1 files changed, 359 insertions, 0 deletions
diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
new file mode 100644
index 000000000000..e59c94add127
--- /dev/null
+++ b/fs/ecryptfs/read_write.c
@@ -0,0 +1,359 @@
+/**
+ * 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 zero on success; non-zero on error
+ */
+int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
+                         loff_t offset, size_t size)
+{
+        struct ecryptfs_inode_info *inode_info;
+        ssize_t octets_written;
+        mm_segment_t fs_save;
+        int rc = 0;
+        inode_info = ecryptfs_inode_to_private(ecryptfs_inode);
+        mutex_lock(&inode_info->lower_file_mutex);
+        BUG_ON(!inode_info->lower_file);
+        inode_info->lower_file->f_pos = offset;
+        fs_save = get_fs();
+        set_fs(get_ds());
+        octets_written = vfs_write(inode_info->lower_file, data, size,
+                                   &inode_info->lower_file->f_pos);
+        set_fs(fs_save);
+        if (octets_written < 0) {
+                printk(KERN_ERR "%s: octets_written = [%td]; "
+                       "expected [%td]\n", __FUNCTION__, octets_written, size);
+                rc = -EINVAL;
+        }
+        mutex_unlock(&inode_info->lower_file_mutex);
+        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 = (page_for_lower->index << PAGE_CACHE_SHIFT) + offset_in_page;
+        virt = kmap(page_for_lower);
+        rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
+        kunmap(page_for_lower);
+        return rc;
+}
+/**
+ * ecryptfs_write
+ * @ecryptfs_file: 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 file *ecryptfs_file, char *data, loff_t offset,
+                   size_t size)
+{
+        struct page *ecryptfs_page;
+        char *ecryptfs_page_virt;
+        u64 ecryptfs_file_size = i_size_read(ecryptfs_file->f_dentry->d_inode);
+        loff_t data_offset = 0;
+        loff_t pos;
+        int rc = 0;
+        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);
+                size_t total_remaining_bytes = ((offset + size) - pos);
+                if (num_bytes > total_remaining_bytes)
+                        num_bytes = total_remaining_bytes;
+                if (pos < offset) {
+                        size_t total_remaining_zeros = (offset - pos);
+                        if (num_bytes > total_remaining_zeros)
+                                num_bytes = total_remaining_zeros;
+                }
+                ecryptfs_page = ecryptfs_get1page(ecryptfs_file,
+                                                  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", __FUNCTION__,
+                               ecryptfs_page_idx, rc);
+                        goto out;
+                }
+                if (start_offset_in_page) {
+                        /* Read in the page from the lower
+                         * into the eCryptfs inode page cache,
+                         * decrypting */
+                        if ((rc = ecryptfs_decrypt_page(NULL, /* placeholder for git-bisect */
+                                                        ecryptfs_page))) {
+                                printk(KERN_ERR "%s: Error decrypting "
+                                       "page; rc = [%d]\n",
+                                       __FUNCTION__, rc);
+                                page_cache_release(ecryptfs_page);
+                                goto out;
+                        }
+                }
+                ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
+                if (pos >= offset) {
+                        memcpy(((char *)ecryptfs_page_virt
+                                + start_offset_in_page),
+                               (data + data_offset), num_bytes);
+                        data_offset += num_bytes;
+                } else {
+                        /* We are extending past the previous end of the file.
