wake up s_wait_unfrozen when ->freeze_fs fails
authorKazuya Mio <k-mio@sx.jp.nec.com>
Thu, 1 Dec 2011 07:51:07 +0000 (16:51 +0900)
committerAl Viro <viro@zeniv.linux.org.uk>
Tue, 17 Jan 2012 21:38:47 +0000 (16:38 -0500)
commite1616300a20c80396109c1cf013ba9a36055a3da
tree97d4bcef12fddf1dc1cdfd22bf226eb36850c6e6
parentc2bc3a316a7281f67e36b34dac2802cbe36a9128
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>
fs/super.c