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e2de225710
I didn't find any possible modular usage in the kernel. Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1679 lines
42 KiB
C
1679 lines
42 KiB
C
/*
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* linux/mm/swapfile.c
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*
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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* Swap reorganised 29.12.95, Stephen Tweedie
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*/
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#include <linux/config.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/mman.h>
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#include <linux/slab.h>
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#include <linux/kernel_stat.h>
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#include <linux/swap.h>
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#include <linux/vmalloc.h>
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#include <linux/pagemap.h>
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#include <linux/namei.h>
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#include <linux/shm.h>
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#include <linux/blkdev.h>
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#include <linux/writeback.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/rmap.h>
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#include <linux/security.h>
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#include <linux/backing-dev.h>
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#include <linux/syscalls.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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#include <linux/swapops.h>
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DEFINE_SPINLOCK(swap_lock);
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unsigned int nr_swapfiles;
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long total_swap_pages;
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static int swap_overflow;
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static const char Bad_file[] = "Bad swap file entry ";
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static const char Unused_file[] = "Unused swap file entry ";
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static const char Bad_offset[] = "Bad swap offset entry ";
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static const char Unused_offset[] = "Unused swap offset entry ";
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struct swap_list_t swap_list = {-1, -1};
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struct swap_info_struct swap_info[MAX_SWAPFILES];
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static DECLARE_MUTEX(swapon_sem);
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/*
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* We need this because the bdev->unplug_fn can sleep and we cannot
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* hold swap_lock while calling the unplug_fn. And swap_lock
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* cannot be turned into a semaphore.
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*/
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static DECLARE_RWSEM(swap_unplug_sem);
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void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page)
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{
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swp_entry_t entry;
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down_read(&swap_unplug_sem);
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entry.val = page_private(page);
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if (PageSwapCache(page)) {
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struct block_device *bdev = swap_info[swp_type(entry)].bdev;
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struct backing_dev_info *bdi;
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/*
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* If the page is removed from swapcache from under us (with a
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* racy try_to_unuse/swapoff) we need an additional reference
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* count to avoid reading garbage from page_private(page) above.
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* If the WARN_ON triggers during a swapoff it maybe the race
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* condition and it's harmless. However if it triggers without
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* swapoff it signals a problem.
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*/
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WARN_ON(page_count(page) <= 1);
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bdi = bdev->bd_inode->i_mapping->backing_dev_info;
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blk_run_backing_dev(bdi, page);
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}
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up_read(&swap_unplug_sem);
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}
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#define SWAPFILE_CLUSTER 256
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#define LATENCY_LIMIT 256
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static inline unsigned long scan_swap_map(struct swap_info_struct *si)
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{
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unsigned long offset, last_in_cluster;
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int latency_ration = LATENCY_LIMIT;
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/*
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* We try to cluster swap pages by allocating them sequentially
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* in swap. Once we've allocated SWAPFILE_CLUSTER pages this
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* way, however, we resort to first-free allocation, starting
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* a new cluster. This prevents us from scattering swap pages
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* all over the entire swap partition, so that we reduce
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* overall disk seek times between swap pages. -- sct
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* But we do now try to find an empty cluster. -Andrea
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*/
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si->flags += SWP_SCANNING;
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if (unlikely(!si->cluster_nr)) {
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si->cluster_nr = SWAPFILE_CLUSTER - 1;
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if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER)
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goto lowest;
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spin_unlock(&swap_lock);
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offset = si->lowest_bit;
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last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
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/* Locate the first empty (unaligned) cluster */
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for (; last_in_cluster <= si->highest_bit; offset++) {
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if (si->swap_map[offset])
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last_in_cluster = offset + SWAPFILE_CLUSTER;
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else if (offset == last_in_cluster) {
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spin_lock(&swap_lock);
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si->cluster_next = offset-SWAPFILE_CLUSTER-1;
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goto cluster;
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}
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if (unlikely(--latency_ration < 0)) {
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cond_resched();
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latency_ration = LATENCY_LIMIT;
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}
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}
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spin_lock(&swap_lock);
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goto lowest;
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}
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si->cluster_nr--;
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cluster:
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offset = si->cluster_next;
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if (offset > si->highest_bit)
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lowest: offset = si->lowest_bit;
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checks: if (!(si->flags & SWP_WRITEOK))
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goto no_page;
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if (!si->highest_bit)
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goto no_page;
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if (!si->swap_map[offset]) {
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if (offset == si->lowest_bit)
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si->lowest_bit++;
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if (offset == si->highest_bit)
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si->highest_bit--;
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si->inuse_pages++;
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if (si->inuse_pages == si->pages) {
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si->lowest_bit = si->max;
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si->highest_bit = 0;
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}
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si->swap_map[offset] = 1;
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si->cluster_next = offset + 1;
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si->flags -= SWP_SCANNING;
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return offset;
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}
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spin_unlock(&swap_lock);
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while (++offset <= si->highest_bit) {
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if (!si->swap_map[offset]) {
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spin_lock(&swap_lock);
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goto checks;
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}
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if (unlikely(--latency_ration < 0)) {
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cond_resched();
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latency_ration = LATENCY_LIMIT;
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}
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}
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spin_lock(&swap_lock);
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goto lowest;
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no_page:
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si->flags -= SWP_SCANNING;
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return 0;
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}
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swp_entry_t get_swap_page(void)
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{
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struct swap_info_struct *si;
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pgoff_t offset;
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int type, next;
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int wrapped = 0;
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spin_lock(&swap_lock);
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if (nr_swap_pages <= 0)
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goto noswap;
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nr_swap_pages--;
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for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) {
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si = swap_info + type;
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next = si->next;
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if (next < 0 ||
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(!wrapped && si->prio != swap_info[next].prio)) {
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next = swap_list.head;
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wrapped++;
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}
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if (!si->highest_bit)
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continue;
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if (!(si->flags & SWP_WRITEOK))
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continue;
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swap_list.next = next;
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offset = scan_swap_map(si);
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if (offset) {
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spin_unlock(&swap_lock);
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return swp_entry(type, offset);
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}
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next = swap_list.next;
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}
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nr_swap_pages++;
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noswap:
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spin_unlock(&swap_lock);
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return (swp_entry_t) {0};
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}
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static struct swap_info_struct * swap_info_get(swp_entry_t entry)
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{
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struct swap_info_struct * p;
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unsigned long offset, type;
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if (!entry.val)
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goto out;
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type = swp_type(entry);
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if (type >= nr_swapfiles)
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goto bad_nofile;
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p = & swap_info[type];
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if (!(p->flags & SWP_USED))
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goto bad_device;
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offset = swp_offset(entry);
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if (offset >= p->max)
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goto bad_offset;
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if (!p->swap_map[offset])
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goto bad_free;
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spin_lock(&swap_lock);
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return p;
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bad_free:
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printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val);
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goto out;
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bad_offset:
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printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val);
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goto out;
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bad_device:
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printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val);
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goto out;
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bad_nofile:
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printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val);
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out:
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return NULL;
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}
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static int swap_entry_free(struct swap_info_struct *p, unsigned long offset)
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{
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int count = p->swap_map[offset];
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if (count < SWAP_MAP_MAX) {
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count--;
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p->swap_map[offset] = count;
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if (!count) {
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if (offset < p->lowest_bit)
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p->lowest_bit = offset;
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if (offset > p->highest_bit)
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p->highest_bit = offset;
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if (p->prio > swap_info[swap_list.next].prio)
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swap_list.next = p - swap_info;
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nr_swap_pages++;
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p->inuse_pages--;
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}
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}
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return count;
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}
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/*
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* Caller has made sure that the swapdevice corresponding to entry
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* is still around or has not been recycled.
