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!

1 files changed, 382 insertions, 0 deletions

diff --git a/mm/swap_state.c b/mm/swap_state.c
new file mode 100644
index 000000000000..a063a902ed03
--- /dev/null
+++ b/mm/swap_state.c
@@ -0,0 +1,382 @@
+/*
+ *  linux/mm/swap_state.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *  Swap reorganised 29.12.95, Stephen Tweedie
+ *
+ *  Rewritten to use page cache, (C) 1998 Stephen Tweedie
+ */
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/kernel_stat.h>
+#include <linux/swap.h>
+#include <linux/init.h>
+#include <linux/pagemap.h>
+#include <linux/buffer_head.h>
+#include <linux/backing-dev.h>
+
+#include <asm/pgtable.h>
+
+/*
+ * swapper_space is a fiction, retained to simplify the path through
+ * vmscan's shrink_list, to make sync_page look nicer, and to allow
+ * future use of radix_tree tags in the swap cache.
+ */
+static struct address_space_operations swap_aops = {
+        .writepage      = swap_writepage,
+        .sync_page      = block_sync_page,
+        .set_page_dirty = __set_page_dirty_nobuffers,
+};
+
+static struct backing_dev_info swap_backing_dev_info = {
+        .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
+        .unplug_io_fn   = swap_unplug_io_fn,
+};
+
+struct address_space swapper_space = {
+        .page_tree      = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
+        .tree_lock      = RW_LOCK_UNLOCKED,
+        .a_ops          = &swap_aops,
+        .i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
+        .backing_dev_info = &swap_backing_dev_info,
+};
+EXPORT_SYMBOL(swapper_space);
+
+#define INC_CACHE_INFO(x)       do { swap_cache_info.x++; } while (0)
+
+static struct {
+        unsigned long add_total;
+        unsigned long del_total;
+        unsigned long find_success;
+        unsigned long find_total;
+        unsigned long noent_race;
+        unsigned long exist_race;
+} swap_cache_info;
+
+void show_swap_cache_info(void)
+{
+        printk("Swap cache: add %lu, delete %lu, find %lu/%lu, race %lu+%lu\n",
+                swap_cache_info.add_total, swap_cache_info.del_total,
+                swap_cache_info.find_success, swap_cache_info.find_total,
+                swap_cache_info.noent_race, swap_cache_info.exist_race);
+        printk("Free swap  = %lukB\n", nr_swap_pages << (PAGE_SHIFT - 10));
+        printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
+}
+
+/*
+ * __add_to_swap_cache resembles add_to_page_cache on swapper_space,
+ * but sets SwapCache flag and private instead of mapping and index.
+ */
+static int __add_to_swap_cache(struct page *page,
+                swp_entry_t entry, int gfp_mask)
+{
+        int error;
+
+        BUG_ON(PageSwapCache(page));
+        BUG_ON(PagePrivate(page));
+        error = radix_tree_preload(gfp_mask);
+        if (!error) {
+                write_lock_irq(&swapper_space.tree_lock);
+                error = radix_tree_insert(&swapper_space.page_tree,
+                                                entry.val, page);
+                if (!error) {
+                        page_cache_get(page);
+                        SetPageLocked(page);
+                        SetPageSwapCache(page);
+                        page->private = entry.val;
+                        total_swapcache_pages++;
+                        pagecache_acct(1);
+                }
+                write_unlock_irq(&swapper_space.tree_lock);
+                radix_tree_preload_end();
+        }
+        return error;
+}
+
+static int add_to_swap_cache(struct page *page, swp_entry_t entry)
+{
+        int error;
+
+        if (!swap_duplicate(entry)) {
+                INC_CACHE_INFO(noent_race);
+                return -ENOENT;
+        }
+        error = __add_to_swap_cache(page, entry, GFP_KERNEL);
+        /*
+         * Anon pages are already on the LRU, we don't run lru_cache_add here.
+         */
+        if (error) {
+                swap_free(entry);
+                if (error == -EEXIST)
+                        INC_CACHE_INFO(exist_race);
+                return error;
+        }
+        INC_CACHE_INFO(add_total);
+        return 0;
+}
+
+/*
+ * This must be called only on pages that have
+ * been verified to be in the swap cache.
