From 67d10dcbeaac765cb85c782b1358676f1bda305c Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@suse.cz>
Date: Mon, 14 May 2012 13:06:13 +0200
Subject: UBUNTU: ubuntu: overlayfs -- vfs: pass struct path to __dentry_open()

Make __dentry_open() take a struct path instead of separate vfsmount and dentry
arguments.

Change semantics as well, so that __dentry_open() acquires a reference to path
instead of transferring it to the open file.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
---
 fs/open.c | 49 ++++++++++++++++++++++---------------------------
 1 file changed, 22 insertions(+), 27 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index 1637b209fa5..b7983d520ab 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -671,24 +671,24 @@ int open_check_o_direct(struct file *f)
 	return 0;
 }
 
-static struct file *do_dentry_open(struct dentry *dentry, struct vfsmount *mnt,
-				   struct file *f,
-				   int (*open)(struct inode *, struct file *),
-				   const struct cred *cred)
+static struct file *do_dentry_open(struct path *path, struct file *f,
+				  int (*open)(struct inode *, struct file *),
+				  const struct cred *cred)
 {
 	static const struct file_operations empty_fops = {};
 	struct inode *inode;
 	int error;
 
+	path_get(path);
 	f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
 				FMODE_PREAD | FMODE_PWRITE;
 
 	if (unlikely(f->f_flags & O_PATH))
 		f->f_mode = FMODE_PATH;
 
-	inode = dentry->d_inode;
+	inode = path->dentry->d_inode;
 	if (f->f_mode & FMODE_WRITE) {
-		error = __get_file_write_access(inode, mnt);
+		error = __get_file_write_access(inode, path->mnt);
 		if (error)
 			goto cleanup_file;
 		if (!special_file(inode->i_mode))
@@ -696,8 +696,7 @@ static struct file *do_dentry_open(struct dentry *dentry, struct vfsmount *mnt,
 	}
 
 	f->f_mapping = inode->i_mapping;
-	f->f_path.dentry = dentry;
-	f->f_path.mnt = mnt;
+	f->f_path = *path;
 	f->f_pos = 0;
 	file_sb_list_add(f, inode->i_sb);
 
@@ -744,24 +743,22 @@ cleanup_all:
 			 * here, so just reset the state.
 			 */
 			file_reset_write(f);
-			mnt_drop_write(mnt);
+			mnt_drop_write(path->mnt);
 		}
 	}
 	file_sb_list_del(f);
 	f->f_path.dentry = NULL;
 	f->f_path.mnt = NULL;
 cleanup_file:
-	dput(dentry);
-	mntput(mnt);
+	path_put(path);
 	return ERR_PTR(error);
 }
 
-static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
-				struct file *f,
+static struct file *__dentry_open(struct path *path, struct file *f,
 				int (*open)(struct inode *, struct file *),
 				const struct cred *cred)
 {
-	struct file *res = do_dentry_open(dentry, mnt, f, open, cred);
+	struct file *res = do_dentry_open(path, f, open, cred);
 	if (!IS_ERR(res)) {
 		int error = open_check_o_direct(f);
 		if (error) {
@@ -796,14 +793,14 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
 		int (*open)(struct inode *, struct file *))
 {
+	struct path path = { .dentry = dentry, .mnt = nd->path.mnt };
 	const struct cred *cred = current_cred();
 
 	if (IS_ERR(nd->intent.open.file))
 		goto out;
 	if (IS_ERR(dentry))
 		goto out_err;
-	nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
-					     nd->intent.open.file,
+	nd->intent.open.file = __dentry_open(&path, nd->intent.open.file,
 					     open, cred);
 out:
 	return nd->intent.open.file;
@@ -835,9 +832,7 @@ struct file *nameidata_to_filp(struct nameidata *nd)
 	} else {
 		struct file *res;
 
-		path_get(&nd->path);
-		res = do_dentry_open(nd->path.dentry, nd->path.mnt,
-				     filp, NULL, cred);
+		res = do_dentry_open(&nd->path, filp, NULL, cred);
 		if (!IS_ERR(res)) {
 			int error;
 
@@ -864,24 +859,24 @@ struct file *nameidata_to_filp(struct nameidata *nd)
 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
 			 const struct cred *cred)
 {
-	int error;
 	struct file *f;
+	struct file *ret;
+	struct path path = { .dentry = dentry, .mnt = mnt };
 
 	validate_creds(cred);
 
 	/* We must always pass in a valid mount pointer. */
 	BUG_ON(!mnt);
 
-	error = -ENFILE;
+	ret = ERR_PTR(-ENFILE);
 	f = get_empty_filp();
-	if (f == NULL) {
-		dput(dentry);
-		mntput(mnt);
-		return ERR_PTR(error);
+	if (f != NULL) {
+		f->f_flags = flags;
+		ret = __dentry_open(&path, f, NULL, cred);
 	}
+	path_put(&path);
 
-	f->f_flags = flags;
-	return __dentry_open(dentry, mnt, f, NULL, cred);
+	return ret;
 }
 EXPORT_SYMBOL(dentry_open);
 
-- 
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