From: Kazuya Mio <[email protected]> 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 <[email protected]> Signed-off-by: Al Viro <[email protected]> --- Please consider for 3.2, seems to have been missed out there. Shipps with >= 3.3 linux. Can be triggered with dd testcase. 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; } -- 1.7.10 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
