bread Gao Xiang 2019-09-04 2:09 ` [PATCH v2 24/25] erofs: always use iget5_locked Gao Xiang 2019-09-04 2:09 ` [PATCH v2 25/25] erofs: use read_cache_page_gfp for erofs_get_meta_page Gao Xiang 2019-09-04 3:27 ` [PATCH v2 00/25] erofs: patchset addressing Christoph's comments Chao Yu 2019-09-05 1:03 ` Gao Xiang via Linux-erofs 2019-09-05 11:30 ` Christoph Hellwig 2019-09-04 5:16 ` Christoph Hellwig 2019-09-04 6:08 ` Gao Xiang via Linux-erofs
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