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linux-next/include/linux/frontswap.h
Minchan Kim 4f89849da2 frontswap: get rid of swap_lock dependency
Frontswap initialization routine depends on swap_lock, which want to be
atomic about frontswap's first appearance.  IOW, frontswap is not present
and will fail all calls OR frontswap is fully functional but if new
swap_info_struct isn't registered by enable_swap_info, swap subsystem
doesn't start I/O so there is no race between init procedure and page I/O
working on frontswap.

So let's remove unnecessary swap_lock dependency.

Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
[v1: Rebased on my branch, reworked to work with backends loading late]
[v2: Added a check for !map]
[v3: Made the invalidate path follow the init path]
[v4: Address comments by Wanpeng Li <liwanp@linux.vnet.ibm.com>]
Signed-off-by: Konrad Rzeszutek Wilk <konrad@darnok.org>
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 17:04:00 -07:00

108 lines
2.5 KiB
C

#ifndef _LINUX_FRONTSWAP_H
#define _LINUX_FRONTSWAP_H
#include <linux/swap.h>
#include <linux/mm.h>
#include <linux/bitops.h>
struct frontswap_ops {
void (*init)(unsigned);
int (*store)(unsigned, pgoff_t, struct page *);
int (*load)(unsigned, pgoff_t, struct page *);
void (*invalidate_page)(unsigned, pgoff_t);
void (*invalidate_area)(unsigned);
};
extern bool frontswap_enabled;
extern struct frontswap_ops *
frontswap_register_ops(struct frontswap_ops *ops);
extern void frontswap_shrink(unsigned long);
extern unsigned long frontswap_curr_pages(void);
extern void frontswap_writethrough(bool);
#define FRONTSWAP_HAS_EXCLUSIVE_GETS
extern void frontswap_tmem_exclusive_gets(bool);
extern bool __frontswap_test(struct swap_info_struct *, pgoff_t);
extern void __frontswap_init(unsigned type, unsigned long *map);
extern int __frontswap_store(struct page *page);
extern int __frontswap_load(struct page *page);
extern void __frontswap_invalidate_page(unsigned, pgoff_t);
extern void __frontswap_invalidate_area(unsigned);
#ifdef CONFIG_FRONTSWAP
#define frontswap_enabled (1)
static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
{
return __frontswap_test(sis, offset);
}
static inline void frontswap_map_set(struct swap_info_struct *p,
unsigned long *map)
{
p->frontswap_map = map;
}
static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
{
return p->frontswap_map;
}
#else
/* all inline routines become no-ops and all externs are ignored */
#define frontswap_enabled (0)
static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
{
return false;
}
static inline void frontswap_map_set(struct swap_info_struct *p,
unsigned long *map)
{
}
static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
{
return NULL;
}
#endif
static inline int frontswap_store(struct page *page)
{
int ret = -1;
if (frontswap_enabled)
ret = __frontswap_store(page);
return ret;
}
static inline int frontswap_load(struct page *page)
{
int ret = -1;
if (frontswap_enabled)
ret = __frontswap_load(page);
return ret;
}
static inline void frontswap_invalidate_page(unsigned type, pgoff_t offset)
{
if (frontswap_enabled)
__frontswap_invalidate_page(type, offset);
}
static inline void frontswap_invalidate_area(unsigned type)
{
if (frontswap_enabled)
__frontswap_invalidate_area(type);
}
static inline void frontswap_init(unsigned type, unsigned long *map)
{
if (frontswap_enabled)
__frontswap_init(type, map);
}
#endif /* _LINUX_FRONTSWAP_H */