int test_clear_page_writeback(struct page *page)
{
	struct address_space *mapping = page_mapping(page);
	int ret;

	if (mapping) {
		struct backing_dev_info *bdi = mapping->backing_dev_info;
		unsigned long flags;

		spin_lock_irqsave(&mapping->tree_lock, flags);
		ret = TestClearPageWriteback(page);
		if (ret) {
			radix_tree_tag_clear(&mapping->page_tree,
						page_index(page),
						PAGECACHE_TAG_WRITEBACK);
			if (bdi_cap_account_writeback(bdi)) {
				__dec_bdi_stat(bdi, BDI_WRITEBACK);
				__bdi_writeout_inc(bdi);
			}
		}
		spin_unlock_irqrestore(&mapping->tree_lock, flags);
	} else {
		ret = TestClearPageWriteback(page);
	}
	if (ret)
		dec_zone_page_state(page, NR_WRITEBACK);
	return ret;
}

/*
 * Clear a page's dirty flag, while caring for dirty memory accounting.
 * Returns true if the page was previously dirty.
 *
 * This is for preparing to put the page under writeout.  We leave the page
 * tagged as dirty in the radix tree so that a concurrent write-for-sync
 * can discover it via a PAGECACHE_TAG_DIRTY walk.  The ->writepage
 * implementation will run either set_page_writeback() or set_page_dirty(),
 * at which stage we bring the page's dirty flag and radix-tree dirty tag
 * back into sync.
 *
 * This incoherency between the page's dirty flag and radix-tree tag is
 * unfortunate, but it only exists while the page is locked.
 */
static int tux3_clear_page_dirty_for_io(struct page *page)
{
	if(DEBUG_MODE_K==1)
	{
		printf("\t\t\t\t%25s[K]  %25s  %4d  #in\n",__FILE__,__func__,__LINE__);
	}
	struct address_space *mapping = page->mapping;

	BUG_ON(!PageLocked(page));

	if (mapping && mapping_cap_account_dirty(mapping)) {
		/*
		 * Yes, Virginia, this is indeed insane.
		 *
		 * We use this sequence to make sure that
		 *  (a) we account for dirty stats properly
		 *  (b) we tell the low-level filesystem to
		 *      mark the whole page dirty if it was
		 *      dirty in a pagetable. Only to then
		 *  (c) clean the page again and return 1 to
		 *      cause the writeback.
		 *
		 * This way we avoid all nasty races with the
		 * dirty bit in multiple places and clearing
		 * them concurrently from different threads.
		 *
		 * Note! Normally the "set_page_dirty(page)"
		 * has no effect on the actual dirty bit - since
		 * that will already usually be set. But we
		 * need the side effects, and it can help us
		 * avoid races.
		 *
		 * We basically use the page "master dirty bit"
		 * as a serialization point for all the different
		 * threads doing their things.
		 */
		/* If PageForked(), don't touch PTE and don't dirty */
		if (!PageForked(page) && page_mkclean(page))
			set_page_dirty(page);
		/*
		 * We carefully synchronise fault handlers against
		 * installing a dirty pte and marking the page dirty
		 * at this point. We do this by having them hold the
		 * page lock at some point after installing their
		 * pte, but before marking the page dirty.
		 * Pages are always locked coming in here, so we get
		 * the desired exclusion. See mm/memory.c:do_wp_page()
		 * for more comments.
		 */
		if (TestClearPageDirty(page)) {
			dec_zone_page_state(page, NR_FILE_DIRTY);
			dec_bdi_stat(mapping->backing_dev_info,
					BDI_RECLAIMABLE);
			return 1;
		}
		return 0;
	}
	return TestClearPageDirty(page);
}

static int
nfs_clear_request_commit(struct nfs_page *req)
{
	struct page *page = req->wb_page;

	if (test_and_clear_bit(PG_CLEAN, &(req)->wb_flags)) {
		dec_zone_page_state(page, NR_UNSTABLE_NFS);
		dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE);
		return 1;
	}
	return 0;
}

