From: Al Viro <viro@ZenIV.linux.org.uk> To: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Christoph Hellwig <hch@infradead.org>, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-embedded@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Brandt <Chris.Brandt@renesas.com> Subject: Re: [PATCH v6 1/4] cramfs: direct memory access support Date: Sat, 14 Oct 2017 01:31:51 +0100 [thread overview] Message-ID: <20171014003151.GK21978@ZenIV.linux.org.uk> (raw) In-Reply-To: <nycvar.YSQ.7.76.1710131532291.1750@knanqh.ubzr> On Fri, Oct 13, 2017 at 04:09:23PM -0400, Nicolas Pitre wrote: > On Fri, 13 Oct 2017, Al Viro wrote: > > > OK... I wonder if it should simply define stubs for kill_mtd_super(), > > mtd_unpoint() and kill_block_super() in !CONFIG_MTD and !CONFIG_BLOCK > > cases. mount_mtd() and mount_bdev() as well - e.g. mount_bdev() > > returning ERR_PTR(-ENODEV) and kill_block_super() being simply BUG() > > in !CONFIG_BLOCK case. Then cramfs_kill_sb() would be > > if (sb->s_mtd) { > > if (sbi->mtd_point_size) > > mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size); > > kill_mtd_super(sb); > > } else { > > kill_block_super(sb); > > } > > kfree(sbi); > > Well... Stubs have to be named differently or they conflict with > existing declarations. At that point that makes for more lines of code > compared to the current patch and the naming indirection makes it less > obvious when reading the code. Alternatively I could add those stubs in > the corresponding header files and #ifdef the existing declarations > away. That might look somewhat less cluttered in the main code but it > also hides what is actually going on and left me unconvinced. And I'm > not sure this is worth it in the end given this is not a common > occurrence in the kernel either. What I mean is this (completely untested) for CONFIG_BLOCK side of things, with something similar for CONFIG_MTD one: Provide definitions of mount_bdev/kill_block_super() in case !CONFIG_BLOCK mount_bdev() and kill_block_super() are defined only when CONFIG_BLOCK is defined; however, their declarations in fs.h are unconditional. We could make these conditional upon CONFIG_BLOCK as well, but it's easy to provide inline definitions for !CONFIG_BLOCK case - mount_bdev() should fail with ENODEV, while kill_block_super() can be simply BUG(); there should be no superblock instances with non-NULL ->s_bdev on such configs. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- diff --git a/include/linux/fs.h b/include/linux/fs.h index 339e73742e73..e773c1c51aad 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2094,9 +2094,18 @@ struct file_system_type { extern struct dentry *mount_ns(struct file_system_type *fs_type, int flags, void *data, void *ns, struct user_namespace *user_ns, int (*fill_super)(struct super_block *, void *, int)); +#ifdef CONFIG_BLOCK extern struct dentry *mount_bdev(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, int (*fill_super)(struct super_block *, void *, int)); +#else +static inline struct dentry *mount_bdev(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data, + int (*fill_super)(struct super_block *, void *, int)) +{ + return ERR_PTR(-ENODEV); +} +#endif extern struct dentry *mount_single(struct file_system_type *fs_type, int flags, void *data, int (*fill_super)(struct super_block *, void *, int)); @@ -2105,7 +2114,14 @@ extern struct dentry *mount_nodev(struct file_system_type *fs_type, int (*fill_super)(struct super_block *, void *, int)); extern struct dentry *mount_subtree(struct vfsmount *mnt, const char *path); void generic_shutdown_super(struct super_block *sb); +#ifdef CONFIG_BLOCK void kill_block_super(struct super_block *sb); +#else +static inline void kill_block_super(struct super_block *sb) +{ + BUG(); +} +#endif void kill_anon_super(struct super_block *sb); void kill_litter_super(struct super_block *sb); void deactivate_super(struct super_block *sb);
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@ZenIV.linux.org.uk> To: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Christoph Hellwig <hch@infradead.org>, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-embedded@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Brandt <Chris.Brandt@renesas.com> Subject: Re: [PATCH v6 1/4] cramfs: direct memory access support Date: Sat, 14 Oct 2017 01:31:51 +0100 [thread overview] Message-ID: <20171014003151.GK21978@ZenIV.linux.org.uk> (raw) In-Reply-To: <nycvar.YSQ.7.76.1710131532291.1750@knanqh.ubzr> On Fri, Oct 13, 2017 at 04:09:23PM -0400, Nicolas Pitre wrote: > On Fri, 13 Oct 2017, Al Viro wrote: > > > OK... I wonder if it should simply define stubs for kill_mtd_super(), > > mtd_unpoint() and kill_block_super() in !CONFIG_MTD and !CONFIG_BLOCK > > cases. mount_mtd() and mount_bdev() as well - e.g. mount_bdev() > > returning ERR_PTR(-ENODEV) and kill_block_super() being simply BUG() > > in !CONFIG_BLOCK case. Then cramfs_kill_sb() would be > > if (sb->s_mtd) { > > if (sbi->mtd_point_size) > > mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size); > > kill_mtd_super(sb); > > } else { > > kill_block_super(sb); > > } > > kfree(sbi); > > Well... Stubs have to be named differently or they conflict with > existing declarations. At that point that makes for more lines of code > compared to the current patch and the naming indirection makes it less > obvious when reading the code. Alternatively I could add those stubs in > the corresponding header files and #ifdef the existing declarations > away. That might look somewhat less cluttered in the main code but it > also hides what is actually going on and left me unconvinced. And I'm > not sure this is worth it in the end given this is not a common > occurrence in the kernel either. What I mean is this (completely untested) for CONFIG_BLOCK side of things, with something similar for CONFIG_MTD one: Provide definitions of mount_bdev/kill_block_super() in case !CONFIG_BLOCK mount_bdev() and kill_block_super() are defined only when CONFIG_BLOCK is defined; however, their declarations in fs.h are unconditional. We could make these conditional upon CONFIG_BLOCK as well, but it's easy to provide inline definitions for !CONFIG_BLOCK case - mount_bdev() should fail with ENODEV, while kill_block_super() can be simply BUG(); there should be no superblock instances with non-NULL ->s_bdev on such configs. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- diff --git a/include/linux/fs.h b/include/linux/fs.h index 339e73742e73..e773c1c51aad 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2094,9 +2094,18 @@ struct file_system_type { extern struct dentry *mount_ns(struct file_system_type *fs_type, int flags, void *data, void *ns, struct user_namespace *user_ns, int (*fill_super)(struct super_block *, void *, int)); +#ifdef CONFIG_BLOCK extern struct dentry *mount_bdev(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, int (*fill_super)(struct super_block *, void *, int)); +#else +static inline struct dentry *mount_bdev(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data, + int (*fill_super)(struct super_block *, void *, int)) +{ + return ERR_PTR(-ENODEV); +} +#endif extern struct dentry *mount_single(struct file_system_type *fs_type, int flags, void *data, int (*fill_super)(struct super_block *, void *, int)); @@ -2105,7 +2114,14 @@ extern struct dentry *mount_nodev(struct file_system_type *fs_type, int (*fill_super)(struct super_block *, void *, int)); extern struct dentry *mount_subtree(struct vfsmount *mnt, const char *path); void generic_shutdown_super(struct super_block *sb); +#ifdef CONFIG_BLOCK void kill_block_super(struct super_block *sb); +#else +static inline void kill_block_super(struct super_block *sb) +{ + BUG(); +} +#endif void kill_anon_super(struct super_block *sb); void kill_litter_super(struct super_block *sb); void deactivate_super(struct super_block *sb); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-10-14 0:31 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-10-12 6:16 [PATCH v6 0/4] cramfs refresh for embedded usage Nicolas Pitre 2017-10-12 6:16 ` Nicolas Pitre 2017-10-12 6:16 ` [PATCH v6 1/4] cramfs: direct memory access support Nicolas Pitre 2017-10-12 6:16 ` Nicolas Pitre 2017-10-12 17:03 ` Chris Brandt 2017-10-12 17:03 ` Chris Brandt 2017-10-13 1:20 ` Nicolas Pitre 2017-10-13 1:20 ` Nicolas Pitre 2017-10-13 7:30 ` Christoph Hellwig 2017-10-13 7:30 ` Christoph Hellwig 2017-10-13 17:29 ` Al Viro 2017-10-13 17:29 ` Al Viro 2017-10-13 17:39 ` Nicolas Pitre 2017-10-13 17:39 ` Nicolas Pitre 2017-10-13 17:52 ` Al Viro 2017-10-13 17:52 ` Al Viro 2017-10-13 18:18 ` Nicolas Pitre 2017-10-13 18:18 ` Nicolas Pitre 2017-10-13 20:09 ` Nicolas Pitre 2017-10-13 20:09 ` Nicolas Pitre 2017-10-14 0:31 ` Al Viro [this message] 2017-10-14 0:31 ` Al Viro 2017-10-14 2:25 ` Nicolas Pitre 2017-10-14 2:25 ` Nicolas Pitre 2017-10-14 2:37 ` Nicolas Pitre 2017-10-14 2:37 ` Nicolas Pitre 2017-10-12 6:16 ` [PATCH v6 2/4] cramfs: implement uncompressed and arbitrary data block positioning Nicolas Pitre 2017-10-12 6:16 ` Nicolas Pitre 2017-10-12 6:16 ` [PATCH v6 3/4] cramfs: add mmap support Nicolas Pitre 2017-10-12 6:16 ` Nicolas Pitre 2017-10-13 7:31 ` Christoph Hellwig 2017-10-13 7:31 ` Christoph Hellwig 2017-10-12 6:16 ` [PATCH v6 4/4] cramfs: rehabilitate it Nicolas Pitre 2017-10-12 6:16 ` Nicolas Pitre
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