On Wed, Apr 20, 2022 at 02:28:34PM -0400, Chuck Lever wrote:
> Attempt to address occasional reports of test failures caused by
> NFSv4 OPEN(CREATE) having failing internally after the target
> file object has been created.
>
> The basic approach is to re-organize the NFSv4 OPEN code path so
> that common failure modes occur /before/ the call to vfs_create()
> rather than afterwards. In addition, the file is opened and created
> atomically so that another client can't race and de-permit the
> file just after it was created but before the server has opened it.
>
> So far I haven't found any regressions. However I have not been
> able to reproduce the original failures.
I'll admit I don't know how big an impact those races have in practice.
But this has bugged me for a long time--thanks for finally tackling it.
I haven't reviewed it in detail but the basic idea looks good.
--b.
> Chuck Lever (8):
> NFSD: Clean up nfsd3_proc_create()
> NFSD: Avoid calling fh_drop_write() twice in do_nfsd_create()
> NFSD: Refactor nfsd_create_setattr()
> NFSD: Refactor NFSv3 CREATE
> NFSD: Refactor NFSv4 OPEN(CREATE)
> NFSD: Remove do_nfsd_create()
> NFSD: Clean up nfsd_open_verified()
> NFSD: Instantiate a struct file when creating a regular NFSv4 file
>
>
> fs/nfsd/filecache.c | 51 +++++++--
> fs/nfsd/filecache.h | 2 +
> fs/nfsd/nfs3proc.c | 141 +++++++++++++++++++++----
> fs/nfsd/nfs4proc.c | 197 +++++++++++++++++++++++++++++++++--
> fs/nfsd/nfs4state.c | 16 ++-
> fs/nfsd/vfs.c | 245 ++++++++++----------------------------------
> fs/nfsd/vfs.h | 14 +--
> fs/nfsd/xdr4.h | 1 +
> fs/open.c | 44 ++++++++
> include/linux/fs.h | 2 +
> 10 files changed, 471 insertions(+), 242 deletions(-)
>
> --
> Chuck Lever