Commit 9bb48c82 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

tty: implement write_iter 



This makes the tty layer use the .write_iter() function instead of the
traditional .write() functionality.

That allows writev(), but more importantly also makes it possible to
enable .splice_write() for ttys, reinstating the "splice to tty"
functionality that was lost in commit 36e2c742 ("fs: don't allow
splice read/write without explicit ops").

Fixes: 36e2c742 ("fs: don't allow splice read/write without explicit ops")
Reported-by: default avatarOliver Giles <ohw.giles@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2c85ebc5

drivers/tty/tty_io.c

+26 −22
Original line number Diff line number Diff line
@@ -143,9 +143,8 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */ 
DEFINE_MUTEX(tty_mutex);



static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);

static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);

ssize_t redirected_tty_write(struct file *, const char __user *,

							size_t, loff_t *);

static ssize_t tty_write(struct kiocb *, struct iov_iter *);

ssize_t redirected_tty_write(struct kiocb *, struct iov_iter *);

static __poll_t tty_poll(struct file *, poll_table *);

static int tty_open(struct inode *, struct file *);

long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
@@ -478,7 +477,8 @@ static void tty_show_fdinfo(struct seq_file *m, struct file *file) 
static const struct file_operations tty_fops = {

	.llseek		= no_llseek,

	.read		= tty_read,

	.write		= tty_write,

	.write_iter	= tty_write,

	.splice_write	= iter_file_splice_write,

	.poll		= tty_poll,

	.unlocked_ioctl	= tty_ioctl,

	.compat_ioctl	= tty_compat_ioctl,
@@ -491,7 +491,8 @@ static const struct file_operations tty_fops = { 
static const struct file_operations console_fops = {

	.llseek		= no_llseek,

	.read		= tty_read,

	.write		= redirected_tty_write,

	.write_iter	= redirected_tty_write,

	.splice_write	= iter_file_splice_write,

	.poll		= tty_poll,

	.unlocked_ioctl	= tty_ioctl,

	.compat_ioctl	= tty_compat_ioctl,
@@ -607,9 +608,9 @@ static void __tty_hangup(struct tty_struct *tty, int exit_session) 
	/* This breaks for file handles being sent over AF_UNIX sockets ? */

	list_for_each_entry(priv, &tty->tty_files, list) {

		filp = priv->file;

		if (filp->f_op->write == redirected_tty_write)

		if (filp->f_op->write_iter == redirected_tty_write)

			cons_filp = filp;

		if (filp->f_op->write != tty_write)

		if (filp->f_op->write_iter != tty_write)

			continue;

		closecount++;

		__tty_fasync(-1, filp, 0);	/* can't block */
@@ -902,9 +903,9 @@ static inline ssize_t do_tty_write( 
	ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),

	struct tty_struct *tty,

	struct file *file,

	const char __user *buf,

	size_t count)

	struct iov_iter *from)

{

	size_t count = iov_iter_count(from);

	ssize_t ret, written = 0;

	unsigned int chunk;
@@ -956,14 +957,20 @@ static inline ssize_t do_tty_write( 
		size_t size = count;

		if (size > chunk)

			size = chunk;



		ret = -EFAULT;

		if (copy_from_user(tty->write_buf, buf, size))

		if (copy_from_iter(tty->write_buf, size, from) != size)

			break;



		ret = write(tty, file, tty->write_buf, size);

		if (ret <= 0)

			break;



		/* FIXME! Have Al check this! */

		if (ret != size)

			iov_iter_revert(from, size-ret);



		written += ret;

		buf += ret;

		count -= ret;

		if (!count)

			break;
@@ -1023,9 +1030,9 @@ void tty_write_message(struct tty_struct *tty, char *msg) 
 *	write method will not be invoked in parallel for each device.

 */



static ssize_t tty_write(struct file *file, const char __user *buf,

						size_t count, loff_t *ppos)

static ssize_t tty_write(struct kiocb *iocb, struct iov_iter *from)

{

	struct file *file = iocb->ki_filp;

	struct tty_struct *tty = file_tty(file);

 	struct tty_ldisc *ld;

	ssize_t ret;
@@ -1038,18 +1045,15 @@ static ssize_t tty_write(struct file *file, const char __user *buf, 
	if (tty->ops->write_room == NULL)

		tty_err(tty, "missing write_room method\n");

	ld = tty_ldisc_ref_wait(tty);

	if (!ld)

		return hung_up_tty_write(file, buf, count, ppos);

	if (!ld->ops->write)

	if (!ld || !ld->ops->write)

		ret = -EIO;

	else

		ret = do_tty_write(ld->ops->write, tty, file, buf, count);

		ret = do_tty_write(ld->ops->write, tty, file, from);

	tty_ldisc_deref(ld);

	return ret;

}



ssize_t redirected_tty_write(struct file *file, const char __user *buf,

						size_t count, loff_t *ppos)

ssize_t redirected_tty_write(struct kiocb *iocb, struct iov_iter *iter)

{

	struct file *p = NULL;
@@ -1060,11 +1064,11 @@ ssize_t redirected_tty_write(struct file *file, const char __user *buf, 


	if (p) {

		ssize_t res;

		res = vfs_write(p, buf, count, &p->f_pos);

		res = vfs_iocb_iter_write(p, iocb, iter);

		fput(p);

		return res;

	}

	return tty_write(file, buf, count, ppos);

	return tty_write(iocb, iter);

}



/**
@@ -2293,7 +2297,7 @@ static int tioccons(struct file *file) 
{

	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;

	if (file->f_op->write == redirected_tty_write) {

	if (file->f_op->write_iter == redirected_tty_write) {

		struct file *f;

		spin_lock(&redirect_lock);

		f = redirect;