K 10
svn:author
V 3
mjg
K 8
svn:date
V 27
2020-07-01T05:56:29.032841Z
K 7
svn:log
V 313
vfs: protect vnodes with smr

vget_prep_smr and vhold_smr can be used to ref a vnode while within vfs_smr
section, allowing consumers to get away without locking.

See vhold_smr and vdropl for comments explaining caveats.

Reviewed by:	kib
Testec by:	pho
Differential Revision:	https://reviews.freebsd.org/D23913

END