C++ page_cache_release函数代码示例

/* mm->page_table_lock is held. mmap_sem is not held */
static inline int try_to_swap_out(struct mm_struct * mm, struct vm_area_struct* vma, unsigned long address, pte_t * page_table, struct page *page, zone_t * classzone)
{
	pte_t pte;
	swp_entry_t entry;

	/* Don't look at this pte if it's been accessed recently. */
	if ((vma->vm_flags & VM_LOCKED) || ptep_test_and_clear_young(page_table)) {
		mark_page_accessed(page);
		return 0;
	}

	/* Don't bother unmapping pages that are active */
	if (PageActive(page))
		return 0;

	/* Don't bother replenishing zones not under pressure.. */
	if (!memclass(page_zone(page), classzone))
		return 0;

	if (TryLockPage(page))
		return 0;

	/* From this point on, the odds are that we're going to
	 * nuke this pte, so read and clear the pte.  This hook
	 * is needed on CPUs which update the accessed and dirty
	 * bits in hardware.
	 */
	flush_cache_page(vma, address);
	pte = ptep_get_and_clear(page_table);
	flush_tlb_page(vma, address);

	if (pte_dirty(pte))
		set_page_dirty(page);

	/*
	 * Is the page already in the swap cache? If so, then
	 * we can just drop our reference to it without doing
	 * any IO - it's already up-to-date on disk.
	 */
	if (PageSwapCache(page)) {
		entry.val = page->index;
		swap_duplicate(entry);
set_swap_pte:
		set_pte(page_table, swp_entry_to_pte(entry));
drop_pte:
		mm->rss--;
		UnlockPage(page);
		{
			int freeable = page_count(page) - !!page->buffers <= 2;
			page_cache_release(page);
			return freeable;
		}
	}

	/*
	 * Is it a clean page? Then it must be recoverable
	 * by just paging it in again, and we can just drop
	 * it..  or if it's dirty but has backing store,
	 * just mark the page dirty and drop it.
	 *
	 * However, this won't actually free any real
	 * memory, as the page will just be in the page cache
	 * somewhere, and as such we should just continue
	 * our scan.
	 *
	 * Basically, this just makes it possible for us to do
	 * some real work in the future in "refill_inactive()".
	 */
	if (page->mapping)
		goto drop_pte;
	if (!PageDirty(page))
		goto drop_pte;

	/*
	 * Anonymous buffercache pages can be left behind by
	 * concurrent truncate and pagefault.
	 */
	if (page->buffers)
		goto preserve;

	/*
	 * This is a dirty, swappable page.  First of all,
	 * get a suitable swap entry for it, and make sure
	 * we have the swap cache set up to associate the
	 * page with that swap entry.
	 */
	for (;;) {
		entry = get_swap_page();
		if (!entry.val)
			break;
		/* Add it to the swap cache and mark it dirty
		 * (adding to the page cache will clear the dirty
		 * and uptodate bits, so we need to do it again)
		 */
		if (add_to_swap_cache(page, entry) == 0) {
			SetPageUptodate(page);
			set_page_dirty(page);
			goto set_swap_pte;
		}
//.........这里部分代码省略.........

static int nilfs_rename(struct inode *old_dir, struct dentry *old_dentry,
			struct inode *new_dir,	struct dentry *new_dentry)
{
	struct inode *old_inode = d_inode(old_dentry);
	struct inode *new_inode = d_inode(new_dentry);
	struct page *dir_page = NULL;
	struct nilfs_dir_entry *dir_de = NULL;
	struct page *old_page;
	struct nilfs_dir_entry *old_de;
	struct nilfs_transaction_info ti;
	int err;

	err = nilfs_transaction_begin(old_dir->i_sb, &ti, 1);
	if (unlikely(err))
		return err;

	err = -ENOENT;
	old_de = nilfs_find_entry(old_dir, &old_dentry->d_name, &old_page);
	if (!old_de)
		goto out;

	if (S_ISDIR(old_inode->i_mode)) {
		err = -EIO;
		dir_de = nilfs_dotdot(old_inode, &dir_page);
		if (!dir_de)
			goto out_old;
	}

	if (new_inode) {
		struct page *new_page;
		struct nilfs_dir_entry *new_de;

		err = -ENOTEMPTY;
		if (dir_de && !nilfs_empty_dir(new_inode))
			goto out_dir;

		err = -ENOENT;
		new_de = nilfs_find_entry(new_dir, &new_dentry->d_name, &new_page);
		if (!new_de)
			goto out_dir;
		nilfs_set_link(new_dir, new_de, new_page, old_inode);
		nilfs_mark_inode_dirty(new_dir);
		new_inode->i_ctime = CURRENT_TIME;
		if (dir_de)
			drop_nlink(new_inode);
		drop_nlink(new_inode);
		nilfs_mark_inode_dirty(new_inode);
	} else {
		err = nilfs_add_link(new_dentry, old_inode);
		if (err)
			goto out_dir;
		if (dir_de) {
			inc_nlink(new_dir);
			nilfs_mark_inode_dirty(new_dir);
		}
	}

