From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20120518211603.854880990@linuxfoundation.org> Date: Fri, 18 May 2012 14:16:47 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Kazuya Mio , Al Viro Subject: [ 48/54] wake up s_wait_unfrozen when ->freeze_fs fails In-Reply-To: <20120518212656.GA4992@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kazuya Mio commit e1616300a20c80396109c1cf013ba9a36055a3da upstream. dd slept infinitely when fsfeeze failed because of EIO. To fix this problem, if ->freeze_fs fails, freeze_super() wakes up the tasks waiting for the filesystem to become unfrozen. When s_frozen isn't SB_UNFROZEN in __generic_file_aio_write(), the function sleeps until FITHAW ioctl wakes up s_wait_unfrozen. However, if ->freeze_fs fails, s_frozen is set to SB_UNFROZEN and then freeze_super() returns an error number. In this case, FITHAW ioctl returns EINVAL because s_frozen is already SB_UNFROZEN. There is no way to wake up s_wait_unfrozen, so __generic_file_aio_write() sleeps infinitely. Signed-off-by: Kazuya Mio Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/super.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/super.c +++ b/fs/super.c @@ -1009,6 +1009,8 @@ int freeze_super(struct super_block *sb) printk(KERN_ERR "VFS:Filesystem freeze failed\n"); sb->s_frozen = SB_UNFROZEN; + smp_wmb(); + wake_up(&sb->s_wait_unfrozen); deactivate_locked_super(sb); return ret; }