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*/
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void swap_free(swp_entry_t entry)
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{
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struct swap_info_struct * p;
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p = swap_info_get(entry);
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if (p) {
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swap_entry_free(p, swp_offset(entry));
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spin_unlock(&swap_lock);
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}
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}
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/*
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* How many references to page are currently swapped out?
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*/
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static inline int page_swapcount(struct page *page)
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{
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int count = 0;
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struct swap_info_struct *p;
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swp_entry_t entry;
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entry.val = page_private(page);
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p = swap_info_get(entry);
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if (p) {
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/* Subtract the 1 for the swap cache itself */
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count = p->swap_map[swp_offset(entry)] - 1;
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spin_unlock(&swap_lock);
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}
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return count;
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}
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/*
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* We can use this swap cache entry directly
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* if there are no other references to it.
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*/
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int can_share_swap_page(struct page *page)
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{
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int count;
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BUG_ON(!PageLocked(page));
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count = page_mapcount(page);
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if (count <= 1 && PageSwapCache(page))
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count += page_swapcount(page);
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return count == 1;
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}
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/*
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* Work out if there are any other processes sharing this
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* swap cache page. Free it if you can. Return success.
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*/
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int remove_exclusive_swap_page(struct page *page)
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{
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int retval;
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struct swap_info_struct * p;
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swp_entry_t entry;
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BUG_ON(PagePrivate(page));
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BUG_ON(!PageLocked(page));
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if (!PageSwapCache(page))
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return 0;
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if (PageWriteback(page))
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return 0;
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if (page_count(page) != 2) /* 2: us + cache */
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return 0;
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entry.val = page_private(page);
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p = swap_info_get(entry);
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if (!p)
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return 0;
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/* Is the only swap cache user the cache itself? */
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retval = 0;
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if (p->swap_map[swp_offset(entry)] == 1) {
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/* Recheck the page count with the swapcache lock held.. */
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write_lock_irq(&swapper_space.tree_lock);
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if ((page_count(page) == 2) && !PageWriteback(page)) {
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__delete_from_swap_cache(page);
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SetPageDirty(page);
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retval = 1;
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}
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write_unlock_irq(&swapper_space.tree_lock);
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}
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spin_unlock(&swap_lock);
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if (retval) {
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swap_free(entry);
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page_cache_release(page);
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}
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return retval;
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}
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/*
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* Free the swap entry like above, but also try to
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* free the page cache entry if it is the last user.
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*/
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void free_swap_and_cache(swp_entry_t entry)
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{
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struct swap_info_struct * p;
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struct page *page = NULL;
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p = swap_info_get(entry);
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if (p) {
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if (swap_entry_free(p, swp_offset(entry)) == 1)
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page = find_trylock_page(&swapper_space, entry.val);
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spin_unlock(&swap_lock);
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}
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if (page) {
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int one_user;
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BUG_ON(PagePrivate(page));
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page_cache_get(page);
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one_user = (page_count(page) == 2);
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/* Only cache user (+us), or swap space full? Free it! */
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if (!PageWriteback(page) && (one_user || vm_swap_full())) {
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delete_from_swap_cache(page);
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SetPageDirty(page);
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}
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unlock_page(page);
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page_cache_release(page);
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}
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}
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/*
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* No need to decide whether this PTE shares the swap entry with others,
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* just let do_wp_page work it out if a write is requested later - to
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* force COW, vm_page_prot omits write permission from any private vma.
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*/
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static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
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unsigned long addr, swp_entry_t entry, struct page *page)
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{
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inc_mm_counter(vma->vm_mm, anon_rss);
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get_page(page);
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set_pte_at(vma->vm_mm, addr, pte,
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pte_mkold(mk_pte(page, vma->vm_page_prot)));
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page_add_anon_rmap(page, vma, addr);
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swap_free(entry);
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/*
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* Move the page to the active list so it is not
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* immediately swapped out again after swapon.
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*/
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activate_page(page);
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}
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static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
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unsigned long addr, unsigned long end,
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swp_entry_t entry, struct page *page)
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{
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pte_t swp_pte = swp_entry_to_pte(entry);
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pte_t *pte;
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spinlock_t *ptl;
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int found = 0;
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pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
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do {
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/*
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* swapoff spends a _lot_ of time in this loop!
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* Test inline before going to call unuse_pte.
|
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*/
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if (unlikely(pte_same(*pte, swp_pte))) {
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unuse_pte(vma, pte++, addr, entry, page);
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found = 1;
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break;
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}
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} while (pte++, addr += PAGE_SIZE, addr != end);
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pte_unmap_unlock(pte - 1, ptl);
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return found;
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}
|
|
|
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static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
|
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unsigned long addr, unsigned long end,
|
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swp_entry_t entry, struct page *page)
|
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{
|
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pmd_t *pmd;
|
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unsigned long next;
|
|
|
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pmd = pmd_offset(pud, addr);
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do {
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next = pmd_addr_end(addr, end);
|
|
if (pmd_none_or_clear_bad(pmd))
|
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continue;
|
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if (unuse_pte_range(vma, pmd, addr, next, entry, page))
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return 1;
|
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} while (pmd++, addr = next, addr != end);
|
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return 0;
|
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}
|
|
|
|
static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
|
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unsigned long addr, unsigned long end,
|
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swp_entry_t entry, struct page *page)
|
|
{
|
|
pud_t *pud;
|
|
unsigned long next;
|
|
|
|
pud = pud_offset(pgd, addr);
|
|
do {
|
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next = pud_addr_end(addr, end);
|
|
if (pud_none_or_clear_bad(pud))
|
|
continue;
|
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if (unuse_pmd_range(vma, pud, addr, next, entry, page))
|
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return 1;
|
|
} while (pud++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
static int unuse_vma(struct vm_area_struct *vma,
|
|
swp_entry_t entry, struct page *page)
|
|
{
|
|
pgd_t *pgd;
|
|
unsigned long addr, end, next;
|
|
|
|
if (page->mapping) {
|
|
addr = page_address_in_vma(page, vma);
|
|
if (addr == -EFAULT)
|
|
return 0;
|
|
else
|
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end = addr + PAGE_SIZE;
|
|
} else {
|
|
addr = vma->vm_start;
|
|
end = vma->vm_end;
|
|
}
|
|
|
|
pgd = pgd_offset(vma->vm_mm, addr);
|
|
do {
|
|
next = pgd_addr_end(addr, end);
|
|
if (pgd_none_or_clear_bad(pgd))
|
|
continue;
|
|
if (unuse_pud_range(vma, pgd, addr, next, entry, page))
|
|
return 1;
|
|
} while (pgd++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
static int unuse_mm(struct mm_struct *mm,
|
|
swp_entry_t entry, struct page *page)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
|
|
if (!down_read_trylock(&mm->mmap_sem)) {
|
|
/*
|
|
* Activate page so shrink_cache is unlikely to unmap its
|
|
* ptes while lock is dropped, so swapoff can make progress.
