vfs: move open right after ->tmpfile()

Create a helper finish_open_simple() that opens the file with the original
dentry.  Handle the error case here as well to simplify callers.

Call this helper right after ->tmpfile() is called.

Next patch will change the tmpfile API and move this call into tmpfile
instances.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/namei.c b/fs/namei.c
index 03ad4e55fb265f642804b07ab55d6a9e3fda7183..fea56fe9f3069500dc2223f118e07a4f13fe67cc 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3583,44 +3583,44 @@ static int do_open(struct nameidata *nd,
  * On non-idmapped mounts or if permission checking is to be performed on the
  * raw inode simply passs init_user_ns.
  */
-static struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
-                          struct dentry *dentry, umode_t mode, int open_flag)
+static int vfs_tmpfile(struct user_namespace *mnt_userns,
+                      const struct path *parentpath,
+                      struct file *file, umode_t mode)
 {
-       struct dentry *child = NULL;
-       struct inode *dir = dentry->d_inode;
+       struct dentry *child;
+       struct inode *dir = d_inode(parentpath->dentry);
        struct inode *inode;
        int error;
 
        /* we want directory to be writable */
        error = inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
        if (error)
-               goto out_err;
-       error = -EOPNOTSUPP;
+               return error;
        if (!dir->i_op->tmpfile)
-               goto out_err;
-       error = -ENOMEM;
-       child = d_alloc(dentry, &slash_name);
+               return -EOPNOTSUPP;
+       child = d_alloc(parentpath->dentry, &slash_name);
        if (unlikely(!child))
-               goto out_err;
+               return -ENOMEM;
+       file->f_path.mnt = parentpath->mnt;
+       file->f_path.dentry = child;
        mode = vfs_prepare_mode(mnt_userns, dir, mode, mode, mode);
        error = dir->i_op->tmpfile(mnt_userns, dir, child, mode);
+       error = finish_open_simple(file, error);
+       dput(child);
        if (error)
-               goto out_err;
-       error = -ENOENT;
-       inode = child->d_inode;
-       if (unlikely(!inode))
-               goto out_err;
-       if (!(open_flag & O_EXCL)) {
+               return error;
+       /* Don't check for other permissions, the inode was just created */
+       error = may_open(mnt_userns, &file->f_path, 0, file->f_flags);
+       if (error)
+               return error;
+       inode = file_inode(file);
+       if (!(file->f_flags & O_EXCL)) {
                spin_lock(&inode->i_lock);
                inode->i_state |= I_LINKABLE;
                spin_unlock(&inode->i_lock);
        }
        ima_post_create_tmpfile(mnt_userns, inode);
-       return child;
-
-out_err:
-       dput(child);
-       return ERR_PTR(error);
+       return 0;
 }
 
 /**
@@ -3641,25 +3641,15 @@ struct file *vfs_tmpfile_open(struct user_namespace *mnt_userns,
 {
        struct file *file;
        int error;
-       struct path path = { .mnt = parentpath->mnt };
-
-       path.dentry = vfs_tmpfile(mnt_userns, parentpath->dentry, mode, open_flag);
-       if (IS_ERR(path.dentry))
-               return ERR_CAST(path.dentry);
-
-       error = may_open(mnt_userns, &path, 0, open_flag);
-       file = ERR_PTR(error);
-       if (error)
-               goto out_dput;
-
-       /*
-        * This relies on the "noaccount" property of fake open, otherwise
-        * equivalent to dentry_open().
-        */
-       file = open_with_fake_path(&path, open_flag, d_inode(path.dentry), cred);
-out_dput:
-       dput(path.dentry);
 
+       file = alloc_empty_file_noaccount(open_flag, cred);
+       if (!IS_ERR(file)) {
+               error = vfs_tmpfile(mnt_userns, parentpath, file, mode);
+               if (error) {
+                       fput(file);
+                       file = ERR_PTR(error);
+               }
+       }
        return file;
 }
 EXPORT_SYMBOL(vfs_tmpfile_open);
@@ -3669,26 +3659,19 @@ static int do_tmpfile(struct nameidata *nd, unsigned flags,
                struct file *file)
 {
        struct user_namespace *mnt_userns;
-       struct dentry *child;
        struct path path;
        int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path);
+
        if (unlikely(error))
                return error;
        error = mnt_want_write(path.mnt);
        if (unlikely(error))
                goto out;
        mnt_userns = mnt_user_ns(path.mnt);
-       child = vfs_tmpfile(mnt_userns, path.dentry, op->mode, op->open_flag);
-       error = PTR_ERR(child);
-       if (IS_ERR(child))
+       error = vfs_tmpfile(mnt_userns, &path, file, op->mode);
+       if (error)
                goto out2;
-       dput(path.dentry);
-       path.dentry = child;
-       audit_inode(nd->name, child, 0);
-       /* Don't check for other permissions, the inode was just created */
-       error = may_open(mnt_userns, &path, 0, op->open_flag);
-       if (!error)
-               error = vfs_open(&path, file);
+       audit_inode(nd->name, file->f_path.dentry, 0);
 out2:
        mnt_drop_write(path.mnt);
 out:

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 02646542f6bb7a2e588f7737496f82836872fd05..a3c50869e79bf06810402c920603579ce16950a5 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2780,6 +2780,15 @@ extern int finish_open(struct file *file, struct dentry *dentry,
                        int (*open)(struct inode *, struct file *));
 extern int finish_no_open(struct file *file, struct dentry *dentry);
 
+/* Helper for the simple case when original dentry is used */
+static inline int finish_open_simple(struct file *file, int error)
+{
+       if (error)
+               return error;
+
+       return finish_open(file, file->f_path.dentry, NULL);
+}
+
 /* fs/dcache.c */
 extern void __init vfs_caches_init_early(void);
 extern void __init vfs_caches_init(void);