[PATCH] ecryptfs: fs/Makefile and fs/Kconfig

eCryptfs is a stacked cryptographic filesystem for Linux.  It is derived from
Erez Zadok's Cryptfs, implemented through the FiST framework for generating
stacked filesystems.  eCryptfs extends Cryptfs to provide advanced key
management and policy features.  eCryptfs stores cryptographic metadata in the
header of each file written, so that encrypted files can be copied between
hosts; the file will be decryptable with the proper key, and there is no need
to keep track of any additional information aside from what is already in the
encrypted file itself.

[akpm@osdl.org: updates for ongoing API changes]
[bunk@stusta.de: cleanups]
[akpm@osdl.org: alpha build fix]
[akpm@osdl.org: cleanups]
[tytso@mit.edu: inode-diet updates]
[pbadari@us.ibm.com: generic_file_*_read/write() interface updates]
[rdunlap@xenotime.net: printk format fixes]
[akpm@osdl.org: make slab creation and teardown table-driven]
Signed-off-by: Phillip Hellewell <phillip@hellewell.homeip.net>
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 788 insertions, 0 deletions

diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
new file mode 100644
index 00000000000..924dd90a4cf
--- /dev/null
+++ b/fs/ecryptfs/mmap.c
@@ -0,0 +1,788 @@
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ * This is where eCryptfs coordinates the symmetric encryption and
+ * decryption of the file data as it passes between the lower
+ * encrypted file and the upper decrypted file.
+ *
+ * Copyright (C) 1997-2003 Erez Zadok
+ * Copyright (C) 2001-2003 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/page-flags.h>
+#include <linux/mount.h>
+#include <linux/file.h>
+#include <linux/crypto.h>
+#include <linux/scatterlist.h>
+#include "ecryptfs_kernel.h"
+
+struct kmem_cache *ecryptfs_lower_page_cache;
+
+/**
+ * ecryptfs_get1page
+ *
+ * Get one page from cache or lower f/s, return error otherwise.
+ *
+ * Returns unlocked and up-to-date page (if ok), with increased
+ * refcnt.
+ */
+static struct page *ecryptfs_get1page(struct file *file, int index)
+{
+	struct page *page;
+	struct dentry *dentry;
+	struct inode *inode;
+	struct address_space *mapping;
+
+	dentry = file->f_dentry;
+	inode = dentry->d_inode;
+	mapping = inode->i_mapping;
+	page = read_cache_page(mapping, index,
+			       (filler_t *)mapping->a_ops->readpage,
+			       (void *)file);
+	if (IS_ERR(page))
+		goto out;
+	wait_on_page_locked(page);
+out:
+	return page;
+}
+
+static
+int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros);
+
+/**
+ * ecryptfs_fill_zeros
+ * @file: The ecryptfs file
+ * @new_length: The new length of the data in the underlying file;
+ *              everything between the prior end of the file and the
+ *              new end of the file will be filled with zero's.
+ *              new_length must be greater than  current length
+ *
+ * Function for handling lseek-ing past the end of the file.
+ *
+ * This function does not support shrinking, only growing a file.
+ *
+ * Returns zero on success; non-zero otherwise.
