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Message-Id: <20250924-dir-deleg-v3-0-9f3af8bc5c40@kernel.org>
Date: Wed, 24 Sep 2025 14:05:46 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
Chuck Lever <chuck.lever@...cle.com>,
Alexander Aring <alex.aring@...il.com>,
Trond Myklebust <trondmy@...nel.org>, Anna Schumaker <anna@...nel.org>,
Steve French <sfrench@...ba.org>,
Ronnie Sahlberg <ronniesahlberg@...il.com>,
Shyam Prasad N <sprasad@...rosoft.com>, Tom Talpey <tom@...pey.com>,
Bharath SM <bharathsm@...rosoft.com>, NeilBrown <neil@...wn.name>,
Olga Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>,
Jonathan Corbet <corbet@....net>, Amir Goldstein <amir73il@...il.com>,
Miklos Szeredi <miklos@...redi.hu>, Paulo Alcantara <pc@...guebit.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>, Danilo Krummrich <dakr@...nel.org>,
David Howells <dhowells@...hat.com>, Tyler Hicks <code@...icks.com>,
Namjae Jeon <linkinjeon@...nel.org>, Steve French <smfrench@...il.com>,
Sergey Senozhatsky <senozhatsky@...omium.org>,
Carlos Maiolino <cem@...nel.org>, Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Paulo Alcantara <pc@...guebit.org>
Cc: Rick Macklem <rick.macklem@...il.com>, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org,
linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
linux-doc@...r.kernel.org, netfs@...ts.linux.dev, ecryptfs@...r.kernel.org,
linux-unionfs@...r.kernel.org, linux-xfs@...r.kernel.org,
linux-trace-kernel@...r.kernel.org, Jeff Layton <jlayton@...nel.org>
Subject: [PATCH v3 00/38] vfs, nfsd: implement directory delegations
This patchset is an update to a patchset that I posted in early June
this year [1]. This version should be basically feature-complete, with a
few caveats.
NFSv4.1 adds a GET_DIR_DELEGATION operation, to allow clients
to request a delegation on a directory. If the client holds a directory
delegation, then it knows that nothing will change the dentries in it
until it has been recalled (modulo the case where the client requests
notifications of directory changes).
In 2023, Rick Macklem gave a talk at the NFS Bakeathon on his
implementation of directory delegations for FreeBSD [2], and showed that
it can greatly improve LOOKUP-heavy workloads. There is also some
earlier work by CITI [3] that showed similar results. The SMB protocol
also has a similar sort of construct, and they have also seen large
performance improvements on certain workloads.
This version also starts with support for trivial directory delegations
that support no notifications. From there it adds VFS support for
ignoring certain break_lease() events in directories. It then adds
support for basic CB_NOTIFY calls (with names only). Next, support for
sending attributes in the notifications is added.
I think that this version should be getting close to merge ready. Anna
has graciously agreed to work on the client-side pieces for this. I've
mostly been testing using pynfs tests (which I will submit soon).
The main limitation at this point is that callback requests are
currently limited to a single page, so we can't send very many in a
single CB_NOTIFY call. This will make it easy to "get into the weeds" if
you're changing a directory quickly. The server will just recall the
delegation in that case, so it's harmless even though it's not ideal.
If this approach looks acceptable I'll see if we can increase that
limitation (it seems doable).
If anyone wishes to try this out, it's in the "dir-deleg" branch in my
tree at kernel.org [4].