|
|
*/
|
|
activate_page(page);
|
|
unlock_page(page);
|
|
down_read(&mm->mmap_sem);
|
|
lock_page(page);
|
|
}
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (vma->anon_vma && unuse_vma(vma, entry, page))
|
|
break;
|
|
}
|
|
up_read(&mm->mmap_sem);
|
|
/*
|
|
* Currently unuse_mm cannot fail, but leave error handling
|
|
* at call sites for now, since we change it from time to time.
|
|
*/
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Scan swap_map from current position to next entry still in use.
|
|
* Recycle to start on reaching the end, returning 0 when empty.
|
|
*/
|
|
static unsigned int find_next_to_unuse(struct swap_info_struct *si,
|
|
unsigned int prev)
|
|
{
|
|
unsigned int max = si->max;
|
|
unsigned int i = prev;
|
|
int count;
|
|
|
|
/*
|
|
* No need for swap_lock here: we're just looking
|
|
* for whether an entry is in use, not modifying it; false
|
|
* hits are okay, and sys_swapoff() has already prevented new
|
|
* allocations from this area (while holding swap_lock).
|
|
*/
|
|
for (;;) {
|
|
if (++i >= max) {
|
|
if (!prev) {
|
|
i = 0;
|
|
break;
|
|
}
|
|
/*
|
|
* No entries in use at top of swap_map,
|
|
* loop back to start and recheck there.
|
|
*/
|
|
max = prev + 1;
|
|
prev = 0;
|
|
i = 1;
|
|
}
|
|
count = si->swap_map[i];
|
|
if (count && count != SWAP_MAP_BAD)
|
|
break;
|
|
}
|
|
return i;
|
|
}
|
|
|
|
/*
|
|
* We completely avoid races by reading each swap page in advance,
|
|
* and then search for the process using it. All the necessary
|
|
* page table adjustments can then be made atomically.
|
|
*/
|
|
static int try_to_unuse(unsigned int type)
|
|
{
|
|
struct swap_info_struct * si = &swap_info[type];
|
|
struct mm_struct *start_mm;
|
|
unsigned short *swap_map;
|
|
unsigned short swcount;
|
|
struct page *page;
|
|
swp_entry_t entry;
|
|
unsigned int i = 0;
|
|
int retval = 0;
|
|
int reset_overflow = 0;
|
|
int shmem;
|
|
|
|
/*
|
|
* When searching mms for an entry, a good strategy is to
|
|
* start at the first mm we freed the previous entry from
|
|
* (though actually we don't notice whether we or coincidence
|
|
* freed the entry). Initialize this start_mm with a hold.
|
|
*
|
|
* A simpler strategy would be to start at the last mm we
|
|
* freed the previous entry from; but that would take less
|
|
* advantage of mmlist ordering, which clusters forked mms
|
|
* together, child after parent. If we race with dup_mmap(), we
|
|
* prefer to resolve parent before child, lest we miss entries
|
|
* duplicated after we scanned child: using last mm would invert
|
|
* that. Though it's only a serious concern when an overflowed
|
|
* swap count is reset from SWAP_MAP_MAX, preventing a rescan.
|
|
*/
|
|
start_mm = &init_mm;
|
|
atomic_inc(&init_mm.mm_users);
|
|
|
|
/*
|
|
* Keep on scanning until all entries have gone. Usually,
|
|
* one pass through swap_map is enough, but not necessarily:
|
|
* there are races when an instance of an entry might be missed.
|
|
*/
|
|
while ((i = find_next_to_unuse(si, i)) != 0) {
|
|
if (signal_pending(current)) {
|
|
retval = -EINTR;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Get a page for the entry, using the existing swap
|
|
* cache page if there is one. Otherwise, get a clean
|
|
* page and read the swap into it.
|
|
*/
|
|
swap_map = &si->swap_map[i];
|
|
entry = swp_entry(type, i);
|
|
page = read_swap_cache_async(entry, NULL, 0);
|
|
if (!page) {
|
|
/*
|
|
* Either swap_duplicate() failed because entry
|
|
* has been freed independently, and will not be
|
|
* reused since sys_swapoff() already disabled
|
|
* allocation from here, or alloc_page() failed.
|
|
*/
|
|
if (!*swap_map)
|
|
continue;
|
|
retval = -ENOMEM;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Don't hold on to start_mm if it looks like exiting.
|
|
*/
|
|
if (atomic_read(&start_mm->mm_users) == 1) {
|
|
mmput(start_mm);
|
|
start_mm = &init_mm;
|
|
atomic_inc(&init_mm.mm_users);
|
|
}
|
|
|
|
/*
|
|
* Wait for and lock page. When do_swap_page races with
|
|
* try_to_unuse, do_swap_page can handle the fault much
|
|
* faster than try_to_unuse can locate the entry. This
|
|
* apparently redundant "wait_on_page_locked" lets try_to_unuse
|
|
* defer to do_swap_page in such a case - in some tests,
|
|
* do_swap_page and try_to_unuse repeatedly compete.
|
|
*/
|
|
wait_on_page_locked(page);
|
|
wait_on_page_writeback(page);
|
|
lock_page(page);
|
|
wait_on_page_writeback(page);
|
|
|
|
/*
|
|
* Remove all references to entry.
|
|
* Whenever we reach init_mm, there's no address space
|
|
* to search, but use it as a reminder to search shmem.