	/*
	 * Like most other Unix systems, set the ctime for inodes on a
	 * rename.
	 */
	old_inode->i_ctime = CURRENT_TIME;

	nilfs_delete_entry(old_de, old_page);

	if (dir_de) {
		nilfs_set_link(old_inode, dir_de, dir_page, new_dir);
		drop_nlink(old_dir);
	}
	nilfs_mark_inode_dirty(old_dir);
	nilfs_mark_inode_dirty(old_inode);

	err = nilfs_transaction_commit(old_dir->i_sb);
	return err;

out_dir:
	if (dir_de) {
		kunmap(dir_page);
		page_cache_release(dir_page);
	}
out_old:
	kunmap(old_page);
	page_cache_release(old_page);
out:
	nilfs_transaction_abort(old_dir->i_sb);
	return err;
}

/*
 * Attempts to free an entry by adding a page to the swap cache,
 * decompressing the entry data into the page, and issuing a
 * bio write to write the page back to the swap device.
 *
 * This can be thought of as a "resumed writeback" of the page
 * to the swap device.  We are basically resuming the same swap
 * writeback path that was intercepted with the frontswap_store()
 * in the first place.  After the page has been decompressed into
 * the swap cache, the compressed version stored by zswap can be
 * freed.
 */
static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
{
	struct zswap_header *zhdr;
	swp_entry_t swpentry;
	struct zswap_tree *tree;
	pgoff_t offset;
	struct zswap_entry *entry;
	struct page *page;
	u8 *src, *dst;
	unsigned int dlen;
	int ret;
	struct writeback_control wbc = {
		.sync_mode = WB_SYNC_NONE,
	};

	/* extract swpentry from data */
	zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
	swpentry = zhdr->swpentry; /* here */
	zpool_unmap_handle(pool, handle);
	tree = zswap_trees[swp_type(swpentry)];
	offset = swp_offset(swpentry);

	/* find and ref zswap entry */
	spin_lock(&tree->lock);
	entry = zswap_entry_find_get(&tree->rbroot, offset);
	if (!entry) {
		/* entry was invalidated */
		spin_unlock(&tree->lock);
		return 0;
	}
	spin_unlock(&tree->lock);
	BUG_ON(offset != entry->offset);

	/* try to allocate swap cache page */
	switch (zswap_get_swap_cache_page(swpentry, &page)) {
	case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
		ret = -ENOMEM;
		goto fail;

	case ZSWAP_SWAPCACHE_EXIST:
		/* page is already in the swap cache, ignore for now */
		page_cache_release(page);
		ret = -EEXIST;
		goto fail;

	case ZSWAP_SWAPCACHE_NEW: /* page is locked */
		/* decompress */
		dlen = PAGE_SIZE;
		src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
				ZPOOL_MM_RO) + sizeof(struct zswap_header);
		dst = kmap_atomic(page);
		ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src,
				entry->length, dst, &dlen);
		kunmap_atomic(dst);
		zpool_unmap_handle(zswap_pool, entry->handle);
		BUG_ON(ret);
		BUG_ON(dlen != PAGE_SIZE);

		/* page is up to date */
		SetPageUptodate(page);
	}

	/* move it to the tail of the inactive list after end_writeback */
	SetPageReclaim(page);

	/* start writeback */
	__swap_writepage(page, &wbc, end_swap_bio_write);
	page_cache_release(page);
	zswap_written_back_pages++;

	spin_lock(&tree->lock);
	/* drop local reference */
	zswap_entry_put(tree, entry);

	/*
	* There are two possible situations for entry here:
	* (1) refcount is 1(normal case),  entry is valid and on the tree
	* (2) refcount is 0, entry is freed and not on the tree
	*     because invalidate happened during writeback
	*  search the tree and free the entry if find entry
	*/
	if (entry == zswap_rb_search(&tree->rbroot, offset))
		zswap_entry_put(tree, entry);
	spin_unlock(&tree->lock);

	goto end;

	/*
//.........这里部分代码省略.........

