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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /mm/swapfile.c
downloadlinux-linaro-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'mm/swapfile.c')
-rw-r--r--mm/swapfile.c1672
1 files changed, 1672 insertions, 0 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
new file mode 100644
index 00000000000..a60e0075d55
--- /dev/null
+++ b/mm/swapfile.c
@@ -0,0 +1,1672 @@
+/*
+ * linux/mm/swapfile.c
+ *
+ * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
+ * Swap reorganised 29.12.95, Stephen Tweedie
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/kernel_stat.h>
+#include <linux/swap.h>
+#include <linux/vmalloc.h>
+#include <linux/pagemap.h>
+#include <linux/namei.h>
+#include <linux/shm.h>
+#include <linux/blkdev.h>
+#include <linux/writeback.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/rmap.h>
+#include <linux/security.h>
+#include <linux/backing-dev.h>
+#include <linux/syscalls.h>
+
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <linux/swapops.h>
+
+DEFINE_SPINLOCK(swaplock);
+unsigned int nr_swapfiles;
+long total_swap_pages;
+static int swap_overflow;
+
+EXPORT_SYMBOL(total_swap_pages);
+
+static const char Bad_file[] = "Bad swap file entry ";
+static const char Unused_file[] = "Unused swap file entry ";
+static const char Bad_offset[] = "Bad swap offset entry ";
+static const char Unused_offset[] = "Unused swap offset entry ";
+
+struct swap_list_t swap_list = {-1, -1};
+
+struct swap_info_struct swap_info[MAX_SWAPFILES];
+
+static DECLARE_MUTEX(swapon_sem);
+
+/*
+ * We need this because the bdev->unplug_fn can sleep and we cannot
+ * hold swap_list_lock while calling the unplug_fn. And swap_list_lock
+ * cannot be turned into a semaphore.
+ */
+static DECLARE_RWSEM(swap_unplug_sem);
+
+#define SWAPFILE_CLUSTER 256
+
+void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page)
+{
+ swp_entry_t entry;
+
+ down_read(&swap_unplug_sem);
+ entry.val = page->private;
+ if (PageSwapCache(page)) {
+ struct block_device *bdev = swap_info[swp_type(entry)].bdev;
+ struct backing_dev_info *bdi;
+
+ /*
+ * If the page is removed from swapcache from under us (with a
+ * racy try_to_unuse/swapoff) we need an additional reference
+ * count to avoid reading garbage from page->private above. If
+ * the WARN_ON triggers during a swapoff it maybe the race
+ * condition and it's harmless. However if it triggers without
+ * swapoff it signals a problem.
+ */
+ WARN_ON(page_count(page) <= 1);
+
+ bdi = bdev->bd_inode->i_mapping->backing_dev_info;
+ bdi->unplug_io_fn(bdi, page);
+ }
+ up_read(&swap_unplug_sem);
+}
+
+static inline int scan_swap_map(struct swap_info_struct *si)
+{
+ unsigned long offset;
+ /*
+ * We try to cluster swap pages by allocating them
+ * sequentially in swap. Once we've allocated
+ * SWAPFILE_CLUSTER pages this way, however, we resort to
+ * first-free allocation, starting a new cluster. This
+ * prevents us from scattering swap pages all over the entire
+ * swap partition, so that we reduce overall disk seek times
+ * between swap pages. -- sct */
+ if (si->cluster_nr) {
+ while (si->cluster_next <= si->highest_bit) {
+ offset = si->cluster_next++;
+ if (si->swap_map[offset])
+ continue;
+ si->cluster_nr--;
+ goto got_page;
+ }
+ }
+ si->cluster_nr = SWAPFILE_CLUSTER;
+
+ /* try to find an empty (even not aligned) cluster. */
+ offset = si->lowest_bit;
+ check_next_cluster:
+ if (offset+SWAPFILE_CLUSTER-1 <= si->highest_bit)
+ {
+ unsigned long nr;
+ for (nr = offset; nr < offset+SWAPFILE_CLUSTER; nr++)
+ if (si->swap_map[nr])
+ {
+ offset = nr+1;
+ goto check_next_cluster;
+ }
+ /* We found a completly empty cluster, so start
+ * using it.