+                         * Fill in zero values up to the start of where we
+                         * will be writing data. */
+                        memset(((char *)ecryptfs_page_virt
+                                + start_offset_in_page), 0, num_bytes);
+                }
+                kunmap_atomic(ecryptfs_page_virt, KM_USER0);
+                flush_dcache_page(ecryptfs_page);
+                rc = ecryptfs_encrypt_page(NULL /* placeholder for git-bisect */);
+                if (rc) {
+                        printk(KERN_ERR "%s: Error encrypting "
+                               "page; rc = [%d]\n", __FUNCTION__, rc);
+                        page_cache_release(ecryptfs_page);
+                        goto out;
+                }
+                page_cache_release(ecryptfs_page);
+                pos += num_bytes;
+        }
+        if ((offset + size) > ecryptfs_file_size) {
+                i_size_write(ecryptfs_file->f_dentry->d_inode, (offset + size));
+                rc = ecryptfs_write_inode_size_to_metadata(NULL, NULL, NULL,
+                                                           NULL, 0); /* placeholders for git-bisect */
+                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 zero on success; non-zero on error
+ */
+int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
+                        struct inode *ecryptfs_inode)
+{
+        struct ecryptfs_inode_info *inode_info =
+                ecryptfs_inode_to_private(ecryptfs_inode);
+        ssize_t octets_read;
+        mm_segment_t fs_save;
+        size_t i;
+        int rc = 0;
+        mutex_lock(&inode_info->lower_file_mutex);
+        BUG_ON(!inode_info->lower_file);
+        inode_info->lower_file->f_pos = offset;
+        fs_save = get_fs();
+        set_fs(get_ds());
+        octets_read = vfs_read(inode_info->lower_file, data, size,
+                               &inode_info->lower_file->f_pos);
+        set_fs(fs_save);
+        if (octets_read < 0) {
+                printk(KERN_ERR "%s: octets_read = [%td]; "
+                       "expected [%td]\n", __FUNCTION__, octets_read, size);
+                rc = -EINVAL;
+        }
+        mutex_unlock(&inode_info->lower_file_mutex);
+        for (i = 0; i < size; i += PAGE_CACHE_SIZE) {
+                struct page *data_page;
+                data_page = virt_to_page(data + i);
+                flush_dcache_page(data_page);
+                if (rc)
+                        ClearPageUptodate(data_page);
+                else
+                        SetPageUptodate(data_page);
+        }
+        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 = ((page_index << PAGE_CACHE_SHIFT) + offset_in_page);
+        virt = kmap(page_for_ecryptfs);
+        rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
+        kunmap(page_for_ecryptfs);
+        return rc;
+}
+/**
+ * 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 page *ecryptfs_page;
+        char *ecryptfs_page_virt;
+        u64 ecryptfs_file_size = i_size_read(ecryptfs_file->f_dentry->d_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",
+                       __FUNCTION__, 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_get1page(ecryptfs_file,
+                                                  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", __FUNCTION__,
+                               ecryptfs_page_idx, rc);
+                        goto out;
+                }
+                rc = ecryptfs_decrypt_page(NULL /* placeholder for git-bisect */, ecryptfs_page);
+                if (rc) {
+                        printk(KERN_ERR "%s: Error decrypting "
+                               "page; rc = [%d]\n", __FUNCTION__, rc);
+                        page_cache_release(ecryptfs_page);
+                        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);
+                page_cache_release(ecryptfs_page);
+                pos += num_bytes;
+                data_offset += num_bytes;
+        }
+out:
+        return rc;
+}

diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c new file mode 100644 index 000000000000..e59c94add127 --- /dev/null +++ b/fs/ecryptfs/read_write.c
@@ -0,0 +1,359 @@
	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	*
	37	* Returns zero on success; non-zero on error
	38	*/
	39	int ecryptfs_write_lower(struct inode ecryptfs_inode, char data,
	40	loff_t offset, size_t size)
	41	{
	42	struct ecryptfs_inode_info *inode_info;
	43	ssize_t octets_written;
	44	mm_segment_t fs_save;
	45	int rc = 0;
	46
	47	inode_info = ecryptfs_inode_to_private(ecryptfs_inode);
	48	mutex_lock(&inode_info->lower_file_mutex);
	49	BUG_ON(!inode_info->lower_file);
	50	inode_info->lower_file->f_pos = offset;
	51	fs_save = get_fs();
	52	set_fs(get_ds());
	53	octets_written = vfs_write(inode_info->lower_file, data, size,
	54	&inode_info->lower_file->f_pos);
	55	set_fs(fs_save);
	56	if (octets_written < 0) {
	57	printk(KERN_ERR "%s: octets_written = [%td]; "
	58	"expected [%td]\n", __FUNCTION__, octets_written, size);
	59	rc = -EINVAL;
	60	}
	61	mutex_unlock(&inode_info->lower_file_mutex);
	62	mark_inode_dirty_sync(ecryptfs_inode);
	63	return rc;
	64	}
	65
	66	/**
	67	* ecryptfs_write_lower_page_segment
	68	* @ecryptfs_inode: The eCryptfs inode
	69	* @page_for_lower: The page containing the data to be written to the
	70	* lower file
	71	* @offset_in_page: The offset in the @page_for_lower from which to
	72	* start writing the data
	73	* @size: The amount of data from @page_for_lower to write to the
	74	* lower file
	75	*
	76	* Determines the byte offset in the file for the given page and
	77	* offset within the page, maps the page, and makes the call to write
	78	* the contents of @page_for_lower to the lower inode.
