[mirror_ubuntu-artful-kernel.git] / fs / ecryptfs / read_write.c

/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 2007 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/fs.h>
#include <linux/pagemap.h>
#include "ecryptfs_kernel.h"

/**
 * ecryptfs_write_lower
 * @ecryptfs_inode: The eCryptfs inode
 * @data: Data to write
 * @offset: Byte offset in the lower file to which to write the data
 * @size: Number of bytes from @data to write at @offset in the lower
 *        file
 *
 * Write data to the lower file.
 *
 * Returns bytes written on success; less than zero on error
 */
int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
			 loff_t offset, size_t size)
{
	struct file *lower_file;
	mm_segment_t fs_save;
	ssize_t rc;

	lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file;
	if (!lower_file)
		return -EIO;
	fs_save = get_fs();
	set_fs(get_ds());
	rc = vfs_write(lower_file, data, size, &offset);
	set_fs(fs_save);
	mark_inode_dirty_sync(ecryptfs_inode);
	return rc;
}

/**
 * ecryptfs_write_lower_page_segment
 * @ecryptfs_inode: The eCryptfs inode
 * @page_for_lower: The page containing the data to be written to the
 *                  lower file
 * @offset_in_page: The offset in the @page_for_lower from which to
 *                  start writing the data
 * @size: The amount of data from @page_for_lower to write to the
 *        lower file
 *
 * Determines the byte offset in the file for the given page and
 * offset within the page, maps the page, and makes the call to write
 * the contents of @page_for_lower to the lower inode.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
				      struct page *page_for_lower,
				      size_t offset_in_page, size_t size)
{
	char *virt;
	loff_t offset;
	int rc;

	offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
		  + offset_in_page);
	virt = kmap(page_for_lower);
	rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
	if (rc > 0)
		rc = 0;
	kunmap(page_for_lower);
	return rc;
}

/**
 * ecryptfs_write
 * @ecryptfs_inode: The eCryptfs file into which to write
 * @data: Virtual address where data to write is located
 * @offset: Offset in the eCryptfs file at which to begin writing the
 *          data from @data
 * @size: The number of bytes to write from @data
 *
 * Write an arbitrary amount of data to an arbitrary location in the
 * eCryptfs inode page cache. This is done on a page-by-page, and then
 * by an extent-by-extent, basis; individual extents are encrypted and
 * written to the lower page cache (via VFS writes). This function
 * takes care of all the address translation to locations in the lower
 * filesystem; it also handles truncate events, writing out zeros
 * where necessary.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
		   size_t size)
{
	struct page *ecryptfs_page;
	struct ecryptfs_crypt_stat *crypt_stat;
	char *ecryptfs_page_virt;
	loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
	loff_t data_offset = 0;
	loff_t pos;
	int rc = 0;

	crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
	/*
	 * if we are writing beyond current size, then start pos
	 * at the current size - we'll fill in zeros from there.
	 */
	if (offset > ecryptfs_file_size)
		pos = ecryptfs_file_size;
	else
		pos = offset;
	while (pos < (offset + size)) {
		pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
		size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
		size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
		loff_t total_remaining_bytes = ((offset + size) - pos);

		if (num_bytes > total_remaining_bytes)
			num_bytes = total_remaining_bytes;
		if (pos < offset) {
			/* remaining zeros to write, up to destination offset */
			loff_t total_remaining_zeros = (offset - pos);

			if (num_bytes > total_remaining_zeros)
				num_bytes = total_remaining_zeros;
		}
		ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode,
							 ecryptfs_page_idx);
		if (IS_ERR(ecryptfs_page)) {
			rc = PTR_ERR(ecryptfs_page);
			printk(KERN_ERR "%s: Error getting page at "
			       "index [%ld] from eCryptfs inode "
			       "mapping; rc = [%d]\n", __func__,
			       ecryptfs_page_idx, rc);
			goto out;
		}
		ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);

