[RFC][PATCH 0/2] Updating overlay inode i_mtime for nfsd

[Amir Goldstein <amir73il@gmail.com>]

Jeff, Bruce,

These RFC patches fix an issue I found when running nfstest_posix
over NFS exported overlayfs.

I am posting these separately from (soon to be posted) overlayfs NFS
export support patches to get your inputs about the preferred way for
a fix.

The 1st patch is a proposal to fix overlay inode i_mtime on inode
modification. This fix is incomplete w.r.t nfstest_posix test failures.
The 2nd patch more or less reverts the 1st patch in favor of updating
overlay inode i_mtime only when nfsd would care. At least as far as
nfstest_posix is concerned this fix is complete.

I lean towards the 2nd fix, but wasn't sure, so posting both suggestions.
Another option would be to call vfs_getattr() from lease_get_mtime(),
which will get the correct i_mtime for overlayfs (upper inode i_mtime),
but wasn't sure if this is a viable option for nfsd.

Would appreciate your thoughts about the issue and about the proposed fix.

Thanks,
Amir.

Amir Goldstein (2):
  vfs: update overlay inode times on write
  vfs: update overlay inode times on lease_get_mtime()

 fs/inode.c    | 15 ++++++++++++---
 fs/internal.h |  1 +
 fs/locks.c    | 12 +++++++++++-
 3 files changed, 24 insertions(+), 4 deletions(-)

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2.7.4