VFS: Allow the filesystem to return a full file pointer on open intent

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---
 fs/exec.c             |   12 ++++++------
 fs/namei.c            |   19 ++++++++++++++++---
 fs/open.c             |   14 +++++++++++++-
 include/linux/namei.h |   10 ++++++++++
 4 files changed, 45 insertions(+), 10 deletions(-)

Index: linux-2.6.12-rc1/fs/namei.c
===================================================================
--- linux-2.6.12-rc1.orig/fs/namei.c
+++ linux-2.6.12-rc1/fs/namei.c
@@ -28,6 +28,7 @@
 #include <linux/syscalls.h>
 #include <linux/mount.h>
 #include <linux/audit.h>
+#include <linux/file.h>
 #include <asm/namei.h>
 #include <asm/uaccess.h>
 
@@ -318,6 +319,19 @@ void path_release_on_umount(struct namei
 }
 
 /*
+ * Open intents have to release any file pointer that was allocated
+ * but not used by the VFS.
+ */
+void path_release_open_intent(struct nameidata *nd)
+{
+	if ((nd->flags & LOOKUP_OPEN) && nd->intent.open.file != NULL) {
+		fput(nd->intent.open.file);
+		nd->intent.open.file = NULL;
+	}
+	path_release(nd);
+}
+
+/*
  * Internal lookup() using the new generic dcache.
  * SMP-safe
  */
@@ -1406,8 +1420,7 @@ int open_namei(const char * pathname, in
 		acc_mode |= MAY_APPEND;
 
 	/* Fill in the open() intent data */
-	nd->intent.open.flags = flag;
-	nd->intent.open.create_mode = mode;
+	nd_init_open_intent(nd, flag, mode);
 
 	/*
 	 * The simplest case - just a plain lookup.
@@ -1498,7 +1511,7 @@ ok:
 exit_dput:
 	dput(dentry);
 exit:
-	path_release(nd);
+	path_release_open_intent(nd);
 	return error;
 
 do_link:
Index: linux-2.6.12-rc1/fs/exec.c
===================================================================
--- linux-2.6.12-rc1.orig/fs/exec.c
+++ linux-2.6.12-rc1/fs/exec.c
@@ -123,7 +123,7 @@ asmlinkage long sys_uselib(const char __
 	struct nameidata nd;
 	int error;
 
-	nd.intent.open.flags = FMODE_READ;
+	nd_init_open_intent(&nd, FMODE_READ, 0);
 	error = __user_walk(library, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
 	if (error)
 		goto out;
@@ -136,7 +136,7 @@ asmlinkage long sys_uselib(const char __
 	if (error)
 		goto exit;
 
-	file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
+	file = nd_open_file(&nd, O_RDONLY);
 	error = PTR_ERR(file);
 	if (IS_ERR(file))
 		goto out;
@@ -164,7 +164,7 @@ asmlinkage long sys_uselib(const char __
 out:
   	return error;
 exit:
-	path_release(&nd);
+	path_release_open_intent(&nd);
 	goto out;
 }
 
@@ -491,7 +491,7 @@ struct file *open_exec(const char *name)
 	int err;
 	struct file *file;
 
-	nd.intent.open.flags = FMODE_READ;
+	nd_init_open_intent(&nd, FMODE_READ, 0);
 	err = path_lookup(name, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
 	file = ERR_PTR(err);
 
@@ -505,7 +505,7 @@ struct file *open_exec(const char *name)
 				err = -EACCES;
 			file = ERR_PTR(err);
 			if (!err) {
-				file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
+				file = nd_open_file(&nd, O_RDONLY);
 				if (!IS_ERR(file)) {
 					err = deny_write_access(file);
 					if (err) {
@@ -517,7 +517,7 @@ out:
 				return file;
 			}
 		}
-		path_release(&nd);
+		path_release_open_intent(&nd);
 	}
 	goto out;
 }
Index: linux-2.6.12-rc1/include/linux/namei.h
===================================================================
--- linux-2.6.12-rc1.orig/include/linux/namei.h
+++ linux-2.6.12-rc1/include/linux/namei.h
@@ -8,6 +8,7 @@ struct vfsmount;
 struct open_intent {
 	int	flags;
 	int	create_mode;
+	struct file *file;
 };
 
 enum { MAX_NESTED_LINKS = 5 };
@@ -64,6 +65,15 @@ extern int FASTCALL(path_walk(const char
 extern int FASTCALL(link_path_walk(const char *, struct nameidata *));
 extern void path_release(struct nameidata *);
 extern void path_release_on_umount(struct nameidata *);
+extern void path_release_open_intent(struct nameidata *);
+
+extern struct file *nd_open_file(struct nameidata *nd, int flags);
+static inline void nd_init_open_intent(struct nameidata *nd, int flags, int mode)
+{
+	nd->intent.open.flags = flags;
+	nd->intent.open.create_mode = mode;
+	nd->intent.open.file = NULL;
+}
 
 extern struct dentry * lookup_one_len(const char *, struct dentry *, int);
 extern struct dentry * lookup_hash(struct qstr *, struct dentry *);
Index: linux-2.6.12-rc1/fs/open.c
===================================================================
--- linux-2.6.12-rc1.orig/fs/open.c
+++ linux-2.6.12-rc1/fs/open.c
@@ -763,13 +763,25 @@ struct file *filp_open(const char * file
 
 	error = open_namei(filename, namei_flags, mode, &nd);
 	if (!error)
-		return dentry_open(nd.dentry, nd.mnt, flags);
+		return nd_open_file(&nd, flags);
 
 	return ERR_PTR(error);
 }
 
 EXPORT_SYMBOL(filp_open);
 
+struct file *nd_open_file(struct nameidata *nd, int flags)
+{
+	struct file *filp;
+
+	if ((nd->flags & LOOKUP_OPEN) && nd->intent.open.file != NULL) {
+		filp = nd->intent.open.file;
+		path_release(nd);
+	} else
+		filp = dentry_open(nd->dentry, nd->mnt, flags);
+	return filp;
+}
+
 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
 {
 	struct file * f;