Update vfs_busy(9) and vfs_unbusy(9) manual pages to better match the

current behaviour of the functions.

Discussed with:	attilio

share/man/man9/vfs_busy.9

@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd November 2, 2008
+.Dd June 14, 2010
 .Dt VFS_BUSY 9
 .Os
 .Sh NAME
@@ -40,9 +40,8 @@
 .Sh DESCRIPTION
 The
 .Fn vfs_busy
-function marks a mount point as busy.
-The purpose of this
-function is to synchronize access to a mount point.
+function marks a mount point as busy by incrementing
+the reference count of a mount point.
 It also delays unmounting by sleeping on
 .Fa mp
 if the
@@ -50,7 +49,7 @@ if the
 flag is set in
 .Fa mp->mnt_kern_flag
 and the
-.Dv LK_NOWAIT
+.Dv MBF_NOWAIT
 flag is
 .Em not
 set.
@@ -75,9 +74,9 @@ drop the mountlist_mtx in the critical path.
 .Sh RETURN VALUES
 A 0 value is returned on success.
 If the mount point is being
-unmounted
+unmounted and MBF_NOWAIT flag is specified
 .Er ENOENT
-will always be returned.
+will be returned.
 .Sh ERRORS
 .Bl -tag -width Er
 .It Bq Er ENOENT

share/man/man9/vfs_unbusy.9

@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 29, 2008
+.Dd June 14, 2010
 .Dt VFS_UNBUSY 9
 .Os
 .Sh NAME
@@ -40,23 +40,17 @@
 .Sh DESCRIPTION
 The
 .Fn vfs_unbusy
-function un-busies a mount point by unlocking
-.Fa mp->mnt_lock .
-The lock is typically acquired by calling
+function un-busies a mount point by decrementing
+the reference count of a mount point.
+The reference count is typically incremented by calling
 .Xr vfs_busy 9
 prior to this call.
 .Pp
 Its arguments are:
 .Bl -tag -width ".Fa mp"
 .It Fa mp
-The mount point to unbusy (unlock).
+The mount point to unbusy.
 .El
-.Sh LOCKS
-.Va mnt_lock
-must be locked in
-.Fa mp
-prior to calling
-this function, and it will be unlocked upon return.
 .Sh SEE ALSO
 .Xr vfs_busy 9
 .Sh AUTHORS