+ */
+ goto got_page;
+ }
+ /* No luck, so now go finegrined as usual. -Andrea */
+ for (offset = si->lowest_bit; offset <= si->highest_bit ; offset++) {
+ if (si->swap_map[offset])
+ continue;
+ si->lowest_bit = offset+1;
+ got_page:
+ if (offset == si->lowest_bit)
+ si->lowest_bit++;
+ if (offset == si->highest_bit)
+ si->highest_bit--;
+ if (si->lowest_bit > si->highest_bit) {
+ si->lowest_bit = si->max;
+ si->highest_bit = 0;
+ }
+ si->swap_map[offset] = 1;
+ si->inuse_pages++;
+ nr_swap_pages--;
+ si->cluster_next = offset+1;
+ return offset;
+ }
+ si->lowest_bit = si->max;
+ si->highest_bit = 0;
+ return 0;
+}
+
+swp_entry_t get_swap_page(void)
+{
+ struct swap_info_struct * p;
+ unsigned long offset;
+ swp_entry_t entry;
+ int type, wrapped = 0;
+
+ entry.val = 0; /* Out of memory */
+ swap_list_lock();
+ type = swap_list.next;
+ if (type < 0)
+ goto out;
+ if (nr_swap_pages <= 0)
+ goto out;
+
+ while (1) {
+ p = &swap_info[type];
+ if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) {
+ swap_device_lock(p);
+ offset = scan_swap_map(p);
+ swap_device_unlock(p);
+ if (offset) {
+ entry = swp_entry(type,offset);
+ type = swap_info[type].next;
+ if (type < 0 ||
+ p->prio != swap_info[type].prio) {
+ swap_list.next = swap_list.head;
+ } else {
+ swap_list.next = type;
+ }
+ goto out;
+ }
+ }
+ type = p->next;
+ if (!wrapped) {
+ if (type < 0 || p->prio != swap_info[type].prio) {
+ type = swap_list.head;
+ wrapped = 1;
+ }
+ } else
+ if (type < 0)
+ goto out; /* out of swap space */
+ }
+out:
+ swap_list_unlock();
+ return entry;
+}
+
+static struct swap_info_struct * swap_info_get(swp_entry_t entry)
+{
+ struct swap_info_struct * p;
+ unsigned long offset, type;
+
+ if (!entry.val)
+ goto out;
+ type = swp_type(entry);
+ if (type >= nr_swapfiles)
+ goto bad_nofile;
+ p = & swap_info[type];
+ if (!(p->flags & SWP_USED))
+ goto bad_device;
+ offset = swp_offset(entry);
+ if (offset >= p->max)
+ goto bad_offset;
+ if (!p->swap_map[offset])
+ goto bad_free;
+ swap_list_lock();
+ if (p->prio > swap_info[swap_list.next].prio)
+ swap_list.next = type;
+ swap_device_lock(p);
+ return p;
+
+bad_free:
+ printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val);
+ goto out;
+bad_offset:
+ printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val);
+ goto out;
+bad_device:
+ printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val);
+ goto out;
+bad_nofile:
+ printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val);
+out:
+ return NULL;
+}
+
+static void swap_info_put(struct swap_info_struct * p)
+{
+ swap_device_unlock(p);
+ swap_list_unlock();
+}
+
+static int swap_entry_free(struct swap_info_struct *p, unsigned long offset)
+{
+ int count = p->swap_map[offset];
+
+ if (count < SWAP_MAP_MAX) {
+ count--;
+ p->swap_map[offset] = count;
+ if (!count) {
+ if (offset < p->lowest_bit)
+ p->lowest_bit = offset;
+ if (offset > p->highest_bit)
+ p->highest_bit = offset;
+ nr_swap_pages++;
+ p->inuse_pages--;
+ }
+ }
+ return count;
+}
+
+/*
+ * Caller has made sure that the swapdevice corresponding to entry
+ * is still around or has not been recycled.
+ */
+void swap_free(swp_entry_t entry)
+{
+ struct swap_info_struct * p;
+
+ p = swap_info_get(entry);
+ if (p) {
+ swap_entry_free(p, swp_offset(entry));
+ swap_info_put(p);
+ }
+}
+
+/*
+ * Check if we're the only user of a swap page,
+ * when the page is locked.
