diff options
| -rw-r--r-- | mm/swapfile.c | 84 |
1 files changed, 42 insertions, 42 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index 465d972f4c7..7243044c413 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1550,6 +1550,36 @@ bad_bmap: goto out; } +static void enable_swap_info(struct swap_info_struct *p, int prio, + unsigned char *swap_map) +{ + int i, prev; + + spin_lock(&swap_lock); + if (prio >= 0) + p->prio = prio; + else + p->prio = --least_priority; + p->swap_map = swap_map; + p->flags |= SWP_WRITEOK; + nr_swap_pages += p->pages; + total_swap_pages += p->pages; + + /* insert swap space into swap_list: */ + prev = -1; + for (i = swap_list.head; i >= 0; i = swap_info[i]->next) { + if (p->prio >= swap_info[i]->prio) + break; + prev = i; + } + p->next = i; + if (prev < 0) + swap_list.head = swap_list.next = p->type; + else + swap_info[prev]->next = p->type; + spin_unlock(&swap_lock); +} + SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) { struct swap_info_struct *p = NULL; @@ -1621,26 +1651,14 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) current->flags &= ~PF_OOM_ORIGIN; if (err) { + /* + * reading p->prio and p->swap_map outside the lock is + * safe here because only sys_swapon and sys_swapoff + * change them, and there can be no other sys_swapon or + * sys_swapoff for this swap_info_struct at this point. + */ /* re-insert swap space back into swap_list */ - spin_lock(&swap_lock); - if (p->prio < 0) - p->prio = --least_priority; - p->flags |= SWP_WRITEOK; - nr_swap_pages += p->pages; - total_swap_pages += p->pages; - - prev = -1; - for (i = swap_list.head; i >= 0; i = swap_info[i]->next) { - if (p->prio >= swap_info[i]->prio) - break; - prev = i; - } - p->next = i; - if (prev < 0) - swap_list.head = swap_list.next = type; - else - swap_info[prev]->next = type; - spin_unlock(&swap_lock); + enable_swap_info(p, p->prio, p->swap_map); goto out_dput; } @@ -2037,7 +2055,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) char *name; struct file *swap_file = NULL; struct address_space *mapping; - int i, prev; + int i; + int prio; int error; union swap_header *swap_header; int nr_extents; @@ -2134,30 +2153,11 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) } mutex_lock(&swapon_mutex); - spin_lock(&swap_lock); + prio = -1; if (swap_flags & SWAP_FLAG_PREFER) - p->prio = + prio = (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT; - else - p->prio = --least_priority; - p->swap_map = swap_map; - p->flags |= SWP_WRITEOK; - nr_swap_pages += p->pages; - total_swap_pages += p->pages; - - /* insert swap space into swap_list: */ - prev = -1; - for (i = swap_list.head; i >= 0; i = swap_info[i]->next) { - if (p->prio >= swap_info[i]->prio) - break; - prev = i; - } - p->next = i; - if (prev < 0) - swap_list.head = swap_list.next = p->type; - else - swap_info[prev]->next = p->type; - spin_unlock(&swap_lock); + enable_swap_info(p, prio, swap_map); printk(KERN_INFO "Adding %uk swap on %s. " "Priority:%d extents:%d across:%lluk %s%s\n", |