Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1721 insertions, 0 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
new file mode 100644
index 000000000..7a2ff6157
--- /dev/null
+++ b/fs/read_write.c
@@ -0,0 +1,1721 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/read_write.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#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 "internal.h"
+
+#include <linux/uaccess.h>
+#include <asm/unistd.h>
+
+const struct file_operations generic_ro_fops = {
+	.llseek		= generic_file_llseek,
+	.read_iter	= generic_file_read_iter,
+	.mmap		= generic_file_readonly_mmap,
+	.splice_read	= generic_file_splice_read,
+};
+
+EXPORT_SYMBOL(generic_ro_fops);
+
+static inline bool unsigned_offsets(struct file *file)
+{
+	return file->f_mode & FMODE_UNSIGNED_OFFSET;
+}
+
+/**
+ * vfs_setpos - update the file offset for lseek
+ * @file:	file structure in question
+ * @offset:	file offset to seek to
+ * @maxsize:	maximum file size
+ *
+ * This is a low-level filesystem helper for updating the file offset to
+ * the value specified by @offset if the given offset is valid and it is
+ * not equal to the current file offset.
+ *
+ * Return the specified offset on success and -EINVAL on invalid offset.
+ */
+loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize)
+{
+	if (offset < 0 && !unsigned_offsets(file))
+		return -EINVAL;
+	if (offset > maxsize)
+		return -EINVAL;
+
+	if (offset != file->f_pos) {
+		file->f_pos = offset;
+		file->f_version = 0;
+	}
+	return offset;
+}
+EXPORT_SYMBOL(vfs_setpos);
+
+/**
+ * generic_file_llseek_size - generic llseek implementation for regular files
+ * @file:	file structure to seek on
+ * @offset:	file offset to seek to
+ * @whence:	type of seek
+ * @size:	max size of this file in file system
+ * @eof:	offset used for SEEK_END position
+ *
+ * This is a variant of generic_file_llseek that allows passing in a custom
+ * maximum file size and a custom EOF position, for e.g. hashed directories
+ *
+ * Synchronization:
+ * SEEK_SET and SEEK_END are unsynchronized (but atomic on 64bit platforms)
+ * SEEK_CUR is synchronized against other SEEK_CURs, but not read/writes.
+ * read/writes behave like SEEK_SET against seeks.
+ */
+loff_t
+generic_file_llseek_size(struct file *file, loff_t offset, int whence,
+		loff_t maxsize, loff_t eof)
+{
+	switch (whence) {
+	case SEEK_END:
+		offset += eof;
+		break;
+	case SEEK_CUR:
+		/*
+		 * Here we special-case the lseek(fd, 0, SEEK_CUR)
+		 * position-querying operation.  Avoid rewriting the "same"
+		 * f_pos value back to the file because a concurrent read(),
+		 * write() or lseek() might have altered it
+		 */
+		if (offset == 0)
+			return file->f_pos;
+		/*
+		 * f_lock protects against read/modify/write race with other
+		 * SEEK_CURs. Note that parallel writes and reads behave
+		 * like SEEK_SET.
+		 */
+		spin_lock(&file->f_lock);
+		offset = vfs_setpos(file, file->f_pos + offset, maxsize);
+		spin_unlock(&file->f_lock);
+		return offset;
+	case SEEK_DATA:
+		/*
+		 * In the generic case the entire file is data, so as long as
+		 * offset isn't at the end of the file then the offset is data.
+		 */
+		if ((unsigned long long)offset >= eof)
+			return -ENXIO;
+		break;
+	case SEEK_HOLE:
+		/*
+		 * There is a virtual hole at the end of the file, so as long as
+		 * offset isn't i_size or larger, return i_size.
+		 */
+		if ((unsigned long long)offset >= eof)
+			return -ENXIO;
+		offset = eof;
+		break;
+	}
+
+	return vfs_setpos(file, offset, maxsize);
+}
+EXPORT_SYMBOL(generic_file_llseek_size);
+
+/**
+ * generic_file_llseek - generic llseek implementation for regular files
+ * @file:	file structure to seek on
+ * @offset:	file offset to seek to
+ * @whence:	type of seek
+ *
+ * This is a generic implemenation of ->llseek useable for all normal local
+ * filesystems.  It just updates the file offset to the value specified by
+ * @offset and @whence.
+ */
+loff_t generic_file_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct inode *inode = file->f_mapping->host;
+
+	return generic_file_llseek_size(file, offset, whence,
+					inode->i_sb->s_maxbytes,
+					i_size_read(inode));
+}
+EXPORT_SYMBOL(generic_file_llseek);
+
+/**
+ * fixed_size_llseek - llseek implementation for fixed-sized devices
+ * @file:	file structure to seek on
+ * @offset:	file offset to seek to
+ * @whence:	type of seek
+ * @size:	size of the file
+ *
+ */
+loff_t fixed_size_llseek(struct file *file, loff_t offset, int whence, loff_t size)
+{
+	switch (whence) {
+	case SEEK_SET: case SEEK_CUR: case SEEK_END:
+		return generic_file_llseek_size(file, offset, whence,
+						size, size);
+	default:
+		return -EINVAL;
+	}
+}
+EXPORT_SYMBOL(fixed_size_llseek);
+
+/**
+ * no_seek_end_llseek - llseek implementation for fixed-sized devices
+ * @file:	file structure to seek on
+ * @offset:	file offset to seek to
+ * @whence:	type of seek
+ *
+ */
+loff_t no_seek_end_llseek(struct file *file, loff_t offset, int whence)
+{
+	switch (whence) {
+	case SEEK_SET: case SEEK_CUR:
+		return generic_file_llseek_size(file, offset, whence,
+						OFFSET_MAX, 0);
+	default:
+		return -EINVAL;
+	}
+}
+EXPORT_SYMBOL(no_seek_end_llseek);
+
+/**
+ * no_seek_end_llseek_size - llseek implementation for fixed-sized devices
+ * @file:	file structure to seek on
+ * @offset:	file offset to seek to
+ * @whence:	type of seek
+ * @size:	maximal offset allowed
+ *
+ */
+loff_t no_seek_end_llseek_size(struct file *file, loff_t offset, int whence, loff_t size)
+{
+	switch (whence) {
+	case SEEK_SET: case SEEK_CUR:
+		return generic_file_llseek_size(file, offset, whence,
+						size, 0);
+	default:
+		return -EINVAL;
+	}
+}
+EXPORT_SYMBOL(no_seek_end_llseek_size);
+
+/**
+ * noop_llseek - No Operation Performed llseek implementation
+ * @file:	file structure to seek on
+ * @offset:	file offset to seek to
+ * @whence:	type of seek
+ *
+ * This is an implementation of ->llseek useable for the rare special case when
+ * userspace expects the seek to succeed but the (device) file is actually not
+ * able to perform the seek. In this case you use noop_llseek() instead of
+ * falling back to the default implementation of ->llseek.
