Linux-2.6.12-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!
diff --git a/mm/swap_state.c b/mm/swap_state.c
new file mode 100644
index 0000000..a063a902
--- /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;
+}