Merge tag 'pull-f_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull file->f_path constification from Al Viro:
 "Only one thing was modifying ->f_path of an opened file - acct(2).

  Massaging that away and constifying a bunch of struct path * arguments
  in functions that might be given &file->f_path ends up with the
  situation where we can turn ->f_path into an anon union of const
  struct path f_path and struct path __f_path, the latter modified only
  in a few places in fs/{file_table,open,namei}.c, all for struct file
  instances that are yet to be opened"

* tag 'pull-f_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (23 commits)
  Have cc(1) catch attempts to modify ->f_path
  kernel/acct.c: saner struct file treatment
  configfs:get_target() - release path as soon as we grab configfs_item reference
  apparmor/af_unix: constify struct path * arguments
  ovl_is_real_file: constify realpath argument
  ovl_sync_file(): constify path argument
  ovl_lower_dir(): constify path argument
  ovl_get_verity_digest(): constify path argument
  ovl_validate_verity(): constify {meta,data}path arguments
  ovl_ensure_verity_loaded(): constify datapath argument
  ksmbd_vfs_set_init_posix_acl(): constify path argument
  ksmbd_vfs_inherit_posix_acl(): constify path argument
  ksmbd_vfs_kern_path_unlock(): constify path argument
  ksmbd_vfs_path_lookup_locked(): root_share_path can be const struct path *
  check_export(): constify path argument
  export_operations->open(): constify path argument
  rqst_exp_get_by_name(): constify path argument
  nfs: constify path argument of __vfs_getattr()
  bpf...d_path(): constify path argument
  done_path_create(): constify path argument
  ...

1 files changed, 7 insertions, 2 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1f4a1c570a2a..540004970ad5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1192,6 +1192,8 @@ static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
  * @f_cred: stashed credentials of creator/opener
  * @f_owner: file owner
  * @f_path: path of the file
+ * @__f_path: writable alias for @f_path; *ONLY* for core VFS and only before
+ *   the file gets open
  * @f_pos_lock: lock protecting file position
  * @f_pipe: specific to pipes
  * @f_pos: file position
@@ -1217,7 +1219,10 @@ struct file {
 	const struct cred		*f_cred;
 	struct fown_struct		*f_owner;
 	/* --- cacheline 1 boundary (64 bytes) --- */
-	struct path			f_path;
+	union {
+		const struct path	f_path;
+		struct path		__f_path;
+	};
 	union {
 		/* regular files (with FMODE_ATOMIC_POS) and directories */
 		struct mutex		f_pos_lock;
@@ -2877,7 +2882,7 @@ struct file *dentry_open_nonotify(const struct path *path, int flags,
 				  const struct cred *cred);
 struct file *dentry_create(const struct path *path, int flags, umode_t mode,
 			   const struct cred *cred);
-struct path *backing_file_user_path(const struct file *f);
+const struct path *backing_file_user_path(const struct file *f);
 
 /*
  * When mmapping a file on a stackable filesystem (e.g., overlayfs), the file