From: Eric Biggers <ebiggers(a)google.com>
commit ffec85d53d0f39ee4680a2cf0795255e000e1feb upstream.
When writing a page from an encrypted file that is using
filesystem-layer encryption (not inline encryption), ext4 encrypts the
pagecache page into a bounce page, then writes the bounce page.
It also passes the bounce page to wbc_account_cgroup_owner(). That's
incorrect, because the bounce page is a newly allocated temporary page
that doesn't have the memory cgroup of the original pagecache page.
This makes wbc_account_cgroup_owner() not account the I/O to the owner
of the pagecache page as it should.
Fix this by always passing the pagecache page to
wbc_account_cgroup_owner().
Fixes: 001e4a8775f6 ("ext4: implement cgroup writeback support")
Cc: stable(a)vger.kernel.org
Reported-by: Matthew Wilcox (Oracle) <willy(a)infradead.org>
Signed-off-by: Eric Biggers <ebiggers(a)google.com>
Acked-by: Tejun Heo <tj(a)kernel.org>
Link: https://lore.kernel.org/r/20230203005503.141557-1-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso(a)mit.edu>
---
fs/ext4/page-io.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index b66b335a0ca6f..5858fb9b5cd53 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -380,7 +380,8 @@ static int io_submit_init_bio(struct ext4_io_submit *io,
static int io_submit_add_bh(struct ext4_io_submit *io,
struct inode *inode,
- struct page *page,
+ struct page *pagecache_page,
+ struct page *bounce_page,
struct buffer_head *bh)
{
int ret;
@@ -395,10 +396,11 @@ static int io_submit_add_bh(struct ext4_io_submit *io,
return ret;
io->io_bio->bi_write_hint = inode->i_write_hint;
}
- ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
+ ret = bio_add_page(io->io_bio, bounce_page ?: pagecache_page,
+ bh->b_size, bh_offset(bh));
if (ret != bh->b_size)
goto submit_and_retry;
- wbc_account_cgroup_owner(io->io_wbc, page, bh->b_size);
+ wbc_account_cgroup_owner(io->io_wbc, pagecache_page, bh->b_size);
io->io_next_block++;
return 0;
}
@@ -511,7 +513,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
do {
if (!buffer_async_write(bh))
continue;
- ret = io_submit_add_bh(io, inode, bounce_page ?: page, bh);
+ ret = io_submit_add_bh(io, inode, page, bounce_page, bh);
if (ret) {
/*
* We only get here on ENOMEM. Not much else
--
2.39.2
If userspace races tcsetattr() with a write, the drained condition
might not be guaranteed by the kernel. There is a race window after
checking Tx is empty before tty_set_termios() takes termios_rwsem for
write. During that race window, more characters can be queued by a
racing writer.
Any ongoing transmission might produce garbage during HW's
->set_termios() call. The intent of TCSADRAIN/FLUSH seems to be
preventing such a character corruption. If those flags are set, take
tty's write lock to stop any writer before performing the lower layer
Tx empty check and wait for the pending characters to be sent (if any).
The initial wait for all-writers-done must be placed outside of tty's
write lock to avoid deadlock which makes it impossible to use
tty_wait_until_sent(). The write lock is retried if a racing write is
detected.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable(a)vger.kernel.org
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen(a)linux.intel.com>
---
drivers/tty/tty.h | 2 ++
drivers/tty/tty_io.c | 4 ++--
drivers/tty/tty_ioctl.c | 45 ++++++++++++++++++++++++++++++-----------
3 files changed, 37 insertions(+), 14 deletions(-)
diff --git a/drivers/tty/tty.h b/drivers/tty/tty.h
index f45cd683c02e..1e0d80e98d26 100644
--- a/drivers/tty/tty.h
+++ b/drivers/tty/tty.h
@@ -62,6 +62,8 @@ int __tty_check_change(struct tty_struct *tty, int sig);
int tty_check_change(struct tty_struct *tty);
void __stop_tty(struct tty_struct *tty);
void __start_tty(struct tty_struct *tty);
+void tty_write_unlock(struct tty_struct *tty);
+int tty_write_lock(struct tty_struct *tty, int ndelay);
void tty_vhangup_session(struct tty_struct *tty);
void tty_open_proc_set_tty(struct file *filp, struct tty_struct *tty);
int tty_signal_session_leader(struct tty_struct *tty, int exit_session);
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 766750e355ac..cfb3da0dee47 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -933,13 +933,13 @@ static ssize_t tty_read(struct kiocb *iocb, struct iov_iter *to)
return i;
}
-static void tty_write_unlock(struct tty_struct *tty)
+void tty_write_unlock(struct tty_struct *tty)
{
mutex_unlock(&tty->atomic_write_lock);
wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
}
-static int tty_write_lock(struct tty_struct *tty, int ndelay)
+int tty_write_lock(struct tty_struct *tty, int ndelay)
{
if (!mutex_trylock(&tty->atomic_write_lock)) {
if (ndelay)
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index 12983ce4e43e..a13e3797c477 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -500,21 +500,42 @@ static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
tmp_termios.c_ispeed = tty_termios_input_baud_rate(&tmp_termios);
tmp_termios.c_ospeed = tty_termios_baud_rate(&tmp_termios);
- ld = tty_ldisc_ref(tty);
+ if (opt & (TERMIOS_FLUSH|TERMIOS_WAIT)) {
+retry_write_wait:
+ retval = wait_event_interruptible(tty->write_wait, !tty_chars_in_buffer(tty));
+ if (retval < 0)
+ return retval;
- if (ld != NULL) {
- if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
- ld->ops->flush_buffer(tty);
- tty_ldisc_deref(ld);
- }
+ if (tty_write_lock(tty, 0) < 0)
+ goto retry_write_wait;
- if (opt & TERMIOS_WAIT) {
- tty_wait_until_sent(tty, 0);
- if (signal_pending(current))
- return -ERESTARTSYS;
- }
+ /* Racing writer? */
+ if (tty_chars_in_buffer(tty)) {
+ tty_write_unlock(tty);
+ goto retry_write_wait;
+ }
- tty_set_termios(tty, &tmp_termios);
+ ld = tty_ldisc_ref(tty);
+ if (ld != NULL) {
+ if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
+ ld->ops->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
+
+ if ((opt & TERMIOS_WAIT) && tty->ops->wait_until_sent) {
+ tty->ops->wait_until_sent(tty, 0);
+ if (signal_pending(current)) {
+ tty_write_unlock(tty);
+ return -ERESTARTSYS;
+ }
+ }
+
+ tty_set_termios(tty, &tmp_termios);
+
+ tty_write_unlock(tty);
+ } else {
+ tty_set_termios(tty, &tmp_termios);
+ }
/* FIXME: Arguably if tmp_termios == tty->termios AND the
actual requested termios was not tmp_termios then we may
--
2.30.2