/*
 * This cancels just the dirty bit on the kernel page itself, it
 * does NOT actually remove dirty bits on any mmap's that may be
 * around. It also leaves the page tagged dirty, so any sync
 * activity will still find it on the dirty lists, and in particular,
 * clear_page_dirty_for_io() will still look at the dirty bits in
 * the VM.
 *
 * Doing this should *normally* only ever be done when a page
 * is truncated, and is not actually mapped anywhere at all. However,
 * fs/buffer.c does this when it notices that somebody has cleaned
 * out all the buffers on a page without actually doing it through
 * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
 */
void cancel_dirty_page(struct page *page, unsigned int account_size)
{
	if (TestClearPageDirty(page)) {
		struct address_space *mapping = page->mapping;
		if (mapping && mapping_cap_account_dirty(mapping)) {
			dec_zone_page_state(page, NR_FILE_DIRTY);
			dec_bdi_stat(mapping->backing_dev_info,
					BDI_RECLAIMABLE);
			if (account_size)
				task_io_account_cancelled_write(account_size);
		}
	}
}

static void bounce_end_io(struct bio *bio, mempool_t *pool)
{
	struct bio *bio_orig = bio->bi_private;
	struct bio_vec *bvec, *org_vec;
	int i;

	/*
	 * free up bounce indirect pages used
	 */
	bio_for_each_segment_all(bvec, bio, i) {
		org_vec = bio_orig->bi_io_vec + i;
		if (bvec->bv_page == org_vec->bv_page)
			continue;

		dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
		mempool_free(bvec->bv_page, pool);
	}

/*
 * Clear a page's dirty flag, while caring for dirty memory accounting.
 * Returns true if the page was previously dirty.
 *
 * This is for preparing to put the page under writeout.  We leave the page
 * tagged as dirty in the radix tree so that a concurrent write-for-sync
 * can discover it via a PAGECACHE_TAG_DIRTY walk.  The ->writepage
 * implementation will run either set_page_writeback() or set_page_dirty(),
 * at which stage we bring the page's dirty flag and radix-tree dirty tag
 * back into sync.
 *
 * This incoherency between the page's dirty flag and radix-tree tag is
 * unfortunate, but it only exists while the page is locked.
 */
int clear_page_dirty_for_io(struct page *page)
{
	struct address_space *mapping = page_mapping(page);

	if (mapping && mapping_cap_account_dirty(mapping)) {
		/*
		 * Yes, Virginia, this is indeed insane.
		 *
		 * We use this sequence to make sure that
		 *  (a) we account for dirty stats properly
		 *  (b) we tell the low-level filesystem to
		 *      mark the whole page dirty if it was
		 *      dirty in a pagetable. Only to then
		 *  (c) clean the page again and return 1 to
		 *      cause the writeback.
		 *
		 * This way we avoid all nasty races with the
		 * dirty bit in multiple places and clearing
		 * them concurrently from different threads.
		 *
		 * Note! Normally the "set_page_dirty(page)"
		 * has no effect on the actual dirty bit - since
		 * that will already usually be set. But we
		 * need the side effects, and it can help us
		 * avoid races.
		 *
		 * We basically use the page "master dirty bit"
		 * as a serialization point for all the different
		 * threads doing their things.
		 *
		 * FIXME! We still have a race here: if somebody
		 * adds the page back to the page tables in
		 * between the "page_mkclean()" and the "TestClearPageDirty()",
		 * we might have it mapped without the dirty bit set.
		 */
		if (page_mkclean(page))
			set_page_dirty(page);
		if (TestClearPageDirty(page)) {
			dec_zone_page_state(page, NR_FILE_DIRTY);
			return 1;
		}
		return 0;
	}
	return TestClearPageDirty(page);
}

/*
 * Put previously isolated pages back onto the appropriate lists
 * from where they were once taken off for compaction/migration.
 *
 * This function shall be used whenever the isolated pageset has been
 * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
 * and isolate_huge_page().
 */
void putback_movable_pages(struct list_head *l)
{
	struct page *page;
	struct page *page2;

	list_for_each_entry_safe(page, page2, l, lru) {
		if (unlikely(PageHuge(page))) {
			putback_active_hugepage(page);
			continue;
		}
		list_del(&page->lru);
		dec_zone_page_state(page, NR_ISOLATED_ANON +
				page_is_file_cache(page));
		if (unlikely(isolated_balloon_page(page)))
			balloon_page_putback(page);
		else
			putback_lru_page(page);
	}
}