static int mcopy_atomic_pte(struct mm_struct *dst_mm,
			    pmd_t *dst_pmd,
			    struct vm_area_struct *dst_vma,
			    unsigned long dst_addr,
			    unsigned long src_addr,
			    struct page **pagep)
{
	struct mem_cgroup *memcg;
	pte_t _dst_pte, *dst_pte;
	spinlock_t *ptl;
	void *page_kaddr;
	int ret;
	struct page *page;

	if (!*pagep) {
		ret = -ENOMEM;
		page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr);
		if (!page)
			goto out;

		page_kaddr = kmap_atomic(page);
		ret = copy_from_user(page_kaddr,
				     (const void __user *) src_addr,
				     PAGE_SIZE);
		kunmap_atomic(page_kaddr);

		/* fallback to copy_from_user outside mmap_sem */
		if (unlikely(ret)) {
			ret = -EFAULT;
			*pagep = page;
			/* don't free the page */
			goto out;
		}
	} else {
		page = *pagep;
		*pagep = NULL;
	}

	/*
	 * The memory barrier inside __SetPageUptodate makes sure that
	 * preceeding stores to the page contents become visible before
	 * the set_pte_at() write.
	 */
	__SetPageUptodate(page);

	ret = -ENOMEM;
	if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg, false))
		goto out_release;

	_dst_pte = mk_pte(page, dst_vma->vm_page_prot);
	if (dst_vma->vm_flags & VM_WRITE)
		_dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));

	ret = -EEXIST;
	dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
	if (!pte_none(*dst_pte))
		goto out_release_uncharge_unlock;

	inc_mm_counter(dst_mm, MM_ANONPAGES);
	page_add_new_anon_rmap(page, dst_vma, dst_addr, false);
	mem_cgroup_commit_charge(page, memcg, false, false);
	lru_cache_add_active_or_unevictable(page, dst_vma);

	set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(dst_vma, dst_addr, dst_pte);

	pte_unmap_unlock(dst_pte, ptl);
	ret = 0;
out:
	return ret;
out_release_uncharge_unlock:
	pte_unmap_unlock(dst_pte, ptl);
	mem_cgroup_cancel_charge(page, memcg, false);
out_release:
	page_cache_release(page);
	goto out;
}

/*
 * Prepare the write for the inline data.
 * If the the data can be written into the inode, we just read
 * the page and make it uptodate, and start the journal.
 * Otherwise read the page, makes it dirty so that it can be
 * handle in writepages(the i_disksize update is left to the
 * normal ext4_da_write_end).
 */
int ext4_da_write_inline_data_begin(struct address_space *mapping,
				    struct inode *inode,
				    loff_t pos, unsigned len,
				    unsigned flags,
				    struct page **pagep,
				    void **fsdata)
{
	int ret, inline_size;
	handle_t *handle;
	struct page *page;
	struct ext4_iloc iloc;

	ret = ext4_get_inode_loc(inode, &iloc);
	if (ret)
		return ret;

	handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		handle = NULL;
		goto out;
	}

	inline_size = ext4_get_max_inline_size(inode);

	ret = -ENOSPC;
	if (inline_size >= pos + len) {
		ret = ext4_prepare_inline_data(handle, inode, pos + len);
		if (ret && ret != -ENOSPC)
			goto out;
	}

	if (ret == -ENOSPC) {
		ret = ext4_da_convert_inline_data_to_extent(mapping,
							    inode,
							    flags,
							    fsdata);
		goto out;
	}

	/*
	 * We cannot recurse into the filesystem as the transaction
	 * is already started.
	 */
	flags |= AOP_FLAG_NOFS;

	page = grab_cache_page_write_begin(mapping, 0, flags);
	if (!page) {
		ret = -ENOMEM;
		goto out;
	}

	down_read(&EXT4_I(inode)->xattr_sem);
	if (!ext4_has_inline_data(inode)) {
		ret = 0;
		goto out_release_page;
	}

	if (!PageUptodate(page)) {
		ret = ext4_read_inline_page(inode, page);
		if (ret < 0)
			goto out_release_page;
	}

	up_read(&EXT4_I(inode)->xattr_sem);
	*pagep = page;
	handle = NULL;
	brelse(iloc.bh);
	return 1;
out_release_page:
	up_read(&EXT4_I(inode)->xattr_sem);
	unlock_page(page);
	page_cache_release(page);
out:
	if (handle)
		ext4_journal_stop(handle);
	brelse(iloc.bh);
	return ret;
}

int rtR0MemObjNativeLockUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess, RTR0PROCESS R0Process)
{
    const int cPages = cb >> PAGE_SHIFT;
    struct task_struct *pTask = rtR0ProcessToLinuxTask(R0Process);
    struct vm_area_struct **papVMAs;
    PRTR0MEMOBJLNX pMemLnx;
    int rc = VERR_NO_MEMORY;
    NOREF(fAccess);

