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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>
This commit is contained in:
Kazuya Mio 2011-12-01 16:51:07 +09:00 committed by Al Viro
parent c2bc3a316a
commit e1616300a2
1 changed files with 2 additions and 0 deletions
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2
fs/super.c
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@ -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;
}