+ */
+loff_t noop_llseek(struct file *file, loff_t offset, int whence)
+{
+	return file->f_pos;
+}
+EXPORT_SYMBOL(noop_llseek);
+
+loff_t default_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct inode *inode = file_inode(file);
+	loff_t retval;
+
+	inode_lock(inode);
+	switch (whence) {
+		case SEEK_END:
+			offset += i_size_read(inode);
+			break;
+		case SEEK_CUR:
+			if (offset == 0) {
+				retval = file->f_pos;
+				goto out;
+			}
+			offset += file->f_pos;
+			break;
+		case SEEK_DATA:
+			/*
+			 * In the generic case the entire file is data, so as
+			 * long as offset isn't at the end of the file then the
+			 * offset is data.
+			 */
+			if (offset >= inode->i_size) {
+				retval = -ENXIO;
+				goto out;
+			}
+			break;
+		case SEEK_HOLE:
+			/*
+			 * There is a virtual hole at the end of the file, so
+			 * as long as offset isn't i_size or larger, return
+			 * i_size.
+			 */
+			if (offset >= inode->i_size) {
+				retval = -ENXIO;
+				goto out;
+			}
+			offset = inode->i_size;
+			break;
+	}
+	retval = -EINVAL;
+	if (offset >= 0 || unsigned_offsets(file)) {
+		if (offset != file->f_pos) {
+			file->f_pos = offset;
+			file->f_version = 0;
+		}
+		retval = offset;
+	}
+out:
+	inode_unlock(inode);
+	return retval;
+}
+EXPORT_SYMBOL(default_llseek);
+
+loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
+{
+	if (!(file->f_mode & FMODE_LSEEK))
+		return -ESPIPE;
+	return file->f_op->llseek(file, offset, whence);
+}
+EXPORT_SYMBOL(vfs_llseek);
+
+static off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence)
+{
+	off_t retval;
+	struct fd f = fdget_pos(fd);
+	if (!f.file)
+		return -EBADF;
+
+	retval = -EINVAL;
+	if (whence <= SEEK_MAX) {
+		loff_t res = vfs_llseek(f.file, offset, whence);
+		retval = res;
+		if (res != (loff_t)retval)
+			retval = -EOVERFLOW;	/* LFS: should only happen on 32 bit platforms */
+	}
+	fdput_pos(f);
+	return retval;
+}
+
+SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence)
+{
+	return ksys_lseek(fd, offset, whence);
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE3(lseek, unsigned int, fd, compat_off_t, offset, unsigned int, whence)
+{
+	return ksys_lseek(fd, offset, whence);
+}
+#endif
+
+#if !defined(CONFIG_64BIT) || defined(CONFIG_COMPAT) || \
+	defined(__ARCH_WANT_SYS_LLSEEK)
+SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high,
+		unsigned long, offset_low, loff_t __user *, result,
+		unsigned int, whence)
+{
+	int retval;
+	struct fd f = fdget_pos(fd);
+	loff_t offset;
+
+	if (!f.file)
+		return -EBADF;
+
+	retval = -EINVAL;
+	if (whence > SEEK_MAX)
+		goto out_putf;
+
+	offset = vfs_llseek(f.file, ((loff_t) offset_high << 32) | offset_low,
+			whence);
+
+	retval = (int)offset;
+	if (offset >= 0) {
+		retval = -EFAULT;
+		if (!copy_to_user(result, &offset, sizeof(offset)))
+			retval = 0;
+	}
+out_putf:
+	fdput_pos(f);
+	return retval;
+}
+#endif
+
+int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t count)
+{
+	if (unlikely((ssize_t) count < 0))
+		return -EINVAL;
+
+	if (ppos) {
+		loff_t pos = *ppos;
+
+		if (unlikely(pos < 0)) {
+			if (!unsigned_offsets(file))
+				return -EINVAL;
+			if (count >= -pos) /* both values are in 0..LLONG_MAX */
+				return -EOVERFLOW;
+		} else if (unlikely((loff_t) (pos + count) < 0)) {
+			if (!unsigned_offsets(file))
+				return -EINVAL;
+		}
+	}
+
+	return security_file_permission(file,
+				read_write == READ ? MAY_READ : MAY_WRITE);
+}
+EXPORT_SYMBOL(rw_verify_area);
+
+static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
+{
+	struct kiocb kiocb;
+	struct iov_iter iter;
+	ssize_t ret;
+
+	init_sync_kiocb(&kiocb, filp);
+	kiocb.ki_pos = (ppos ? *ppos : 0);
+	iov_iter_ubuf(&iter, ITER_DEST, buf, len);
+
+	ret = call_read_iter(filp, &kiocb, &iter);
+	BUG_ON(ret == -EIOCBQUEUED);
+	if (ppos)
+		*ppos = kiocb.ki_pos;
+	return ret;
+}
+
+static int warn_unsupported(struct file *file, const char *op)
+{
+	pr_warn_ratelimited(
+		"kernel %s not supported for file %pD4 (pid: %d comm: %.20s)\n",
+		op, file, current->pid, current->comm);
+	return -EINVAL;
+}
+
+ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
+{
+	struct kvec iov = {
+		.iov_base	= buf,
+		.iov_len	= min_t(size_t, count, MAX_RW_COUNT),
+	};
+	struct kiocb kiocb;
+	struct iov_iter iter;
+	ssize_t ret;
+
+	if (WARN_ON_ONCE(!(file->f_mode & FMODE_READ)))
+		return -EINVAL;
+	if (!(file->f_mode & FMODE_CAN_READ))
+		return -EINVAL;
+	/*
+	 * Also fail if ->read_iter and ->read are both wired up as that
+	 * implies very convoluted semantics.
