Commit e1616300 authored Dec 01, 2011 by Kazuya Mio Committed by Al Viro Jan 17, 2012

wake up s_wait_unfrozen when ->freeze_fs fails

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 <k-mio@sx.jp.nec.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent c2bc3a31

fs/super.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1186,6 +1186,8 @@ 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;
		}

Admin message