		/*
		 * pos: where we're now writing, offset: where the request was
		 * If current pos is before request, we are filling zeros
		 * If we are at or beyond request, we are writing the *data*
		 * If we're in a fresh page beyond eof, zero it in either case
		 */
		if (pos < offset || !start_offset_in_page) {
			/* We are extending past the previous end of the file.
			 * Fill in zero values to the end of the page */
			memset(((char *)ecryptfs_page_virt
				+ start_offset_in_page), 0,
				PAGE_CACHE_SIZE - start_offset_in_page);
		}

		/* pos >= offset, we are now writing the data request */
		if (pos >= offset) {
			memcpy(((char *)ecryptfs_page_virt
				+ start_offset_in_page),
			       (data + data_offset), num_bytes);
			data_offset += num_bytes;
		}
		kunmap_atomic(ecryptfs_page_virt, KM_USER0);
		flush_dcache_page(ecryptfs_page);
		SetPageUptodate(ecryptfs_page);
		unlock_page(ecryptfs_page);
		if (crypt_stat->flags & ECRYPTFS_ENCRYPTED)
			rc = ecryptfs_encrypt_page(ecryptfs_page);
		else
			rc = ecryptfs_write_lower_page_segment(ecryptfs_inode,
						ecryptfs_page,
						start_offset_in_page,
						data_offset);
		page_cache_release(ecryptfs_page);
		if (rc) {
			printk(KERN_ERR "%s: Error encrypting "
			       "page; rc = [%d]\n", __func__, rc);
			goto out;
		}
		pos += num_bytes;
	}
	if ((offset + size) > ecryptfs_file_size) {
		i_size_write(ecryptfs_inode, (offset + size));
		if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) {
			rc = ecryptfs_write_inode_size_to_metadata(
								ecryptfs_inode);
			if (rc) {
				printk(KERN_ERR	"Problem with "
				       "ecryptfs_write_inode_size_to_metadata; "
				       "rc = [%d]\n", rc);
				goto out;
			}
		}
	}
out:
	return rc;
}

/**
 * ecryptfs_read_lower
 * @data: The read data is stored here by this function
 * @offset: Byte offset in the lower file from which to read the data
 * @size: Number of bytes to read from @offset of the lower file and
 *        store into @data
 * @ecryptfs_inode: The eCryptfs inode
 *
 * Read @size bytes of data at byte offset @offset from the lower
 * inode into memory location @data.
 *
 * Returns bytes read on success; 0 on EOF; less than zero on error
 */
int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
			struct inode *ecryptfs_inode)
{
	struct file *lower_file;
	mm_segment_t fs_save;
	ssize_t rc;

	lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file;
	if (!lower_file)
		return -EIO;
	fs_save = get_fs();
	set_fs(get_ds());
	rc = vfs_read(lower_file, data, size, &offset);
	set_fs(fs_save);
	return rc;
}

/**
 * ecryptfs_read_lower_page_segment
 * @page_for_ecryptfs: The page into which data for eCryptfs will be
 *                     written
 * @offset_in_page: Offset in @page_for_ecryptfs from which to start
 *                  writing
 * @size: The number of bytes to write into @page_for_ecryptfs
 * @ecryptfs_inode: The eCryptfs inode
 *
 * Determines the byte offset in the file for the given page and
 * offset within the page, maps the page, and makes the call to read
 * the contents of @page_for_ecryptfs from the lower inode.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
				     pgoff_t page_index,
				     size_t offset_in_page, size_t size,
				     struct inode *ecryptfs_inode)
{
	char *virt;
	loff_t offset;
	int rc;

	offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page);
	virt = kmap(page_for_ecryptfs);
	rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
	if (rc > 0)
		rc = 0;
	kunmap(page_for_ecryptfs);
	flush_dcache_page(page_for_ecryptfs);
	return rc;
}

