From: Gao Xiang <hsiangkao@aol.com> To: Christoph Hellwig <hch@infradead.org> Cc: Jan Kara <jack@suse.cz>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 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>, Chao Yu <yuchao0@huawei.com>, Alexander Viro <viro@zeniv.linux.org.uk>, Jaegeuk Kim <jaegeuk@kernel.org>, Theodore Ts'o <tytso@mit.edu>, Linus Torvalds <torvalds@linux-foundation.org>, LKML <linux-kernel@vger.kernel.org>, Li Guifu <bluce.liguifu@huawei.com>, Fang Wei <fangwei1@huawei.com>, Pavel Machek <pavel@denx.de>, 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: Sun, 1 Sep 2019 16:54:55 +0800 Message-ID: <20190901085452.GA4663@hsiangkao-HP-ZHAN-66-Pro-G1> (raw) In-Reply-To: <20190829101545.GC20598@infradead.org> Hi Christoph, Here is also my redo-ed comments... On Thu, Aug 29, 2019 at 03:15:45AM -0700, Christoph Hellwig wrote: > On Fri, Aug 02, 2019 at 08:53:26PM +0800, Gao Xiang wrote: > > +static int __init erofs_init_inode_cache(void) > > +{ > > + erofs_inode_cachep = kmem_cache_create("erofs_inode", > > + sizeof(struct erofs_vnode), 0, > > + SLAB_RECLAIM_ACCOUNT, > > + init_once); > > + > > + return erofs_inode_cachep ? 0 : -ENOMEM; > > Please just use normal if/else. Also having this function seems > entirely pointless. Fixed in https://lore.kernel.org/r/20190901055130.30572-7-hsiangkao@aol.com/ > > > +static void erofs_exit_inode_cache(void) > > +{ > > + kmem_cache_destroy(erofs_inode_cachep); > > +} > > Same for this one. Fixed in https://lore.kernel.org/r/20190901055130.30572-7-hsiangkao@aol.com/ > > > +static void free_inode(struct inode *inode) > > Please use an erofs_ prefix for all your functions. free_inode and most short, common static functions are fixed in https://lore.kernel.org/r/20190901055130.30572-19-hsiangkao@aol.com/ For all non-static functions, all are prefixed with "erofs_" > > > +{ > > + struct erofs_vnode *vi = EROFS_V(inode); > > Why is this called vnode instead of inode? That seems like a rather > odd naming for a Linux file system. Fixed in https://lore.kernel.org/r/20190901055130.30572-8-hsiangkao@aol.com/ > > > + > > + /* be careful RCU symlink path (see ext4_inode_info->i_data)! */ > > + if (is_inode_fast_symlink(inode)) > > + kfree(inode->i_link); > > is_inode_fast_symlink only shows up in a later patch. And really > obsfucates the check here in the only caller as you can just do an > unconditional kfree here - i_link will be NULL except for the case > where you explicitly set it. Fixed in https://lore.kernel.org/r/20190901055130.30572-10-hsiangkao@aol.com/ and with my following comments.... https://lore.kernel.org/r/20190831005446.GA233871@architecture4/ > > Also this code is nothing like ext4, so the code seems a little confusing. > > > +static bool check_layout_compatibility(struct super_block *sb, > > + struct erofs_super_block *layout) > > +{ > > + const unsigned int requirements = le32_to_cpu(layout->requirements); > > Why is the variable name for the on-disk subperblock layout? We usually > still calls this something with sb in the name, e.g. dsb. for disk > super block. Fixed in https://lore.kernel.org/r/20190901055130.30572-12-hsiangkao@aol.com/ > > > + EROFS_SB(sb)->requirements = requirements; > > + > > + /* check if current kernel meets all mandatory requirements */ > > + if (requirements & (~EROFS_ALL_REQUIREMENTS)) { > > + errln("unidentified requirements %x, please upgrade kernel version", > > + requirements & ~EROFS_ALL_REQUIREMENTS); > > + return false; > > + } > > + return true; > > Note that normally we call this features, but that doesn't really > matter too much. 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 }; > > > +static int superblock_read(struct super_block *sb) > > +{ > > + struct erofs_sb_info *sbi; > > + struct buffer_head *bh; > > + struct erofs_super_block *layout; > > + unsigned int blkszbits; > > + int ret; > > + > > + 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... > > > + > > + sbi->blocks = le32_to_cpu(layout->blocks); > > + sbi->meta_blkaddr = le32_to_cpu(layout->meta_blkaddr); > > + sbi->islotbits = ffs(sizeof(struct erofs_inode_v1)) - 1; > > + sbi->root_nid = le16_to_cpu(layout->root_nid); > > + sbi->inos = le64_to_cpu(layout->inos); > > + > > + 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...) > > > +/* set up default EROFS parameters */ > > +static void default_options(struct erofs_sb_info *sbi) > > +{ > > +} > > No need to add an empty function. My fault of spilting patches... > > > +static int erofs_fill_super(struct super_block *sb, void *data, int silent) > > +{ > > + struct inode *inode; > > + struct erofs_sb_info *sbi; > > + int err; > > + > > + infoln("fill_super, device -> %s", sb->s_id); > > + infoln("options -> %s", (char *)data); > > That is some very verbose debug info. We usually don't add that and > let people trace the function instead. Also you should probably > implement the new mount API. > new mount API. Fixed in https://lore.kernel.org/r/20190901055130.30572-13-hsiangkao@aol.com/ (For new mount API, https://lore.kernel.org/r/20190721040547.GF17978@ZenIV.linux.org.uk/ , I will a look later) > > > +static void erofs_kill_sb(struct super_block *sb) > > +{ > > + struct erofs_sb_info *sbi; > > + > > + WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC); > > + infoln("unmounting for %s", sb->s_id); > > + > > + kill_block_super(sb); > > + > > + sbi = EROFS_SB(sb); > > + if (!sbi) > > + return; > > + kfree(sbi); > > + sb->s_fs_info = NULL; > > +} > > Why is this needed? You can just free your sb privatte information in > ->put_super and wire up kill_block_super as the ->kill_sb method > directly. 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(). " Thanks, Gao Xiang _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
next prev parent reply index Thread overview: 141+ 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 [not found] ` <20190829095954.GB20598@infradead.org> 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 [not found] ` <20190829103252.GA64893@architecture4> [not found] ` <67d6efbbc9ac6db23215660cb970b7ef29dc0c1d.camel@perches.com> [not found] ` <20190830120714.GN2752@twin.jikos.cz> 2019-09-02 8:43 ` Pavel Machek 2019-09-02 14:07 ` David Sterba 2019-09-03 11:27 ` Pavel Machek 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 [not found] ` <20190829101545.GC20598@infradead.org> [not found] ` <20190829105048.GB64893@architecture4> 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 [this message] 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 2019-08-02 12:53 ` [PATCH v6 04/24] erofs: add raw address_space operations Gao Xiang [not found] ` <20190829101721.GD20598@infradead.org> [not found] ` <20190829114610.GF64893@architecture4> 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 [not found] ` <20190829102426.GE20598@infradead.org> [not found] ` <20190829115922.GG64893@architecture4> 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 [not found] ` <20190829102503.GF20598@infradead.org> 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 2019-08-02 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 2019-09-01 5:51 ` [PATCH 01/21] erofs: remove all the byte offset comments Gao Xiang 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 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 2019-09-02 12:06 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 04/21] erofs: kill __packed for on-disk structures Gao Xiang 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 2019-09-02 12:07 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 06/21] erofs: kill erofs_{init,exit}_inode_cache Gao Xiang 2019-09-02 12:09 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 07/21] erofs: use erofs_inode naming Gao Xiang 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 2019-09-01 5:51 ` [PATCH 09/21] erofs: update erofs symlink stuffs Gao Xiang 2019-09-02 12:11 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 10/21] erofs: kill is_inode_layout_compression() Gao Xiang 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 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 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 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 2019-09-02 12:21 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 15/21] erofs: kill __submit_bio() Gao Xiang 2019-09-01 5:51 ` [PATCH 16/21] erofs: kill magic underscores Gao Xiang 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 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 2019-09-02 12:28 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 19/21] erofs: kill all erofs specific fault injection Gao Xiang 2019-09-02 12:28 ` Christoph Hellwig 2019-09-01 5:51 ` [PATCH 20/21] erofs: kill use_vmap module parameter Gao Xiang 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 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 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 2019-09-05 11:30 ` Christoph Hellwig 2019-09-04 5:16 ` Christoph Hellwig 2019-09-04 6:08 ` Gao Xiang
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