[linux-lvm] snapshots and VFS lock patch

[Rich Turner]

the way i understand it is that the only way to create a snapshot of a
journaled filesystem (ext3, XFS, etc.) is to have the VFS lock patch
applied to the kernel. this will lock the filesystem and allow it to
flush the journal before it creates the snapshot. is this true?

is there anyway to check to see if the VFS lock patch has been applied
on a system before creating the snapshot?

has this patch ever been added to the stock kernel or will every user
that wishes to create a snapshot of a journaled filesystem have to
manually apply the patch?

is the VFS lock patch required for LVM2?

what happens when a snapshot is created with a kernel that does not have
the VFS lock patch? does the snapshot creation fail with valid return
code? does the snapshot just hang up? is there any effect on the
original LV?