void destroy_context_skas(struct mm_struct *mm)
{
	struct mmu_context_skas *mmu = &mm->context.skas;

	if(proc_mm)
		os_close_file(mmu->id.u.mm_fd);
	else
		os_kill_ptraced_process(mmu->id.u.pid, 1);

	if(!proc_mm || !ptrace_faultinfo){
		free_page(mmu->id.stack);
		pte_lock_deinit(virt_to_page(mmu->last_page_table));
		pte_free_kernel((pte_t *) mmu->last_page_table);
		dec_zone_page_state(virt_to_page(mmu->last_page_table), NR_PAGETABLE);
#ifdef CONFIG_3_LEVEL_PGTABLES
		pmd_free((pmd_t *) mmu->last_pmd);
#endif
	}
}

int test_clear_page_writeback(struct page *page)
{
	struct address_space *mapping = page_mapping(page);
	int ret;

	if (mapping) {
		unsigned long flags;

		write_lock_irqsave(&mapping->tree_lock, flags);
		ret = TestClearPageWriteback(page);
		if (ret)
			radix_tree_tag_clear(&mapping->page_tree,
						page_index(page),
						PAGECACHE_TAG_WRITEBACK);
		write_unlock_irqrestore(&mapping->tree_lock, flags);
	} else {
		ret = TestClearPageWriteback(page);
	}
	if (ret)
		dec_zone_page_state(page, NR_WRITEBACK);
	return ret;
}

/*
 * Set up the argument/result storage required for the RPC call.
 */
static int nfs_commit_rpcsetup(struct list_head *head,
		struct nfs_write_data *data,
		int how)
{
	struct nfs_page *first = nfs_list_entry(head->next);
	struct inode *inode = first->wb_context->path.dentry->d_inode;
	int flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
	int priority = flush_task_priority(how);
	struct rpc_task *task;
	struct rpc_message msg = {
		.rpc_argp = &data->args,
		.rpc_resp = &data->res,
		.rpc_cred = first->wb_context->cred,
	};
	struct rpc_task_setup task_setup_data = {
		.task = &data->task,
		.rpc_client = NFS_CLIENT(inode),
		.rpc_message = &msg,
		.callback_ops = &nfs_commit_ops,
		.callback_data = data,
		.workqueue = nfsiod_workqueue,
		.flags = flags,
		.priority = priority,
	};

	/* Set up the RPC argument and reply structs
	 * NB: take care not to mess about with data->commit et al. */

	list_splice_init(head, &data->pages);

	data->inode	  = inode;
	data->cred	  = msg.rpc_cred;

	data->args.fh     = NFS_FH(data->inode);
	/* Note: we always request a commit of the entire inode */
	data->args.offset = 0;
	data->args.count  = 0;
	data->args.context = get_nfs_open_context(first->wb_context);
	data->res.count   = 0;
	data->res.fattr   = &data->fattr;
	data->res.verf    = &data->verf;
	nfs_fattr_init(&data->fattr);

	/* Set up the initial task struct.  */
	NFS_PROTO(inode)->commit_setup(data, &msg);

	dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);

	task = rpc_run_task(&task_setup_data);
	if (IS_ERR(task))
		return PTR_ERR(task);
	rpc_put_task(task);
	return 0;
}

/*
 * Commit dirty pages
 */
static int
nfs_commit_list(struct inode *inode, struct list_head *head, int how)
{
	struct nfs_write_data	*data;
	struct nfs_page         *req;

	data = nfs_commitdata_alloc();

	if (!data)
		goto out_bad;

	/* Set up the argument struct */
	return nfs_commit_rpcsetup(head, data, how);
 out_bad:
	while (!list_empty(head)) {
		req = nfs_list_entry(head->next);
		nfs_list_remove_request(req);
		nfs_mark_request_commit(req);
		dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
		dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
				BDI_RECLAIMABLE);
		nfs_clear_page_tag_locked(req);
	}
	return -ENOMEM;
}

/*
 * COMMIT call returned
 */
static void nfs_commit_done(struct rpc_task *task, void *calldata)
{
	struct nfs_write_data	*data = calldata;

        dprintk("NFS: %5u nfs_commit_done (status %d)\n",
                                task->tk_pid, task->tk_status);

	/* Call the NFS version-specific code */
	if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
		return;
//.........这里部分代码省略.........