	79	*
	80	* Returns zero on success; non-zero otherwise
	81	*/
	82	int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
	83	struct page *page_for_lower,
	84	size_t offset_in_page, size_t size)
	85	{
	86	char *virt;
	87	loff_t offset;
	88	int rc;
	89
	90	offset = (page_for_lower->index << PAGE_CACHE_SHIFT) + offset_in_page;
	91	virt = kmap(page_for_lower);
	92	rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
	93	kunmap(page_for_lower);
	94	return rc;
	95	}
	96
	97	/**
	98	* ecryptfs_write
	99	* @ecryptfs_file: The eCryptfs file into which to write
	100	* @data: Virtual address where data to write is located
	101	* @offset: Offset in the eCryptfs file at which to begin writing the
	102	* data from @data
	103	* @size: The number of bytes to write from @data
	104	*
	105	* Write an arbitrary amount of data to an arbitrary location in the
	106	* eCryptfs inode page cache. This is done on a page-by-page, and then
	107	* by an extent-by-extent, basis; individual extents are encrypted and
	108	* written to the lower page cache (via VFS writes). This function
	109	* takes care of all the address translation to locations in the lower
	110	* filesystem; it also handles truncate events, writing out zeros
	111	* where necessary.
	112	*
	113	* Returns zero on success; non-zero otherwise
	114	*/
	115	int ecryptfs_write(struct file ecryptfs_file, char data, loff_t offset,
	116	size_t size)
	117	{
	118	struct page *ecryptfs_page;
	119	char *ecryptfs_page_virt;
	120	u64 ecryptfs_file_size = i_size_read(ecryptfs_file->f_dentry->d_inode);
	121	loff_t data_offset = 0;
	122	loff_t pos;
	123	int rc = 0;
	124
	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);
	133	size_t total_remaining_bytes = ((offset + size) - pos);
	134
	135	if (num_bytes > total_remaining_bytes)
	136	num_bytes = total_remaining_bytes;
	137	if (pos < offset) {
	138	size_t total_remaining_zeros = (offset - pos);
	139
	140	if (num_bytes > total_remaining_zeros)
	141	num_bytes = total_remaining_zeros;
	142	}
	143	ecryptfs_page = ecryptfs_get1page(ecryptfs_file,
	144	ecryptfs_page_idx);
	145	if (IS_ERR(ecryptfs_page)) {
	146	rc = PTR_ERR(ecryptfs_page);
	147	printk(KERN_ERR "%s: Error getting page at "
	148	"index [%ld] from eCryptfs inode "
	149	"mapping; rc = [%d]\n", __FUNCTION__,
	150	ecryptfs_page_idx, rc);
	151	goto out;
	152	}
	153	if (start_offset_in_page) {
	154	/* Read in the page from the lower
	155	* into the eCryptfs inode page cache,
	156	* decrypting */
	157	if ((rc = ecryptfs_decrypt_page(NULL, /* placeholder for git-bisect */
	158	ecryptfs_page))) {
	159	printk(KERN_ERR "%s: Error decrypting "
	160	"page; rc = [%d]\n",
	161	__FUNCTION__, rc);
	162	page_cache_release(ecryptfs_page);
	163	goto out;
	164	}
	165	}
	166	ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
	167	if (pos >= offset) {
	168	memcpy(((char *)ecryptfs_page_virt
	169	+ start_offset_in_page),
	170	(data + data_offset), num_bytes);
	171	data_offset += num_bytes;
	172	} else {
	173	/* We are extending past the previous end of the file.
