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[PATCH] inode_diet: Replace inode.u.generic_ip with inode.i_private

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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>
This commit is contained in:
Theodore Ts'o
2006-09-27 01:50:46 -07:00
committed by Linus Torvalds
parent 6a1d9805ec
commit 8e18e2941c
36 changed files with 88 additions and 90 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
fs/debugfs/inode.c
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@@ -168,7 +168,7 @@ static int debugfs_create_by_name(const char *name, mode_t mode,
* directory dentry if set. If this paramater is NULL, then the
* file will be created in the root of the debugfs filesystem.
* @data: a pointer to something that the caller will want to get to later
* on. The inode.u.generic_ip pointer will point to this value on
* on. The inode.i_private pointer will point to this value on
* the open() call.
* @fops: a pointer to a struct file_operations that should be used for
* this file.
@@ -209,7 +209,7 @@ struct dentry *debugfs_create_file(const char *name, mode_t mode,
if (dentry->d_inode) {
if (data)
dentry->d_inode->u.generic_ip = data;
dentry->d_inode->i_private = data;
if (fops)
dentry->d_inode->i_fop = fops;
}