#if 0
/**
 * ecryptfs_read
 * @data: The virtual address into which to write the data read (and
 *        possibly decrypted) from the lower file
 * @offset: The offset in the decrypted view of the file from which to
 *          read into @data
 * @size: The number of bytes to read into @data
 * @ecryptfs_file: The eCryptfs file from which to read
 *
 * Read an arbitrary amount of data from an arbitrary location in the
 * eCryptfs page cache. This is done on an extent-by-extent basis;
 * individual extents are decrypted and read from the lower page
 * cache (via VFS reads). This function takes care of all the
 * address translation to locations in the lower filesystem.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_read(char *data, loff_t offset, size_t size,
		  struct file *ecryptfs_file)
{
	struct inode *ecryptfs_inode = ecryptfs_file->f_dentry->d_inode;
	struct page *ecryptfs_page;
	char *ecryptfs_page_virt;
	loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
	loff_t data_offset = 0;
	loff_t pos;
	int rc = 0;

	if ((offset + size) > ecryptfs_file_size) {
		rc = -EINVAL;
		printk(KERN_ERR "%s: Attempt to read data past the end of the "
			"file; offset = [%lld]; size = [%td]; "
		       "ecryptfs_file_size = [%lld]\n",
		       __func__, offset, size, ecryptfs_file_size);
		goto out;
	}
	pos = offset;
	while (pos < (offset + size)) {
		pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
		size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
		size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
		size_t total_remaining_bytes = ((offset + size) - pos);