	174	* Fill in zero values up to the start of where we
	175	* will be writing data. */
	176	memset(((char *)ecryptfs_page_virt
	177	+ start_offset_in_page), 0, num_bytes);
	178	}
	179	kunmap_atomic(ecryptfs_page_virt, KM_USER0);
	180	flush_dcache_page(ecryptfs_page);
	181	rc = ecryptfs_encrypt_page(NULL /* placeholder for git-bisect */);
	182	if (rc) {
	183	printk(KERN_ERR "%s: Error encrypting "
	184	"page; rc = [%d]\n", __FUNCTION__, rc);
	185	page_cache_release(ecryptfs_page);
	186	goto out;
	187	}
	188	page_cache_release(ecryptfs_page);
	189	pos += num_bytes;
	190	}
	191	if ((offset + size) > ecryptfs_file_size) {
	192	i_size_write(ecryptfs_file->f_dentry->d_inode, (offset + size));
	193	rc = ecryptfs_write_inode_size_to_metadata(NULL, NULL, NULL,
	194	NULL, 0); /* placeholders for git-bisect */
	195	if (rc) {
	196	printk(KERN_ERR "Problem with "
	197	"ecryptfs_write_inode_size_to_metadata; "
	198	"rc = [%d]\n", rc);
	199	goto out;
	200	}
	201	}
	202	out:
	203	return rc;
	204	}
	205
	206	/**
	207	* ecryptfs_read_lower
	208	* @data: The read data is stored here by this function
	209	* @offset: Byte offset in the lower file from which to read the data
	210	* @size: Number of bytes to read from @offset of the lower file and
	211	* store into @data
	212	* @ecryptfs_inode: The eCryptfs inode
	213	*
	214	* Read @size bytes of data at byte offset @offset from the lower
	215	* inode into memory location @data.
	216	*
	217	* Returns zero on success; non-zero on error
	218	*/
	219	int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
	220	struct inode *ecryptfs_inode)
	221	{
	222	struct ecryptfs_inode_info *inode_info =
	223	ecryptfs_inode_to_private(ecryptfs_inode);
	224	ssize_t octets_read;
	225	mm_segment_t fs_save;
	226	size_t i;
	227	int rc = 0;
	228
	229	mutex_lock(&inode_info->lower_file_mutex);
	230	BUG_ON(!inode_info->lower_file);
	231	inode_info->lower_file->f_pos = offset;
	232	fs_save = get_fs();
	233	set_fs(get_ds());
	234	octets_read = vfs_read(inode_info->lower_file, data, size,
	235	&inode_info->lower_file->f_pos);
	236	set_fs(fs_save);
	237	if (octets_read < 0) {
	238	printk(KERN_ERR "%s: octets_read = [%td]; "
	239	"expected [%td]\n", __FUNCTION__, octets_read, size);
	240	rc = -EINVAL;
	241	}
	242	mutex_unlock(&inode_info->lower_file_mutex);
	243	for (i = 0; i < size; i += PAGE_CACHE_SIZE) {
	244	struct page *data_page;
	245
	246	data_page = virt_to_page(data + i);
	247	flush_dcache_page(data_page);
	248	if (rc)
	249	ClearPageUptodate(data_page);
	250	else
	251	SetPageUptodate(data_page);
	252	}
	253	return rc;
	254	}
	255
	256	/**
	257	* ecryptfs_read_lower_page_segment
	258	* @page_for_ecryptfs: The page into which data for eCryptfs will be
	259	* written
	260	* @offset_in_page: Offset in @page_for_ecryptfs from which to start
	261	* writing
	262	* @size: The number of bytes to write into @page_for_ecryptfs
	263	* @ecryptfs_inode: The eCryptfs inode
	264	*
	265	* Determines the byte offset in the file for the given page and
	266	* offset within the page, maps the page, and makes the call to read
	267	* the contents of @page_for_ecryptfs from the lower inode.