+	 */
+	if (unlikely(!file->f_op->read_iter || file->f_op->read))
+		return warn_unsupported(file, "read");
+
+	init_sync_kiocb(&kiocb, file);
+	kiocb.ki_pos = pos ? *pos : 0;
+	iov_iter_kvec(&iter, ITER_DEST, &iov, 1, iov.iov_len);
+	ret = file->f_op->read_iter(&kiocb, &iter);
+	if (ret > 0) {
+		if (pos)
+			*pos = kiocb.ki_pos;
+		fsnotify_access(file);
+		add_rchar(current, ret);
+	}
+	inc_syscr(current);
+	return ret;
+}
+
+ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
+{
+	ssize_t ret;
+
+	ret = rw_verify_area(READ, file, pos, count);
+	if (ret)
+		return ret;
+	return __kernel_read(file, buf, count, pos);
+}
+EXPORT_SYMBOL(kernel_read);
+
+ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
+{
+	ssize_t ret;
+
+	if (!(file->f_mode & FMODE_READ))
+		return -EBADF;
+	if (!(file->f_mode & FMODE_CAN_READ))
+		return -EINVAL;
+	if (unlikely(!access_ok(buf, count)))
+		return -EFAULT;
+
+	ret = rw_verify_area(READ, file, pos, count);
+	if (ret)
+		return ret;
+	if (count > MAX_RW_COUNT)
+		count =  MAX_RW_COUNT;
+
+	if (file->f_op->read)
+		ret = file->f_op->read(file, buf, count, pos);
+	else if (file->f_op->read_iter)
+		ret = new_sync_read(file, buf, count, pos);
+	else
+		ret = -EINVAL;
+	if (ret > 0) {
+		fsnotify_access(file);
+		add_rchar(current, ret);
+	}
+	inc_syscr(current);
+	return ret;
+}
+
+static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
+{
+	struct kiocb kiocb;
+	struct iov_iter iter;
+	ssize_t ret;
+
+	init_sync_kiocb(&kiocb, filp);
+	kiocb.ki_pos = (ppos ? *ppos : 0);
+	iov_iter_ubuf(&iter, ITER_SOURCE, (void __user *)buf, len);
+
+	ret = call_write_iter(filp, &kiocb, &iter);
+	BUG_ON(ret == -EIOCBQUEUED);
+	if (ret > 0 && ppos)
+		*ppos = kiocb.ki_pos;
+	return ret;
+}
+
+/* caller is responsible for file_start_write/file_end_write */
+ssize_t __kernel_write_iter(struct file *file, struct iov_iter *from, loff_t *pos)
+{
+	struct kiocb kiocb;
+	ssize_t ret;
+
+	if (WARN_ON_ONCE(!(file->f_mode & FMODE_WRITE)))
+		return -EBADF;
+	if (!(file->f_mode & FMODE_CAN_WRITE))
+		return -EINVAL;
+	/*
+	 * Also fail if ->write_iter and ->write are both wired up as that
+	 * implies very convoluted semantics.
+	 */
+	if (unlikely(!file->f_op->write_iter || file->f_op->write))
+		return warn_unsupported(file, "write");
+
+	init_sync_kiocb(&kiocb, file);
+	kiocb.ki_pos = pos ? *pos : 0;
+	ret = file->f_op->write_iter(&kiocb, from);
+	if (ret > 0) {
+		if (pos)
+			*pos = kiocb.ki_pos;
+		fsnotify_modify(file);
+		add_wchar(current, ret);
+	}
+	inc_syscw(current);
+	return ret;
+}
+
+/* caller is responsible for file_start_write/file_end_write */
+ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos)
+{
+	struct kvec iov = {
+		.iov_base	= (void *)buf,
+		.iov_len	= min_t(size_t, count, MAX_RW_COUNT),
+	};
+	struct iov_iter iter;
+	iov_iter_kvec(&iter, ITER_SOURCE, &iov, 1, iov.iov_len);
+	return __kernel_write_iter(file, &iter, pos);
+}
+/*
+ * This "EXPORT_SYMBOL_GPL()" is more of a "EXPORT_SYMBOL_DONTUSE()",
+ * but autofs is one of the few internal kernel users that actually
+ * wants this _and_ can be built as a module. So we need to export
+ * this symbol for autofs, even though it really isn't appropriate
+ * for any other kernel modules.
+ */
+EXPORT_SYMBOL_GPL(__kernel_write);
+
+ssize_t kernel_write(struct file *file, const void *buf, size_t count,
+			    loff_t *pos)
+{
+	ssize_t ret;
+
+	ret = rw_verify_area(WRITE, file, pos, count);
+	if (ret)
+		return ret;
+
+	file_start_write(file);
+	ret =  __kernel_write(file, buf, count, pos);
+	file_end_write(file);
+	return ret;
+}
+EXPORT_SYMBOL(kernel_write);
+
+ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
+{
+	ssize_t ret;
+
+	if (!(file->f_mode & FMODE_WRITE))
+		return -EBADF;
+	if (!(file->f_mode & FMODE_CAN_WRITE))
+		return -EINVAL;
+	if (unlikely(!access_ok(buf, count)))
+		return -EFAULT;
+
+	ret = rw_verify_area(WRITE, file, pos, count);
+	if (ret)
+		return ret;
+	if (count > MAX_RW_COUNT)
+		count =  MAX_RW_COUNT;
+	file_start_write(file);
+	if (file->f_op->write)
+		ret = file->f_op->write(file, buf, count, pos);
+	else if (file->f_op->write_iter)
+		ret = new_sync_write(file, buf, count, pos);
+	else
+		ret = -EINVAL;
+	if (ret > 0) {
+		fsnotify_modify(file);
+		add_wchar(current, ret);
+	}
+	inc_syscw(current);
+	file_end_write(file);
+	return ret;
+}
+
+/* file_ppos returns &file->f_pos or NULL if file is stream */
+static inline loff_t *file_ppos(struct file *file)
+{
+	return file->f_mode & FMODE_STREAM ? NULL : &file->f_pos;
+}
+
+ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count)
+{
+	struct fd f = fdget_pos(fd);
+	ssize_t ret = -EBADF;
+
+	if (f.file) {
+		loff_t pos, *ppos = file_ppos(f.file);
+		if (ppos) {
+			pos = *ppos;
+			ppos = &pos;
+		}
+		ret = vfs_read(f.file, buf, count, ppos);
+		if (ret >= 0 && ppos)
+			f.file->f_pos = pos;
+		fdput_pos(f);
+	}
+	return ret;
+}
+
+SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
+{
+	return ksys_read(fd, buf, count);
+}
+
+ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count)
+{
+	struct fd f = fdget_pos(fd);