		if (num_bytes > total_remaining_bytes)
			num_bytes = total_remaining_bytes;
		ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode,
							 ecryptfs_page_idx);
		if (IS_ERR(ecryptfs_page)) {
			rc = PTR_ERR(ecryptfs_page);
			printk(KERN_ERR "%s: Error getting page at "
			       "index [%ld] from eCryptfs inode "
			       "mapping; rc = [%d]\n", __func__,
			       ecryptfs_page_idx, rc);
			goto out;
		}
		ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
		memcpy((data + data_offset),
		       ((char *)ecryptfs_page_virt + start_offset_in_page),
		       num_bytes);
		kunmap_atomic(ecryptfs_page_virt, KM_USER0);
		flush_dcache_page(ecryptfs_page);
		SetPageUptodate(ecryptfs_page);
		unlock_page(ecryptfs_page);
		page_cache_release(ecryptfs_page);
		pos += num_bytes;
		data_offset += num_bytes;
	}
out:
	return rc;
}
#endif  /*  0  */
Commit	Line	Data
da0102a1 MH	1	/**
	2	* eCryptfs: Linux filesystem encryption layer
	3	*
	4	* Copyright (C) 2007 International Business Machines Corp.
	5	* Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
	6	*
	7	* This program is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU General Public License as
	9	* published by the Free Software Foundation; either version 2 of the
	10	* License, or (at your option) any later version.
	11	*
	12	* This program is distributed in the hope that it will be useful, but
	13	* WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	15	* General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
	19	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
	20	* 02111-1307, USA.
	21	*/
	22
	23	#include <linux/fs.h>
	24	#include <linux/pagemap.h>
	25	#include "ecryptfs_kernel.h"
	26
	27	/**
	28	* ecryptfs_write_lower
	29	* @ecryptfs_inode: The eCryptfs inode
	30	* @data: Data to write
	31	* @offset: Byte offset in the lower file to which to write the data
	32	* @size: Number of bytes from @data to write at @offset in the lower
	33	* file
	34	*
	35	* Write data to the lower file.
	36	*
96a7b9c2	37	* Returns bytes written on success; less than zero on error
da0102a1 MH	38	*/
	39	int ecryptfs_write_lower(struct inode ecryptfs_inode, char data,
	40	loff_t offset, size_t size)
	41	{
f61500e0	42	struct file *lower_file;
da0102a1	43	mm_segment_t fs_save;
96a7b9c2	44	ssize_t rc;
da0102a1	45
f61500e0 TH	46	lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file;
	47	if (!lower_file)
	48	return -EIO;
da0102a1 MH	49	fs_save = get_fs();
da0102a1 MH	50	set_fs(get_ds());
f61500e0	51	rc = vfs_write(lower_file, data, size, &offset);
da0102a1	52	set_fs(fs_save);
da0102a1 MH	53	mark_inode_dirty_sync(ecryptfs_inode);
	54	return rc;
	55	}
	56
	57	/**
	58	* ecryptfs_write_lower_page_segment
	59	* @ecryptfs_inode: The eCryptfs inode
	60	* @page_for_lower: The page containing the data to be written to the
	61	* lower file
	62	* @offset_in_page: The offset in the @page_for_lower from which to
	63	* start writing the data
	64	* @size: The amount of data from @page_for_lower to write to the
	65	* lower file
	66	*
	67	* Determines the byte offset in the file for the given page and
	68	* offset within the page, maps the page, and makes the call to write
	69	* the contents of @page_for_lower to the lower inode.
	70	*
	71	* Returns zero on success; non-zero otherwise
	72	*/
	73	int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
	74	struct page *page_for_lower,
	75	size_t offset_in_page, size_t size)
	76	{
	77	char *virt;
	78	loff_t offset;
	79	int rc;
	80
8a146a2b	81	offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
d6a13c17	82	+ offset_in_page);
da0102a1 MH	83	virt = kmap(page_for_lower);
da0102a1 MH	84	rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
96a7b9c2 TH	85	if (rc > 0)
96a7b9c2 TH	86	rc = 0;
da0102a1 MH	87	kunmap(page_for_lower);
	88	return rc;
	89	}
	90
	91	/**
	92	* ecryptfs_write
48c1e44a	93	* @ecryptfs_inode: The eCryptfs file into which to write
da0102a1 MH	94	* @data: Virtual address where data to write is located
	95	* @offset: Offset in the eCryptfs file at which to begin writing the
	96	* data from @data
	97	* @size: The number of bytes to write from @data
	98	*
	99	* Write an arbitrary amount of data to an arbitrary location in the
	100	* eCryptfs inode page cache. This is done on a page-by-page, and then
	101	* by an extent-by-extent, basis; individual extents are encrypted and
	102	* written to the lower page cache (via VFS writes). This function
	103	* takes care of all the address translation to locations in the lower
