[GFS2] inode_diet: Replace inode.u.generic_ip with inode.i_private (gfs)

The following patches reduce the size of the VFS inode structure by 28 bytes
on a UP x86.  (It would be more on an x86_64 system).  This is a 10% reduction
in the inode size on a UP kernel that is configured in a production mode
(i.e., with no spinlock or other debugging functions enabled; if you want to
save memory taken up by in-core inodes, the first thing you should do is
disable the debugging options; they are responsible for a huge amount of bloat
in the VFS inode structure).

This patch:

The filesystem or device-specific pointer in the inode is inside a union,
which is pretty pointless given that all 30+ users of this field have been
using the void pointer.  Get rid of the union and rename it to i_private, with
a comment to explain who is allowed to use the void pointer.  This is just a
cleanup, but it allows us to reuse the union 'u' for something something where
the union will actually be used.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index d3708af0a4d1..731799153187 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -78,7 +78,7 @@ struct inode *gfs2_aspace_get(struct gfs2_sbd *sdp)
                 mapping_set_gfp_mask(aspace->i_mapping, GFP_NOFS);
                 aspace->i_mapping->a_ops = &aspace_aops;
                 aspace->i_size = ~0ULL;
-                aspace->u.generic_ip = NULL;
+                aspace->i_private = NULL;
                 insert_inode_hash(aspace);
         }
         return aspace;