[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>

2 files changed, 8 insertions, 8 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_fs.c b/drivers/infiniband/hw/ipath/ipath_fs.c
index a5eb30a06a5c..055cdd089b28 100644
--- a/drivers/infiniband/hw/ipath/ipath_fs.c
+++ b/drivers/infiniband/hw/ipath/ipath_fs.c
@@ -64,7 +64,7 @@ static int ipathfs_mknod(struct inode *dir, struct dentry *dentry,
         inode->i_blksize = PAGE_CACHE_SIZE;
         inode->i_blocks = 0;
         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
-        inode->u.generic_ip = data;
+        inode->i_private = data;
         if ((mode & S_IFMT) == S_IFDIR) {
                 inode->i_op = &simple_dir_inode_operations;
                 inode->i_nlink++;
@@ -119,7 +119,7 @@ static ssize_t atomic_counters_read(struct file *file, char __user *buf,
         u16 i;
         struct ipath_devdata *dd;
 
-        dd = file->f_dentry->d_inode->u.generic_ip;
+        dd = file->f_dentry->d_inode->i_private;
 
         for (i = 0; i < NUM_COUNTERS; i++)
                 counters[i] = ipath_snap_cntr(dd, i);
@@ -139,7 +139,7 @@ static ssize_t atomic_node_info_read(struct file *file, char __user *buf,
         struct ipath_devdata *dd;
         u64 guid;
 
-        dd = file->f_dentry->d_inode->u.generic_ip;
+        dd = file->f_dentry->d_inode->i_private;
 
         guid = be64_to_cpu(dd->ipath_guid);
 
@@ -178,7 +178,7 @@ static ssize_t atomic_port_info_read(struct file *file, char __user *buf,
         u32 tmp, tmp2;
         struct ipath_devdata *dd;
 
-        dd = file->f_dentry->d_inode->u.generic_ip;
+        dd = file->f_dentry->d_inode->i_private;
 
         /* so we only initialize non-zero fields. */
         memset(portinfo, 0, sizeof portinfo);
@@ -325,7 +325,7 @@ static ssize_t flash_read(struct file *file, char __user *buf,
                 goto bail;
         }
 
-        dd = file->f_dentry->d_inode->u.generic_ip;
+        dd = file->f_dentry->d_inode->i_private;
         if (ipath_eeprom_read(dd, pos, tmp, count)) {
                 ipath_dev_err(dd, "failed to read from flash\n");
                 ret = -ENXIO;
@@ -381,7 +381,7 @@ static ssize_t flash_write(struct file *file, const char __user *buf,
                 goto bail_tmp;
         }
 
-        dd = file->f_dentry->d_inode->u.generic_ip;
+        dd = file->f_dentry->d_inode->i_private;
         if (ipath_eeprom_write(dd, pos, tmp, count)) {
                 ret = -ENXIO;
                 ipath_dev_err(dd, "failed to write to flash\n");
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_fs.c b/drivers/infiniband/ulp/ipoib/ipoib_fs.c
index 5dde380e8dbe..f1cb83688b31 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_fs.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_fs.c
@@ -141,7 +141,7 @@ static int ipoib_mcg_open(struct inode *inode, struct file *file)
                 return ret;
 
         seq = file->private_data;
-        seq->private = inode->u.generic_ip;
+        seq->private = inode->i_private;
 
         return 0;
 }
@@ -247,7 +247,7 @@ static int ipoib_path_open(struct inode *inode, struct file *file)
                 return ret;
 
         seq = file->private_data;
-        seq->private = inode->u.generic_ip;
+        seq->private = inode->i_private;
 
         return 0;
 }