+ */
+int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
+{
+	int rc = 0;
+	struct dentry *dentry = file->f_dentry;
+	struct inode *inode = dentry->d_inode;
+	pgoff_t old_end_page_index = 0;
+	pgoff_t index = old_end_page_index;
+	int old_end_pos_in_page = -1;
+	pgoff_t new_end_page_index;
+	int new_end_pos_in_page;
+	loff_t cur_length = i_size_read(inode);
+
+	if (cur_length != 0) {
+		index = old_end_page_index =
+		    ((cur_length - 1) >> PAGE_CACHE_SHIFT);
+		old_end_pos_in_page = ((cur_length - 1) & ~PAGE_CACHE_MASK);
+	}
+	new_end_page_index = ((new_length - 1) >> PAGE_CACHE_SHIFT);
+	new_end_pos_in_page = ((new_length - 1) & ~PAGE_CACHE_MASK);
+	ecryptfs_printk(KERN_DEBUG, "old_end_page_index = [0x%.16x]; "
+			"old_end_pos_in_page = [%d]; "
+			"new_end_page_index = [0x%.16x]; "
+			"new_end_pos_in_page = [%d]\n",
+			old_end_page_index, old_end_pos_in_page,
+			new_end_page_index, new_end_pos_in_page);
+	if (old_end_page_index == new_end_page_index) {
+		/* Start and end are in the same page; we just need to
+		 * set a portion of the existing page to zero's */
+		rc = write_zeros(file, index, (old_end_pos_in_page + 1),
+				 (new_end_pos_in_page - old_end_pos_in_page));
+		if (rc)
+			ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
+					"index=[0x%.16x], "
+					"old_end_pos_in_page=[d], "
+					"(PAGE_CACHE_SIZE - new_end_pos_in_page"
+					"=[%d]"
+					")=[d]) returned [%d]\n", file, index,
+					old_end_pos_in_page,
+					new_end_pos_in_page,
+					(PAGE_CACHE_SIZE - new_end_pos_in_page),
+					rc);
+		goto out;
+	}
+	/* Fill the remainder of the previous last page with zeros */
+	rc = write_zeros(file, index, (old_end_pos_in_page + 1),
+			 ((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page));
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
+				"index=[0x%.16x], old_end_pos_in_page=[d], "
+				"(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) "
+				"returned [%d]\n", file, index,
+				old_end_pos_in_page,
+				(PAGE_CACHE_SIZE - old_end_pos_in_page), rc);
+		goto out;
+	}
+	index++;
+	while (index < new_end_page_index) {
+		/* Fill all intermediate pages with zeros */
+		rc = write_zeros(file, index, 0, PAGE_CACHE_SIZE);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
+					"index=[0x%.16x], "
+					"old_end_pos_in_page=[d], "
+					"(PAGE_CACHE_SIZE - new_end_pos_in_page"
+					"=[%d]"
+					")=[d]) returned [%d]\n", file, index,
+					old_end_pos_in_page,
+					new_end_pos_in_page,
+					(PAGE_CACHE_SIZE - new_end_pos_in_page),
+					rc);
+			goto out;
+		}
+		index++;
+	}
+	/* Fill the portion at the beginning of the last new page with
+	 * zero's */
+	rc = write_zeros(file, index, 0, (new_end_pos_in_page + 1));
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "write_zeros(file="
+				"[%p], index=[0x%.16x], 0, "
+				"new_end_pos_in_page=[%d]"
+				"returned [%d]\n", file, index,
+				new_end_pos_in_page, rc);
+		goto out;
+	}
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_writepage
+ * @page: Page that is locked before this call is made
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct ecryptfs_page_crypt_context ctx;
+	int rc;
+
+	ctx.page = page;
+	ctx.mode = ECRYPTFS_WRITEPAGE_MODE;
+	ctx.param.wbc = wbc;
+	rc = ecryptfs_encrypt_page(&ctx);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error encrypting "
+				"page (upper index [0x%.16x])\n", page->index);
+		ClearPageUptodate(page);
+		goto out;
+	}
+	SetPageUptodate(page);
+	unlock_page(page);
+out:
+	return rc;
+}
+
+/**
+ * Reads the data from the lower file file at index lower_page_index
+ * and copies that data into page.