+	ssize_t ret = -EBADF;
+
+	if (f.file) {
+		loff_t pos, *ppos = file_ppos(f.file);
+		if (ppos) {
+			pos = *ppos;
+			ppos = &pos;
+		}
+		ret = vfs_write(f.file, buf, count, ppos);
+		if (ret >= 0 && ppos)
+			f.file->f_pos = pos;
+		fdput_pos(f);
+	}
+
+	return ret;
+}
+
+SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf,
+		size_t, count)
+{
+	return ksys_write(fd, buf, count);
+}
+
+ssize_t ksys_pread64(unsigned int fd, char __user *buf, size_t count,
+		     loff_t pos)
+{
+	struct fd f;
+	ssize_t ret = -EBADF;
+
+	if (pos < 0)
+		return -EINVAL;
+
+	f = fdget(fd);
+	if (f.file) {
+		ret = -ESPIPE;
+		if (f.file->f_mode & FMODE_PREAD)
+			ret = vfs_read(f.file, buf, count, &pos);
+		fdput(f);
+	}
+
+	return ret;
+}
+
+SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf,
+			size_t, count, loff_t, pos)
+{
+	return ksys_pread64(fd, buf, count, pos);
+}
+
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_PREAD64)
+COMPAT_SYSCALL_DEFINE5(pread64, unsigned int, fd, char __user *, buf,
+		       size_t, count, compat_arg_u64_dual(pos))
+{
+	return ksys_pread64(fd, buf, count, compat_arg_u64_glue(pos));
+}
+#endif
+
+ssize_t ksys_pwrite64(unsigned int fd, const char __user *buf,
+		      size_t count, loff_t pos)
+{
+	struct fd f;
+	ssize_t ret = -EBADF;
+
+	if (pos < 0)
+		return -EINVAL;
+
+	f = fdget(fd);
+	if (f.file) {
+		ret = -ESPIPE;
+		if (f.file->f_mode & FMODE_PWRITE)  
+			ret = vfs_write(f.file, buf, count, &pos);
+		fdput(f);
+	}
+
+	return ret;
+}
+
+SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf,
+			 size_t, count, loff_t, pos)
+{
+	return ksys_pwrite64(fd, buf, count, pos);
+}
+
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_PWRITE64)
+COMPAT_SYSCALL_DEFINE5(pwrite64, unsigned int, fd, const char __user *, buf,
+		       size_t, count, compat_arg_u64_dual(pos))
+{
+	return ksys_pwrite64(fd, buf, count, compat_arg_u64_glue(pos));
+}
+#endif
+
+static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
+		loff_t *ppos, int type, rwf_t flags)
+{
+	struct kiocb kiocb;
+	ssize_t ret;
+
+	init_sync_kiocb(&kiocb, filp);
+	ret = kiocb_set_rw_flags(&kiocb, flags);
+	if (ret)
+		return ret;
+	kiocb.ki_pos = (ppos ? *ppos : 0);
+
+	if (type == READ)
+		ret = call_read_iter(filp, &kiocb, iter);
+	else
+		ret = call_write_iter(filp, &kiocb, iter);
+	BUG_ON(ret == -EIOCBQUEUED);
+	if (ppos)
+		*ppos = kiocb.ki_pos;
+	return ret;
+}
+
+/* Do it by hand, with file-ops */
+static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
+		loff_t *ppos, int type, rwf_t flags)
+{
+	ssize_t ret = 0;
+
+	if (flags & ~RWF_HIPRI)
+		return -EOPNOTSUPP;
+
+	while (iov_iter_count(iter)) {
+		struct iovec iovec = iov_iter_iovec(iter);
+		ssize_t nr;
+
+		if (type == READ) {
+			nr = filp->f_op->read(filp, iovec.iov_base,
+					      iovec.iov_len, ppos);
+		} else {
+			nr = filp->f_op->write(filp, iovec.iov_base,
+					       iovec.iov_len, ppos);
+		}
+
+		if (nr < 0) {
+			if (!ret)
+				ret = nr;
+			break;
+		}
+		ret += nr;
+		if (nr != iovec.iov_len)
+			break;
+		iov_iter_advance(iter, nr);
+	}
+
+	return ret;
+}
+
+static ssize_t do_iter_read(struct file *file, struct iov_iter *iter,
+		loff_t *pos, rwf_t flags)
+{
+	size_t tot_len;
+	ssize_t ret = 0;
+
+	if (!(file->f_mode & FMODE_READ))
+		return -EBADF;
+	if (!(file->f_mode & FMODE_CAN_READ))
+		return -EINVAL;
+
+	tot_len = iov_iter_count(iter);
+	if (!tot_len)
+		goto out;
+	ret = rw_verify_area(READ, file, pos, tot_len);
+	if (ret < 0)
+		return ret;
+
+	if (file->f_op->read_iter)
+		ret = do_iter_readv_writev(file, iter, pos, READ, flags);
+	else
+		ret = do_loop_readv_writev(file, iter, pos, READ, flags);
+out:
+	if (ret >= 0)
+		fsnotify_access(file);
+	return ret;
+}
+
+ssize_t vfs_iocb_iter_read(struct file *file, struct kiocb *iocb,
+			   struct iov_iter *iter)
+{
+	size_t tot_len;
+	ssize_t ret = 0;
+
+	if (!file->f_op->read_iter)
+		return -EINVAL;
+	if (!(file->f_mode & FMODE_READ))
+		return -EBADF;
+	if (!(file->f_mode & FMODE_CAN_READ))
+		return -EINVAL;
+
+	tot_len = iov_iter_count(iter);
+	if (!tot_len)
+		goto out;
+	ret = rw_verify_area(READ, file, &iocb->ki_pos, tot_len);
+	if (ret < 0)
+		return ret;
+
+	ret = call_read_iter(file, iocb, iter);
+out:
+	if (ret >= 0)
+		fsnotify_access(file);
+	return ret;
+}
+EXPORT_SYMBOL(vfs_iocb_iter_read);
+
+ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
+		rwf_t flags)
+{
+	if (!file->f_op->read_iter)
+		return -EINVAL;
+	return do_iter_read(file, iter, ppos, flags);
+}
+EXPORT_SYMBOL(vfs_iter_read);
+
+static ssize_t do_iter_write(struct file *file, struct iov_iter *iter,
+		loff_t *pos, rwf_t flags)
+{
+	size_t tot_len;
+	ssize_t ret = 0;
+
+	if (!(file->f_mode & FMODE_WRITE))
+		return -EBADF;
+	if (!(file->f_mode & FMODE_CAN_WRITE))
+		return -EINVAL;
+
+	tot_len = iov_iter_count(iter);
+	if (!tot_len)
+		return 0;
+	ret = rw_verify_area(WRITE, file, pos, tot_len);
+	if (ret < 0)
+		return ret;
+
+	if (file->f_op->write_iter)
+		ret = do_iter_readv_writev(file, iter, pos, WRITE, flags);
+	else
+		ret = do_loop_readv_writev(file, iter, pos, WRITE, flags);
+	if (ret > 0)
