After my last posting, Trond pointed out that my interpretation of RFC 9754 was wrong. The "original time" as mentioned in the spec is the time of the grant of the delegation, and not the current timestamp in the inode before the update. Given that, there is no longer a need to do any sort of complicated handling of delegated timestamps at the VFS layer, so this set removes inode_set_ctime_deleg(). We do however need a way to set a ctime that isn't current_time() via notify_change(). This patchset adds an ATTR_CTIME_SET flag, which mirrors ATTR_ATIME_SET and ATTR_MTIME_SET semantics. The rest of the patchset reworks nfsd to properly vet timestamp updates on its own and just call down into the OS to do a normal notify_change(). With this patchset in place I haven't seen any git regression suite failures yet (4 passes so far under kdevops in the "stress" configuration). I should point out that there is at least one potential problem with this implementation: The kernel does not block getattr operations when there is a delegation outstanding. When the client issues read and write ops to the server, while holding the delegation, the timestamps on the file get updated to the server's time as usual. Later, the client will send a SETATTR (or a CB_GETTTR reply) that may have times that are earlier than the timestamps currently on the inode. This means that userland applications running on the NFS server can observe timestamps going backward. This applies even for the ctime. NFS clients should be fine, as the server will do a CB_GETATTR to satisfy them. Server-side applications can't do much else with the inode without recalling the delegation, so my thinking is that the effect should be "mostly harmless". Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> --- Changes in v2: - add ATTR_CTIME_SET and remove inode_set_ctime_deleg() - track original timestamps in struct nfs4_delegation - fix delegated timestamp updates to respect saved timestamps - Link to v1: https://lore.kernel.org/r/20250722-nfsd-testing-v1-0-31321c7fc97f@xxxxxxxxxx --- Jeff Layton (7): vfs: add ATTR_CTIME_SET flag nfsd: ignore ATTR_DELEG when checking ia_valid before notify_change() nfsd: use ATTR_CTIME_SET for delegated ctime updates nfsd: track original timestamps in nfs4_delegation nfsd: fix SETATTR updates for delegated timestamps nfsd: fix timestamp updates in CB_GETATTR vfs: remove inode_set_ctime_deleg() fs/attr.c | 34 ++++++++++--------------- fs/inode.c | 73 ----------------------------------------------------- fs/nfsd/nfs4proc.c | 31 ++++++++++++++++++++++- fs/nfsd/nfs4state.c | 44 +++++++++++++++++--------------- fs/nfsd/nfs4xdr.c | 5 ++-- fs/nfsd/state.h | 8 ++++++ fs/nfsd/vfs.c | 2 +- include/linux/fs.h | 3 +-- 8 files changed, 79 insertions(+), 121 deletions(-) --- base-commit: b05f077b59098b4760e3f675b00a4e6a1ad4b0ad change-id: 20250722-nfsd-testing-5e861a3cf3a0 Best regards, -- Jeff Layton <jlayton@xxxxxxxxxx>
