3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kazuya Mio <k-...@sx.jp.nec.com>
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 <k-...@sx.jp.nec.com>
Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
fs/super.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/super.c b/fs/super.c
index de41e1e..6015c02 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -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;
}
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