[PATCH] inode_diet: Replace inode.u.generic_ip with inode.i_private
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.
[judith@osdl.org: powerpc build fix]
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Judith Lebzelter <judith@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/freevxfs/vxfs.h b/fs/freevxfs/vxfs.h
index d35979a..c8a9265 100644
--- a/fs/freevxfs/vxfs.h
+++ b/fs/freevxfs/vxfs.h
@@ -252,7 +252,7 @@
* Get filesystem private data from VFS inode.
*/
#define VXFS_INO(ip) \
- ((struct vxfs_inode_info *)(ip)->u.generic_ip)
+ ((struct vxfs_inode_info *)(ip)->i_private)
/*
* Get filesystem private data from VFS superblock.
diff --git a/fs/freevxfs/vxfs_inode.c b/fs/freevxfs/vxfs_inode.c
index ca6a397..32a82ed 100644
--- a/fs/freevxfs/vxfs_inode.c
+++ b/fs/freevxfs/vxfs_inode.c
@@ -243,7 +243,7 @@
ip->i_blocks = vip->vii_blocks;
ip->i_generation = vip->vii_gen;
- ip->u.generic_ip = (void *)vip;
+ ip->i_private = vip;
}
@@ -338,5 +338,5 @@
void
vxfs_clear_inode(struct inode *ip)
{
- kmem_cache_free(vxfs_inode_cachep, ip->u.generic_ip);
+ kmem_cache_free(vxfs_inode_cachep, ip->i_private);
}