NetBSD master CVS tree commits

[source%NetBSD.ORG@localhost]

pk
Sun May 25 15:27:20 PDT 1997
Update of /cvsroot/src/sys/dev
In directory netbsd1:/var/slash-tmp/cvs-serv22691

Modified Files:
        vnd.c 
Log Message:
Add code (#ifdef'ed VND_FILLHOLES for now) to fall back on vn_rdwr()
if VOP_BMAP() does not produce a translation.

IO_SYNC is used to prevent dirty file cache buffers. On a ffs filesystem,
once a hole is filled, subsequent vnd accesses find will find valid
VOP_BMAP() translations.

Concerns:
        * is the assumed semantics correct for all filesystems?
        * do we actually want the automagic extension on the VND
          backing store..