Hi Al,

I'd like to hear your opinion on this patchset before queuing up for 4.10.

Here's the problem:

A file is opened for read-only, opened read-write (resulting in a copy up)
and modified.  The data read back from the the read-only fd will be stale
in this case (the read-only file descriptor still refers to the lower,
unmodified file).

This patchset fixes issues related to this corner case.

The VFS impact is minimal and performance in the non-corner cases shouldn't

Git tree is here:

  git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git #overlayfs-rorw

Pathset is against #overlayfs-next.


Miklos Szeredi (8):
  vfs: allow overlayfs to intercept file ops
  vfs: export filp_clone_open()
  mm: ovl: copy-up on MAP_SHARED
  ovl: add infrastructure for intercepting file ops
  ovl: intercept read_iter
  ovl: intercept mmap
  ovl: intercept fsync
  Revert "ovl: Warn on copy up if a process has a R/O fd open to the
    lower file"

 fs/internal.h            |   1 -
 fs/open.c                |   2 +-
 fs/overlayfs/copy_up.c   |  34 -------
 fs/overlayfs/inode.c     | 227 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/overlayfs/overlayfs.h |   2 +
 fs/overlayfs/super.c     |   1 +
 include/linux/fs.h       |   1 +
 mm/util.c                |  22 +++++
 8 files changed, 254 insertions(+), 36 deletions(-)


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