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-a7919700d...@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 <jlay...@kernel.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-a7919700d...@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-a1d6209a3...@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 <jlay...@kernel.org>
