linux/fs/ecryptfs/read_write.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 2007 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <[email protected]>
 */

#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/sched/signal.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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * ecryptfs_read_lower_page_segment
 * @page_for_ecryptfs: The page into which data for eCryptfs will be
 *                     written
 * @page_index: Page index in @page_for_ecryptfs from which to start
 *		writing
 * @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)
{ … }