[PATCH 00/10] Towards safer path_* API

[Mateusz Guzik]

Currently the handling is highly error-prone with consumers allowed to
arbitrarily manipulate references, notably with path_get().

In the past this resulted in preventable bugs.

The end goal, not yet achieved with this patchset, will provide an
invariant that a populated 'struct path' has precisely one set of
references on it.

While consumers can still cause leaks by neglecting to path_put(), the
footgun of path_get() can be eliminated.

With this patchset instead of hand-rolling a path copy and issuing
path_get() on it, callers can resort to path_clone() instead.

Almost all path_get() consumers get converted, most of which with
coccinelle.

Few instances are left until I figure out a nice way to sort them out.

Overall almost entirety of this patchset is a NOP.

Mateusz Guzik (10):
  fs: unexport backing_file_set_user_path() and make it take the ref on
    its own
  fs: add path_create(), path_move() and path_clone()
  fs: use path_clone() in path_init()
  fs: use path_clone() and path_move() in vfs_open*
  fs: use path_clone() in backing_file_set_user_path()
  Coccinelle-based conversion of path_* consumers to use the new
    primitives
  autofs: use path_create()
  fsnotify: use path_clone()
  proc: use path_clone()
  nfsd: use path_clone()

 drivers/block/loop.c               |  3 +-
 fs/autofs/dev-ioctl.c              |  3 +-
 fs/autofs/expire.c                 |  4 +--
 fs/backing-file.c                  |  2 --
 fs/devpts/inode.c                  |  6 ++--
 fs/failfs.c                        |  3 +-
 fs/fhandle.c                       |  3 +-
 fs/file_attr.c                     |  6 ++--
 fs/file_table.c                    |  3 +-
 fs/fs_struct.c                     |  6 ++--
 fs/namei.c                         | 44 ++++++++++++++++++++++++------
 fs/namespace.c                     |  3 +-
 fs/nfsd/export.c                   |  6 ++--
 fs/nfsd/nfs4xdr.c                  |  8 +++---
 fs/notify/fanotify/fanotify.c      |  6 ++--
 fs/notify/fanotify/fanotify_user.c |  3 +-
 fs/nsfs.c                          |  3 +-
 fs/open.c                          | 10 ++-----
 fs/overlayfs/params.c              |  3 +-
 fs/pidfs.c                         |  3 +-
 fs/proc/base.c                     |  6 ++--
 fs/proc/fd.c                       |  3 +-
 fs/smb/server/vfs.c                |  3 +-
 fs/xfs/xfs_handle.c                |  3 +-
 include/linux/path.h               | 14 ++++++++--
 kernel/trace/bpf_trace.c           |  3 +-
 security/apparmor/task.c           |  3 +-
 security/keys/big_key.c            |  3 +-
 security/landlock/fs.c             |  3 +-
 security/landlock/syscalls.c       |  3 +-
 30 files changed, 87 insertions(+), 85 deletions(-)

-- 
2.53.0