K 10
svn:author
V 3
kib
K 8
svn:date
V 27
2016-11-08T10:10:55.055097Z
K 7
svn:log
V 339
Tweaks for the buffer pager.

Pass current thread credentials instead of NOCRED.
Only allow unmapped buffers for filesystem which proclaimed the support.

For all filesystems which currently use buffer pager (UFS, msdosfs and
cd9660), the changes are effectively nop.

Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week

END