[PATCH v5 00/68] struct filename series

[Al Viro <viro@zeniv.linux.org.uk>]

[See https://lore.kernel.org/all/20260108073803.425343-1-viro@zeniv.linux.org.uk
for previous variant]

Changes compared to v4:
	* rebased to v6.19-rc5
	* replaced do_renameat2() et.al. with variants (filename_renameat2(), etc.)
that do not consume filename references
	* did the same (sans renaming, since it's static in file) to
do_execveat(); folded its callers into their sole callers.
	* CLASS(filename_consume) dropped; no users left.
	* fixed an embarrassing braino in EMBEDDED_NAME_MAX definition
	* reordered things a bit

Practically all destructor calls are done via CLASS(filename...) now;
only 3 explicit calls left (one in audit, dropping the references it has
grabbed for itself, two in the vicinity of fsconfig - separate story).
Only two explicit calls of constructors left (around fsconfig).
No uses of __free(putname) remain; I haven't removed DEFINE_FREE yet,
but it's really tempting.

The branch lives in
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git #work.filename
now; individual patches in followups.

Please, review.

Rough overview:
	Preliminary bits:

1--4:	get rid of open-coded duplicates of do_mkdirat() et.al. in
	fs/init.c
5:	CLASS(filename...) definitions (part of old #17)

	Trimming struct filename down, saner allocation, io_uring
interactions, etc. (that's old core of the series - ##1--16,18--20)

6--15:	moving pathname import out of retry loops.
15:	now we can get rid of "reuse the struct filename if
we'd just imported it from the same address _and_ audit is
enabled" logics.
16:	get rid of names_cachep abuse in ntfs
17--20: embed reasonably short pathnames into struct filename,
*always* get struct filename out names_cachep, take the long
names into explicitly kmalloc'ed objects.
21:	runtime_const machinery for names_cachep; there's
a potentially better variant (statically allocated kmem_cache),
but that's a separate series.
22:	switch __getname_maybe_null() to CLASS(filename)
23:	delayed_filename machinery, solves the audit vs. io_uring
problems.
24:	now we don't need filename->refcnt to be atomic.

	Calling conventions work:
25--29:
	simplify checks in callers of pathwalk primitives - they
	(with exception of do_filp_open()) will do the right
	thing if given ERR_PTR() for name.
30--45:	... get rid of that one exception and simplify
	more callers; get saner calling conventions for
	do_execveat_common() (lift consuming the filename into
	callers), do_renameat2() et.al. (renamed to filename_...())
	and filename_...xattr().

46--66:
	conversions to CLASS(filename...), cleanups
67, 68:
	... and these should not have been using getname().

