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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

2
fs/autofs/inode.c
View File

@@ -241,7 +241,7 @@ static void autofs_read_inode(struct inode *inode)
inode->i_op = &autofs_symlink_inode_operations;
sl = &sbi->symlink[n];
inode->u.generic_ip = sl;
inode->i_private = sl;
inode->i_mode = S_IFLNK | S_IRWXUGO;
inode->i_mtime.tv_sec = inode->i_ctime.tv_sec = sl->mtime;
inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;

2
fs/autofs/symlink.c
View File

@@ -15,7 +15,7 @@
/* Nothing to release.. */
static void *autofs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
char *s=((struct autofs_symlink *)dentry->d_inode->u.generic_ip)->data;
char *s=((struct autofs_symlink *)dentry->d_inode->i_private)->data;
nd_set_link(nd, s);
return NULL;
}