Fix a bunch of typos.

Some Submitted by:	docs/18543 (Anatoly Vorobey)

sbin/mount_null/mount_null.8

@@ -96,7 +96,7 @@ which does nothing.
 which is slightly more than nothing.)
 Second, the null layer can serve as a prototype layer.
 Since it provides all necessary layer framework,
-new file system layers can be created very easily be starting
+new file system layers can be created very easily by starting
 with a null layer.
 .Pp
 The remainder of this man page examines the null layer as a basis
@@ -118,7 +118,7 @@ of target-pn subtree will be aliased under mount-point-pn.
 The null layer is the minimum file system layer,
 simply bypassing all possible operations to the lower layer
 for processing there.  The majority of its activity centers
-on the bypass routine, though which nearly all vnode operations
+on the bypass routine, through which nearly all vnode operations
 pass.
 .Pp
 The bypass routine accepts arbitrary vnode operations for
@@ -139,7 +139,9 @@ are not bypassed.
 .Em Vop_getattr
 must change the fsid being returned.
 .Em Vop_inactive
-and vop_reclaim are not bypassed so that
+and
+.Em vop_reclaim
+are not bypassed so that
 they can handle freeing null-layer specific data.
 .Em Vop_print
 is not bypassed to avoid excessive debugging
@@ -204,23 +206,24 @@ when the operation cannot be completely bypassed.  Each method
 is appropriate in different situations.  In both cases,
 it is the responsibility of the aliasing layer to make
 the operation arguments "correct" for the lower layer
-by mapping an vnode arguments to the lower layer.
+by mapping a vnode argument to the lower layer.
 .Pp
 The first approach is to call the aliasing layer's bypass routine.
 This method is most suitable when you wish to invoke the operation
-currently being handled on the lower layer.  It has the advantage
+currently being handled on the lower layer.
+It has the advantage that
 the bypass routine already must do argument mapping.
 An example of this is 
 .Em null_getattrs
 in the null layer.
 .Pp
-A second approach is to directly invoked vnode operations on
+A second approach is to directly invoke vnode operations on
 the lower layer with the
 .Em VOP_OPERATIONNAME
 interface.
 The advantage of this method is that it is easy to invoke
 arbitrary operations on the lower layer.  The disadvantage
-is that vnodes arguments must be manually mapped.
+is that vnode arguments must be manually mapped.
 .\"
 .\"
 .Sh SEE ALSO

sbin/mount_nullfs/mount_nullfs.8

@@ -96,7 +96,7 @@ which does nothing.
 which is slightly more than nothing.)
 Second, the null layer can serve as a prototype layer.
 Since it provides all necessary layer framework,
-new file system layers can be created very easily be starting
+new file system layers can be created very easily by starting
 with a null layer.
 .Pp
 The remainder of this man page examines the null layer as a basis
@@ -118,7 +118,7 @@ of target-pn subtree will be aliased under mount-point-pn.
 The null layer is the minimum file system layer,
 simply bypassing all possible operations to the lower layer
 for processing there.  The majority of its activity centers
-on the bypass routine, though which nearly all vnode operations
+on the bypass routine, through which nearly all vnode operations
 pass.
 .Pp
 The bypass routine accepts arbitrary vnode operations for
@@ -139,7 +139,9 @@ are not bypassed.
 .Em Vop_getattr
 must change the fsid being returned.
 .Em Vop_inactive
-and vop_reclaim are not bypassed so that
+and
+.Em vop_reclaim
+are not bypassed so that
 they can handle freeing null-layer specific data.
 .Em Vop_print
 is not bypassed to avoid excessive debugging
@@ -204,23 +206,24 @@ when the operation cannot be completely bypassed.  Each method
 is appropriate in different situations.  In both cases,
 it is the responsibility of the aliasing layer to make
 the operation arguments "correct" for the lower layer
-by mapping an vnode arguments to the lower layer.
+by mapping a vnode argument to the lower layer.
 .Pp
 The first approach is to call the aliasing layer's bypass routine.
 This method is most suitable when you wish to invoke the operation
-currently being handled on the lower layer.  It has the advantage
+currently being handled on the lower layer.
+It has the advantage that
 the bypass routine already must do argument mapping.
 An example of this is 
 .Em null_getattrs
 in the null layer.
 .Pp
-A second approach is to directly invoked vnode operations on
+A second approach is to directly invoke vnode operations on
 the lower layer with the
 .Em VOP_OPERATIONNAME
 interface.
 The advantage of this method is that it is easy to invoke
 arbitrary operations on the lower layer.  The disadvantage
-is that vnodes arguments must be manually mapped.
+is that vnode arguments must be manually mapped.
 .\"
 .\"
 .Sh SEE ALSO