On Tue, 2007-07-03 at 16:08 +1000, Nigel Cunningham wrote:
No, that's not what I'm saying. I'm saying we've been doing STR without
the freezer and that's the way to go imho.
Oops, yeah, sorry.
Heh, that might be the case :-)
Well, I was saying that in the context of the -current- snapshotting
mechanism which is based on the freezer, then you should not
sys_sync().
Some random user or kernel thread doing a sync is not a problem. It will
stop in the middle of sync and resume on wakeup.
The problem is currently because STD -itself- attempts to sync after it
has frozen things.
I think that should be changed. If you want to sync for whatever reason,
(mostly save RAM ?) do it before the freeze. That means you may get new
dirty data in memory that isn't written out by the sync before you
freeze, but that's allright, that data will be in the suspend image
anyway. If you fail to wakeup, that's akin to a normal crash, the user
will only lose the last data written at the time of the suspend and
journaling fs'es should take care of fs metadata integrity.
So to summarize, the plan that makes things work with fuse is:
- For STR, don't do the freezer thing.
- For STD, don't sys_sync() after you froze
There might be -other- issues, but that should get you through some of
them at least. Of course, you'll be in trouble if you try to do things
like STD-to-a-file which sits on a fuse FS but there's a limit to
insanity :-)
Cheers,
Ben.
-