Shortlog:
Al Viro (67):
  init_mknod(): turn into a trivial wrapper for do_mknodat()
  init_mkdir(): turn into a trivial wrapper for do_mkdirat()
  init_symlink(): turn into a trivial wrapper for do_symlinkat()
  init_link(): turn into a trivial wrapper for do_linkat()
  allow to use CLASS() for struct filename *
  do_faccessat(): import pathname only once
  do_fchmodat(): import pathname only once
  do_fchownat(): import pathname only once
  do_utimes_path(): import pathname only once
  chdir(2): import pathname only once
  chroot(2): import pathname only once
  user_statfs(): import pathname only once
  do_sys_truncate(): import pathname only once
  do_readlinkat(): import pathname only once
  get rid of audit_reusename()
  ntfs: ->d_compare() must not block
  getname_flags() massage, part 1
  getname_flags() massage, part 2
  struct filename: use names_cachep only for getname() and friends
  struct filename: saner handling of long names
  switch __getname_maybe_null() to CLASS(filename_flags)
  allow incomplete imports of filenames
  struct filename ->refcnt doesn't need to be atomic
  file_getattr(): filename_lookup() accepts ERR_PTR() as filename
  file_setattr(): filename_lookup() accepts ERR_PTR() as filename
  move_mount(): filename_lookup() accepts ERR_PTR() as filename
  ksmbd_vfs_path_lookup(): vfs_path_parent_lookup() accepts ERR_PTR() as
    name
  ksmbd_vfs_rename(): vfs_path_parent_lookup() accepts ERR_PTR() as name
  do_filp_open(): DTRT when getting ERR_PTR() as pathname
  rename do_filp_open() to do_file_open()
  do_sys_openat2(): get rid of useless check, switch to CLASS(filename)
  simplify the callers of file_open_name()
  simplify the callers of do_open_execat()
  simplify the callers of alloc_bprm()
  execve: fold {compat_,}do_execve{,at}() into their sole callers
  do_execveat_common(): don't consume filename reference
  switch {alloc,free}_bprm() to CLASS()
  non-consuming variant of do_renameat2()
  non-consuming variant of do_linkat()
  non-consuming variant of do_symlinkat()
  non-consuming variant of do_mkdirat()
  non-consuming variant of do_mknodat()
  non-consuming variants of do_{unlinkat,rmdir}()
  file_[gs]etattr(2): switch to CLASS(filename_maybe_null)
  mount_setattr(2): don't mess with LOOKUP_EMPTY
  do_open_execat(): don't care about LOOKUP_EMPTY
  vfs_open_tree(): use CLASS(filename_uflags)
  name_to_handle_at(): use CLASS(filename_uflags)
  fspick(2): use CLASS(filename_flags)
  do_fchownat(): unspaghettify a bit...
  chdir(2): unspaghettify a bit...
  do_utimes_path(): switch to CLASS(filename_uflags)
  do_sys_truncate(): switch to CLASS(filename)
  do_readlinkat(): switch to CLASS(filename_flags)
  do_f{chmod,chown,access}at(): use CLASS(filename_uflags)
  namei.c: convert getname_kernel() callers to CLASS(filename_kernel)
  namei.c: switch user pathname imports to CLASS(filename{,_flags})
  filename_...xattr(): don't consume filename reference
  move_mount(2): switch to CLASS(filename_maybe_null)
  chroot(2): switch to CLASS(filename)
  quotactl_block(): switch to CLASS(filename)
  statx: switch to CLASS(filename_maybe_null)
  user_statfs(): switch to CLASS(filename)
  mqueue: switch to CLASS(filename)
  ksmbd: use CLASS(filename_kernel)
  alpha: switch osf_mount() to strndup_user()
  sysfs(2): fs_index() argument is _not_ a pathname

Mateusz Guzik (1):
  fs: hide names_cache behind runtime const machinery

Diffstat:
 Documentation/filesystems/porting.rst |   8 +
 arch/alpha/kernel/osf_sys.c           |  34 +--
 fs/coredump.c                         |   3 +-
 fs/dcache.c                           |   8 +-
 fs/exec.c                             | 178 ++++-------
 fs/fhandle.c                          |   5 +-
 fs/file_attr.c                        |  12 +-
 fs/filesystems.c                      |   9 +-
 fs/fsopen.c                           |   6 +-
 fs/init.c                             |  98 +-----
 fs/internal.h                         |  17 +-
 fs/namei.c                            | 420 ++++++++++++++------------
 fs/namespace.c                        |  22 +-
 fs/ntfs3/dir.c                        |   5 +-
 fs/ntfs3/fsntfs.c                     |   4 +-
 fs/ntfs3/inode.c                      |  13 +-
 fs/ntfs3/namei.c                      |  17 +-
 fs/ntfs3/xattr.c                      |   5 +-
 fs/open.c                             | 119 +++-----
 fs/quota/quota.c                      |   3 +-
 fs/smb/server/vfs.c                   |  15 +-
 fs/stat.c                             |  28 +-
 fs/statfs.c                           |   3 +-
 fs/utimes.c                           |   8 +-
 fs/xattr.c                            |  33 +-
 include/asm-generic/vmlinux.lds.h     |   3 +-
 include/linux/audit.h                 |  11 -
 include/linux/fs.h                    |  41 ++-
 io_uring/fs.c                         | 106 ++++---
 io_uring/openclose.c                  |  26 +-
 io_uring/statx.c                      |  17 +-
 io_uring/xattr.c                      |  30 +-
 ipc/mqueue.c                          |  11 +-
 kernel/acct.c                         |   4 +-
 kernel/auditsc.c                      |  29 +-
 mm/huge_memory.c                      |  15 +-
 mm/swapfile.c                         |  21 +-
 37 files changed, 560 insertions(+), 827 deletions(-)

-- 
2.47.3