    /*
     * Check for valid task and size overflows.
     */
    if (!pTask)
        return VERR_NOT_SUPPORTED;
    if (((size_t)cPages << PAGE_SHIFT) != cb)
        return VERR_OUT_OF_RANGE;

    /*
     * Allocate the memory object and a temporary buffer for the VMAs.
     */
    pMemLnx = (PRTR0MEMOBJLNX)rtR0MemObjNew(RT_OFFSETOF(RTR0MEMOBJLNX, apPages[cPages]), RTR0MEMOBJTYPE_LOCK, (void *)R3Ptr, cb);
    if (!pMemLnx)
        return VERR_NO_MEMORY;

    papVMAs = (struct vm_area_struct **)RTMemAlloc(sizeof(*papVMAs) * cPages);
    if (papVMAs)
    {
        down_read(&pTask->mm->mmap_sem);

        /*
         * Get user pages.
         */
        rc = get_user_pages(pTask,                  /* Task for fault acounting. */
                            pTask->mm,              /* Whose pages. */
                            R3Ptr,                  /* Where from. */
                            cPages,                 /* How many pages. */
                            1,                      /* Write to memory. */
                            0,                      /* force. */
                            &pMemLnx->apPages[0],   /* Page array. */
                            papVMAs);               /* vmas */
        if (rc == cPages)
        {
            /*
             * Flush dcache (required?), protect against fork and _really_ pin the page
             * table entries. get_user_pages() will protect against swapping out the
             * pages but it will NOT protect against removing page table entries. This
             * can be achieved with
             *   - using mlock / mmap(..., MAP_LOCKED, ...) from userland. This requires
             *     an appropriate limit set up with setrlimit(..., RLIMIT_MEMLOCK, ...).
             *     Usual Linux distributions support only a limited size of locked pages
             *     (e.g. 32KB).
             *   - setting the PageReserved bit (as we do in rtR0MemObjLinuxAllocPages()
             *     or by
             *   - setting the VM_LOCKED flag. This is the same as doing mlock() without
             *     a range check.
             */
            /** @todo The Linux fork() protection will require more work if this API
             * is to be used for anything but locking VM pages. */
            while (rc-- > 0)
            {
                flush_dcache_page(pMemLnx->apPages[rc]);
                papVMAs[rc]->vm_flags |= (VM_DONTCOPY | VM_LOCKED);
            }

            up_read(&pTask->mm->mmap_sem);

            RTMemFree(papVMAs);

            pMemLnx->Core.u.Lock.R0Process = R0Process;
            pMemLnx->cPages = cPages;
            Assert(!pMemLnx->fMappedToRing0);
            *ppMem = &pMemLnx->Core;

            return VINF_SUCCESS;
        }

        /*
         * Failed - we need to unlock any pages that we succeeded to lock.
         */
        while (rc-- > 0)
        {
            if (!PageReserved(pMemLnx->apPages[rc]))
                SetPageDirty(pMemLnx->apPages[rc]);
            page_cache_release(pMemLnx->apPages[rc]);
        }

        up_read(&pTask->mm->mmap_sem);

        RTMemFree(papVMAs);
        rc = VERR_LOCK_FAILED;
    }

    rtR0MemObjDelete(&pMemLnx->Core);
    return rc;
}

int j4fs_write_begin(struct file *filp, struct address_space *mapping,
				loff_t pos, unsigned len, unsigned flags,
				struct page **pagep, void **fsdata)
{
	struct page *pg = NULL;
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	uint32_t offset = pos & (PAGE_CACHE_SIZE - 1);
	uint32_t to = offset + len;

	int ret = 0;
	int space_held = 0;

	if(j4fs_panic==1) {
		T(J4FS_TRACE_ALWAYS,("%s %d: j4fs panic\n",__FUNCTION__,__LINE__));
		return -ENOSPC;
	}

	T(J4FS_TRACE_FS, ("start j4fs_write_begin\n"));

	if(to>PAGE_CACHE_SIZE) {
		T(J4FS_TRACE_ALWAYS,("%s %d: page size overflow(pos,index,offset,len,to)=(%d,%d,%d,%d,%d)\n",__FUNCTION__,__LINE__,pos,index,offset,len,to));
		j4fs_panic("page size overflow");
		return -ENOSPC;
	}

	/* Get a page */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 28)
	pg = grab_cache_page_write_begin(mapping, index, flags);
#else
	pg = __grab_cache_page(mapping, index);
#endif

