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tty: implement write_iter

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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 36e2c7421f ("fs: don't allow
splice read/write without explicit ops").

Fixes: 36e2c7421f ("fs: don't allow splice read/write without explicit ops")
Reported-by: Oliver 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: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2021-01-19 11:41:16 -08:00
parent 2c85ebc57b
commit 9bb48c82ac
1 changed files with 26 additions and 22 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

48
drivers/tty/tty_io.c
View file

@ -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;