[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.

[[email protected]: powerpc build fix]
Signed-off-by: "Theodore Ts'o" <[email protected]>
Signed-off-by: Judith Lebzelter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Theodore Ts'o 2006-09-27 01:50:46 -07:00 • committed by Linus Torvalds
commit 8e18e2941c
36 changed files with 88 additions and 90 deletions

View file

@ -23,7 +23,7 @@ static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
{
struct fuse_conn *fc;
mutex_lock(&fuse_mutex);
fc = file->f_dentry->d_inode->u.generic_ip;
fc = file->f_dentry->d_inode->i_private;
if (fc)
fc = fuse_conn_get(fc);
mutex_unlock(&fuse_mutex);
@ -98,7 +98,7 @@ static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
inode->i_op = iop;
inode->i_fop = fop;
inode->i_nlink = nlink;
inode->u.generic_ip = fc;
inode->i_private = fc;
d_add(dentry, inode);
return dentry;
}
@ -150,7 +150,7 @@ void fuse_ctl_remove_conn(struct fuse_conn *fc)
for (i = fc->ctl_ndents - 1; i >= 0; i--) {
struct dentry *dentry = fc->ctl_dentry[i];
dentry->d_inode->u.generic_ip = NULL;
dentry->d_inode->i_private = NULL;
d_drop(dentry);
dput(dentry);
}