+ *
+ * @param page	Page to fill
+ * @param lower_page_index Index of the page in the lower file to get
+ */
+int ecryptfs_do_readpage(struct file *file, struct page *page,
+			 pgoff_t lower_page_index)
+{
+	int rc;
+	struct dentry *dentry;
+	struct file *lower_file;
+	struct dentry *lower_dentry;
+	struct inode *inode;
+	struct inode *lower_inode;
+	char *page_data;
+	struct page *lower_page = NULL;
+	char *lower_page_data;
+	const struct address_space_operations *lower_a_ops;
+
+	dentry = file->f_dentry;
+	lower_file = ecryptfs_file_to_lower(file);
+	lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	inode = dentry->d_inode;
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	lower_a_ops = lower_inode->i_mapping->a_ops;
+	lower_page = read_cache_page(lower_inode->i_mapping, lower_page_index,
+				     (filler_t *)lower_a_ops->readpage,
+				     (void *)lower_file);
+	if (IS_ERR(lower_page)) {
+		rc = PTR_ERR(lower_page);
+		lower_page = NULL;
+		ecryptfs_printk(KERN_ERR, "Error reading from page cache\n");
+		goto out;
+	}
+	wait_on_page_locked(lower_page);
+	page_data = (char *)kmap(page);
+	if (!page_data) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR, "Error mapping page\n");
+		goto out;
+	}
+	lower_page_data = (char *)kmap(lower_page);
+	if (!lower_page_data) {
+		rc = -ENOMEM;
+		ecryptfs_printk(KERN_ERR, "Error mapping page\n");
+		kunmap(page);
+		goto out;
+	}
+	memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);
+	kunmap(lower_page);
+	kunmap(page);
+	rc = 0;
+out:
+	if (likely(lower_page))
+		page_cache_release(lower_page);
+	if (rc == 0)
+		SetPageUptodate(page);
+	else
+		ClearPageUptodate(page);
+	return rc;
+}
+
+/**
+ * ecryptfs_readpage
+ * @file: This is an ecryptfs file
+ * @page: ecryptfs associated page to stick the read data into
+ *
+ * Read in a page, decrypting if necessary.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int ecryptfs_readpage(struct file *file, struct page *page)
+{
+	int rc = 0;
+	struct ecryptfs_crypt_stat *crypt_stat;
+
+	BUG_ON(!(file && file->f_dentry && file->f_dentry->d_inode));
+	crypt_stat =
+		&ecryptfs_inode_to_private(file->f_dentry->d_inode)->crypt_stat;
+	if (!crypt_stat
+	    || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)
+	    || ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) {
+		ecryptfs_printk(KERN_DEBUG,
+				"Passing through unencrypted page\n");
+		rc = ecryptfs_do_readpage(file, page, page->index);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error reading page; rc = "
+					"[%d]\n", rc);
+			goto out;
+		}
+	} else {
+		rc = ecryptfs_decrypt_page(file, page);
+		if (rc) {
+
+			ecryptfs_printk(KERN_ERR, "Error decrypting page; "
+					"rc = [%d]\n", rc);
+			goto out;
+		}
+	}
+	SetPageUptodate(page);
+out:
+	if (rc)
+		ClearPageUptodate(page);
+	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
+			page->index);
+	unlock_page(page);
+	return rc;
+}
+
+static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
+{
+	struct inode *inode = page->mapping->host;
+	int end_byte_in_page;
+	int rc = 0;
+	char *page_virt;
+
+	if ((i_size_read(inode) / PAGE_CACHE_SIZE) == page->index) {
+		end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
+		if (to > end_byte_in_page)
+			end_byte_in_page = to;
+		page_virt = kmap(page);
+		if (!page_virt) {
+			rc = -ENOMEM;
+			ecryptfs_printk(KERN_WARNING,
+					"Could not map page\n");
+			goto out;
+		}
+		memset((page_virt + end_byte_in_page), 0,
+		       (PAGE_CACHE_SIZE - end_byte_in_page));
+		kunmap(page);
+	}
+out:
+	return rc;
+}
+
+static int ecryptfs_prepare_write(struct file *file, struct page *page,
+				  unsigned from, unsigned to)
+{
+	int rc = 0;
+
+	kmap(page);
+	if (from == 0 && to == PAGE_CACHE_SIZE)
+		goto out;	/* If we are writing a full page, it will be
+				   up to date. */
+	if (!PageUptodate(page))
+		rc = ecryptfs_do_readpage(file, page, page->index);
+out:
+	return rc;
+}
+
+int ecryptfs_grab_and_map_lower_page(struct page **lower_page,
