GFS2: combine gfs2_alloc_block and gfs2_alloc_di

GFS2 functions gfs2_alloc_block and gfs2_alloc_di do basically
the same things, with a few exceptions. This patch combines
the two functions into a slightly more generic gfs2_alloc_block.
Having one centralized block allocation function will reduce
code redundancy and make it easier to implement multi-block
reservations to reduce file fragmentation in the future.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/bmap.c

@@ -133,7 +133,7 @@ int gfs2_unstuff_dinode(struct gfs2_inode *ip, struct page *page)
 		   and write it out to disk */
 
 		unsigned int n = 1;
-		error = gfs2_alloc_block(ip, &block, &n);
+		error = gfs2_alloc_block(ip, &block, &n, 0, NULL);
 		if (error)
 			goto out_brelse;
 		if (isdir) {
@@ -503,7 +503,7 @@ static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,
 	do {
 		int error;
 		n = blks - alloced;
-		error = gfs2_alloc_block(ip, &bn, &n);
+		error = gfs2_alloc_block(ip, &bn, &n, 0, NULL);
 		if (error)
 			return error;
 		alloced += n;