[1]: https://lore.kernel.org/linux-nfs/20250602-dir-deleg-v2-0-a7919700de86@kernel.org/
[2]: https://www.youtube.com/watch?v=DdFyH3BN5pI
[3]: https://linux-nfs.org/wiki/index.php/CITI_Experience_with_Directory_Delegations
[4]: https://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux.git/
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
Changes in v3:
- Rework to do minimal work in fsnotify callbacks
- Add support for sending attributes in CB_NOTIFY calls
- Add support for dir attr change notifications
- Link to v2: https://lore.kernel.org/r/20250602-dir-deleg-v2-0-a7919700de86@kernel.org
Changes in v2:
- add support for ignoring certain break_lease() events
- basic support for CB_NOTIFY
- Link to v1: https://lore.kernel.org/r/20240315-dir-deleg-v1-0-a1d6209a3654@kernel.org
---
Jeff Layton (38):
filelock: push the S_ISREG check down to ->setlease handlers
filelock: add a lm_may_setlease lease_manager callback
vfs: add try_break_deleg calls for parents to vfs_{link,rename,unlink}
vfs: allow mkdir to wait for delegation break on parent
vfs: allow rmdir to wait for delegation break on parent
vfs: break parent dir delegations in open(..., O_CREAT) codepath
vfs: make vfs_create break delegations on parent directory
vfs: make vfs_mknod break delegations on parent directory
filelock: lift the ban on directory leases in generic_setlease
nfsd: allow filecache to hold S_IFDIR files
nfsd: allow DELEGRETURN on directories
nfsd: check for delegation conflicts vs. the same client
nfsd: wire up GET_DIR_DELEGATION handling
filelock: rework the __break_lease API to use flags
filelock: add struct delegated_inode
filelock: add support for ignoring deleg breaks for dir change events
filelock: add a tracepoint to start of break_lease()
filelock: add an inode_lease_ignore_mask helper
nfsd: add protocol support for CB_NOTIFY
nfs_common: add new NOTIFY4_* flags proposed in RFC8881bis
nfsd: allow nfsd to get a dir lease with an ignore mask
vfs: add fsnotify_modify_mark_mask()
nfsd: update the fsnotify mark when setting or removing a dir delegation
nfsd: make nfsd4_callback_ops->prepare operation bool return
nfsd: add callback encoding and decoding linkages for CB_NOTIFY
nfsd: add data structures for handling CB_NOTIFY to directory delegation
nfsd: add notification handlers for dir events
nfsd: add tracepoint to dir_event handler
nfsd: apply the notify mask to the delegation when requested
nfsd: add helper to marshal a fattr4 from completed args
nfsd: allow nfsd4_encode_fattr4_change() to work with no export
nfsd: send basic file attributes in CB_NOTIFY
nfsd: allow encoding a filehandle into fattr4 without a svc_fh
nfsd: add a fi_connectable flag to struct nfs4_file
nfsd: add the filehandle to returned attributes in CB_NOTIFY
nfsd: properly track requested child attributes
nfsd: track requested dir attributes
nfsd: add support to CB_NOTIFY for dir attribute changes
Documentation/sunrpc/xdr/nfs4_1.x | 267 +++++++++++++++++-
drivers/base/devtmpfs.c | 2 +-
fs/attr.c | 4 +-
fs/cachefiles/namei.c | 2 +-
fs/ecryptfs/inode.c | 2 +-
fs/fuse/dir.c | 1 +
fs/init.c | 2 +-
fs/locks.c | 122 ++++++--
fs/namei.c | 253 +++++++++++------
fs/nfs/nfs4file.c | 2 +
fs/nfsd/filecache.c | 101 +++++--
fs/nfsd/filecache.h | 2 +
fs/nfsd/nfs4callback.c | 60 +++-
fs/nfsd/nfs4layouts.c | 3 +-
fs/nfsd/nfs4proc.c | 36 ++-
fs/nfsd/nfs4recover.c | 2 +-
fs/nfsd/nfs4state.c | 531 +++++++++++++++++++++++++++++++++--
fs/nfsd/nfs4xdr.c | 298 +++++++++++++++++---
fs/nfsd/nfs4xdr_gen.c | 506 ++++++++++++++++++++++++++++++++-
fs/nfsd/nfs4xdr_gen.h | 20 +-
fs/nfsd/state.h | 73 ++++-
fs/nfsd/trace.h | 21 ++
fs/nfsd/vfs.c | 7 +-
fs/nfsd/vfs.h | 2 +-
fs/nfsd/xdr4.h | 3 +
fs/nfsd/xdr4cb.h | 12 +
fs/notify/mark.c | 29 ++
fs/open.c | 8 +-
fs/overlayfs/overlayfs.h | 2 +-
fs/posix_acl.c | 12 +-
fs/smb/client/cifsfs.c | 3 +
fs/smb/server/vfs.c | 2 +-
fs/utimes.c | 4 +-
fs/xattr.c | 16 +-
fs/xfs/scrub/orphanage.c | 2 +-
include/linux/filelock.h | 143 +++++++---
include/linux/fs.h | 11 +-
include/linux/fsnotify_backend.h | 1 +
include/linux/nfs4.h | 127 ---------
include/linux/sunrpc/xdrgen/nfs4_1.h | 304 +++++++++++++++++++-
include/linux/xattr.h | 4 +-
include/trace/events/filelock.h | 38 ++-
include/uapi/linux/nfs4.h | 2 -
43 files changed, 2636 insertions(+), 406 deletions(-)
---
base-commit: 36c204d169319562eed170f266c58460d5dad635
change-id: 20240215-dir-deleg-e212210ba9d4
Best regards,
--
Jeff Layton <jlayton@...nel.org>
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