On Fri, Mar 28, 2008 at 06:07:36PM +0900, Takashi Sato wrote: > The timeout feature is added to freeze ioctl. And new ioctl > to reset the timeout period is added. > o Freeze the filesystem > int ioctl(int fd, int FIFREEZE, long *timeval) > fd: The file descriptor of the mountpoint > FIFREEZE: request code for the freeze > timeval: the timeout period in seconds > If it's 0 or 1, the timeout isn't set. > This special case of "1" is implemented to keep > the compatibility with XFS applications. > Return value: 0 if the operation succeeds. Otherwise, -1 The timeout is not for the freeze operation - the timeout is only set up once the freeze is complete. i.e: $ time sudo ~/test_src/xfs_io -f -x -c 'gfreeze 10' /mnt/scratch/test freezing with level = 10 real 0m23.204s user 0m0.008s sys 0m0.012s The freeze takes 23s, and then the 10s timeout is started. So this timeout does not protect against freeze_bdev() hangs at all. All it does is introduce silent unfreezing of the block device that can not be synchronised with the application that is operating on the frozen device. FWIW, resetting this timeout from userspace is unreliable - there's no guarantee that under load your userspace process will get to run again inside the timeout to reset it, hence leaving you with a unfrozen filesystem when you really want it frozen... Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