|
|
*/
|
|
shmem = 0;
|
|
swcount = *swap_map;
|
|
if (swcount > 1) {
|
|
if (start_mm == &init_mm)
|
|
shmem = shmem_unuse(entry, page);
|
|
else
|
|
retval = unuse_mm(start_mm, entry, page);
|
|
}
|
|
if (*swap_map > 1) {
|
|
int set_start_mm = (*swap_map >= swcount);
|
|
struct list_head *p = &start_mm->mmlist;
|
|
struct mm_struct *new_start_mm = start_mm;
|
|
struct mm_struct *prev_mm = start_mm;
|
|
struct mm_struct *mm;
|
|
|
|
atomic_inc(&new_start_mm->mm_users);
|
|
atomic_inc(&prev_mm->mm_users);
|
|
spin_lock(&mmlist_lock);
|
|
while (*swap_map > 1 && !retval &&
|
|
(p = p->next) != &start_mm->mmlist) {
|
|
mm = list_entry(p, struct mm_struct, mmlist);
|
|
if (atomic_inc_return(&mm->mm_users) == 1) {
|
|
atomic_dec(&mm->mm_users);
|
|
continue;
|
|
}
|
|
spin_unlock(&mmlist_lock);
|
|
mmput(prev_mm);
|
|
prev_mm = mm;
|
|
|
|
cond_resched();
|
|
|
|
swcount = *swap_map;
|
|
if (swcount <= 1)
|
|
;
|
|
else if (mm == &init_mm) {
|
|
set_start_mm = 1;
|
|
shmem = shmem_unuse(entry, page);
|
|
} else
|
|
retval = unuse_mm(mm, entry, page);
|
|
if (set_start_mm && *swap_map < swcount) {
|
|
mmput(new_start_mm);
|
|
atomic_inc(&mm->mm_users);
|
|
new_start_mm = mm;
|
|
set_start_mm = 0;
|
|
}
|
|
spin_lock(&mmlist_lock);
|
|
}
|
|
spin_unlock(&mmlist_lock);
|
|
mmput(prev_mm);
|
|
mmput(start_mm);
|
|
start_mm = new_start_mm;
|
|
}
|
|
if (retval) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* How could swap count reach 0x7fff when the maximum
|
|
* pid is 0x7fff, and there's no way to repeat a swap
|
|
* page within an mm (except in shmem, where it's the
|
|
* shared object which takes the reference count)?
|
|
* We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
|
|
*
|
|
* If that's wrong, then we should worry more about
|
|
* exit_mmap() and do_munmap() cases described above:
|
|
* we might be resetting SWAP_MAP_MAX too early here.
|
|
* We know "Undead"s can happen, they're okay, so don't
|
|
* report them; but do report if we reset SWAP_MAP_MAX.
|
|
*/
|
|
if (*swap_map == SWAP_MAP_MAX) {
|
|
spin_lock(&swap_lock);
|
|
*swap_map = 1;
|
|
spin_unlock(&swap_lock);
|
|
reset_overflow = 1;
|
|
}
|
|
|
|
/*
|
|
* If a reference remains (rare), we would like to leave
|
|
* the page in the swap cache; but try_to_unmap could
|
|
* then re-duplicate the entry once we drop page lock,
|
|
* so we might loop indefinitely; also, that page could
|
|
* not be swapped out to other storage meanwhile. So:
|
|
* delete from cache even if there's another reference,
|
|
* after ensuring that the data has been saved to disk -
|
|
* since if the reference remains (rarer), it will be
|
|
* read from disk into another page. Splitting into two
|
|
* pages would be incorrect if swap supported "shared
|
|
* private" pages, but they are handled by tmpfs files.
|
|
*
|
|
* Note shmem_unuse already deleted a swappage from
|
|
* the swap cache, unless the move to filepage failed:
|
|
* in which case it left swappage in cache, lowered its
|
|
* swap count to pass quickly through the loops above,
|
|
* and now we must reincrement count to try again later.
|
|
*/
|
|
if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) {
|
|
struct writeback_control wbc = {
|
|
.sync_mode = WB_SYNC_NONE,
|
|
};
|
|
|
|
swap_writepage(page, &wbc);
|
|
lock_page(page);
|
|
wait_on_page_writeback(page);
|
|
}
|
|
if (PageSwapCache(page)) {
|
|
if (shmem)
|
|
swap_duplicate(entry);
|
|
else
|
|
delete_from_swap_cache(page);
|
|
}
|
|
|
|
/*
|
|
* So we could skip searching mms once swap count went
|
|
* to 1, we did not mark any present ptes as dirty: must
|
|
* mark page dirty so shrink_list will preserve it.
|
|
*/
|
|
SetPageDirty(page);
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
|
|
/*
|
|
* Make sure that we aren't completely killing
|
|
* interactive performance.
|
|
*/
|
|
cond_resched();
|
|
}
|
|
|
|
mmput(start_mm);
|
|
if (reset_overflow) {
|
|
printk(KERN_WARNING "swapoff: cleared swap entry overflow\n");
|
|
swap_overflow = 0;
|
|
}
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* After a successful try_to_unuse, if no swap is now in use, we know
|
|
* we can empty the mmlist. swap_lock must be held on entry and exit.
|
|
* Note that mmlist_lock nests inside swap_lock, and an mm must be
|
|
* added to the mmlist just after page_duplicate - before would be racy.
|
|
*/
|
|
static void drain_mmlist(void)
|
|
{
|
|
struct list_head *p, *next;
|
|
unsigned int i;
|
|
|
|
for (i = 0; i < nr_swapfiles; i++)
|
|
if (swap_info[i].inuse_pages)
|
|
return;
|
|
spin_lock(&mmlist_lock);
|
|
list_for_each_safe(p, next, &init_mm.mmlist)
|
|
list_del_init(p);
|
|
spin_unlock(&mmlist_lock);
|
|
}
|
|
|
|
/*
|
|
* Use this swapdev's extent info to locate the (PAGE_SIZE) block which
|
|
* corresponds to page offset `offset'.
|
|
*/
|
|
sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
|
|
{
|
|
struct swap_extent *se = sis->curr_swap_extent;
|
|
struct swap_extent *start_se = se;
|
|
|
|
for ( ; ; ) {
|
|
struct list_head *lh;
|
|
|
|
if (se->start_page <= offset &&
|
|
offset < (se->start_page + se->nr_pages)) {
|
|
return se->start_block + (offset - se->start_page);
|
|
}
|
|
lh = se->list.next;
|
|
if (lh == &sis->extent_list)
|
|
lh = lh->next;
|
|
se = list_entry(lh, struct swap_extent, list);
|
|
sis->curr_swap_extent = se;
|
|
BUG_ON(se == start_se); /* It *must* be present */
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Free all of a swapdev's extent information
|
|
*/
|
|
static void destroy_swap_extents(struct swap_info_struct *sis)
|
|
{
|
|
while (!list_empty(&sis->extent_list)) {
|
|
struct swap_extent *se;
|
|
|
|
se = list_entry(sis->extent_list.next,
|
|
struct swap_extent, list);
|
|
list_del(&se->list);
|
|
kfree(se);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Add a block range (and the corresponding page range) into this swapdev's
|
|
* extent list. The extent list is kept sorted in page order.
|
|
*
|
|
* This function rather assumes that it is called in ascending page order.
|
|
*/
|
|
static int
|
|
add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
|
|
unsigned long nr_pages, sector_t start_block)
|
|
{
|
|
struct swap_extent *se;
|
|
struct swap_extent *new_se;
|
|
struct list_head *lh;
|
|
|
|
lh = sis->extent_list.prev; /* The highest page extent */
|
|
if (lh != &sis->extent_list) {
|
|
se = list_entry(lh, struct swap_extent, list);
|
|
BUG_ON(se->start_page + se->nr_pages != start_page);
|
|
if (se->start_block + se->nr_pages == start_block) {
|
|
/* Merge it */
|
|
se->nr_pages += nr_pages;
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* No merge. Insert a new extent, preserving ordering.