	*pagep = pg;
	if (!pg) {
		ret =  -ENOMEM;
		goto out;
	}

	/* Get fs space */
	space_held = j4fs_hold_space(PAGE_CACHE_SIZE);

	if (!space_held) {
		ret = -ENOSPC;
		goto out;
	}

	/* Update page if required */
	if (!Page_Uptodate(pg) && (offset || to < PAGE_CACHE_SIZE))
		ret = j4fs_readpage_nolock(filp, pg);

	if (ret)
		goto out;

	/* Happy path return */
	T(J4FS_TRACE_FS, ("end j4fs_write_begin - ok\n"));

	return 0;

out:
	T(J4FS_TRACE_FS, ("end j4fs_write_begin fail returning %d\n", ret));

	if (pg) {
		unlock_page(pg);
		page_cache_release(pg);
	}
	return ret;
}

/* 
 * 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, gfp_t gfp_mask,
			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_mask, vma, addr);
			if (!new_page)
				break;		/* Out of memory */
		}

		/*
		 * call radix_tree_preload() while we can wait.
		 */
		err = radix_tree_preload(gfp_mask & GFP_KERNEL);
		if (err)
			break;

		/*
		 * Swap entry may have been freed since our caller observed it.
		 */
		err = swapcache_prepare(entry);
		if (err == -EEXIST) {
			radix_tree_preload_end();
			/*
			 * We might race against get_swap_page() and stumble
			 * across a SWAP_HAS_CACHE swap_map entry whose page
			 * has not been brought into the swapcache yet, while
			 * the other end is scheduled away waiting on discard
			 * I/O completion at scan_swap_map().
			 *
			 * In order to avoid turning this transitory state
			 * into a permanent loop around this -EEXIST case
			 * if !CONFIG_PREEMPT and the I/O completion happens
			 * to be waiting on the CPU waitqueue where we are now
			 * busy looping, we just conditionally invoke the
			 * scheduler here, if there are some more important
			 * tasks to run.
			 */
			cond_resched();
			continue;
		}
		if (err) {		/* swp entry is obsolete ? */
			radix_tree_preload_end();
			break;
		}

		/* May fail (-ENOMEM) if radix-tree node allocation failed. */
		__set_page_locked(new_page);
		SetPageSwapBacked(new_page);
		err = __add_to_swap_cache(new_page, entry);
		if (likely(!err)) {
			radix_tree_preload_end();
			/*
			 * Initiate read into locked page and return.
			 */
			lru_cache_add_anon(new_page);
			swap_readpage(new_page);
			return new_page;
		}
		radix_tree_preload_end();
		ClearPageSwapBacked(new_page);
		__clear_page_locked(new_page);
		/*
		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
		 * clear SWAP_HAS_CACHE flag.
		 */
		swapcache_free(entry, NULL);
	} while (err != -ENOMEM);

	if (new_page)
		page_cache_release(new_page);
	return found_page;
}

int rtR0MemObjNativeFree(RTR0MEMOBJ pMem)
{
    PRTR0MEMOBJLNX pMemLnx = (PRTR0MEMOBJLNX)pMem;

    /*
     * Release any memory that we've allocated or locked.
     */
    switch (pMemLnx->Core.enmType)
    {
        case RTR0MEMOBJTYPE_LOW:
        case RTR0MEMOBJTYPE_PAGE:
        case RTR0MEMOBJTYPE_CONT:
        case RTR0MEMOBJTYPE_PHYS:
        case RTR0MEMOBJTYPE_PHYS_NC:
            rtR0MemObjLinuxVUnmap(pMemLnx);
            rtR0MemObjLinuxFreePages(pMemLnx);
            break;

        case RTR0MEMOBJTYPE_LOCK:
            if (pMemLnx->Core.u.Lock.R0Process != NIL_RTR0PROCESS)
            {
                struct task_struct *pTask = rtR0ProcessToLinuxTask(pMemLnx->Core.u.Lock.R0Process);
                size_t              iPage;
                Assert(pTask);
                if (pTask && pTask->mm)
                    down_read(&pTask->mm->mmap_sem);

                iPage = pMemLnx->cPages;
                while (iPage-- > 0)
                {
                    if (!PageReserved(pMemLnx->apPages[iPage]))
                        SetPageDirty(pMemLnx->apPages[iPage]);
                    page_cache_release(pMemLnx->apPages[iPage]);
                }

                if (pTask && pTask->mm)
                    up_read(&pTask->mm->mmap_sem);
            }
            /* else: kernel memory - nothing to do here. */
            break;

        case RTR0MEMOBJTYPE_RES_VIRT:
            Assert(pMemLnx->Core.pv);
            if (pMemLnx->Core.u.ResVirt.R0Process != NIL_RTR0PROCESS)
            {
                struct task_struct *pTask = rtR0ProcessToLinuxTask(pMemLnx->Core.u.Lock.R0Process);
                Assert(pTask);
                if (pTask && pTask->mm)
                {
                    MY_DO_MUNMAP(pTask->mm, (unsigned long)pMemLnx->Core.pv, pMemLnx->Core.cb);
                }
            }
            else
            {
                vunmap(pMemLnx->Core.pv);

