[GFS2] Readpages support

This adds readpages support (and also corrects a small bug in
the readpage error path at the same time). Hopefully this will
improve performance by allowing GFS to submit larger lumps of
I/O at a time.

In order to simplify the setting of BH_Boundary, it currently gets
set when we hit the end of a indirect pointer block. There is
always a boundary at this point with the current allocation code.
It doesn't get all the boundaries right though, so there is still
room for improvement in this.

See comments in fs/gfs2/ops_address.c for further information about
readpages with GFS2.

Signed-off-by: Steven Whitehouse

fs/gfs2/inode.c

@@ -1606,9 +1606,8 @@ int gfs2_glock_nq_atime(struct gfs2_holder *gh)
 	curtime = get_seconds();
 	if (curtime - ip->i_di.di_atime >= quantum) {
 		gfs2_glock_dq(gh);
-		gfs2_holder_reinit(LM_ST_EXCLUSIVE,
-				  gh->gh_flags & ~LM_FLAG_ANY,
-				  gh);
+		gfs2_holder_reinit(LM_ST_EXCLUSIVE, gh->gh_flags & ~LM_FLAG_ANY,
+				   gh);
 		error = gfs2_glock_nq(gh);
 		if (error)
 			return error;