+		fsnotify_modify(file);
+	return ret;
+}
+
+ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb,
+			    struct iov_iter *iter)
+{
+	size_t tot_len;
+	ssize_t ret = 0;
+
+	if (!file->f_op->write_iter)
+		return -EINVAL;
+	if (!(file->f_mode & FMODE_WRITE))
+		return -EBADF;
+	if (!(file->f_mode & FMODE_CAN_WRITE))
+		return -EINVAL;
+
+	tot_len = iov_iter_count(iter);
+	if (!tot_len)
+		return 0;
+	ret = rw_verify_area(WRITE, file, &iocb->ki_pos, tot_len);
+	if (ret < 0)
+		return ret;
+
+	ret = call_write_iter(file, iocb, iter);
+	if (ret > 0)
+		fsnotify_modify(file);
+
+	return ret;
+}
+EXPORT_SYMBOL(vfs_iocb_iter_write);
+
+ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
+		rwf_t flags)
+{
+	if (!file->f_op->write_iter)
+		return -EINVAL;
+	return do_iter_write(file, iter, ppos, flags);
+}
+EXPORT_SYMBOL(vfs_iter_write);
+
+static ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
+		  unsigned long vlen, loff_t *pos, rwf_t flags)
+{
+	struct iovec iovstack[UIO_FASTIOV];
+	struct iovec *iov = iovstack;
+	struct iov_iter iter;
+	ssize_t ret;
+
+	ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
+	if (ret >= 0) {
+		ret = do_iter_read(file, &iter, pos, flags);
+		kfree(iov);
+	}
+
+	return ret;
+}
+
+static ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
+		   unsigned long vlen, loff_t *pos, rwf_t flags)
+{
+	struct iovec iovstack[UIO_FASTIOV];
+	struct iovec *iov = iovstack;
+	struct iov_iter iter;
+	ssize_t ret;
+
+	ret = import_iovec(ITER_SOURCE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
+	if (ret >= 0) {
+		file_start_write(file);
+		ret = do_iter_write(file, &iter, pos, flags);
+		file_end_write(file);
+		kfree(iov);
+	}
+	return ret;
+}
+
+static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec,
+			unsigned long vlen, rwf_t flags)
+{
+	struct fd f = fdget_pos(fd);
+	ssize_t ret = -EBADF;
+
+	if (f.file) {
+		loff_t pos, *ppos = file_ppos(f.file);
+		if (ppos) {
+			pos = *ppos;
+			ppos = &pos;
+		}
+		ret = vfs_readv(f.file, vec, vlen, ppos, flags);
+		if (ret >= 0 && ppos)
+			f.file->f_pos = pos;
+		fdput_pos(f);
+	}
+
+	if (ret > 0)
+		add_rchar(current, ret);
+	inc_syscr(current);
+	return ret;
+}
+
+static ssize_t do_writev(unsigned long fd, const struct iovec __user *vec,
+			 unsigned long vlen, rwf_t flags)
+{
+	struct fd f = fdget_pos(fd);
+	ssize_t ret = -EBADF;
+
+	if (f.file) {
+		loff_t pos, *ppos = file_ppos(f.file);
+		if (ppos) {
+			pos = *ppos;
+			ppos = &pos;
+		}
+		ret = vfs_writev(f.file, vec, vlen, ppos, flags);
+		if (ret >= 0 && ppos)
+			f.file->f_pos = pos;
+		fdput_pos(f);
+	}
+
+	if (ret > 0)
+		add_wchar(current, ret);
+	inc_syscw(current);
+	return ret;
+}
+
+static inline loff_t pos_from_hilo(unsigned long high, unsigned long low)
+{
+#define HALF_LONG_BITS (BITS_PER_LONG / 2)
+	return (((loff_t)high << HALF_LONG_BITS) << HALF_LONG_BITS) | low;
+}
+
+static ssize_t do_preadv(unsigned long fd, const struct iovec __user *vec,
+			 unsigned long vlen, loff_t pos, rwf_t flags)
+{
+	struct fd f;
+	ssize_t ret = -EBADF;
+
+	if (pos < 0)
+		return -EINVAL;
+
+	f = fdget(fd);
+	if (f.file) {
+		ret = -ESPIPE;
+		if (f.file->f_mode & FMODE_PREAD)
+			ret = vfs_readv(f.file, vec, vlen, &pos, flags);
+		fdput(f);
+	}
+
+	if (ret > 0)
+		add_rchar(current, ret);
+	inc_syscr(current);
+	return ret;
+}
+
+static ssize_t do_pwritev(unsigned long fd, const struct iovec __user *vec,
+			  unsigned long vlen, loff_t pos, rwf_t flags)
+{
+	struct fd f;
+	ssize_t ret = -EBADF;
+
+	if (pos < 0)
+		return -EINVAL;
+
+	f = fdget(fd);
+	if (f.file) {
+		ret = -ESPIPE;
+		if (f.file->f_mode & FMODE_PWRITE)
+			ret = vfs_writev(f.file, vec, vlen, &pos, flags);
+		fdput(f);
+	}
+
+	if (ret > 0)
+		add_wchar(current, ret);
+	inc_syscw(current);
+	return ret;
+}
+
+SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen)
+{
+	return do_readv(fd, vec, vlen, 0);
+}
+
+SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen)
+{
+	return do_writev(fd, vec, vlen, 0);
+}
+
+SYSCALL_DEFINE5(preadv, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
+{
+	loff_t pos = pos_from_hilo(pos_h, pos_l);
+
+	return do_preadv(fd, vec, vlen, pos, 0);
+}
+
+SYSCALL_DEFINE6(preadv2, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
+		rwf_t, flags)
+{
+	loff_t pos = pos_from_hilo(pos_h, pos_l);
+
+	if (pos == -1)
+		return do_readv(fd, vec, vlen, flags);
+
+	return do_preadv(fd, vec, vlen, pos, flags);
+}
+
+SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h)
+{
+	loff_t pos = pos_from_hilo(pos_h, pos_l);
+
+	return do_pwritev(fd, vec, vlen, pos, 0);
+}
+
+SYSCALL_DEFINE6(pwritev2, unsigned long, fd, const struct iovec __user *, vec,
+		unsigned long, vlen, unsigned long, pos_l, unsigned long, pos_h,
+		rwf_t, flags)
+{
+	loff_t pos = pos_from_hilo(pos_h, pos_l);
+
+	if (pos == -1)
+		return do_writev(fd, vec, vlen, flags);
+
+	return do_pwritev(fd, vec, vlen, pos, flags);
+}
+
+/*
+ * Various compat syscalls.  Note that they all pretend to take a native
+ * iovec - import_iovec will properly treat those as compat_iovecs based on
+ * in_compat_syscall().