+				     char **lower_virt,
+				     struct inode *lower_inode,
+				     unsigned long lower_page_index)
+{
+	int rc = 0;
+
+	(*lower_page) = grab_cache_page(lower_inode->i_mapping,
+					lower_page_index);
+	if (!(*lower_page)) {
+		ecryptfs_printk(KERN_ERR, "grab_cache_page for "
+				"lower_page_index = [0x%.16x] failed\n",
+				lower_page_index);
+		rc = -EINVAL;
+		goto out;
+	}
+	if (lower_virt)
+		(*lower_virt) = kmap((*lower_page));
+	else
+		kmap((*lower_page));
+out:
+	return rc;
+}
+
+int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
+					      struct inode *lower_inode,
+					      struct writeback_control *wbc)
+{
+	int rc = 0;
+
+	rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); "
+				"rc = [%d]\n", rc);
+		goto out;
+	}
+	lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+	page_cache_release(lower_page);
+out:
+	return rc;
+}
+
+static void ecryptfs_unmap_and_release_lower_page(struct page *lower_page)
+{
+	kunmap(lower_page);
+	ecryptfs_printk(KERN_DEBUG, "Unlocking lower page with index = "
+			"[0x%.16x]\n", lower_page->index);
+	unlock_page(lower_page);
+	page_cache_release(lower_page);
+}
+
+/**
+ * ecryptfs_write_inode_size_to_header
+ *
+ * Writes the lower file size to the first 8 bytes of the header.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+int
+ecryptfs_write_inode_size_to_header(struct file *lower_file,
+				    struct inode *lower_inode,
+				    struct inode *inode)
+{
+	int rc = 0;
+	struct page *header_page;
+	char *header_virt;
+	const struct address_space_operations *lower_a_ops;
+	u64 file_size;
+
+	rc = ecryptfs_grab_and_map_lower_page(&header_page, &header_virt,
+					      lower_inode, 0);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "grab_cache_page for header page "
+				"failed\n");
+		goto out;
+	}
+	lower_a_ops = lower_inode->i_mapping->a_ops;
+	rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
+	file_size = (u64)i_size_read(inode);
+	ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
+	file_size = cpu_to_be64(file_size);
+	memcpy(header_virt, &file_size, sizeof(u64));
+	rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
+	if (rc < 0)
+		ecryptfs_printk(KERN_ERR, "Error commiting header page "
+				"write\n");
+	ecryptfs_unmap_and_release_lower_page(header_page);
+	lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+	mark_inode_dirty_sync(inode);
+out:
+	return rc;
+}
+
+int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
+			    struct file *lower_file,
+			    unsigned long lower_page_index, int byte_offset,
+			    int region_bytes)
+{
+	int rc = 0;
+
+	rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL, lower_inode,
+					      lower_page_index);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error attempting to grab and map "
+				"lower page with index [0x%.16x]\n",
+				lower_page_index);
+		goto out;
+	}
+	rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file,
+							  (*lower_page),
+							  byte_offset,
+							  region_bytes);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "prepare_write for "
+				"lower_page_index = [0x%.16x] failed; rc = "
+				"[%d]\n", lower_page_index, rc);
+	}
+out:
+	if (rc && (*lower_page)) {
+		ecryptfs_unmap_and_release_lower_page(*lower_page);
+		(*lower_page) = NULL;
+	}
+	return rc;
+}
+
+/**
+ * ecryptfs_commit_lower_page
+ *
+ * Returns zero on success; non-zero on error
+ */
+int
+ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
+			   struct file *lower_file, int byte_offset,
+			   int region_size)
+{
+	int rc = 0;
+
+	rc = lower_inode->i_mapping->a_ops->commit_write(
+		lower_file, lower_page, byte_offset, region_size);
+	if (rc < 0) {
+		ecryptfs_printk(KERN_ERR,
+				"Error committing write; rc = [%d]\n", rc);
+	} else
+		rc = 0;
+	ecryptfs_unmap_and_release_lower_page(lower_page);
+	return rc;
+}
+
+/**
+ * ecryptfs_copy_page_to_lower
+ *
+ * Used for plaintext pass-through; no page index interpolation
+ * required.
