[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/arch/s390/hypfs/inode.c b/arch/s390/hypfs/inode.c
index bdade5f..8735024 100644
--- a/arch/s390/hypfs/inode.c
+++ b/arch/s390/hypfs/inode.c
@@ -104,13 +104,13 @@
static void hypfs_drop_inode(struct inode *inode)
{
- kfree(inode->u.generic_ip);
+ kfree(inode->i_private);
generic_delete_inode(inode);
}
static int hypfs_open(struct inode *inode, struct file *filp)
{
- char *data = filp->f_dentry->d_inode->u.generic_ip;
+ char *data = filp->f_dentry->d_inode->i_private;
struct hypfs_sb_info *fs_info;
if (filp->f_mode & FMODE_WRITE) {
@@ -352,7 +352,7 @@
parent->d_inode->i_nlink++;
} else
BUG();
- inode->u.generic_ip = data;
+ inode->i_private = data;
d_instantiate(dentry, inode);
dget(dentry);
return dentry;