GFS2: Fix address space from page function

Now that rgrps use the address space which is part of the super
block, we need to update gfs2_mapping2sbd() to take account of
that. The only way to do that easily is to use a different set
of address_space_operations for rgrps.
Reported-by: NAbhi Das <adas@redhat.com>
Tested-by: NAbhi Das <adas@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

fs/gfs2/meta_io.c

@@ -97,6 +97,11 @@ const struct address_space_operations gfs2_meta_aops = {
 	.releasepage = gfs2_releasepage,
 };
 
+const struct address_space_operations gfs2_rgrp_aops = {
+	.writepage = gfs2_aspace_writepage,
+	.releasepage = gfs2_releasepage,
+};
+
 /**
  * gfs2_getbuf - Get a buffer with a given address space
  * @gl: the glock

fs/gfs2/meta_io.h

@@ -38,12 +38,15 @@ static inline void gfs2_buffer_copy_tail(struct buffer_head *to_bh,
 }
 
 extern const struct address_space_operations gfs2_meta_aops;
+extern const struct address_space_operations gfs2_rgrp_aops;
 
 static inline struct gfs2_sbd *gfs2_mapping2sbd(struct address_space *mapping)
 {
 	struct inode *inode = mapping->host;
 	if (mapping->a_ops == &gfs2_meta_aops)
 		return (((struct gfs2_glock *)mapping) - 1)->gl_sbd;
+	else if (mapping->a_ops == &gfs2_rgrp_aops)
+		return container_of(mapping, struct gfs2_sbd, sd_aspace);
 	else
 		return inode->i_sb->s_fs_info;
 }

fs/gfs2/ops_fstype.c

@@ -106,7 +106,7 @@ static struct gfs2_sbd *init_sbd(struct super_block *sb)
 	mapping = &sdp->sd_aspace;
 
 	address_space_init_once(mapping);
-	mapping->a_ops = &gfs2_meta_aops;
+	mapping->a_ops = &gfs2_rgrp_aops;
 	mapping->host = sb->s_bdev->bd_inode;
 	mapping->flags = 0;
 	mapping_set_gfp_mask(mapping, GFP_NOFS);