Re: [PATCH 1/8] exofs: Kbuild, Headers and osd utils

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 18 Mar 2009 19:57:36 +0200 Boaz Harrosh <bharrosh@panasas.com> wrote:

> This patch includes osd infrastructure that will be used later by
> the file system.
> 
> Also the declarations of constants, on disk structures,
> and prototypes.
> 
> And the Kbuild+Kconfig files needed to build the exofs module.
> 
> ...
>
> --- /dev/null
> +++ b/fs/exofs/Kbuild
> @@ -0,0 +1,30 @@
> +#
> +# Kbuild for the EXOFS module
> +#
> +# Copyright (C) 2008 Panasas Inc.  All rights reserved.
> +#
> +# Authors:
> +#   Boaz Harrosh <bharrosh@panasas.com>
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License version 2
> +#
> +# Kbuild - Gets included from the Kernels Makefile and build system
> +#
> +
> +ifneq ($(OSD_INC),)
> +# we are built out-of-tree Kconfigure everything as on
> +
> +CONFIG_EXOFS_FS=m
> +ccflags-y += -DCONFIG_EXOFS_FS -DCONFIG_EXOFS_FS_MODULE
> +# ccflags-y += -DCONFIG_EXOFS_DEBUG
> +
> +# if we are built out-of-tree and the hosting kernel has OSD headers
> +# then "ccflags-y +=" will not pick the out-off-tree headers. Only by doing
> +# this it will work. This might break in future kernels
> +KBUILD_CPPFLAGS := -I$(OSD_INC) $(KBUILD_CPPFLAGS)
> +
> +endif

But this patch is putting the fs into the tree, so all the above is unneeded.

>
> ...
>
> + * Object IDs 0, 1, and 2 are always in use (see above defines).
> + */
> +enum {
> +	EXOFS_UINT64_MAX = (~0LL),

Use ULLONG_MAX?

~0ULL would be more consistent.

> +	EXOFS_MAX_INO_ID = (sizeof(ino_t) * 8 == 64) ? EXOFS_UINT64_MAX :
> +					(1LL << (sizeof(ino_t) * 8 - 1)),

Tricky, needs a comment.

Would be clearer to use 1ULL.

> +	EXOFS_MAX_ID	 = (EXOFS_MAX_INO_ID - 1 - EXOFS_OBJ_OFF),
> +};
> +
> +/****************************************************************************
> + * Misc.
> + ****************************************************************************/
> +#define EXOFS_BLKSHIFT	12
> +#define EXOFS_BLKSIZE	(1UL << EXOFS_BLKSHIFT)
> +
> +/****************************************************************************
> + * superblock-related things
> + ****************************************************************************/
> +#define EXOFS_SUPER_MAGIC	0x5DF5

Should be in include/linux/magic.h

>
> ...
>
> +/*
> + * The file control block - stored in an object's attributes.  This is where
> + * the in-memory inode is stored on disk.
> + */
> +struct exofs_fcb {
> +	__le64  i_size;			/* Size of the file */
> +	__le16  i_mode;         	/* File mode */
> +	__le16  i_links_count;  	/* Links count */
> +	__le32  i_uid;          	/* Owner Uid */
> +	__le32  i_gid;          	/* Group Id */
> +	__le32  i_atime;        	/* Access time */
> +	__le32  i_ctime;        	/* Creation time */
> +	__le32  i_mtime;        	/* Modification time */
> +	__le32  i_flags;        	/* File flags (unused for now)*/
> +	__le32  i_generation;   	/* File version (for NFS) */
> +	__le32  i_data[EXOFS_IDATA];	/* Short symlink names and device #s */
> +};

There is no room for future expansion.  Would that be appropriate/wise?
I guess it would need versioning information somewhere too.

>
> ...
>
> +/* u64 has problems with printk this will cast it to unsigned long long */
> +#define _LLU(x) (unsigned long long)(x)

ug.

Normally the response is "please open-code this".  But given that one
day real soon this printk(u64) problem will be fixed, I guess the use
of _LLU will make it easy to find and delete all the now-unneeded
casts.

>
> ...
>
> +/*
> + * our inode flags
> + */
> +#define OBJ_2BCREATED	0	/* object will be created soon*/
> +#define OBJ_CREATED	1	/* object has been created on the osd*/
> +
> +static inline int obj_2bcreated(struct exofs_i_info *oi)
> +{
> +	return test_bit(OBJ_2BCREATED, &(oi->i_flags));
> +}

unneeded parentheses around oi->i_flags.

> +static inline void set_obj_2bcreated(struct exofs_i_info *oi)
> +{
> +	set_bit(OBJ_2BCREATED, &(oi->i_flags));
> +}
> +
> +static inline int obj_created(struct exofs_i_info *oi)
> +{
> +	return test_bit(OBJ_CREATED, &(oi->i_flags));
> +}
> +
> +static inline void set_obj_created(struct exofs_i_info *oi)
> +{
> +	set_bit(OBJ_CREATED, &(oi->i_flags));
> +}

dittoes.

>
> ...
>