+ */
+int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
+				struct file *lower_file)
+{
+	int rc = 0;
+	struct page *lower_page;
+
+	rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file,
+				     page->index, 0, PAGE_CACHE_SIZE);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error attempting to get page "
+				"at index [0x%.16x]\n", page->index);
+		goto out;
+	}
+	/* TODO: aops */
+	memcpy((char *)page_address(lower_page), page_address(page),
+	       PAGE_CACHE_SIZE);
+	rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file,
+					0, PAGE_CACHE_SIZE);
+	if (rc)
+		ecryptfs_printk(KERN_ERR, "Error attempting to commit page "
+				"at index [0x%.16x]\n", page->index);
+out:
+	return rc;
+}
+
+static int
+process_new_file(struct ecryptfs_crypt_stat *crypt_stat,
+		 struct file *file, struct inode *inode)
+{
+	struct page *header_page;
+	const struct address_space_operations *lower_a_ops;
+	struct inode *lower_inode;
+	struct file *lower_file;
+	char *header_virt;
+	int rc = 0;
+	int current_header_page = 0;
+	int header_pages;
+	int more_header_data_to_be_written = 1;
+
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	lower_file = ecryptfs_file_to_lower(file);
+	lower_a_ops = lower_inode->i_mapping->a_ops;
+	header_pages = ((crypt_stat->header_extent_size
+			 * crypt_stat->num_header_extents_at_front)
+			/ PAGE_CACHE_SIZE);
+	BUG_ON(header_pages < 1);
+	while (current_header_page < header_pages) {
+		rc = ecryptfs_grab_and_map_lower_page(&header_page,
+						      &header_virt,
+						      lower_inode,
+						      current_header_page);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "grab_cache_page for "
+					"header page [%d] failed; rc = [%d]\n",
+					current_header_page, rc);
+			goto out;
+		}
+		rc = lower_a_ops->prepare_write(lower_file, header_page, 0,
+						PAGE_CACHE_SIZE);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error preparing to write "
+					"header page out; rc = [%d]\n", rc);
+			goto out;
+		}
+		memset(header_virt, 0, PAGE_CACHE_SIZE);
+		if (more_header_data_to_be_written) {
+			rc = ecryptfs_write_headers_virt(header_virt,
+							 crypt_stat,
+							 file->f_dentry);
+			if (rc) {
+				ecryptfs_printk(KERN_WARNING, "Error "
+						"generating header; rc = "
+						"[%d]\n", rc);
+				rc = -EIO;
+				memset(header_virt, 0, PAGE_CACHE_SIZE);
+				ecryptfs_unmap_and_release_lower_page(
+					header_page);
+				goto out;
+			}
+			if (current_header_page == 0)
+				memset(header_virt, 0, 8);
+			more_header_data_to_be_written = 0;
+		}
+		rc = lower_a_ops->commit_write(lower_file, header_page, 0,
+					       PAGE_CACHE_SIZE);
+		ecryptfs_unmap_and_release_lower_page(header_page);
+		if (rc < 0) {
+			ecryptfs_printk(KERN_ERR,
+					"Error commiting header page write; "
+					"rc = [%d]\n", rc);
+			break;
+		}
+		current_header_page++;
+	}
+	if (rc >= 0) {
+		rc = 0;
+		ecryptfs_printk(KERN_DEBUG, "lower_inode->i_blocks = "
+				"[0x%.16x]\n", lower_inode->i_blocks);
+		i_size_write(inode, 0);
+		lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+		mark_inode_dirty_sync(inode);
+	}
+	ecryptfs_printk(KERN_DEBUG, "Clearing ECRYPTFS_NEW_FILE flag in "
+			"crypt_stat at memory location [%p]\n", crypt_stat);
+	ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE);
+out:
+	return rc;
+}
+
+/**
+ * ecryptfs_commit_write
+ * @file: The eCryptfs file object
+ * @page: The eCryptfs page
+ * @from: Ignored (we rotate the page IV on each write)
+ * @to: Ignored
+ *
+ * This is where we encrypt the data and pass the encrypted data to
+ * the lower filesystem.  In OpenPGP-compatible mode, we operate on
+ * entire underlying packets.