+ */
+static int exclusive_swap_page(struct page *page)
+{
+ int retval = 0;
+ struct swap_info_struct * p;
+ swp_entry_t entry;
+
+ entry.val = page->private;
+ p = swap_info_get(entry);
+ if (p) {
+ /* Is the only swap cache user the cache itself? */
+ if (p->swap_map[swp_offset(entry)] == 1) {
+ /* Recheck the page count with the swapcache lock held.. */
+ write_lock_irq(&swapper_space.tree_lock);
+ if (page_count(page) == 2)
+ retval = 1;
+ write_unlock_irq(&swapper_space.tree_lock);
+ }
+ swap_info_put(p);
+ }
+ return retval;
+}
+
+/*
+ * We can use this swap cache entry directly
+ * if there are no other references to it.
+ *
+ * Here "exclusive_swap_page()" does the real
+ * work, but we opportunistically check whether
+ * we need to get all the locks first..
+ */
+int can_share_swap_page(struct page *page)
+{
+ int retval = 0;
+
+ if (!PageLocked(page))
+ BUG();
+ switch (page_count(page)) {
+ case 3:
+ if (!PagePrivate(page))
+ break;
+ /* Fallthrough */
+ case 2:
+ if (!PageSwapCache(page))
+ break;
+ retval = exclusive_swap_page(page);
+ break;
+ case 1:
+ if (PageReserved(page))
+ break;
+ retval = 1;
+ }
+ return retval;
+}
+
+/*
+ * Work out if there are any other processes sharing this
+ * swap cache page. Free it if you can. Return success.
+ */
+int remove_exclusive_swap_page(struct page *page)
+{
+ int retval;
+ struct swap_info_struct * p;
+ swp_entry_t entry;
+
+ BUG_ON(PagePrivate(page));
+ BUG_ON(!PageLocked(page));
+
+ if (!PageSwapCache(page))
+ return 0;
+ if (PageWriteback(page))
+ return 0;
+ if (page_count(page) != 2) /* 2: us + cache */
+ return 0;
+
+ entry.val = page->private;
+ p = swap_info_get(entry);
+ if (!p)
+ return 0;
+
+ /* Is the only swap cache user the cache itself? */
+ retval = 0;
+ if (p->swap_map[swp_offset(entry)] == 1) {
+ /* Recheck the page count with the swapcache lock held.. */
+ write_lock_irq(&swapper_space.tree_lock);
+ if ((page_count(page) == 2) && !PageWriteback(page)) {
+ __delete_from_swap_cache(page);
+ SetPageDirty(page);
+ retval = 1;
+ }
+ write_unlock_irq(&swapper_space.tree_lock);
+ }
+ swap_info_put(p);
+
+ if (retval) {
+ swap_free(entry);
+ page_cache_release(page);
+ }
+
+ return retval;
+}
+
+/*
+ * Free the swap entry like above, but also try to
+ * free the page cache entry if it is the last user.
+ */
+void free_swap_and_cache(swp_entry_t entry)
+{
+ struct swap_info_struct * p;
+ struct page *page = NULL;
+
+ p = swap_info_get(entry);
+ if (p) {
+ if (swap_entry_free(p, swp_offset(entry)) == 1)
+ page = find_trylock_page(&swapper_space, entry.val);
+ swap_info_put(p);
+ }
+ if (page) {
+ int one_user;
+
+ BUG_ON(PagePrivate(page));
+ page_cache_get(page);
+ one_user = (page_count(page) == 2);
+ /* Only cache user (+us), or swap space full? Free it! */
+ if (!PageWriteback(page) && (one_user || vm_swap_full())) {
+ delete_from_swap_cache(page);
+ SetPageDirty(page);
+ }
+ unlock_page(page);
+ page_cache_release(page);
+ }
+}
+
+/*
+ * Always set the resulting pte to be nowrite (the same as COW pages
+ * after one process has exited). We don't know just how many PTEs will
+ * share this swap entry, so be cautious and let do_wp_page work out
+ * what to do if a write is requested later.
+ *
+ * vma->vm_mm->page_table_lock is held.
