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