Messages in this thread | | | Subject | Re: [PATCH 00/22][RFC] Unionfs: Stackable Namespace Unification Filesystem | From | Shaya Potter <> | Date | Mon, 04 Sep 2006 17:43:04 -0400 |
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On Mon, 2006-09-04 at 22:33 +0200, Pavel Machek wrote: > On Mon 2006-09-04 09:28:26, Shaya Potter wrote: > > On Sun, 2006-09-03 at 11:05 +0000, Pavel Machek wrote: > > > Hi! > > > > > > > - Modifying a Unionfs branch directly, while the union is mounted, is > > > > currently unsupported. Any such change may cause Unionfs to oops and it > > > > can even result in data loss! > > > > > > I'm not sure if that is acceptable. Even root user should be unable to > > > oops the kernel using 'normal' actions. > > > > As I said in the other case. imagine ext2/3 on a a san file system > > where 2 systems try to make use of it. Will they not have issues? > > They probably will have issues (altrough I'm not sure, perhaps ext2 > has been debugged enough), but they'll fix them (as opposed to > document that oopses are okay).
I agree that unionfs shouldn't oops, it should handle that situation in a more graceful manner, but once the "backing store" is modified underneath it, all bets are off for either unionfs or ext2/3 behaving "correctly" (where "correctly" doesn't just mean handle the error gracefully).
But are you also 100% sure that messing with the underlying backing store wouldn't be considered an admin bug as opposed to an administrator bug? I mean there's nothing that we can do to prevent an administrator from FUBAR'ing their system by
dd if=/dev/random of=/dev/kmem.
where does one draw the line? I agree that stackable file systems make this a more pressing issue, as the "backing store" can be visible within the file system namespace as a regular file system that people are generally accustomed to interacting with.
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