	104	* filesystem; it also handles truncate events, writing out zeros
	105	* where necessary.
	106	*
	107	* Returns zero on success; non-zero otherwise
	108	*/
48c1e44a	109	int ecryptfs_write(struct inode ecryptfs_inode, char data, loff_t offset,
da0102a1 MH	110	size_t size)
	111	{
	112	struct page *ecryptfs_page;
13a791b4	113	struct ecryptfs_crypt_stat *crypt_stat;
da0102a1	114	char *ecryptfs_page_virt;
13a791b4	115	loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
da0102a1 MH	116	loff_t data_offset = 0;
	117	loff_t pos;
	118	int rc = 0;
	119
13a791b4	120	crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
7a3f595c ES	121	/*
	122	* if we are writing beyond current size, then start pos
	123	* at the current size - we'll fill in zeros from there.
	124	*/
da0102a1 MH	125	if (offset > ecryptfs_file_size)
	126	pos = ecryptfs_file_size;
	127	else
	128	pos = offset;
	129	while (pos < (offset + size)) {
	130	pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
	131	size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
	132	size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
684a3ff7	133	loff_t total_remaining_bytes = ((offset + size) - pos);
da0102a1 MH	134
	135	if (num_bytes > total_remaining_bytes)
	136	num_bytes = total_remaining_bytes;
	137	if (pos < offset) {
7a3f595c	138	/* remaining zeros to write, up to destination offset */
684a3ff7	139	loff_t total_remaining_zeros = (offset - pos);
da0102a1 MH	140
	141	if (num_bytes > total_remaining_zeros)
	142	num_bytes = total_remaining_zeros;
	143	}
02bd9799	144	ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode,
16a72c45	145	ecryptfs_page_idx);
da0102a1 MH	146	if (IS_ERR(ecryptfs_page)) {
	147	rc = PTR_ERR(ecryptfs_page);
	148	printk(KERN_ERR "%s: Error getting page at "
	149	"index [%ld] from eCryptfs inode "
18d1dbf1	150	"mapping; rc = [%d]\n", __func__,
da0102a1 MH	151	ecryptfs_page_idx, rc);
	152	goto out;
	153	}
da0102a1	154	ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
7a3f595c ES	155
	156	/*
	157	* pos: where we're now writing, offset: where the request was
	158	* If current pos is before request, we are filling zeros
	159	* If we are at or beyond request, we are writing the data
	160	* If we're in a fresh page beyond eof, zero it in either case
	161	*/
	162	if (pos < offset \|\| !start_offset_in_page) {
	163	/* We are extending past the previous end of the file.
	164	* Fill in zero values to the end of the page */
	165	memset(((char *)ecryptfs_page_virt
	166	+ start_offset_in_page), 0,
	167	PAGE_CACHE_SIZE - start_offset_in_page);
	168	}
	169
	170	/* pos >= offset, we are now writing the data request */
da0102a1 MH	171	if (pos >= offset) {
	172	memcpy(((char *)ecryptfs_page_virt
	173	+ start_offset_in_page),
	174	(data + data_offset), num_bytes);
	175	data_offset += num_bytes;
da0102a1 MH	176	}
	177	kunmap_atomic(ecryptfs_page_virt, KM_USER0);
	178	flush_dcache_page(ecryptfs_page);
16a72c45 MH	179	SetPageUptodate(ecryptfs_page);
16a72c45 MH	180	unlock_page(ecryptfs_page);
13a791b4 TH	181	if (crypt_stat->flags & ECRYPTFS_ENCRYPTED)
	182	rc = ecryptfs_encrypt_page(ecryptfs_page);
	183	else
	184	rc = ecryptfs_write_lower_page_segment(ecryptfs_inode,
	185	ecryptfs_page,
	186	start_offset_in_page,
	187	data_offset);
16a72c45	188	page_cache_release(ecryptfs_page);
da0102a1 MH	189	if (rc) {
da0102a1 MH	190	printk(KERN_ERR "%s: Error encrypting "
18d1dbf1	191	"page; rc = [%d]\n", __func__, rc);
da0102a1 MH	192	goto out;
da0102a1 MH	193	}
da0102a1 MH	194	pos += num_bytes;
	195	}
	196	if ((offset + size) > ecryptfs_file_size) {
13a791b4 TH	197	i_size_write(ecryptfs_inode, (offset + size));
	198	if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) {
	199	rc = ecryptfs_write_inode_size_to_metadata(
	200	ecryptfs_inode);
	201	if (rc) {
	202	printk(KERN_ERR "Problem with "
	203	"ecryptfs_write_inode_size_to_metadata; "
	204	"rc = [%d]\n", rc);
	205	goto out;
	206	}
da0102a1 MH	207	}
	208	}
	209	out:
	210	return rc;
	211	}
	212
	213	/**
	214	* ecryptfs_read_lower
	215	* @data: The read data is stored here by this function
	216	* @offset: Byte offset in the lower file from which to read the data
	217	* @size: Number of bytes to read from @offset of the lower file and
	218	* store into @data
	219	* @ecryptfs_inode: The eCryptfs inode
	220	*
	221	* Read @size bytes of data at byte offset @offset from the lower
	222	* inode into memory location @data.
	223	*
96a7b9c2	224	* Returns bytes read on success; 0 on EOF; less than zero on error
da0102a1 MH	225	*/
	226	int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
