fs: port inode_init_owner() to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

1 files changed, 13 insertions, 10 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index d354ea2b74f9..f6e27224bd59 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -777,7 +777,7 @@ xfs_inode_inherit_flags2(
  */
 int
 xfs_init_new_inode(
-	struct user_namespace	*mnt_userns,
+	struct mnt_idmap	*idmap,
 	struct xfs_trans	*tp,
 	struct xfs_inode	*pip,
 	xfs_ino_t		ino,
@@ -788,6 +788,7 @@ xfs_init_new_inode(
 	bool			init_xattrs,
 	struct xfs_inode	**ipp)
 {
+	struct user_namespace	*mnt_userns = mnt_idmap_owner(idmap);
 	struct inode		*dir = pip ? VFS_I(pip) : NULL;
 	struct xfs_mount	*mp = tp->t_mountp;
 	struct xfs_inode	*ip;
@@ -827,7 +828,7 @@ xfs_init_new_inode(
 		inode->i_gid = dir->i_gid;
 		inode->i_mode = mode;
 	} else {
-		inode_init_owner(mnt_userns, inode, dir, mode);
+		inode_init_owner(idmap, inode, dir, mode);
 	}
 
 	/*
@@ -946,7 +947,7 @@ xfs_bumplink(
 
 int
 xfs_create(
-	struct user_namespace	*mnt_userns,
+	struct mnt_idmap	*idmap,
 	xfs_inode_t		*dp,
 	struct xfs_name		*name,
 	umode_t			mode,
@@ -954,6 +955,7 @@ xfs_create(
 	bool			init_xattrs,
 	xfs_inode_t		**ipp)
 {
+	struct user_namespace	*mnt_userns = mnt_idmap_owner(idmap);
 	int			is_dir = S_ISDIR(mode);
 	struct xfs_mount	*mp = dp->i_mount;
 	struct xfs_inode	*ip = NULL;
@@ -1020,7 +1022,7 @@ xfs_create(
 	 */
 	error = xfs_dialloc(&tp, dp->i_ino, mode, &ino);
 	if (!error)
-		error = xfs_init_new_inode(mnt_userns, tp, dp, ino, mode,
+		error = xfs_init_new_inode(idmap, tp, dp, ino, mode,
 				is_dir ? 2 : 1, rdev, prid, init_xattrs, &ip);
 	if (error)
 		goto out_trans_cancel;
@@ -1102,11 +1104,12 @@ xfs_create(
 
 int
 xfs_create_tmpfile(
-	struct user_namespace	*mnt_userns,
+	struct mnt_idmap	*idmap,
 	struct xfs_inode	*dp,
 	umode_t			mode,
 	struct xfs_inode	**ipp)
 {
+	struct user_namespace	*mnt_userns = mnt_idmap_owner(idmap);
 	struct xfs_mount	*mp = dp->i_mount;
 	struct xfs_inode	*ip = NULL;
 	struct xfs_trans	*tp = NULL;
@@ -1144,7 +1147,7 @@ xfs_create_tmpfile(
 
 	error = xfs_dialloc(&tp, dp->i_ino, mode, &ino);
 	if (!error)
-		error = xfs_init_new_inode(mnt_userns, tp, dp, ino, mode,
+		error = xfs_init_new_inode(idmap, tp, dp, ino, mode,
 				0, 0, prid, false, &ip);
 	if (error)
 		goto out_trans_cancel;
@@ -2709,7 +2712,7 @@ out_trans_abort:
  */
 static int
 xfs_rename_alloc_whiteout(
-	struct user_namespace	*mnt_userns,
+	struct mnt_idmap	*idmap,
 	struct xfs_name		*src_name,
 	struct xfs_inode	*dp,
 	struct xfs_inode	**wip)
@@ -2718,7 +2721,7 @@ xfs_rename_alloc_whiteout(
 	struct qstr		name;
 	int			error;
 
-	error = xfs_create_tmpfile(mnt_userns, dp, S_IFCHR | WHITEOUT_MODE,
+	error = xfs_create_tmpfile(idmap, dp, S_IFCHR | WHITEOUT_MODE,
 				   &tmpfile);
 	if (error)
 		return error;
@@ -2750,7 +2753,7 @@ xfs_rename_alloc_whiteout(
  */
 int
 xfs_rename(
-	struct user_namespace	*mnt_userns,
+	struct mnt_idmap	*idmap,
 	struct xfs_inode	*src_dp,
 	struct xfs_name		*src_name,
 	struct xfs_inode	*src_ip,
@@ -2782,7 +2785,7 @@ xfs_rename(
 	 * appropriately.
 	 */
 	if (flags & RENAME_WHITEOUT) {
-		error = xfs_rename_alloc_whiteout(mnt_userns, src_name,
+		error = xfs_rename_alloc_whiteout(idmap, src_name,
 						  target_dp, &wip);
 		if (error)
 			return error;