+ */
+static int ecryptfs_commit_write(struct file *file, struct page *page,
+				 unsigned from, unsigned to)
+{
+	struct ecryptfs_page_crypt_context ctx;
+	loff_t pos;
+	struct inode *inode;
+	struct inode *lower_inode;
+	struct file *lower_file;
+	struct ecryptfs_crypt_stat *crypt_stat;
+	int rc;
+
+	inode = page->mapping->host;
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	lower_file = ecryptfs_file_to_lower(file);
+	mutex_lock(&lower_inode->i_mutex);
+	crypt_stat =
+		&ecryptfs_inode_to_private(file->f_dentry->d_inode)->crypt_stat;
+	if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) {
+		ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
+			"crypt_stat at memory location [%p]\n", crypt_stat);
+		rc = process_new_file(crypt_stat, file, inode);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR, "Error processing new "
+					"file; rc = [%d]\n", rc);
+			goto out;
+		}
+	} else
+		ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
+	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
+			"(page w/ index = [0x%.16x], to = [%d])\n", page->index,
+			to);
+	rc = fill_zeros_to_end_of_page(page, to);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
+				"zeros in page with index = [0x%.16x]\n",
+				page->index);
+		goto out;
+	}
+	ctx.page = page;
+	ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE;
+	ctx.param.lower_file = lower_file;
+	rc = ecryptfs_encrypt_page(&ctx);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
+				"index [0x%.16x])\n", page->index);
+		goto out;
+	}
+	rc = 0;
+	inode->i_blocks = lower_inode->i_blocks;
+	pos = (page->index << PAGE_CACHE_SHIFT) + to;
+	if (pos > i_size_read(inode)) {
+		i_size_write(inode, pos);
+		ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
+				"[0x%.16x]\n", i_size_read(inode));
+	}
+	ecryptfs_write_inode_size_to_header(lower_file, lower_inode, inode);
+	lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+	mark_inode_dirty_sync(inode);
+out:
+	kunmap(page); /* mapped in prior call (prepare_write) */
+	if (rc < 0)
+		ClearPageUptodate(page);
+	else
+		SetPageUptodate(page);
+	mutex_unlock(&lower_inode->i_mutex);
+	return rc;
+}
+
+/**
+ * write_zeros
+ * @file: The ecryptfs file
+ * @index: The index in which we are writing
+ * @start: The position after the last block of data
+ * @num_zeros: The number of zeros to write
+ *
+ * Write a specified number of zero's to a page.
+ *
+ * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
+ */
+static
+int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
+{
+	int rc = 0;
+	struct page *tmp_page;
+
+	tmp_page = ecryptfs_get1page(file, index);
+	if (IS_ERR(tmp_page)) {
+		ecryptfs_printk(KERN_ERR, "Error getting page at index "
+				"[0x%.16x]\n", index);
+		rc = PTR_ERR(tmp_page);
+		goto out;
+	}
+	kmap(tmp_page);
+	rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros);
+	if (rc) {
+		ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
+				"to remainder of page at index [0x%.16x]\n",
+				index);
+		kunmap(tmp_page);
+		page_cache_release(tmp_page);
+		goto out;
+	}
+	memset(((char *)page_address(tmp_page) + start), 0, num_zeros);
+	rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
+	if (rc < 0) {
+		ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
+				"to remainder of page at index [0x%.16x]\n",
+				index);
+		kunmap(tmp_page);
+		page_cache_release(tmp_page);
+		goto out;
+	}
+	rc = 0;
+	kunmap(tmp_page);
+	page_cache_release(tmp_page);
+out:
+	return rc;
+}
+
+static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
+{
+	int rc = 0;
+	struct inode *inode;
+	struct inode *lower_inode;
+
+	inode = (struct inode *)mapping->host;
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	if (lower_inode->i_mapping->a_ops->bmap)
+		rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
+							 block);
+	return rc;
+}
+
+static void ecryptfs_sync_page(struct page *page)
+{
+	struct inode *inode;
+	struct inode *lower_inode;
+	struct page *lower_page;
+
+	inode = page->mapping->host;
+	lower_inode = ecryptfs_inode_to_lower(inode);
+	/* NOTE: Recently swapped with grab_cache_page(), since
+	 * sync_page() just makes sure that pending I/O gets done. */
+	lower_page = find_lock_page(lower_inode->i_mapping, page->index);
+	if (!lower_page) {
+		ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
+		return;
+	}
+	lower_page->mapping->a_ops->sync_page(lower_page);
+	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
+			lower_page->index);
+	unlock_page(lower_page);
+	page_cache_release(lower_page);
+}
+
+struct address_space_operations ecryptfs_aops = {
+	.writepage = ecryptfs_writepage,
+	.readpage = ecryptfs_readpage,
+	.prepare_write = ecryptfs_prepare_write,
+	.commit_write = ecryptfs_commit_write,
+	.bmap = ecryptfs_bmap,
+	.sync_page = ecryptfs_sync_page,
+};