|
|
*/
|
|
new_se = kmalloc(sizeof(*se), GFP_KERNEL);
|
|
if (new_se == NULL)
|
|
return -ENOMEM;
|
|
new_se->start_page = start_page;
|
|
new_se->nr_pages = nr_pages;
|
|
new_se->start_block = start_block;
|
|
|
|
list_add_tail(&new_se->list, &sis->extent_list);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* A `swap extent' is a simple thing which maps a contiguous range of pages
|
|
* onto a contiguous range of disk blocks. An ordered list of swap extents
|
|
* is built at swapon time and is then used at swap_writepage/swap_readpage
|
|
* time for locating where on disk a page belongs.
|
|
*
|
|
* If the swapfile is an S_ISBLK block device, a single extent is installed.
|
|
* This is done so that the main operating code can treat S_ISBLK and S_ISREG
|
|
* swap files identically.
|
|
*
|
|
* Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
|
|
* extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
|
|
* swapfiles are handled *identically* after swapon time.
|
|
*
|
|
* For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
|
|
* and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
|
|
* some stray blocks are found which do not fall within the PAGE_SIZE alignment
|
|
* requirements, they are simply tossed out - we will never use those blocks
|
|
* for swapping.
|
|
*
|
|
* For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
|
|
* prevents root from shooting her foot off by ftruncating an in-use swapfile,
|
|
* which will scribble on the fs.
|
|
*
|
|
* The amount of disk space which a single swap extent represents varies.
|
|
* Typically it is in the 1-4 megabyte range. So we can have hundreds of
|
|
* extents in the list. To avoid much list walking, we cache the previous
|
|
* search location in `curr_swap_extent', and start new searches from there.
|
|
* This is extremely effective. The average number of iterations in
|
|
* map_swap_page() has been measured at about 0.3 per page. - akpm.
|
|
*/
|
|
static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
|
|
{
|
|
struct inode *inode;
|
|
unsigned blocks_per_page;
|
|
unsigned long page_no;
|
|
unsigned blkbits;
|
|
sector_t probe_block;
|
|
sector_t last_block;
|
|
sector_t lowest_block = -1;
|
|
sector_t highest_block = 0;
|
|
int nr_extents = 0;
|
|
int ret;
|
|
|
|
inode = sis->swap_file->f_mapping->host;
|
|
if (S_ISBLK(inode->i_mode)) {
|
|
ret = add_swap_extent(sis, 0, sis->max, 0);
|
|
*span = sis->pages;
|
|
goto done;
|
|
}
|
|
|
|
blkbits = inode->i_blkbits;
|
|
blocks_per_page = PAGE_SIZE >> blkbits;
|
|
|
|
/*
|
|
* Map all the blocks into the extent list. This code doesn't try
|
|
* to be very smart.
|
|
*/
|
|
probe_block = 0;
|
|
page_no = 0;
|
|
last_block = i_size_read(inode) >> blkbits;
|
|
while ((probe_block + blocks_per_page) <= last_block &&
|
|
page_no < sis->max) {
|
|
unsigned block_in_page;
|
|
sector_t first_block;
|
|
|
|
first_block = bmap(inode, probe_block);
|
|
if (first_block == 0)
|
|
goto bad_bmap;
|
|
|
|
/*
|
|
* It must be PAGE_SIZE aligned on-disk
|
|
*/
|
|
if (first_block & (blocks_per_page - 1)) {
|
|
probe_block++;
|
|
goto reprobe;
|
|
}
|
|
|
|
for (block_in_page = 1; block_in_page < blocks_per_page;
|
|
block_in_page++) {
|
|
sector_t block;
|
|
|
|
block = bmap(inode, probe_block + block_in_page);
|
|
if (block == 0)
|
|
goto bad_bmap;
|
|
if (block != first_block + block_in_page) {
|
|
/* Discontiguity */
|
|
probe_block++;
|
|
goto reprobe;
|
|
}
|
|
}
|
|
|
|
first_block >>= (PAGE_SHIFT - blkbits);
|
|
if (page_no) { /* exclude the header page */
|
|
if (first_block < lowest_block)
|
|
lowest_block = first_block;
|
|
if (first_block > highest_block)
|
|
highest_block = first_block;
|
|
}
|
|
|
|
/*
|
|
* We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
|
|
*/
|
|
ret = add_swap_extent(sis, page_no, 1, first_block);
|
|
if (ret < 0)
|
|
goto out;
|
|
nr_extents += ret;
|
|
page_no++;
|
|
probe_block += blocks_per_page;
|
|
reprobe:
|
|
continue;
|
|
}
|
|
ret = nr_extents;
|
|
*span = 1 + highest_block - lowest_block;
|
|
if (page_no == 0)
|
|
page_no = 1; /* force Empty message */
|
|
sis->max = page_no;
|
|
sis->pages = page_no - 1;
|
|
sis->highest_bit = page_no - 1;
|
|
done:
|
|
sis->curr_swap_extent = list_entry(sis->extent_list.prev,
|
|
struct swap_extent, list);
|
|
goto out;
|
|
bad_bmap:
|
|
printk(KERN_ERR "swapon: swapfile has holes\n");
|
|
ret = -EINVAL;
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
#if 0 /* We don't need this yet */
|
|
#include <linux/backing-dev.h>
|
|
int page_queue_congested(struct page *page)
|
|
{
|
|
struct backing_dev_info *bdi;
|
|
|
|
BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */
|
|
|
|
if (PageSwapCache(page)) {
|
|
swp_entry_t entry = { .val = page_private(page) };
|
|
struct swap_info_struct *sis;
|
|
|
|
sis = get_swap_info_struct(swp_type(entry));
|
|
bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info;
|
|
} else
|
|
bdi = page->mapping->backing_dev_info;
|
|
return bdi_write_congested(bdi);
|
|
}
|
|
#endif
|
|
|
|
asmlinkage long sys_swapoff(const char __user * specialfile)
|
|
{
|
|
struct swap_info_struct * p = NULL;
|
|
unsigned short *swap_map;
|
|
struct file *swap_file, *victim;
|
|
struct address_space *mapping;