+ */
+#ifdef CONFIG_COMPAT
+#ifdef __ARCH_WANT_COMPAT_SYS_PREADV64
+COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd,
+		const struct iovec __user *, vec,
+		unsigned long, vlen, loff_t, pos)
+{
+	return do_preadv(fd, vec, vlen, pos, 0);
+}
+#endif
+
+COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd,
+		const struct iovec __user *, vec,
+		compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
+{
+	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
+
+	return do_preadv(fd, vec, vlen, pos, 0);
+}
+
+#ifdef __ARCH_WANT_COMPAT_SYS_PREADV64V2
+COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
+		const struct iovec __user *, vec,
+		unsigned long, vlen, loff_t, pos, rwf_t, flags)
+{
+	if (pos == -1)
+		return do_readv(fd, vec, vlen, flags);
+	return do_preadv(fd, vec, vlen, pos, flags);
+}
+#endif
+
+COMPAT_SYSCALL_DEFINE6(preadv2, compat_ulong_t, fd,
+		const struct iovec __user *, vec,
+		compat_ulong_t, vlen, u32, pos_low, u32, pos_high,
+		rwf_t, flags)
+{
+	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
+
+	if (pos == -1)
+		return do_readv(fd, vec, vlen, flags);
+	return do_preadv(fd, vec, vlen, pos, flags);
+}
+
+#ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64
+COMPAT_SYSCALL_DEFINE4(pwritev64, unsigned long, fd,
+		const struct iovec __user *, vec,
+		unsigned long, vlen, loff_t, pos)
+{
+	return do_pwritev(fd, vec, vlen, pos, 0);
+}
+#endif
+
+COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
+		const struct iovec __user *,vec,
+		compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
+{
+	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
+
+	return do_pwritev(fd, vec, vlen, pos, 0);
+}
+
+#ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
+COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
+		const struct iovec __user *, vec,
+		unsigned long, vlen, loff_t, pos, rwf_t, flags)
+{
+	if (pos == -1)
+		return do_writev(fd, vec, vlen, flags);
+	return do_pwritev(fd, vec, vlen, pos, flags);
+}
+#endif
+
+COMPAT_SYSCALL_DEFINE6(pwritev2, compat_ulong_t, fd,
+		const struct iovec __user *,vec,
+		compat_ulong_t, vlen, u32, pos_low, u32, pos_high, rwf_t, flags)
+{
+	loff_t pos = ((loff_t)pos_high << 32) | pos_low;
+
+	if (pos == -1)
+		return do_writev(fd, vec, vlen, flags);
+	return do_pwritev(fd, vec, vlen, pos, flags);
+}
+#endif /* CONFIG_COMPAT */
+
+static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
+		  	   size_t count, loff_t max)
+{
+	struct fd in, out;
+	struct inode *in_inode, *out_inode;
+	struct pipe_inode_info *opipe;
+	loff_t pos;
+	loff_t out_pos;
+	ssize_t retval;
+	int fl;
+
+	/*
+	 * Get input file, and verify that it is ok..
+	 */
+	retval = -EBADF;
+	in = fdget(in_fd);
+	if (!in.file)
+		goto out;
+	if (!(in.file->f_mode & FMODE_READ))
+		goto fput_in;
+	retval = -ESPIPE;
+	if (!ppos) {
+		pos = in.file->f_pos;
+	} else {
+		pos = *ppos;
+		if (!(in.file->f_mode & FMODE_PREAD))
+			goto fput_in;
+	}
+	retval = rw_verify_area(READ, in.file, &pos, count);
+	if (retval < 0)
+		goto fput_in;
+	if (count > MAX_RW_COUNT)
+		count =  MAX_RW_COUNT;
+
+	/*
+	 * Get output file, and verify that it is ok..
+	 */
+	retval = -EBADF;
+	out = fdget(out_fd);
+	if (!out.file)
+		goto fput_in;
+	if (!(out.file->f_mode & FMODE_WRITE))
+		goto fput_out;
+	in_inode = file_inode(in.file);
+	out_inode = file_inode(out.file);
+	out_pos = out.file->f_pos;
+
+	if (!max)
+		max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
+
+	if (unlikely(pos + count > max)) {
+		retval = -EOVERFLOW;
+		if (pos >= max)
+			goto fput_out;
+		count = max - pos;
+	}
+
+	fl = 0;
+#if 0
+	/*
+	 * We need to debate whether we can enable this or not. The
+	 * man page documents EAGAIN return for the output at least,
+	 * and the application is arguably buggy if it doesn't expect
+	 * EAGAIN on a non-blocking file descriptor.