                Assert(pMemLnx->cPages == 1 && pMemLnx->apPages[0] != NULL);
                __free_page(pMemLnx->apPages[0]);
                pMemLnx->apPages[0] = NULL;
                pMemLnx->cPages = 0;
            }
            pMemLnx->Core.pv = NULL;
            break;

        case RTR0MEMOBJTYPE_MAPPING:
            Assert(pMemLnx->cPages == 0); Assert(pMemLnx->Core.pv);
            if (pMemLnx->Core.u.ResVirt.R0Process != NIL_RTR0PROCESS)
            {
                struct task_struct *pTask = rtR0ProcessToLinuxTask(pMemLnx->Core.u.Lock.R0Process);
                Assert(pTask);
                if (pTask && pTask->mm)
                {
                    MY_DO_MUNMAP(pTask->mm, (unsigned long)pMemLnx->Core.pv, pMemLnx->Core.cb);
                }
            }
            else
                vunmap(pMemLnx->Core.pv);
            pMemLnx->Core.pv = NULL;
            break;

        default:
            AssertMsgFailed(("enmType=%d\n", pMemLnx->Core.enmType));
            return VERR_INTERNAL_ERROR;
    }
    return VINF_SUCCESS;
}

int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
                              sector_t pblocknr, struct buffer_head **pbh,
                              int newblk)
{
    struct buffer_head *bh;
    struct inode *inode = NILFS_BTNC_I(btnc);
    int err;

    bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
    if (unlikely(!bh))
        return -ENOMEM;

    err = -EEXIST; /* internal code */
    if (newblk) {
        if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
                     buffer_dirty(bh))) {
            brelse(bh);
            BUG();
        }
        memset(bh->b_data, 0, 1 << inode->i_blkbits);
        bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
        bh->b_blocknr = blocknr;
        set_buffer_mapped(bh);
        set_buffer_uptodate(bh);
        goto found;
    }

    if (buffer_uptodate(bh) || buffer_dirty(bh))
        goto found;

    if (pblocknr == 0) {
        pblocknr = blocknr;
        if (inode->i_ino != NILFS_DAT_INO) {
            struct inode *dat =
                nilfs_dat_inode(NILFS_I_NILFS(inode));

            /* blocknr is a virtual block number */
            err = nilfs_dat_translate(dat, blocknr, &pblocknr);
            if (unlikely(err)) {
                brelse(bh);
                goto out_locked;
            }
        }
    }
    lock_buffer(bh);
    if (buffer_uptodate(bh)) {
        unlock_buffer(bh);
        err = -EEXIST; /* internal code */
        goto found;
    }
    set_buffer_mapped(bh);
    bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
    bh->b_blocknr = pblocknr; /* set block address for read */
    bh->b_end_io = end_buffer_read_sync;
    get_bh(bh);
    submit_bh(READ, bh);
    bh->b_blocknr = blocknr; /* set back to the given block address */
    err = 0;
found:
    *pbh = bh;

out_locked:
    unlock_page(bh->b_page);
    page_cache_release(bh->b_page);
    return err;
}

/*
 * Create dentry/inode for this file and add it to the dircache.
 */
int
smb_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
	       struct smb_cache_control *ctrl, struct qstr *qname,
	       struct smb_fattr *entry)
{
	struct dentry *newdent, *dentry = filp->f_dentry;
	struct inode *newino, *inode = dentry->d_inode;
	struct smb_cache_control ctl = *ctrl;
	int valid = 0;
	int hashed = 0;
	ino_t ino = 0;

	qname->hash = full_name_hash(qname->name, qname->len);

	if (dentry->d_op && dentry->d_op->d_hash)
		if (dentry->d_op->d_hash(dentry, qname) != 0)
			goto end_advance;

	newdent = d_lookup(dentry, qname);

	if (!newdent) {
		newdent = d_alloc(dentry, qname);
		if (!newdent)
			goto end_advance;
	} else {
		hashed = 1;
		memcpy((char *) newdent->d_name.name, qname->name,
		       newdent->d_name.len);
	}

	if (!newdent->d_inode) {
		smb_renew_times(newdent);
		entry->f_ino = iunique(inode->i_sb, 2);
		newino = smb_iget(inode->i_sb, entry);
		if (newino) {
			smb_new_dentry(newdent);
			d_instantiate(newdent, newino);
			if (!hashed)
				d_rehash(newdent);
		}
	} else
		smb_set_inode_attr(newdent->d_inode, entry);