|
|
struct inode *inode;
|
|
char * pathname;
|
|
int i, type, prev;
|
|
int err;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
pathname = getname(specialfile);
|
|
err = PTR_ERR(pathname);
|
|
if (IS_ERR(pathname))
|
|
goto out;
|
|
|
|
victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0);
|
|
putname(pathname);
|
|
err = PTR_ERR(victim);
|
|
if (IS_ERR(victim))
|
|
goto out;
|
|
|
|
mapping = victim->f_mapping;
|
|
prev = -1;
|
|
spin_lock(&swap_lock);
|
|
for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
|
|
p = swap_info + type;
|
|
if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
|
|
if (p->swap_file->f_mapping == mapping)
|
|
break;
|
|
}
|
|
prev = type;
|
|
}
|
|
if (type < 0) {
|
|
err = -EINVAL;
|
|
spin_unlock(&swap_lock);
|
|
goto out_dput;
|
|
}
|
|
if (!security_vm_enough_memory(p->pages))
|
|
vm_unacct_memory(p->pages);
|
|
else {
|
|
err = -ENOMEM;
|
|
spin_unlock(&swap_lock);
|
|
goto out_dput;
|
|
}
|
|
if (prev < 0) {
|
|
swap_list.head = p->next;
|
|
} else {
|
|
swap_info[prev].next = p->next;
|
|
}
|
|
if (type == swap_list.next) {
|
|
/* just pick something that's safe... */
|
|
swap_list.next = swap_list.head;
|
|
}
|
|
nr_swap_pages -= p->pages;
|
|
total_swap_pages -= p->pages;
|
|
p->flags &= ~SWP_WRITEOK;
|
|
spin_unlock(&swap_lock);
|
|
|
|
current->flags |= PF_SWAPOFF;
|
|
err = try_to_unuse(type);
|
|
current->flags &= ~PF_SWAPOFF;
|
|
|
|
if (err) {
|
|
/* re-insert swap space back into swap_list */
|
|
spin_lock(&swap_lock);
|
|
for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
|
|
if (p->prio >= swap_info[i].prio)
|
|
break;
|
|
p->next = i;
|
|
if (prev < 0)
|
|
swap_list.head = swap_list.next = p - swap_info;
|
|
else
|
|
swap_info[prev].next = p - swap_info;
|
|
nr_swap_pages += p->pages;
|
|
total_swap_pages += p->pages;
|
|
p->flags |= SWP_WRITEOK;
|
|
spin_unlock(&swap_lock);
|
|
goto out_dput;
|
|
}
|
|
|
|
/* wait for any unplug function to finish */
|
|
down_write(&swap_unplug_sem);
|
|
up_write(&swap_unplug_sem);
|
|
|
|
destroy_swap_extents(p);
|
|
down(&swapon_sem);
|
|
spin_lock(&swap_lock);
|
|
drain_mmlist();
|
|
|
|
/* wait for anyone still in scan_swap_map */
|
|
p->highest_bit = 0; /* cuts scans short */
|
|
while (p->flags >= SWP_SCANNING) {
|
|
spin_unlock(&swap_lock);
|
|
schedule_timeout_uninterruptible(1);
|
|
spin_lock(&swap_lock);
|
|
}
|
|
|
|
swap_file = p->swap_file;
|
|
p->swap_file = NULL;
|
|
p->max = 0;
|
|
swap_map = p->swap_map;
|
|
p->swap_map = NULL;
|
|
p->flags = 0;
|
|
spin_unlock(&swap_lock);
|
|
up(&swapon_sem);
|
|
vfree(swap_map);
|
|
inode = mapping->host;
|
|
if (S_ISBLK(inode->i_mode)) {
|
|
struct block_device *bdev = I_BDEV(inode);
|
|
set_blocksize(bdev, p->old_block_size);
|
|
bd_release(bdev);
|
|
} else {
|
|
down(&inode->i_sem);
|
|
inode->i_flags &= ~S_SWAPFILE;
|
|
up(&inode->i_sem);
|
|
}
|
|
filp_close(swap_file, NULL);
|
|
err = 0;
|
|
|
|
out_dput:
|
|
filp_close(victim, NULL);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
/* iterator */
|
|
static void *swap_start(struct seq_file *swap, loff_t *pos)
|
|
{
|
|
struct swap_info_struct *ptr = swap_info;
|
|
int i;
|
|
loff_t l = *pos;
|
|
|
|
down(&swapon_sem);
|
|
|
|
for (i = 0; i < nr_swapfiles; i++, ptr++) {
|
|
if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
|
|
continue;
|
|
if (!l--)
|
|
return ptr;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
|
|
{
|
|
struct swap_info_struct *ptr = v;
|
|
struct swap_info_struct *endptr = swap_info + nr_swapfiles;
|
|
|
|
for (++ptr; ptr < endptr; ptr++) {
|
|
if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
|
|
continue;
|
|
++*pos;
|
|
return ptr;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void swap_stop(struct seq_file *swap, void *v)
|
|
{
|
|
up(&swapon_sem);
|
|
}
|
|
|
|
static int swap_show(struct seq_file *swap, void *v)
|
|
{
|
|
struct swap_info_struct *ptr = v;
|
|
struct file *file;
|
|
int len;
|
|
|
|
if (v == swap_info)
|
|
seq_puts(swap, "Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
|
|
|
|
file = ptr->swap_file;
|
|
len = seq_path(swap, file->f_vfsmnt, file->f_dentry, " \t\n\\");
|
|
seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
|
|
len < 40 ? 40 - len : 1, " ",
|
|
S_ISBLK(file->f_dentry->d_inode->i_mode) ?
|
|
"partition" : "file\t",
|
|
ptr->pages << (PAGE_SHIFT - 10),
|
|
ptr->inuse_pages << (PAGE_SHIFT - 10),
|
|
ptr->prio);
|
|
return 0;
|
|
}
|
|
|
|
static struct seq_operations swaps_op = {
|
|
.start = swap_start,
|
|
.next = swap_next,
|
|
.stop = swap_stop,
|
|
.show = swap_show
|
|
};
|
|
|
|
static int swaps_open(struct inode *inode, struct file *file)
|
|
{
|
|
return seq_open(file, &swaps_op);
|
|
}
|
|
|
|
static struct file_operations proc_swaps_operations = {
|
|
.open = swaps_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = seq_release,
|
|
};
|
|
|
|
static int __init procswaps_init(void)
|
|
{
|
|
struct proc_dir_entry *entry;
|
|
|
|
entry = create_proc_entry("swaps", 0, NULL);
|
|
if (entry)
|
|
entry->proc_fops = &proc_swaps_operations;
|
|
return 0;
|
|
}
|
|
__initcall(procswaps_init);
|
|
#endif /* CONFIG_PROC_FS */
|
|
|
|
/*
|
|
* Written 01/25/92 by Simmule Turner, heavily changed by Linus.
