1
linux/fs/read_write.c
Prasad Singamsetty c34fc6f26a fs: Initial atomic write support
An atomic write is a write issued with torn-write protection, meaning
that for a power failure or any other hardware failure, all or none of the
data from the write will be stored, but never a mix of old and new data.

Userspace may add flag RWF_ATOMIC to pwritev2() to indicate that the
write is to be issued with torn-write prevention, according to special
alignment and length rules.

For any syscall interface utilizing struct iocb, add IOCB_ATOMIC for
iocb->ki_flags field to indicate the same.

A call to statx will give the relevant atomic write info for a file:
- atomic_write_unit_min
- atomic_write_unit_max
- atomic_write_segments_max

Both min and max values must be a power-of-2.

Applications can avail of atomic write feature by ensuring that the total
length of a write is a power-of-2 in size and also sized between
atomic_write_unit_min and atomic_write_unit_max, inclusive. Applications
must ensure that the write is at a naturally-aligned offset in the file
wrt the total write length. The value in atomic_write_segments_max
indicates the upper limit for IOV_ITER iovcnt.

Add file mode flag FMODE_CAN_ATOMIC_WRITE, so files which do not have the
flag set will have RWF_ATOMIC rejected and not just ignored.

Add a type argument to kiocb_set_rw_flags() to allows reads which have
RWF_ATOMIC set to be rejected.

Helper function generic_atomic_write_valid() can be used by FSes to verify
compliant writes. There we check for iov_iter type is for ubuf, which
implies iovcnt==1 for pwritev2(), which is an initial restriction for
atomic_write_segments_max. Initially the only user will be bdev file
operations write handler. We will rely on the block BIO submission path to
ensure write sizes are compliant for the bdev, so we don't need to check
atomic writes sizes yet.

Signed-off-by: Prasad Singamsetty <prasad.singamsetty@oracle.com>
jpg: merge into single patch and much rewrite
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-4-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-06-20 15:19:17 -06:00

1755 lines
41 KiB
C

// 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 = filemap_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
* @maxsize: 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)
{
int mask = read_write == READ ? MAY_READ : MAY_WRITE;
int ret;
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;
}
}
ret = security_file_permission(file, mask);
if (ret)
return ret;
return fsnotify_file_area_perm(file, mask, ppos, count);
}
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 = filp->f_op->read_iter(&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 = filp->f_op->write_iter(&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, type);
if (ret)
return ret;
kiocb.ki_pos = (ppos ? *ppos : 0);
if (type == READ)
ret = filp->f_op->read_iter(&kiocb, iter);
else
ret = filp->f_op->write_iter(&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)) {
ssize_t nr;
if (type == READ) {
nr = filp->f_op->read(filp, iter_iov_addr(iter),
iter_iov_len(iter), ppos);
} else {
nr = filp->f_op->write(filp, iter_iov_addr(iter),
iter_iov_len(iter), ppos);
}
if (nr < 0) {
if (!ret)
ret = nr;
break;
}
ret += nr;
if (nr != iter_iov_len(iter))
break;
iov_iter_advance(iter, nr);
}
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 = file->f_op->read_iter(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)
{
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, ppos, tot_len);
if (ret < 0)
return ret;
ret = do_iter_readv_writev(file, iter, ppos, READ, flags);
out:
if (ret >= 0)
fsnotify_access(file);
return ret;
}
EXPORT_SYMBOL(vfs_iter_read);
/*
* Caller is responsible for calling kiocb_end_write() on completion
* if async iocb was queued.
*/
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;
kiocb_start_write(iocb);
ret = file->f_op->write_iter(iocb, iter);
if (ret != -EIOCBQUEUED)
kiocb_end_write(iocb);
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)
{
size_t tot_len;
ssize_t ret;
if (!(file->f_mode & FMODE_WRITE))
return -EBADF;
if (!(file->f_mode & FMODE_CAN_WRITE))
return -EINVAL;
if (!file->f_op->write_iter)
return -EINVAL;
tot_len = iov_iter_count(iter);
if (!tot_len)
return 0;
ret = rw_verify_area(WRITE, file, ppos, tot_len);
if (ret < 0)
return ret;
file_start_write(file);
ret = do_iter_readv_writev(file, iter, ppos, WRITE, flags);
if (ret > 0)
fsnotify_modify(file);
file_end_write(file);
return ret;
}
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;
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;
ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov,
&iter);
if (ret < 0)
return ret;
tot_len = iov_iter_count(&iter);
if (!tot_len)
goto out;
ret = rw_verify_area(READ, file, pos, tot_len);
if (ret < 0)
goto out;
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);
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;
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;
ret = import_iovec(ITER_SOURCE, vec, vlen, ARRAY_SIZE(iovstack), &iov,
&iter);
if (ret < 0)
return ret;
tot_len = iov_iter_count(&iter);
if (!tot_len)
goto out;
ret = rw_verify_area(WRITE, file, pos, tot_len);
if (ret < 0)
goto out;
file_start_write(file);
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);
file_end_write(file);
out:
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;
retval = do_splice_direct(in.file, &pos, out.file, &out_pos,
count, fl);
} 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
/*
* 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;
bool samesb = file_inode(file_in)->i_sb == file_inode(file_out)->i_sb;
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);
} else if (!splice && file_in->f_op->remap_file_range && samesb) {
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);
/* fallback to splice */
if (ret <= 0)
splice = true;
} else if (samesb) {
/* Fallback to splice for same sb copy for backward compat */
splice = true;
}
file_end_write(file_out);
if (!splice)
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
* for server-side-copy between any two sb.
*
* In any case, we call do_splice_direct() and not splice_file_range(),
* without file_start_write() held, to avoid possible deadlocks related
* to splicing from input file, while file_start_write() is held on
* the output file on a different sb.
*/
ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
min_t(size_t, len, MAX_RW_COUNT), 0);
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);
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;
}
EXPORT_SYMBOL_GPL(generic_write_check_limits);
/* 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_op->fop_flags & FOP_BUFFER_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;
}
bool generic_atomic_write_valid(struct iov_iter *iter, loff_t pos)
{
size_t len = iov_iter_count(iter);
if (!iter_is_ubuf(iter))
return false;
if (!is_power_of_2(len))
return false;
if (!IS_ALIGNED(pos, len))
return false;
return true;
}