        if (newdent->d_inode) {
		ino = newdent->d_inode->i_ino;
		newdent->d_fsdata = (void *) ctl.fpos;
		smb_new_dentry(newdent);
	}

	if (ctl.idx >= SMB_DIRCACHE_SIZE) {
		if (ctl.page) {
			kunmap(ctl.page);
			SetPageUptodate(ctl.page);
			unlock_page(ctl.page);
			page_cache_release(ctl.page);
		}
		ctl.cache = NULL;
		ctl.idx  -= SMB_DIRCACHE_SIZE;
		ctl.ofs  += 1;
		ctl.page  = grab_cache_page(&inode->i_data, ctl.ofs);
		if (ctl.page)
			ctl.cache = kmap(ctl.page);
	}
	if (ctl.cache) {
		ctl.cache->dentry[ctl.idx] = newdent;
		valid = 1;
	}
	dput(newdent);

end_advance:
	if (!valid)
		ctl.valid = 0;
	if (!ctl.filled && (ctl.fpos == filp->f_pos)) {
		if (!ino)
			ino = find_inode_number(dentry, qname);
		if (!ino)
			ino = iunique(inode->i_sb, 2);
		ctl.filled = filldir(dirent, qname->name, qname->len,
				     filp->f_pos, ino, DT_UNKNOWN);
		if (!ctl.filled)
			filp->f_pos += 1;
	}
	ctl.fpos += 1;
	ctl.idx  += 1;
	*ctrl = ctl;
	return (ctl.valid || !ctl.filled);
}

/* 
 * Perform a free_page(), also freeing any swap cache associated with
 * this page if it is the last user of the page.
 */
void free_page_and_swap_cache(struct page *page)
{
	free_swap_cache(page);
	page_cache_release(page);
}

/*
 * Returns a pointer to a buffer containing at least LEN bytes of
 * filesystem starting at byte offset OFFSET into the filesystem.
 */
static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
{
	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
	struct page *pages[BLKS_PER_BUF];
	unsigned i, blocknr, buffer, unread;
	unsigned long devsize;
	char *data;

	if (!len)
		return NULL;
	blocknr = offset >> PAGE_CACHE_SHIFT;
	offset &= PAGE_CACHE_SIZE - 1;

	/* Check if an existing buffer already has the data.. */
	for (i = 0; i < READ_BUFFERS; i++) {
		unsigned int blk_offset;

		if (buffer_dev[i] != sb)
			continue;
		if (blocknr < buffer_blocknr[i])
			continue;
		blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
		blk_offset += offset;
		if (blk_offset + len > BUFFER_SIZE)
			continue;
		return read_buffers[i] + blk_offset;
	}

	devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;

	/* Ok, read in BLKS_PER_BUF pages completely first. */
	unread = 0;
	for (i = 0; i < BLKS_PER_BUF; i++) {
		struct page *page = NULL;

		if (blocknr + i < devsize) {
			page = read_mapping_page(mapping, blocknr + i, NULL);
			/* synchronous error? */
			if (IS_ERR(page))
				page = NULL;
		}
		pages[i] = page;
	}

	for (i = 0; i < BLKS_PER_BUF; i++) {
		struct page *page = pages[i];
		if (page) {
			wait_on_page_locked(page);
			if (!PageUptodate(page)) {
				/* asynchronous error */
				page_cache_release(page);
				pages[i] = NULL;
			}
		}
	}

	buffer = next_buffer;
	next_buffer = NEXT_BUFFER(buffer);
	buffer_blocknr[buffer] = blocknr;
	buffer_dev[buffer] = sb;

	data = read_buffers[buffer];
	for (i = 0; i < BLKS_PER_BUF; i++) {
		struct page *page = pages[i];
		if (page) {
			memcpy(data, kmap(page), PAGE_CACHE_SIZE);
			kunmap(page);
			page_cache_release(page);
		} else
			memset(data, 0, PAGE_CACHE_SIZE);
		data += PAGE_CACHE_SIZE;
	}
	return read_buffers[buffer] + offset;
}

//.........这里部分代码省略.........
	/*
	 * FIXME: only allow copying on anonymous vmas, tmpfs should
	 * be added.
	 */
	if (dst_vma->vm_ops)
		goto out_unlock;

	/*
	 * Ensure the dst_vma has a anon_vma or this page
	 * would get a NULL anon_vma when moved in the
	 * dst_vma.
	 */
	err = -ENOMEM;
	if (unlikely(anon_vma_prepare(dst_vma)))
		goto out_unlock;

	while (src_addr < src_start + len) {
		pmd_t dst_pmdval;