|
|
*
|
|
* The swapon system call
|
|
*/
|
|
asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
|
|
{
|
|
struct swap_info_struct * p;
|
|
char *name = NULL;
|
|
struct block_device *bdev = NULL;
|
|
struct file *swap_file = NULL;
|
|
struct address_space *mapping;
|
|
unsigned int type;
|
|
int i, prev;
|
|
int error;
|
|
static int least_priority;
|
|
union swap_header *swap_header = NULL;
|
|
int swap_header_version;
|
|
unsigned int nr_good_pages = 0;
|
|
int nr_extents = 0;
|
|
sector_t span;
|
|
unsigned long maxpages = 1;
|
|
int swapfilesize;
|
|
unsigned short *swap_map;
|
|
struct page *page = NULL;
|
|
struct inode *inode = NULL;
|
|
int did_down = 0;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
spin_lock(&swap_lock);
|
|
p = swap_info;
|
|
for (type = 0 ; type < nr_swapfiles ; type++,p++)
|
|
if (!(p->flags & SWP_USED))
|
|
break;
|
|
error = -EPERM;
|
|
/*
|
|
* Test if adding another swap device is possible. There are
|
|
* two limiting factors: 1) the number of bits for the swap
|
|
* type swp_entry_t definition and 2) the number of bits for
|
|
* the swap type in the swap ptes as defined by the different
|
|
* architectures. To honor both limitations a swap entry
|
|
* with swap offset 0 and swap type ~0UL is created, encoded
|
|
* to a swap pte, decoded to a swp_entry_t again and finally
|
|
* the swap type part is extracted. This will mask all bits
|
|
* from the initial ~0UL that can't be encoded in either the
|
|
* swp_entry_t or the architecture definition of a swap pte.
|
|
*/
|
|
if (type > swp_type(pte_to_swp_entry(swp_entry_to_pte(swp_entry(~0UL,0))))) {
|
|
spin_unlock(&swap_lock);
|
|
goto out;
|
|
}
|
|
if (type >= nr_swapfiles)
|
|
nr_swapfiles = type+1;
|
|
INIT_LIST_HEAD(&p->extent_list);
|
|
p->flags = SWP_USED;
|
|
p->swap_file = NULL;
|
|
p->old_block_size = 0;
|
|
p->swap_map = NULL;
|
|
p->lowest_bit = 0;
|
|
p->highest_bit = 0;
|
|
p->cluster_nr = 0;
|
|
p->inuse_pages = 0;
|
|
p->next = -1;
|
|
if (swap_flags & SWAP_FLAG_PREFER) {
|
|
p->prio =
|
|
(swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
|
|
} else {
|
|
p->prio = --least_priority;
|
|
}
|
|
spin_unlock(&swap_lock);
|
|
name = getname(specialfile);
|
|
error = PTR_ERR(name);
|
|
if (IS_ERR(name)) {
|
|
name = NULL;
|
|
goto bad_swap_2;
|
|
}
|
|
swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0);
|
|
error = PTR_ERR(swap_file);
|
|
if (IS_ERR(swap_file)) {
|
|
swap_file = NULL;
|
|
goto bad_swap_2;
|
|
}
|
|
|
|
p->swap_file = swap_file;
|
|
mapping = swap_file->f_mapping;
|
|
inode = mapping->host;
|
|
|
|
error = -EBUSY;
|
|
for (i = 0; i < nr_swapfiles; i++) {
|
|
struct swap_info_struct *q = &swap_info[i];
|
|
|
|
if (i == type || !q->swap_file)
|
|
continue;
|
|
if (mapping == q->swap_file->f_mapping)
|
|
goto bad_swap;
|
|
}
|
|
|
|
error = -EINVAL;
|
|
if (S_ISBLK(inode->i_mode)) {
|
|
bdev = I_BDEV(inode);
|
|
error = bd_claim(bdev, sys_swapon);
|
|
if (error < 0) {
|
|
bdev = NULL;
|
|
error = -EINVAL;
|
|
goto bad_swap;
|
|
}
|
|
p->old_block_size = block_size(bdev);
|
|
error = set_blocksize(bdev, PAGE_SIZE);
|
|
if (error < 0)
|
|
goto bad_swap;
|
|
p->bdev = bdev;
|
|
} else if (S_ISREG(inode->i_mode)) {
|
|
p->bdev = inode->i_sb->s_bdev;
|
|
down(&inode->i_sem);
|
|
did_down = 1;
|
|
if (IS_SWAPFILE(inode)) {
|
|
error = -EBUSY;
|
|
goto bad_swap;
|
|
}
|
|
} else {
|
|
goto bad_swap;
|
|
}
|
|
|
|
swapfilesize = i_size_read(inode) >> PAGE_SHIFT;
|
|
|
|
/*
|
|
* Read the swap header.
|
|
*/
|
|
if (!mapping->a_ops->readpage) {
|
|
error = -EINVAL;
|
|
goto bad_swap;
|
|
}
|
|
page = read_cache_page(mapping, 0,
|
|
(filler_t *)mapping->a_ops->readpage, swap_file);
|
|
if (IS_ERR(page)) {
|
|
error = PTR_ERR(page);
|
|
goto bad_swap;
|
|
}
|
|
wait_on_page_locked(page);
|
|
if (!PageUptodate(page))
|
|
goto bad_swap;
|
|
kmap(page);
|
|
swap_header = page_address(page);
|
|
|
|
if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
|
|
swap_header_version = 1;
|
|
else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
|
|
swap_header_version = 2;
|
|
else {
|
|
printk("Unable to find swap-space signature\n");
|
|
error = -EINVAL;
|
|
goto bad_swap;
|
|
}
|
|
|
|
switch (swap_header_version) {
|
|
case 1:
|
|
printk(KERN_ERR "version 0 swap is no longer supported. "
|
|
"Use mkswap -v1 %s\n", name);
|
|
error = -EINVAL;
|
|
goto bad_swap;
|
|
case 2:
|
|
/* Check the swap header's sub-version and the size of
|
|
the swap file and bad block lists */
|
|
if (swap_header->info.version != 1) {
|
|
printk(KERN_WARNING
|
|
"Unable to handle swap header version %d\n",
|
|
swap_header->info.version);
|
|
error = -EINVAL;
|
|
goto bad_swap;
|
|
}
|
|
|
|
p->lowest_bit = 1;
|
|
p->cluster_next = 1;
|
|
|
|
/*
|
|
* Find out how many pages are allowed for a single swap
|
|
* device. There are two limiting factors: 1) the number of
|
|
* bits for the swap offset in the swp_entry_t type and
|
|
* 2) the number of bits in the a swap pte as defined by
|
|
* the different architectures. In order to find the
|
|
* largest possible bit mask a swap entry with swap type 0
|
|
* and swap offset ~0UL is created, encoded to a swap pte,
|
|
* decoded to a swp_entry_t again and finally the swap
|
|
* offset is extracted. This will mask all the bits from
|
|
* the initial ~0UL mask that can't be encoded in either
|
|
* the swp_entry_t or the architecture definition of a
|
|
* swap pte.
