Re: [PATCH v2 3/3] vfs: Use per-cpu list for superblock's inode list

[Waiman Long]

On 02/21/2016 04:34 PM, Dave Chinner wrote:
> On Fri, Feb 19, 2016 at 04:10:45PM -0500, Waiman Long wrote:
> > +/*
> > + * Superblock's inode list iterator function and arguments macros
> > + */
> > +#define SB_INODES_ITER_FUNC(name, lock, struct_fields)			\
> > +	struct name ## _arg {						\
> > +		struct_fields;						\
> > +	};								\
> > +	static int name ## _iter(struct pcpu_list_node *_node,		\
> > +				 struct pcpu_list_node **_pnext,	\
> > +				 spinlock_t *lock, void *_arg)
> > +
> > +#define SB_INODES_ITER_ARGS(name, i, a)					\
> > +	struct inode *i = container_of(_node, struct inode, i_sb_list);	\
> > +	struct name ## _arg *a = (struct name ## _arg *)_arg
> > +
> > +#define SB_INODES_ITER_ARGS_SAFE(name, i, n, a)				\
> > +	struct inode *i = container_of(_node, struct inode, i_sb_list);	\
> > +	struct inode *n = container_of(*_pnext, struct inode, i_sb_list);\
> > +	struct name ## _arg *a = (struct name ## _arg *)_arg
> > +
> > +#define SB_INODES_ITER_SET_PCPU_LIST_NEXT(n)				\
> > +	{ *_pnext =&(n)->i_sb_list; }
> > +
> > +#define SB_INODES_ITER_CALL(name, sb)					\
> > +	pcpu_list_iterate(sb->s_inodes, false, NULL, name ## _iter,&arg)
> > +
> > +#define SB_INODES_ITER_CALL_SAFE(name, sb, phead)			\
> > +	pcpu_list_iterate(sb->s_inodes, true, phead, name ## _iter,&arg)
> > +
> No, just no.
>
> Ungreppable, breaks cscope, obfuscates everything, shouts a lot,
> code using the API looks completely broken (e.g. semi-colons in
> "function declarations"), and it reminds me of the worst of the
> worst unmaintainable code in an exceedingly buggy and undebuggable
> proprietary filesystem I've previously had the "joy" of working
> with.
>
> Just fix the bug in the previous version; it's so much cleaner than
> this .... mess.
>
> Cheers,
>
> Dave.

Sorry for that. I will scrap the current approach and use another way to 
iterate the list instead. I will send out an updated patch soon.

Cheers,
Longman