A simple wrapper for updating ovl inode size/mtime, to conform
with ovl_file_accessed().

Signed-off-by: Amir Goldstein <amir73il@gmail.com>

We want to protect concurrent updates of ovl inode size and mtime
(i.e. ovl_copyattr()) from aio completion context.

Punt write aio completion to a workqueue so that we can protect
ovl_copyattr() with a spinlock.

Export sb_init_dio_done_wq(), so that overlayfs can use its own
dio workqueue to punt aio completions.

Suggested-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/8620dfd3-372d-4ae0-aa3f-2fe97dda1bca@kernel.dk/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

If ovl file is opened O_APPEND, the underlying realfile is also
opened O_APPEND, so it makes sense to propagate the IOCB_APPEND flags
on sync writes to realfile, just as we do with aio writes.

Effectively, because sync ovl writes are protected by inode lock,
this change only makes a difference if the realfile is written to (size
extending writes) from underneath overlayfs.  The behavior in this case
is undefined, so it is ok if we change the behavior (to fail the ovl
IOCB_APPEND write).

Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Overlayfs implements its own function to translate iocb flags into rw
flags, so that they can be passed into another vfs call.

With commit ce71bfea207b4 ("fs: align IOCB_* flags with RWF_* flags")
Jens created a 1:1 matching between the iocb flags and rw flags,
simplifying the conversion.

Signed-off-by: Alessio Balsini <balsini@android.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Convert to using the new inode timestamp accessor functions.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20231004185347.80880-58-jlayton@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

Commit 724768a39374 ("ovl: fix incorrect fdput() on aio completion")
took a refcount on real file before submitting aio, but forgot to
avoid clearing FDPUT_FPUT from real.flags stack variable.
This can result in a file reference leak.

Fixes: 724768a39374 ("ovl: fix incorrect fdput() on aio completion")
Reported-by: Gil Lev <contact@levgil.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Pull vfs fixes from Christian Brauner:
 "This contains the usual miscellaneous fixes and cleanups for vfs and
  individual fses:

  Fixes:
   - Revert ki_pos on error from buffered writes for direct io fallback
   - Add missing documentation for block device and superblock handling
     for changes merged this cycle
   - Fix reiserfs flexible array usage
   - Ensure that overlayfs sets ctime when setting mtime and atime
   - Disable deferred caller completions with overlayfs writes until
     proper support exists

  Cleanups:
   - Remove duplicate initialization in pipe code
   - Annotate aio kioctx_table with __counted_by"

* tag 'v6.6-rc4.vfs.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
  overlayfs: set ctime when setting mtime and atime
  ntfs3: put resources during ntfs_fill_super()
  ovl: disable IOCB_DIO_CALLER_COMP
  porting: document superblock as block device holder
  porting: document new block device opening order
  fs/pipe: remove duplicate "offset" initializer
  fs-writeback: do not requeue a clean inode having skipped pages
  aio: Annotate struct kioctx_table with __counted_by
  direct_write_fallback(): on error revert the ->ki_pos update from buffered write
  reiserfs: Replace 1-element array with C99 style flex-array

overlayfs copies the kiocb flags when it sets up a new kiocb to handle
a write, but it doesn't properly support dealing with the deferred
caller completions of the kiocb. This means it doesn't get the final
write completion value, and hence will complete the write with '0' as
the result.

We could support the caller completions in overlayfs, but for now let's
just disable them in the generated write kiocb.

Reported-by: Zorro Lang <zlang@redhat.com>
Link: https://lore.kernel.org/io-uring/20230924142754.ejwsjen5pvyc32l4@dell-per750-06-vm-08.rhts.eng.pek2.redhat.com/
Fixes: 8c052fb3002e ("iomap: support IOCB_DIO_CALLER_COMP")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Message-Id: <71897125-e570-46ce-946a-d4729725e28f@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>

ovl_{read,write}_iter() always call fdput(real) to put one or zero
refcounts of the real file, but for aio, whether it was submitted or not,
ovl_aio_put() also calls fdput(), which is not balanced.  This is only a
problem in the less common case when FDPUT_FPUT flag is set.

To fix the problem use get_file() to take file refcount and use fput()
instead of fdput() in ovl_aio_put().

Fixes: 2406a307ac7d ("ovl: implement async IO routines")
Cc: <stable@vger.kernel.org> # v5.6
Reviewed-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Pull overlayfs updates from Amir Goldstein:

 - add verification feature needed by composefs (Alexander Larsson)

 - improve integration of overlayfs and fanotify (Amir Goldstein)

 - fortify some overlayfs code (Andrea Righi)

* tag 'ovl-update-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
  ovl: validate superblock in OVL_FS()
  ovl: make consistent use of OVL_FS()
  ovl: Kconfig: introduce CONFIG_OVERLAY_FS_DEBUG
  ovl: auto generate uuid for new overlay filesystems
  ovl: store persistent uuid/fsid with uuid=on
  ovl: add support for unique fsid per instance
  ovl: support encoding non-decodable file handles
  ovl: Handle verity during copy-up
  ovl: Validate verity xattr when resolving lowerdata
  ovl: Add versioned header for overlay.metacopy xattr
  ovl: Add framework for verity support