|
|
*/
|
|
maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1;
|
|
if (maxpages > swap_header->info.last_page)
|
|
maxpages = swap_header->info.last_page;
|
|
p->highest_bit = maxpages - 1;
|
|
|
|
error = -EINVAL;
|
|
if (!maxpages)
|
|
goto bad_swap;
|
|
if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
|
|
goto bad_swap;
|
|
if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
|
|
goto bad_swap;
|
|
|
|
/* OK, set up the swap map and apply the bad block list */
|
|
if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) {
|
|
error = -ENOMEM;
|
|
goto bad_swap;
|
|
}
|
|
|
|
error = 0;
|
|
memset(p->swap_map, 0, maxpages * sizeof(short));
|
|
for (i=0; i<swap_header->info.nr_badpages; i++) {
|
|
int page = swap_header->info.badpages[i];
|
|
if (page <= 0 || page >= swap_header->info.last_page)
|
|
error = -EINVAL;
|
|
else
|
|
p->swap_map[page] = SWAP_MAP_BAD;
|
|
}
|
|
nr_good_pages = swap_header->info.last_page -
|
|
swap_header->info.nr_badpages -
|
|
1 /* header page */;
|
|
if (error)
|
|
goto bad_swap;
|
|
}
|
|
|
|
if (swapfilesize && maxpages > swapfilesize) {
|
|
printk(KERN_WARNING
|
|
"Swap area shorter than signature indicates\n");
|
|
error = -EINVAL;
|
|
goto bad_swap;
|
|
}
|
|
if (nr_good_pages) {
|
|
p->swap_map[0] = SWAP_MAP_BAD;
|
|
p->max = maxpages;
|
|
p->pages = nr_good_pages;
|
|
nr_extents = setup_swap_extents(p, &span);
|
|
if (nr_extents < 0) {
|
|
error = nr_extents;
|
|
goto bad_swap;
|
|
}
|
|
nr_good_pages = p->pages;
|
|
}
|
|
if (!nr_good_pages) {
|
|
printk(KERN_WARNING "Empty swap-file\n");
|
|
error = -EINVAL;
|
|
goto bad_swap;
|
|
}
|
|
|
|
down(&swapon_sem);
|
|
spin_lock(&swap_lock);
|
|
p->flags = SWP_ACTIVE;
|
|
nr_swap_pages += nr_good_pages;
|
|
total_swap_pages += nr_good_pages;
|
|
|
|
printk(KERN_INFO "Adding %uk swap on %s. "
|
|
"Priority:%d extents:%d across:%lluk\n",
|
|
nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
|
|
nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
|
|
|
|
/* 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 - swap_info;
|
|
} else {
|
|
swap_info[prev].next = p - swap_info;
|
|
}
|
|
spin_unlock(&swap_lock);
|
|
up(&swapon_sem);
|
|
error = 0;
|
|
goto out;
|
|
bad_swap:
|
|
if (bdev) {
|
|
set_blocksize(bdev, p->old_block_size);
|
|
bd_release(bdev);
|
|
}
|
|
destroy_swap_extents(p);
|
|
bad_swap_2:
|
|
spin_lock(&swap_lock);
|
|
swap_map = p->swap_map;
|
|
p->swap_file = NULL;
|
|
p->swap_map = NULL;
|
|
p->flags = 0;
|
|
if (!(swap_flags & SWAP_FLAG_PREFER))
|
|
++least_priority;
|
|
spin_unlock(&swap_lock);
|
|
vfree(swap_map);
|
|
if (swap_file)
|
|
filp_close(swap_file, NULL);
|
|
out:
|
|
if (page && !IS_ERR(page)) {
|
|
kunmap(page);
|
|
page_cache_release(page);
|
|
}
|
|
if (name)
|
|
putname(name);
|
|
if (did_down) {
|
|
if (!error)
|
|
inode->i_flags |= S_SWAPFILE;
|
|
up(&inode->i_sem);
|
|
}
|
|
return error;
|
|
}
|
|
|
|
void si_swapinfo(struct sysinfo *val)
|
|
{
|
|
unsigned int i;
|
|
unsigned long nr_to_be_unused = 0;
|
|
|
|
spin_lock(&swap_lock);
|
|
for (i = 0; i < nr_swapfiles; i++) {
|
|
if (!(swap_info[i].flags & SWP_USED) ||
|
|
(swap_info[i].flags & SWP_WRITEOK))
|
|
continue;
|
|
nr_to_be_unused += swap_info[i].inuse_pages;
|
|
}
|
|
val->freeswap = nr_swap_pages + nr_to_be_unused;
|
|
val->totalswap = total_swap_pages + nr_to_be_unused;
|
|
spin_unlock(&swap_lock);
|
|
}
|
|
|
|
/*
|
|
* Verify that a swap entry is valid and increment its swap map count.
|
|
*
|
|
* Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
|
|
* "permanent", but will be reclaimed by the next swapoff.
|
|
*/
|
|
int swap_duplicate(swp_entry_t entry)
|
|
{
|
|
struct swap_info_struct * p;
|
|
unsigned long offset, type;
|
|
int result = 0;
|
|
|
|
type = swp_type(entry);
|
|
if (type >= nr_swapfiles)
|
|
goto bad_file;
|
|
p = type + swap_info;
|
|
offset = swp_offset(entry);
|
|
|
|
spin_lock(&swap_lock);
|
|
if (offset < p->max && p->swap_map[offset]) {
|
|
if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
|
|
p->swap_map[offset]++;
|
|
result = 1;
|
|
} else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
|
|
if (swap_overflow++ < 5)
|
|
printk(KERN_WARNING "swap_dup: swap entry overflow\n");
|
|
p->swap_map[offset] = SWAP_MAP_MAX;
|
|
result = 1;
|
|
}
|
|
}
|
|
spin_unlock(&swap_lock);
|
|
out:
|
|
return result;
|
|
|
|
bad_file:
|
|
printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
|
|
goto out;
|
|
}
|
|
|
|
struct swap_info_struct *
|
|
get_swap_info_struct(unsigned type)
|
|
{
|
|
return &swap_info[type];
|
|
}
|
|
|
|
/*
|
|
* swap_lock prevents swap_map being freed. Don't grab an extra
|
|
* reference on the swaphandle, it doesn't matter if it becomes unused.
|
|
*/
|
|
int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
|
|
{
|
|
int ret = 0, i = 1 << page_cluster;
|
|
unsigned long toff;
|
|
struct swap_info_struct *swapdev = swp_type(entry) + swap_info;
|
|
|
|
if (!page_cluster) /* no readahead */
|
|
return 0;
|
|
toff = (swp_offset(entry) >> page_cluster) << page_cluster;
|
|
if (!toff) /* first page is swap header */
|
|
toff++, i--;
|
|
*offset = toff;
|
|
|
|
spin_lock(&swap_lock);
|
|
do {
|
|
/* Don't read-ahead past the end of the swap area */
|
|
if (toff >= swapdev->max)
|
|
break;
|
|
/* Don't read in free or bad pages */
|
|
if (!swapdev->swap_map[toff])
|
|
break;
|
|
if (swapdev->swap_map[toff] == SWAP_MAP_BAD)
|
|
break;
|
|
toff++;
|
|
ret++;
|
|
} while (--i);
|
|
spin_unlock(&swap_lock);
|
|
return ret;
|
|
}
|