From 4f89849da22db9d0edb378acea65e23fcd546173 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Tue, 30 Apr 2013 15:26:54 -0700 Subject: 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 Signed-off-by: Minchan Kim [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 ] Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: Bob Liu Cc: Wanpeng Li Cc: Andor Daam Cc: Florian Schmaus Cc: Stefan Hengelein Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/swapfile.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) (limited to 'mm/swapfile.c') diff --git a/mm/swapfile.c b/mm/swapfile.c index d417efddfe74..6c340d908b27 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1509,8 +1509,7 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) } static void _enable_swap_info(struct swap_info_struct *p, int prio, - unsigned char *swap_map, - unsigned long *frontswap_map) + unsigned char *swap_map) { int i, prev; @@ -1519,7 +1518,6 @@ static void _enable_swap_info(struct swap_info_struct *p, int prio, else p->prio = --least_priority; p->swap_map = swap_map; - frontswap_map_set(p, frontswap_map); p->flags |= SWP_WRITEOK; atomic_long_add(p->pages, &nr_swap_pages); total_swap_pages += p->pages; @@ -1542,10 +1540,10 @@ static void enable_swap_info(struct swap_info_struct *p, int prio, unsigned char *swap_map, unsigned long *frontswap_map) { + frontswap_init(p->type, frontswap_map); spin_lock(&swap_lock); spin_lock(&p->lock); - _enable_swap_info(p, prio, swap_map, frontswap_map); - frontswap_init(p->type); + _enable_swap_info(p, prio, swap_map); spin_unlock(&p->lock); spin_unlock(&swap_lock); } @@ -1554,7 +1552,7 @@ static void reinsert_swap_info(struct swap_info_struct *p) { spin_lock(&swap_lock); spin_lock(&p->lock); - _enable_swap_info(p, p->prio, p->swap_map, frontswap_map_get(p)); + _enable_swap_info(p, p->prio, p->swap_map); spin_unlock(&p->lock); spin_unlock(&swap_lock); } @@ -1563,6 +1561,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) { struct swap_info_struct *p = NULL; unsigned char *swap_map; + unsigned long *frontswap_map; struct file *swap_file, *victim; struct address_space *mapping; struct inode *inode; @@ -1662,12 +1661,14 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) swap_map = p->swap_map; p->swap_map = NULL; p->flags = 0; - frontswap_invalidate_area(type); + frontswap_map = frontswap_map_get(p); + frontswap_map_set(p, NULL); spin_unlock(&p->lock); spin_unlock(&swap_lock); + frontswap_invalidate_area(type); mutex_unlock(&swapon_mutex); vfree(swap_map); - vfree(frontswap_map_get(p)); + vfree(frontswap_map); /* Destroy swap account informatin */ swap_cgroup_swapoff(type); -- cgit v1.2.3-55-g7522