On Sun, May 30, 2004 at 03:59:03PM +0900, YAMAMOTO Takashi wrote: > hi, > > > Module Name: src > > Committed By: wrstuden > > Date: Sat May 29 23:49:32 UTC 2004 > > > > Modified Files: > > src/sys/fs/union: union_vfsops.c > > > > Log Message: > > unionfs can use layerfs_snapshot() too. > > "file-system union" doesn't pull in layer_vfsops.c. > and you need to include layer_extern.h. Thank you and Kimmo for noting this to me. I've since reverted the change as I remembered that layerfs won't work with unionfs - layerfs requires a common structure for the vnodes which unionfs doesn't (and shoudn't) use. > although i doubt the benefit to use layerfs_snapshot here. > (the concept "snapshot through layered filesystem" isn't clear to me.) I think the concept of a "snapshot through layered file system" depends both on the underlying file system and the layer. Say it's a layered file system that provides snapshotting. ;-) More specifically, given our current fss and ffs, "snapshot through layered file system" could mean one of two practical things. One, say you're using an overlay-class layer. You _have_ to go through the layered file system to get at the underlying ffs, so a functioning layerfs_snapshot() would permit using the two together. Two, say you have some sort of chroot environment that you null-mount a file system into, and you don't mind making snapshots in there. I'm not quite sure why you would want to permit snapshotting in a chroot, but people have done stranger things. Note that for now layerfs_snapshot() serves as an error-returning routine that comments why snapshots won't work through a layered file system. Take care, Bill
Attachment:
pgp39DAK73ilB.pgp
Description: PGP signature