+ */
+void __delete_from_swap_cache(struct page *page)
+{
+        BUG_ON(!PageLocked(page));
+        BUG_ON(!PageSwapCache(page));
+        BUG_ON(PageWriteback(page));
+
+        radix_tree_delete(&swapper_space.page_tree, page->private);
+        page->private = 0;
+        ClearPageSwapCache(page);
+        total_swapcache_pages--;
+        pagecache_acct(-1);
+        INC_CACHE_INFO(del_total);
+}
+
+/**
+ * add_to_swap - allocate swap space for a page
+ * @page: page we want to move to swap
+ *
+ * Allocate swap space for the page and add the page to the
+ * swap cache.  Caller needs to hold the page lock. 
+ */
+int add_to_swap(struct page * page)
+{
+        swp_entry_t entry;
+        int pf_flags;
+        int err;
+
+        if (!PageLocked(page))
+                BUG();
+
+        for (;;) {
+                entry = get_swap_page();
+                if (!entry.val)
+                        return 0;
+
+                /* Radix-tree node allocations are performing
+                 * GFP_ATOMIC allocations under PF_MEMALLOC.  
+                 * They can completely exhaust the page allocator.  
+                 *
+                 * So PF_MEMALLOC is dropped here.  This causes the slab 
+                 * allocations to fail earlier, so radix-tree nodes will 
+                 * then be allocated from the mempool reserves.
+                 *
+                 * We're still using __GFP_HIGH for radix-tree node
+                 * allocations, so some of the emergency pools are available,
+                 * just not all of them.
+                 */
+
+                pf_flags = current->flags;
+                current->flags &= ~PF_MEMALLOC;
+
+                /*
+                 * Add it to the swap cache and mark it dirty
+                 */
+                err = __add_to_swap_cache(page, entry, GFP_ATOMIC|__GFP_NOWARN);
+
+                if (pf_flags & PF_MEMALLOC)
+                        current->flags |= PF_MEMALLOC;
+
+                switch (err) {
+                case 0:                         /* Success */
+                        SetPageUptodate(page);
+                        SetPageDirty(page);
+                        INC_CACHE_INFO(add_total);
+                        return 1;
+                case -EEXIST:
+                        /* Raced with "speculative" read_swap_cache_async */
+                        INC_CACHE_INFO(exist_race);
+                        swap_free(entry);
+                        continue;
+                default:
+                        /* -ENOMEM radix-tree allocation failure */
+                        swap_free(entry);
+                        return 0;
+                }
+        }
+}
+
+/*
+ * This must be called only on pages that have
+ * been verified to be in the swap cache and locked.
+ * It will never put the page into the free list,
+ * the caller has a reference on the page.
+ */
+void delete_from_swap_cache(struct page *page)
+{
+        swp_entry_t entry;
+
+        BUG_ON(!PageSwapCache(page));
+        BUG_ON(!PageLocked(page));
+        BUG_ON(PageWriteback(page));
+        BUG_ON(PagePrivate(page));
+  
+        entry.val = page->private;
+
+        write_lock_irq(&swapper_space.tree_lock);
+        __delete_from_swap_cache(page);
+        write_unlock_irq(&swapper_space.tree_lock);
+
+        swap_free(entry);
+        page_cache_release(page);
+}
+
+/*
+ * Strange swizzling function only for use by shmem_writepage
+ */
+int move_to_swap_cache(struct page *page, swp_entry_t entry)
+{
+        int err = __add_to_swap_cache(page, entry, GFP_ATOMIC);
+        if (!err) {
+                remove_from_page_cache(page);
+                page_cache_release(page);       /* pagecache ref */
+                if (!swap_duplicate(entry))
+                        BUG();
+                SetPageDirty(page);
+                INC_CACHE_INFO(add_total);
+        } else if (err == -EEXIST)
+                INC_CACHE_INFO(exist_race);
+        return err;
+}
+
+/*
+ * Strange swizzling function for shmem_getpage (and shmem_unuse)
+ */
+int move_from_swap_cache(struct page *page, unsigned long index,
+                struct address_space *mapping)
+{
+        int err = add_to_page_cache(page, mapping, index, GFP_ATOMIC);
+        if (!err) {
+                delete_from_swap_cache(page);
+                /* shift page from clean_pages to dirty_pages list */
+                ClearPageDirty(page);
+                set_page_dirty(page);
+        }
+        return err;
+}
+
+/* 
+ * If we are the only user, then try to free up the swap cache. 
