linux/fs/remap_range.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/sched/xacct.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/uio.h>
#include <linux/fsnotify.h>
#include <linux/security.h>
#include <linux/export.h>
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/splice.h>
#include <linux/compat.h>
#include <linux/mount.h>
#include <linux/fs.h>
#include <linux/dax.h>
#include <linux/overflow.h>
#include "internal.h"

#include <linux/uaccess.h>
#include <asm/unistd.h>

/*
 * Performs necessary checks before doing a clone.
 *
 * Can adjust amount of bytes to clone via @req_count argument.
 * Returns appropriate error code that caller should return or
 * zero in case the clone should be allowed.
 */
static int generic_remap_checks(struct file *file_in, loff_t pos_in,
				struct file *file_out, loff_t pos_out,
				loff_t *req_count, unsigned int remap_flags)
{ … }

int remap_verify_area(struct file *file, loff_t pos, loff_t len, bool write)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * Ensure that we don't remap a partial EOF block in the middle of something
 * else.  Assume that the offsets have already been checked for block
 * alignment.
 *
 * For clone we only link a partial EOF block above or at the destination file's
 * EOF.  For deduplication we accept a partial EOF block only if it ends at the
 * destination file's EOF (can not link it into the middle of a file).
 *
 * Shorten the request if possible.
 */
static int generic_remap_check_len(struct inode *inode_in,
				   struct inode *inode_out,
				   loff_t pos_out,
				   loff_t *len,
				   unsigned int remap_flags)
{ … }

/* Read a page's worth of file data into the page cache. */
static struct folio *vfs_dedupe_get_folio(struct file *file, loff_t pos)
{ … }

/*
 * Lock two folios, ensuring that we lock in offset order if the folios
 * are from the same file.
 */
static void vfs_lock_two_folios(struct folio *folio1, struct folio *folio2)
{ … }

/* Unlock two folios, being careful not to unlock the same folio twice. */
static void vfs_unlock_two_folios(struct folio *folio1, struct folio *folio2)
{ … }

/*
 * Compare extents of two files to see if they are the same.
 * Caller must have locked both inodes to prevent write races.
 */
static int vfs_dedupe_file_range_compare(struct file *src, loff_t srcoff,
					 struct file *dest, loff_t dstoff,
					 loff_t len, bool *is_same)
{ … }

/*
 * Check that the two inodes are eligible for cloning, the ranges make
 * sense, and then flush all dirty data.  Caller must ensure that the
 * inodes have been locked against any other modifications.
 *
 * If there's an error, then the usual negative error code is returned.
 * Otherwise returns 0 with *len set to the request length.
 */
int
__generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
				struct file *file_out, loff_t pos_out,
				loff_t *len, unsigned int remap_flags,
				const struct iomap_ops *dax_read_ops)
{ … }

int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
				  struct file *file_out, loff_t pos_out,
				  loff_t *len, unsigned int remap_flags)
{ … }
EXPORT_SYMBOL(…);

loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
			    struct file *file_out, loff_t pos_out,
			    loff_t len, unsigned int remap_flags)
{ … }
EXPORT_SYMBOL(…);

/* Check whether we are allowed to dedupe the destination file */
static bool may_dedupe_file(struct file *file)
{ … }

loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
				 struct file *dst_file, loff_t dst_pos,
				 loff_t len, unsigned int remap_flags)
{ … }
EXPORT_SYMBOL(…);

int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
{ … }
EXPORT_SYMBOL(…);