+	 */
+	if (in.file->f_flags & O_NONBLOCK)
+		fl = SPLICE_F_NONBLOCK;
+#endif
+	opipe = get_pipe_info(out.file, true);
+	if (!opipe) {
+		retval = rw_verify_area(WRITE, out.file, &out_pos, count);
+		if (retval < 0)
+			goto fput_out;
+		file_start_write(out.file);
+		retval = do_splice_direct(in.file, &pos, out.file, &out_pos,
+					  count, fl);
+		file_end_write(out.file);
+	} else {
+		if (out.file->f_flags & O_NONBLOCK)
+			fl |= SPLICE_F_NONBLOCK;
+
+		retval = splice_file_to_pipe(in.file, opipe, &pos, count, fl);
+	}
+
+	if (retval > 0) {
+		add_rchar(current, retval);
+		add_wchar(current, retval);
+		fsnotify_access(in.file);
+		fsnotify_modify(out.file);
+		out.file->f_pos = out_pos;
+		if (ppos)
+			*ppos = pos;
+		else
+			in.file->f_pos = pos;
+	}
+
+	inc_syscr(current);
+	inc_syscw(current);
+	if (pos > max)
+		retval = -EOVERFLOW;
+
+fput_out:
+	fdput(out);
+fput_in:
+	fdput(in);
+out:
+	return retval;
+}
+
+SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd, off_t __user *, offset, size_t, count)
+{
+	loff_t pos;
+	off_t off;
+	ssize_t ret;
+
+	if (offset) {
+		if (unlikely(get_user(off, offset)))
+			return -EFAULT;
+		pos = off;
+		ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
+		if (unlikely(put_user(pos, offset)))
+			return -EFAULT;
+		return ret;
+	}
+
+	return do_sendfile(out_fd, in_fd, NULL, count, 0);
+}
+
+SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, loff_t __user *, offset, size_t, count)
+{
+	loff_t pos;
+	ssize_t ret;
+
+	if (offset) {
+		if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
+			return -EFAULT;
+		ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
+		if (unlikely(put_user(pos, offset)))
+			return -EFAULT;
+		return ret;
+	}
+
+	return do_sendfile(out_fd, in_fd, NULL, count, 0);
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE4(sendfile, int, out_fd, int, in_fd,
+		compat_off_t __user *, offset, compat_size_t, count)
+{
+	loff_t pos;
+	off_t off;
+	ssize_t ret;
+
+	if (offset) {
+		if (unlikely(get_user(off, offset)))
+			return -EFAULT;
+		pos = off;
+		ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
+		if (unlikely(put_user(pos, offset)))
+			return -EFAULT;
+		return ret;
+	}
+
+	return do_sendfile(out_fd, in_fd, NULL, count, 0);
+}
+
+COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
+		compat_loff_t __user *, offset, compat_size_t, count)
+{
+	loff_t pos;
+	ssize_t ret;
+
+	if (offset) {
+		if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
+			return -EFAULT;
+		ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
+		if (unlikely(put_user(pos, offset)))
+			return -EFAULT;
+		return ret;
+	}
+
+	return do_sendfile(out_fd, in_fd, NULL, count, 0);
+}
+#endif
+
+/**
+ * generic_copy_file_range - copy data between two files
+ * @file_in:	file structure to read from
+ * @pos_in:	file offset to read from
+ * @file_out:	file structure to write data to
+ * @pos_out:	file offset to write data to
+ * @len:	amount of data to copy
+ * @flags:	copy flags
+ *
+ * This is a generic filesystem helper to copy data from one file to another.
+ * It has no constraints on the source or destination file owners - the files
+ * can belong to different superblocks and different filesystem types. Short
+ * copies are allowed.
+ *
+ * This should be called from the @file_out filesystem, as per the
+ * ->copy_file_range() method.
+ *
+ * Returns the number of bytes copied or a negative error indicating the
+ * failure.
+ */
+
+ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
+				struct file *file_out, loff_t pos_out,
+				size_t len, unsigned int flags)
+{
+	lockdep_assert(sb_write_started(file_inode(file_out)->i_sb));
+
+	return do_splice_direct(file_in, &pos_in, file_out, &pos_out,
+				len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
+}
+EXPORT_SYMBOL(generic_copy_file_range);
+
+/*
+ * Performs necessary checks before doing a file copy
+ *
+ * Can adjust amount of bytes to copy via @req_count argument.
+ * Returns appropriate error code that caller should return or
+ * zero in case the copy should be allowed.
+ */
+static int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
+				    struct file *file_out, loff_t pos_out,
+				    size_t *req_count, unsigned int flags)
+{
+	struct inode *inode_in = file_inode(file_in);
+	struct inode *inode_out = file_inode(file_out);
+	uint64_t count = *req_count;
+	loff_t size_in;
+	int ret;
+
+	ret = generic_file_rw_checks(file_in, file_out);
+	if (ret)
+		return ret;
+
+	/*
+	 * We allow some filesystems to handle cross sb copy, but passing
+	 * a file of the wrong filesystem type to filesystem driver can result
+	 * in an attempt to dereference the wrong type of ->private_data, so
+	 * avoid doing that until we really have a good reason.
+	 *
+	 * nfs and cifs define several different file_system_type structures
+	 * and several different sets of file_operations, but they all end up
+	 * using the same ->copy_file_range() function pointer.
+	 */
+	if (flags & COPY_FILE_SPLICE) {
+		/* cross sb splice is allowed */
+	} else if (file_out->f_op->copy_file_range) {
+		if (file_in->f_op->copy_file_range !=
+		    file_out->f_op->copy_file_range)
+			return -EXDEV;
+	} else if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb) {
+		return -EXDEV;
+	}
+
+	/* Don't touch certain kinds of inodes */
+	if (IS_IMMUTABLE(inode_out))
+		return -EPERM;
+
+	if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
+		return -ETXTBSY;
+
+	/* Ensure offsets don't wrap. */
+	if (pos_in + count < pos_in || pos_out + count < pos_out)
+		return -EOVERFLOW;
+
+	/* Shorten the copy to EOF */
+	size_in = i_size_read(inode_in);
+	if (pos_in >= size_in)
+		count = 0;
+	else
+		count = min(count, size_in - (uint64_t)pos_in);
+
+	ret = generic_write_check_limits(file_out, pos_out, &count);
+	if (ret)
+		return ret;
+
+	/* Don't allow overlapped copying within the same file. */
+	if (inode_in == inode_out &&
+	    pos_out + count > pos_in &&
+	    pos_out < pos_in + count)
+		return -EINVAL;
+
+	*req_count = count;
+	return 0;
+}
+
+/*
+ * copy_file_range() differs from regular file read and write in that it
+ * specifically allows return partial success.  When it does so is up to
+ * the copy_file_range method.
+ */
+ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
+			    struct file *file_out, loff_t pos_out,
+			    size_t len, unsigned int flags)
+{
+	ssize_t ret;
+	bool splice = flags & COPY_FILE_SPLICE;
+
+	if (flags & ~COPY_FILE_SPLICE)
+		return -EINVAL;
+
+	ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
+				       flags);
+	if (unlikely(ret))
+		return ret;
+
+	ret = rw_verify_area(READ, file_in, &pos_in, len);
+	if (unlikely(ret))
+		return ret;
+
+	ret = rw_verify_area(WRITE, file_out, &pos_out, len);
+	if (unlikely(ret))
+		return ret;
+
+	if (len == 0)
+		return 0;
+
+	file_start_write(file_out);
+
+	/*
+	 * Cloning is supported by more file systems, so we implement copy on
+	 * same sb using clone, but for filesystems where both clone and copy
+	 * are supported (e.g. nfs,cifs), we only call the copy method.