+ * 
+ * Its ok to check for PageSwapCache without the page lock
+ * here because we are going to recheck again inside 
+ * exclusive_swap_page() _with_ the lock. 
+ *                                      - Marcelo
+ */
+static inline void free_swap_cache(struct page *page)
+{
+        if (PageSwapCache(page) && !TestSetPageLocked(page)) {
+                remove_exclusive_swap_page(page);
+                unlock_page(page);
+        }
+}
+
+/* 
+ * Perform a free_page(), also freeing any swap cache associated with
+ * this page if it is the last user of the page. Can not do a lock_page,
+ * as we are holding the page_table_lock spinlock.
+ */
+void free_page_and_swap_cache(struct page *page)
+{
+        free_swap_cache(page);
+        page_cache_release(page);
+}
+
+/*
+ * Passed an array of pages, drop them all from swapcache and then release
+ * them.  They are removed from the LRU and freed if this is their last use.
+ */
+void free_pages_and_swap_cache(struct page **pages, int nr)
+{
+        int chunk = 16;
+        struct page **pagep = pages;
+
+        lru_add_drain();
+        while (nr) {
+                int todo = min(chunk, nr);
+                int i;
+
+                for (i = 0; i < todo; i++)
+                        free_swap_cache(pagep[i]);
+                release_pages(pagep, todo, 0);
+                pagep += todo;
+                nr -= todo;
+        }
+}
+
+/*
+ * Lookup a swap entry in the swap cache. A found page will be returned
+ * unlocked and with its refcount incremented - we rely on the kernel
+ * lock getting page table operations atomic even if we drop the page
+ * lock before returning.
+ */
+struct page * lookup_swap_cache(swp_entry_t entry)
+{
+        struct page *page;
+
+        page = find_get_page(&swapper_space, entry.val);
+
+        if (page)
+                INC_CACHE_INFO(find_success);
+
+        INC_CACHE_INFO(find_total);
+        return page;
+}
+
+/* 
+ * Locate a page of swap in physical memory, reserving swap cache space
+ * and reading the disk if it is not already cached.
+ * A failure return means that either the page allocation failed or that
+ * the swap entry is no longer in use.
+ */
+struct page *read_swap_cache_async(swp_entry_t entry,
+                        struct vm_area_struct *vma, unsigned long addr)
+{
+        struct page *found_page, *new_page = NULL;
+        int err;
+
+        do {
+                /*
+                 * First check the swap cache.  Since this is normally
+                 * called after lookup_swap_cache() failed, re-calling
+                 * that would confuse statistics.
+                 */
+                found_page = find_get_page(&swapper_space, entry.val);
+                if (found_page)
+                        break;
+
+                /*
+                 * Get a new page to read into from swap.
+                 */
+                if (!new_page) {
+                        new_page = alloc_page_vma(GFP_HIGHUSER, vma, addr);
+                        if (!new_page)
+                                break;          /* Out of memory */
+                }
+
+                /*
+                 * Associate the page with swap entry in the swap cache.
+                 * May fail (-ENOENT) if swap entry has been freed since
+                 * our caller observed it.  May fail (-EEXIST) if there
+                 * is already a page associated with this entry in the
+                 * swap cache: added by a racing read_swap_cache_async,
+                 * or by try_to_swap_out (or shmem_writepage) re-using
+                 * the just freed swap entry for an existing page.
+                 * May fail (-ENOMEM) if radix-tree node allocation failed.
+                 */
+                err = add_to_swap_cache(new_page, entry);
+                if (!err) {
+                        /*
+                         * Initiate read into locked page and return.
+                         */
+                        lru_cache_add_active(new_page);
+                        swap_readpage(NULL, new_page);
+                        return new_page;
+                }
+        } while (err != -ENOENT && err != -ENOMEM);
+
+        if (new_page)
+                page_cache_release(new_page);
+        return found_page;
+}