	227	struct inode *ecryptfs_inode)
	228	{
f61500e0	229	struct file *lower_file;
da0102a1	230	mm_segment_t fs_save;
96a7b9c2	231	ssize_t rc;
da0102a1	232
f61500e0 TH	233	lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file;
	234	if (!lower_file)
	235	return -EIO;
da0102a1 MH	236	fs_save = get_fs();
da0102a1 MH	237	set_fs(get_ds());
f61500e0	238	rc = vfs_read(lower_file, data, size, &offset);
da0102a1	239	set_fs(fs_save);
da0102a1 MH	240	return rc;
	241	}
	242
	243	/**
	244	* ecryptfs_read_lower_page_segment
	245	* @page_for_ecryptfs: The page into which data for eCryptfs will be
	246	* written
	247	* @offset_in_page: Offset in @page_for_ecryptfs from which to start
	248	* writing
	249	* @size: The number of bytes to write into @page_for_ecryptfs
	250	* @ecryptfs_inode: The eCryptfs inode
	251	*
	252	* Determines the byte offset in the file for the given page and
	253	* offset within the page, maps the page, and makes the call to read
	254	* the contents of @page_for_ecryptfs from the lower inode.
	255	*
	256	* Returns zero on success; non-zero otherwise
	257	*/
	258	int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
	259	pgoff_t page_index,
	260	size_t offset_in_page, size_t size,
	261	struct inode *ecryptfs_inode)
	262	{
	263	char *virt;
	264	loff_t offset;
	265	int rc;
	266
d6a13c17	267	offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page);
da0102a1 MH	268	virt = kmap(page_for_ecryptfs);
da0102a1 MH	269	rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
96a7b9c2 TH	270	if (rc > 0)
96a7b9c2 TH	271	rc = 0;
da0102a1	272	kunmap(page_for_ecryptfs);
16a72c45	273	flush_dcache_page(page_for_ecryptfs);
da0102a1 MH	274	return rc;
	275	}
	276
7896b631	277	#if 0
da0102a1 MH	278	/**
	279	* ecryptfs_read
	280	* @data: The virtual address into which to write the data read (and
	281	* possibly decrypted) from the lower file
	282	* @offset: The offset in the decrypted view of the file from which to
	283	* read into @data
	284	* @size: The number of bytes to read into @data
	285	* @ecryptfs_file: The eCryptfs file from which to read
	286	*
	287	* Read an arbitrary amount of data from an arbitrary location in the
	288	* eCryptfs page cache. This is done on an extent-by-extent basis;
	289	* individual extents are decrypted and read from the lower page
	290	* cache (via VFS reads). This function takes care of all the
	291	* address translation to locations in the lower filesystem.
	292	*
	293	* Returns zero on success; non-zero otherwise
	294	*/
	295	int ecryptfs_read(char *data, loff_t offset, size_t size,
	296	struct file *ecryptfs_file)
	297	{
02bd9799	298	struct inode *ecryptfs_inode = ecryptfs_file->f_dentry->d_inode;
da0102a1 MH	299	struct page *ecryptfs_page;
da0102a1 MH	300	char *ecryptfs_page_virt;
02bd9799	301	loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
da0102a1 MH	302	loff_t data_offset = 0;
	303	loff_t pos;
	304	int rc = 0;
	305
	306	if ((offset + size) > ecryptfs_file_size) {
	307	rc = -EINVAL;
	308	printk(KERN_ERR "%s: Attempt to read data past the end of the "
	309	"file; offset = [%lld]; size = [%td]; "
	310	"ecryptfs_file_size = [%lld]\n",
18d1dbf1	311	__func__, offset, size, ecryptfs_file_size);
da0102a1 MH	312	goto out;
	313	}
	314	pos = offset;
	315	while (pos < (offset + size)) {
	316	pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
	317	size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
	318	size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
	319	size_t total_remaining_bytes = ((offset + size) - pos);
	320
	321	if (num_bytes > total_remaining_bytes)
	322	num_bytes = total_remaining_bytes;
02bd9799	323	ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode,
16a72c45	324	ecryptfs_page_idx);
da0102a1 MH	325	if (IS_ERR(ecryptfs_page)) {
	326	rc = PTR_ERR(ecryptfs_page);
	327	printk(KERN_ERR "%s: Error getting page at "
	328	"index [%ld] from eCryptfs inode "
18d1dbf1	329	"mapping; rc = [%d]\n", __func__,
da0102a1 MH	330	ecryptfs_page_idx, rc);
	331	goto out;
	332	}
da0102a1 MH	333	ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
	334	memcpy((data + data_offset),
	335	((char *)ecryptfs_page_virt + start_offset_in_page),
	336	num_bytes);
	337	kunmap_atomic(ecryptfs_page_virt, KM_USER0);
16a72c45 MH	338	flush_dcache_page(ecryptfs_page);
	339	SetPageUptodate(ecryptfs_page);
	340	unlock_page(ecryptfs_page);
da0102a1 MH	341	page_cache_release(ecryptfs_page);
	342	pos += num_bytes;
	343	data_offset += num_bytes;
	344	}
	345	out:
	346	return rc;
	347	}
7896b631	348	#endif /* 0 */