[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
diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c
index 0404783..7f8b27e 100644
--- a/fs/gfs2/dir.c
+++ b/fs/gfs2/dir.c
@@ -197,8 +197,8 @@
 
 		if (!extlen) {
 			new = 1;
-			error = gfs2_block_map(ip, lblock, &new, &dblock,
-					       &extlen);
+			error = gfs2_extent_map(ip->i_vnode, lblock, &new,
+						&dblock, &extlen);
 			if (error)
 				goto fail;
 			error = -EIO;
@@ -314,8 +314,8 @@
 
 		if (!extlen) {
 			new = 0;
-			error = gfs2_block_map(ip, lblock, &new, &dblock,
-					       &extlen);
+			error = gfs2_extent_map(ip->i_vnode, lblock, &new,
+						&dblock, &extlen);
 			if (error)
 				goto fail;
 		}