+ */
+static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
+ unsigned long addr, swp_entry_t entry, struct page *page)
+{
+ inc_mm_counter(vma->vm_mm, rss);
+ get_page(page);
+ set_pte_at(vma->vm_mm, addr, pte,
+ pte_mkold(mk_pte(page, vma->vm_page_prot)));
+ page_add_anon_rmap(page, vma, addr);
+ swap_free(entry);
+ /*
+ * Move the page to the active list so it is not
+ * immediately swapped out again after swapon.
+ */
+ activate_page(page);
+}
+
+static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long addr, unsigned long end,
+ swp_entry_t entry, struct page *page)
+{
+ pte_t *pte;
+ pte_t swp_pte = swp_entry_to_pte(entry);
+
+ pte = pte_offset_map(pmd, addr);
+ do {
+ /*
+ * swapoff spends a _lot_ of time in this loop!
+ * Test inline before going to call unuse_pte.
+ */
+ if (unlikely(pte_same(*pte, swp_pte))) {
+ unuse_pte(vma, pte, addr, entry, page);
+ pte_unmap(pte);
+ return 1;
+ }
+ } while (pte++, addr += PAGE_SIZE, addr != end);
+ pte_unmap(pte - 1);
+ return 0;
+}
+
+static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
+ unsigned long addr, unsigned long end,
+ swp_entry_t entry, struct page *page)
+{
+ pmd_t *pmd;
+ unsigned long next;
+
+ pmd = pmd_offset(pud, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ if (pmd_none_or_clear_bad(pmd))
+ continue;
+ if (unuse_pte_range(vma, pmd, addr, next, entry, page))
+ return 1;
+ } while (pmd++, addr = next, addr != end);
+ return 0;
+}
+
+static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
+ unsigned long addr, unsigned long end,
+ swp_entry_t entry, struct page *page)
+{
+ pud_t *pud;
+ unsigned long next;
+
+ pud = pud_offset(pgd, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (pud_none_or_clear_bad(pud))
+ continue;
+ if (unuse_pmd_range(vma, pud, addr, next, entry, page))
+ 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
+ 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)) {
+ /*
+ * Our reference to the page stops try_to_unmap_one from
+ * unmapping its ptes, so swapoff can make progress.
+ */
+ unlock_page(page);
+ down_read(&mm->mmap_sem);
+ lock_page(page);
+ }
+ spin_lock(&mm->page_table_lock);
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (vma->anon_vma && unuse_vma(vma, entry, page))
+ break;
+ }
+ spin_unlock(&mm->page_table_lock);
+ 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 int find_next_to_unuse(struct swap_info_struct *si, int prev)
+{
+ int max = si->max;
+ int i = prev;
+ int count;
+
+ /*
+ * No need for swap_device_lock(si) 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_list_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;
+ 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) {
+ swap_device_lock(si);
+ *swap_map = 1;
+ swap_device_unlock(si);
+ 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_list_lock must be held on entry and exit.
+ * Note that mmlist_lock nests inside swap_list_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.prev;
+ if (lh == &sis->extent_list)
+ lh = lh->prev;
+ 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);
+ }
+ sis->nr_extents = 0;
+}
+
+/*
+ * Add a block range (and the corresponding page range) into this swapdev's
+ * extent list. The extent list is kept sorted in block order.
+ *
+ * This function rather assumes that it is called in ascending sector_t order.
+ * It doesn't look for extent coalescing opportunities.