		BUG_ON(dst_addr >= dst_start + len);

		dst_pmd = mm_alloc_pmd(dst_mm, dst_addr);
		if (unlikely(!dst_pmd)) {
			err = -ENOMEM;
			break;
		}

		dst_pmdval = pmd_read_atomic(dst_pmd);
		/*
		 * If the dst_pmd is mapped as THP don't
		 * override it and just be strict.
		 */
		if (unlikely(pmd_trans_huge(dst_pmdval))) {
			err = -EEXIST;
			break;
		}
		if (unlikely(pmd_none(dst_pmdval)) &&
		    unlikely(__pte_alloc(dst_mm, dst_pmd, dst_addr))) {
			err = -ENOMEM;
			break;
		}
		/* If an huge pmd materialized from under us fail */
		if (unlikely(pmd_trans_huge(*dst_pmd))) {
			err = -EFAULT;
			break;
		}

		BUG_ON(pmd_none(*dst_pmd));
		BUG_ON(pmd_trans_huge(*dst_pmd));

		if (!zeropage)
			err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
					       dst_addr, src_addr, &page);
		else
			err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma,
						 dst_addr);

		cond_resched();

		if (unlikely(err == -EFAULT)) {
			void *page_kaddr;

			up_read(&dst_mm->mmap_sem);
			BUG_ON(!page);

			page_kaddr = kmap(page);
			err = copy_from_user(page_kaddr,
					     (const void __user *) src_addr,
					     PAGE_SIZE);
			kunmap(page);
			if (unlikely(err)) {
				err = -EFAULT;
				goto out;
			}
			goto retry;
		} else
			BUG_ON(page);

		if (!err) {
			dst_addr += PAGE_SIZE;
			src_addr += PAGE_SIZE;
			copied += PAGE_SIZE;

			if (fatal_signal_pending(current))
				err = -EINTR;
		}
		if (err)
			break;
	}

out_unlock:
	up_read(&dst_mm->mmap_sem);
out:
	if (page)
		page_cache_release(page);
	BUG_ON(copied < 0);
	BUG_ON(err > 0);
	BUG_ON(!copied && !err);
	return copied ? copied : err;
}

int ttm_tt_swapout(struct ttm_tt *ttm, struct file *persistant_swap_storage)
{
	struct address_space *swap_space;
	struct file *swap_storage;
	struct page *from_page;
	struct page *to_page;
	void *from_virtual;
	void *to_virtual;
	int i;

	BUG_ON(ttm->state != tt_unbound && ttm->state != tt_unpopulated);
	BUG_ON(ttm->caching_state != tt_cached);

	/*
	 * For user buffers, just unpin the pages, as there should be
	 * vma references.
	 */

	if (ttm->page_flags & TTM_PAGE_FLAG_USER) {
		ttm_tt_free_user_pages(ttm);
		ttm->page_flags |= TTM_PAGE_FLAG_SWAPPED;
		ttm->swap_storage = NULL;
		return 0;
	}

	if (!persistant_swap_storage) {
		swap_storage = shmem_file_setup("ttm swap",
						ttm->num_pages << PAGE_SHIFT,
						0);
		if (unlikely(IS_ERR(swap_storage))) {
			printk(KERN_ERR "Failed allocating swap storage.\n");
			return -ENOMEM;
		}
	} else
		swap_storage = persistant_swap_storage;

	swap_space = swap_storage->f_path.dentry->d_inode->i_mapping;

	for (i = 0; i < ttm->num_pages; ++i) {
		from_page = ttm->pages[i];
		if (unlikely(from_page == NULL))
			continue;
		to_page = read_mapping_page(swap_space, i, NULL);
		if (unlikely(to_page == NULL))
			goto out_err;

		preempt_disable();
		from_virtual = kmap_atomic(from_page, KM_USER0);
		to_virtual = kmap_atomic(to_page, KM_USER1);
		memcpy(to_virtual, from_virtual, PAGE_SIZE);
		kunmap_atomic(to_virtual, KM_USER1);
		kunmap_atomic(from_virtual, KM_USER0);
		preempt_enable();
		set_page_dirty(to_page);
		mark_page_accessed(to_page);
		page_cache_release(to_page);
	}

	ttm_tt_free_alloced_pages(ttm);
	ttm->swap_storage = swap_storage;
	ttm->page_flags |= TTM_PAGE_FLAG_SWAPPED;
	if (persistant_swap_storage)
		ttm->page_flags |= TTM_PAGE_FLAG_PERSISTANT_SWAP;

	return 0;
out_err:
	if (!persistant_swap_storage)
		fput(swap_storage);

	return -ENOMEM;
}