Here is a patch with request for comment.
The create, lookup, and permission inode operations are all passed a full
nameidata. This is unfortunate because in nfsd and the mqueue filesystem we
must instantiate a struct nameidata, but cannot provide all of the same
information of a regular lookup. The unused fields take up space on the
stack, but more importantly, it is not obvious which fields have meaningful
values and which don't, and so things might easily break.
This patch introduces struct nameidata2 with only the fields that make sense
independent of an actual lookup, and uses that struct in those places where a
full nameidata is not needed.
The entire patch is a little big so I'm only including the key parts here. The
complete version is here:
http://forgeftp.novell.com/apparmor/LKML_Submission-April_07/split-up-nameidata.diff
Signed-off-by: Andreas Gruenbacher <[EMAIL PROTECTED]>
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -14,21 +14,39 @@ struct open_intent {
enum { MAX_NESTED_LINKS = 8 };
+/**
+ * Fields shared between nameidata and nameidata2 -- nameidata2 could
+ * be embedded in nameidata, but then the vfs code would become
+ * cluttered with dereferences.
+ */
+#define __NAMEIDATA2 \
+ struct dentry *dentry;\
+ struct vfsmount *mnt; \
+ unsigned intflags; \
+ \
+ union { \
+ struct open_intent open;\
+ } intent;
+
struct nameidata {
- struct dentry *dentry;
- struct vfsmount *mnt;
+ __NAMEIDATA2
struct qstr last;
- unsigned intflags;
int last_type;
unsigneddepth;
char *saved_names[MAX_NESTED_LINKS + 1];
+};
- /* Intent data */
- union {
- struct open_intent open;
- } intent;
+struct nameidata2 {
+ __NAMEIDATA2
};
+#undef __NAMEIDATA2
+
+static inline struct nameidata2 *ND2(struct nameidata *nd)
+{
+ return container_of(&nd->dentry, struct nameidata2, dentry);
+}
+
struct path {
struct vfsmount *mnt;
struct dentry *dentry;
@@ -76,10 +94,9 @@ extern void path_release_on_umount(struc
extern int __user_path_lookup_open(const char __user *, unsigned lookup_flags,
struct nameidata *nd, int open_flags);
extern int path_lookup_open(int dfd, const char *name, unsigned lookup_flags,
struct nameidata *, int open_flags);
-extern struct file *lookup_instantiate_filp(struct nameidata *nd, struct
dentry *dentry,
- int (*open)(struct inode *, struct file *));
+extern struct file *lookup_instantiate_filp(struct nameidata2 *nd, struct
dentry *dentry, int (*open)(struct inode *, struct file *));
extern struct file *nameidata_to_filp(struct nameidata *nd, int flags);
-extern void release_open_intent(struct nameidata *);
+extern void release_open_intent(struct nameidata2 *);
extern struct dentry * lookup_one_len(const char *, struct dentry *, int);
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -225,7 +225,7 @@ int generic_permission(struct inode *ino
return -EACCES;
}
-int permission(struct inode *inode, int mask, struct nameidata *nd)
+int permission(struct inode *inode, int mask, struct nameidata2 *nd)
{
umode_t mode = inode->i_mode;
int retval, submask;
@@ -278,7 +278,7 @@ int permission(struct inode *inode, int
* for filesystem access without changing the "normal" uids which
* are used for other things.
*/
-int vfs_permission(struct nameidata *nd, int mask)
+int vfs_permission(struct nameidata2 *nd, int mask)
{
return permission(nd->dentry->d_inode, mask, nd);
}
@@ -366,7 +366,7 @@ void path_release_on_umount(struct namei
* release_open_intent - free up open intent resources
* @nd: pointer to nameidata
*/
-void release_open_intent(struct nameidata *nd)
+void release_open_intent(struct nameidata2 *nd)
{
if (nd->intent.open.file->f_path.dentry == NULL)
put_filp(nd->intent.open.file);
@@ -377,7 +377,7 @@ void release_open_intent(struct nameidat
static inline struct dentry *
do_revalidate(struct dentry *dentry, struct nameidata *nd)
{
- int status = dentry->d_op->d_revalidate(dentry, nd);
+ int status = dentry->d_op->d_revalidate(dentry, ND2(nd));
if (unlikely(status <= 0)) {
/*
* The dentry failed validation.
@@ -455,7 +455,7 @@ static int exec_permission_lite(struct i
return -EACCES;
ok:
- return security_inode_permission(inode, MAY_EXEC, nd);
+ return security_inode_permission(inode, MAY_EXEC, ND2(nd));
}
/*
@@ -491,7 +491,7 @@ static struct dentry * real_lookup(struc
struct dentry * dentry = d_alloc(parent, name);
result = ERR_PTR(-ENOMEM);
if (dentry) {
- result = dir->i_op->lo