+ */
+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.next; /* The highest-addressed block */
+ while (lh != &sis->extent_list) {
+ se = list_entry(lh, struct swap_extent, list);
+ if (se->start_block + se->nr_pages == start_block &&
+ se->start_page + se->nr_pages == start_page) {
+ /* Merge it */
+ se->nr_pages += nr_pages;
+ return 0;
+ }
+ lh = lh->next;
+ }
+
+ /*
+ * 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;
+
+ lh = sis->extent_list.prev; /* The lowest block */
+ while (lh != &sis->extent_list) {
+ se = list_entry(lh, struct swap_extent, list);
+ if (se->start_block > start_block)
+ break;
+ lh = lh->prev;
+ }
+ list_add_tail(&new_se->list, lh);
+ sis->nr_extents++;
+ return 0;
+}
+
+/*
+ * 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 hold i_sem 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)
+{
+ struct inode *inode;
+ unsigned blocks_per_page;
+ unsigned long page_no;
+ unsigned blkbits;
+ sector_t probe_block;
+ sector_t last_block;
+ int ret;
+
+ inode = sis->swap_file->f_mapping->host;
+ if (S_ISBLK(inode->i_mode)) {
+ ret = add_swap_extent(sis, 0, sis->max, 0);
+ 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;
+ }
+ }
+
+ /*
+ * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
+ */
+ ret = add_swap_extent(sis, page_no, 1,
+ first_block >> (PAGE_SHIFT - blkbits));
+ if (ret)
+ goto out;
+ page_no++;
+ probe_block += blocks_per_page;
+reprobe:
+ continue;
+ }
+ ret = 0;
+ if (page_no == 0)
+ ret = -EINVAL;
+ sis->max = page_no;
+ 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 };
+ 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;
+ swap_list_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;
+ swap_list_unlock();
+ goto out_dput;
+ }
+ if (!security_vm_enough_memory(p->pages))
+ vm_unacct_memory(p->pages);
+ else {
+ err = -ENOMEM;
+ swap_list_unlock();
+ 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;
+ swap_list_unlock();
+ current->flags |= PF_SWAPOFF;
+ err = try_to_unuse(type);
+ current->flags &= ~PF_SWAPOFF;
+
+ /* wait for any unplug function to finish */
+ down_write(&swap_unplug_sem);
+ up_write(&swap_unplug_sem);
+
+ if (err) {
+ /* re-insert swap space back into swap_list */
+ swap_list_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;
+ swap_list_unlock();
+ goto out_dput;
+ }
+ down(&swapon_sem);
+ swap_list_lock();
+ drain_mmlist();
+ swap_device_lock(p);
+ swap_file = p->swap_file;
+ p->swap_file = NULL;
+ p->max = 0;
+ swap_map = p->swap_map;
+ p->swap_map = NULL;
+ p->flags = 0;
+ destroy_swap_extents(p);
+ swap_device_unlock(p);
+ swap_list_unlock();
+ 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%d\t%ld\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;
+ int nr_good_pages = 0;
+ 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;
+ swap_list_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))))) {
+ swap_list_unlock();
+ goto out;
+ }
+ if (type >= nr_swapfiles)
+ nr_swapfiles = type+1;
+ INIT_LIST_HEAD(&p->extent_list);
+ p->flags = SWP_USED;
+ p->nr_extents = 0;
+ 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;
+ spin_lock_init(&p->sdev_lock);
+ 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;
+ }
+ swap_list_unlock();
+ 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;
+ 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;
+ /*
+ * 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 (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) {
+ printk(KERN_WARNING "Empty swap-file\n");
+ error = -EINVAL;
+ goto bad_swap;
+ }
+ p->swap_map[0] = SWAP_MAP_BAD;
+ p->max = maxpages;
+ p->pages = nr_good_pages;
+
+ error = setup_swap_extents(p);
+ if (error)
+ goto bad_swap;
+
+ down(&swapon_sem);
+ swap_list_lock();
+ swap_device_lock(p);
+ p->flags = SWP_ACTIVE;
+ nr_swap_pages += nr_good_pages;
+ total_swap_pages += nr_good_pages;
+ printk(KERN_INFO "Adding %dk swap on %s. Priority:%d extents:%d\n",
+ nr_good_pages<<(PAGE_SHIFT-10), name,
+ p->prio, p->nr_extents);
+
+ /* 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;
+ }
+ swap_device_unlock(p);
+ swap_list_unlock();
+ up(&swapon_sem);
+ error = 0;
+ goto out;
+bad_swap:
+ if (bdev) {
+ set_blocksize(bdev, p->old_block_size);
+ bd_release(bdev);
+ }
+bad_swap_2:
+ swap_list_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;
+ swap_list_unlock();
+ destroy_swap_extents(p);
+ 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;
+
+ swap_list_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;
+ swap_list_unlock();
+}
+
+/*
+ * 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);
+
+ swap_device_lock(p);
+ 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;
+ }
+ }
+ swap_device_unlock(p);
+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_device_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;
+
+ swap_device_lock(swapdev);
+ 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);
+ swap_device_unlock(swapdev);
+ return ret;
+}