+	 */
+	if (!splice && file_out->f_op->copy_file_range) {
+		ret = file_out->f_op->copy_file_range(file_in, pos_in,
+						      file_out, pos_out,
+						      len, flags);
+		goto done;
+	}
+
+	if (!splice && file_in->f_op->remap_file_range &&
+	    file_inode(file_in)->i_sb == file_inode(file_out)->i_sb) {
+		ret = file_in->f_op->remap_file_range(file_in, pos_in,
+				file_out, pos_out,
+				min_t(loff_t, MAX_RW_COUNT, len),
+				REMAP_FILE_CAN_SHORTEN);
+		if (ret > 0)
+			goto done;
+	}
+
+	/*
+	 * We can get here for same sb copy of filesystems that do not implement
+	 * ->copy_file_range() in case filesystem does not support clone or in
+	 * case filesystem supports clone but rejected the clone request (e.g.
+	 * because it was not block aligned).
+	 *
+	 * In both cases, fall back to kernel copy so we are able to maintain a
+	 * consistent story about which filesystems support copy_file_range()
+	 * and which filesystems do not, that will allow userspace tools to
+	 * make consistent desicions w.r.t using copy_file_range().
+	 *
+	 * We also get here if caller (e.g. nfsd) requested COPY_FILE_SPLICE.
+	 */
+	ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,
+				      flags);
+
+done:
+	if (ret > 0) {
+		fsnotify_access(file_in);
+		add_rchar(current, ret);
+		fsnotify_modify(file_out);
+		add_wchar(current, ret);
+	}
+
+	inc_syscr(current);
+	inc_syscw(current);
+
+	file_end_write(file_out);
+
+	return ret;
+}
+EXPORT_SYMBOL(vfs_copy_file_range);
+
+SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in,
+		int, fd_out, loff_t __user *, off_out,
+		size_t, len, unsigned int, flags)
+{
+	loff_t pos_in;
+	loff_t pos_out;
+	struct fd f_in;
+	struct fd f_out;
+	ssize_t ret = -EBADF;
+
+	f_in = fdget(fd_in);
+	if (!f_in.file)
+		goto out2;
+
+	f_out = fdget(fd_out);
+	if (!f_out.file)
+		goto out1;
+
+	ret = -EFAULT;
+	if (off_in) {
+		if (copy_from_user(&pos_in, off_in, sizeof(loff_t)))
+			goto out;
+	} else {
+		pos_in = f_in.file->f_pos;
+	}
+
+	if (off_out) {
+		if (copy_from_user(&pos_out, off_out, sizeof(loff_t)))
+			goto out;
+	} else {
+		pos_out = f_out.file->f_pos;
+	}
+
+	ret = -EINVAL;
+	if (flags != 0)
+		goto out;
+
+	ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len,
+				  flags);
+	if (ret > 0) {
+		pos_in += ret;
+		pos_out += ret;
+
+		if (off_in) {
+			if (copy_to_user(off_in, &pos_in, sizeof(loff_t)))
+				ret = -EFAULT;
+		} else {
+			f_in.file->f_pos = pos_in;
+		}
+
+		if (off_out) {
+			if (copy_to_user(off_out, &pos_out, sizeof(loff_t)))
+				ret = -EFAULT;
+		} else {
+			f_out.file->f_pos = pos_out;
+		}
+	}
+
+out:
+	fdput(f_out);
+out1:
+	fdput(f_in);
+out2:
+	return ret;
+}
+
+/*
+ * Don't operate on ranges the page cache doesn't support, and don't exceed the
+ * LFS limits.  If pos is under the limit it becomes a short access.  If it
+ * exceeds the limit we return -EFBIG.
+ */
+int generic_write_check_limits(struct file *file, loff_t pos, loff_t *count)
+{
+	struct inode *inode = file->f_mapping->host;
+	loff_t max_size = inode->i_sb->s_maxbytes;
+	loff_t limit = rlimit(RLIMIT_FSIZE);
+
+	if (limit != RLIM_INFINITY) {
+		if (pos >= limit) {
+			send_sig(SIGXFSZ, current, 0);
+			return -EFBIG;
+		}
+		*count = min(*count, limit - pos);
+	}
+
+	if (!(file->f_flags & O_LARGEFILE))
+		max_size = MAX_NON_LFS;
+
+	if (unlikely(pos >= max_size))
+		return -EFBIG;
+
+	*count = min(*count, max_size - pos);
+
+	return 0;
+}
+
+/* Like generic_write_checks(), but takes size of write instead of iter. */
+int generic_write_checks_count(struct kiocb *iocb, loff_t *count)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+
+	if (IS_SWAPFILE(inode))
+		return -ETXTBSY;
+
+	if (!*count)
+		return 0;
+
+	if (iocb->ki_flags & IOCB_APPEND)
+		iocb->ki_pos = i_size_read(inode);
+
+	if ((iocb->ki_flags & IOCB_NOWAIT) &&
+	    !((iocb->ki_flags & IOCB_DIRECT) ||
+	      (file->f_mode & FMODE_BUF_WASYNC)))
+		return -EINVAL;
+
+	return generic_write_check_limits(iocb->ki_filp, iocb->ki_pos, count);
+}
+EXPORT_SYMBOL(generic_write_checks_count);
+
+/*
+ * Performs necessary checks before doing a write
+ *
+ * Can adjust writing position or amount of bytes to write.
+ * Returns appropriate error code that caller should return or
+ * zero in case that write should be allowed.
+ */
+ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
+{
+	loff_t count = iov_iter_count(from);
+	int ret;
+
+	ret = generic_write_checks_count(iocb, &count);
+	if (ret)
+		return ret;
+
+	iov_iter_truncate(from, count);
+	return iov_iter_count(from);
+}
+EXPORT_SYMBOL(generic_write_checks);
+
+/*
+ * Performs common checks before doing a file copy/clone
+ * from @file_in to @file_out.
+ */
+int generic_file_rw_checks(struct file *file_in, struct file *file_out)
+{
+	struct inode *inode_in = file_inode(file_in);
+	struct inode *inode_out = file_inode(file_out);
+
+	/* Don't copy dirs, pipes, sockets... */
+	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
+		return -EISDIR;
+	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
+		return -EINVAL;
+
+	if (!(file_in->f_mode & FMODE_READ) ||
+	    !(file_out->f_mode & FMODE_WRITE) ||
+	    (file_out->f_flags & O_APPEND))
+		return -EBADF;
+
+	return 0;
+}