[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/binfmt_misc.c b/fs/binfmt_misc.c
index 34ebbc1..6759b98 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -517,7 +517,7 @@
static void bm_clear_inode(struct inode *inode)
{
- kfree(inode->u.generic_ip);
+ kfree(inode->i_private);
}
static void kill_node(Node *e)
@@ -545,7 +545,7 @@
static ssize_t
bm_entry_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
{
- Node *e = file->f_dentry->d_inode->u.generic_ip;
+ Node *e = file->f_dentry->d_inode->i_private;
loff_t pos = *ppos;
ssize_t res;
char *page;
@@ -579,7 +579,7 @@
size_t count, loff_t *ppos)
{
struct dentry *root;
- Node *e = file->f_dentry->d_inode->u.generic_ip;
+ Node *e = file->f_dentry->d_inode->i_private;
int res = parse_command(buffer, count);
switch (res) {
@@ -646,7 +646,7 @@
}
e->dentry = dget(dentry);
- inode->u.generic_ip = e;
+ inode->i_private = e;
inode->i_fop = &bm_entry_operations;
d_instantiate(dentry, inode);