	268	*
	269	* Returns zero on success; non-zero otherwise
	270	*/
	271	int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
	272	pgoff_t page_index,
	273	size_t offset_in_page, size_t size,
	274	struct inode *ecryptfs_inode)
	275	{
	276	char *virt;
	277	loff_t offset;
	278	int rc;
	279
	280	offset = ((page_index << PAGE_CACHE_SHIFT) + offset_in_page);
	281	virt = kmap(page_for_ecryptfs);
	282	rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
	283	kunmap(page_for_ecryptfs);
	284	return rc;
	285	}
	286
	287	/**
	288	* ecryptfs_read
	289	* @data: The virtual address into which to write the data read (and
	290	* possibly decrypted) from the lower file
	291	* @offset: The offset in the decrypted view of the file from which to
	292	* read into @data
	293	* @size: The number of bytes to read into @data
	294	* @ecryptfs_file: The eCryptfs file from which to read
	295	*
	296	* Read an arbitrary amount of data from an arbitrary location in the
	297	* eCryptfs page cache. This is done on an extent-by-extent basis;
	298	* individual extents are decrypted and read from the lower page
	299	* cache (via VFS reads). This function takes care of all the
	300	* address translation to locations in the lower filesystem.
	301	*
	302	* Returns zero on success; non-zero otherwise
	303	*/
	304	int ecryptfs_read(char *data, loff_t offset, size_t size,
	305	struct file *ecryptfs_file)
	306	{
	307	struct page *ecryptfs_page;
	308	char *ecryptfs_page_virt;
	309	u64 ecryptfs_file_size = i_size_read(ecryptfs_file->f_dentry->d_inode);
	310	loff_t data_offset = 0;
	311	loff_t pos;
	312	int rc = 0;
	313
	314	if ((offset + size) > ecryptfs_file_size) {
	315	rc = -EINVAL;
	316	printk(KERN_ERR "%s: Attempt to read data past the end of the "
	317	"file; offset = [%lld]; size = [%td]; "
	318	"ecryptfs_file_size = [%lld]\n",
	319	__FUNCTION__, offset, size, ecryptfs_file_size);
	320	goto out;
	321	}
	322	pos = offset;
	323	while (pos < (offset + size)) {
	324	pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
	325	size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
	326	size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
	327	size_t total_remaining_bytes = ((offset + size) - pos);
	328
	329	if (num_bytes > total_remaining_bytes)
	330	num_bytes = total_remaining_bytes;
	331	ecryptfs_page = ecryptfs_get1page(ecryptfs_file,
	332	ecryptfs_page_idx);
	333	if (IS_ERR(ecryptfs_page)) {
	334	rc = PTR_ERR(ecryptfs_page);
	335	printk(KERN_ERR "%s: Error getting page at "
	336	"index [%ld] from eCryptfs inode "
	337	"mapping; rc = [%d]\n", __FUNCTION__,
	338	ecryptfs_page_idx, rc);
	339	goto out;
	340	}
	341	rc = ecryptfs_decrypt_page(NULL /* placeholder for git-bisect */, ecryptfs_page);
	342	if (rc) {
	343	printk(KERN_ERR "%s: Error decrypting "
	344	"page; rc = [%d]\n", __FUNCTION__, rc);
	345	page_cache_release(ecryptfs_page);
	346	goto out;
	347	}
	348	ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
	349	memcpy((data + data_offset),
	350	((char *)ecryptfs_page_virt + start_offset_in_page),
	351	num_bytes);
	352	kunmap_atomic(ecryptfs_page_virt, KM_USER0);
	353	page_cache_release(ecryptfs_page);
	354	pos += num_bytes;
	355	data_offset += num_bytes;
	356	}
	357	out:
	358	return rc;
	359	}