[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/fuse/control.c b/fs/fuse/control.c
index 46fe60b..79ec1f2 100644
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -23,7 +23,7 @@
{
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 @@
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 @@
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);
}