kernel/linux.git/include/linux/nfslocalio.h, branch v6.19.11

Merge tag 'nfsd-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux

2025-10-06T20:22:21+00:00

Pull nfsd updates from Chuck Lever: "Mike Snitzer has prototyped a mechanism for disabling I/O caching in NFSD. This is introduced in v6.18 as an experimental feature. This enables scaling NFSD in /both/ directions: - NFS service can be supported on systems with small memory footprints, such as low-cost cloud instances - Large NFS workloads will be less likely to force the eviction of server-local activity, helping it avoid thrashing Jeff Layton contributed a number of fixes to the new attribute delegation implementation (based on a pending Internet RFC) that we hope will make attribute delegation reliable enough to enable by default, as it is on the Linux NFS client. The remaining patches in this pull request are clean-ups and minor optimizations. Many thanks to the contributors, reviewers, testers, and bug reporters who participated during the v6.18 NFSD development cycle" * tag 'nfsd-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux: (42 commits) nfsd: discard nfserr_dropit SUNRPC: Make RPCSEC_GSS_KRB5 select CRYPTO instead of depending on it NFSD: Add io_cache_{read,write} controls to debugfs NFSD: Do the grace period check in ->proc_layoutget nfsd: delete unnecessary NULL check in __fh_verify() NFSD: Allow layoutcommit during grace period NFSD: Disallow layoutget during grace period sunrpc: fix "occurence"->"occurrence" nfsd: Don't force CRYPTO_LIB_SHA256 to be built-in nfsd: nfserr_jukebox in nlm_fopen should lead to a retry NFSD: Reduce DRC bucket size NFSD: Delay adding new entries to LRU SUNRPC: Move the svc_rpcb_cleanup() call sites NFS: Remove rpcbind cleanup for NFSv4.0 callback nfsd: unregister with rpcbind when deleting a transport NFSD: Drop redundant conversion to bool sunrpc: eliminate return pointer in svc_tcp_sendmsg() sunrpc: fix pr_notice in svc_tcp_sendto() to show correct length nfsd: decouple the xprtsec policy check from check_nfsd_access() NFSD: Fix destination buffer size in nfsd4_ssc_setup_dul() ...

nfs/localio: avoid issuing misaligned IO using O_DIRECT

2025-09-30T20:10:29+00:00

Add nfsd_file_dio_alignment and use it to avoid issuing misaligned IO using O_DIRECT. Any misaligned DIO falls back to using buffered IO. Because misaligned DIO is now handled safely, remove the nfs modparam 'localio_O_DIRECT_semantics' that was added to require users opt-in to the requirement that all O_DIRECT be properly DIO-aligned. Also, introduce nfs_iov_iter_aligned_bvec() which is a variant of iov_iter_aligned_bvec() that also verifies the offset associated with an iov_iter is DIO-aligned. NOTE: in a parallel effort, iov_iter_aligned_bvec() is being removed along with iov_iter_is_aligned(). Lastly, add pr_info_ratelimited if underlying filesystem returns -EINVAL because it was made to try O_DIRECT for IO that is not DIO-aligned (shouldn't happen, so its best to be louder if it does). Fixes: 3feec68563d ("nfs/localio: add direct IO enablement with sync and async IO support") Signed-off-by: Mike Snitzer Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker

nfsd: discard nfsd_file_get_local()

2025-09-21T23:24:50+00:00

This interface was deprecated by commit e6f7e1487ab5 ("nfs_localio: simplify interface to nfsd for getting nfsd_file") and is now unused. So let's remove it. Signed-off-by: NeilBrown Reviewed-by: Mike Snitzer Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

nfs_localio: change nfsd_file_put_local() to take a pointer to __rcu pointer

2025-05-28T21:17:14+00:00

Instead of calling xchg() and unrcu_pointer() before nfsd_file_put_local(), we now pass pointer to the __rcu pointer and call xchg() and unrcu_pointer() inside that function. Where unrcu_pointer() is currently called the internals of "struct nfsd_file" are not known and that causes older compilers such as gcc-8 to complain. In some cases we have a __kernel (aka normal) pointer not an __rcu pointer so we need to cast it to __rcu first. This is strictly a weakening so no information is lost. Somewhat surprisingly, this cast is accepted by gcc-8. This has the pleasing result that the cmpxchg() which sets ro_file and rw_file, and also the xchg() which clears them, are both now in the nfsd code. Reported-by: Pali Rohár Reported-by: Vincent Mailhol Fixes: 86e00412254a ("nfs: cache all open LOCALIO nfsd_file(s) in client") Signed-off-by: NeilBrown Signed-off-by: Anna Schumaker

nfs_localio: always hold nfsd net ref with nfsd_file ref

2025-05-28T21:17:14+00:00

Having separate nfsd_file_put and nfsd_file_put_local in struct nfsd_localio_operations doesn't make much sense. The difference is that nfsd_file_put doesn't drop a reference to the nfs_net which is what keeps nfsd from shutting down. Currently, if nfsd tries to shutdown it will invalidate the files stored in the list from the nfs_uuid and this will drop all references to the nfsd net that the client holds. But the client could still hold some references to nfsd_files for active IO. So nfsd might think is has completely shut down local IO, but hasn't and has no way to wait for those active IO requests to complete. So this patch changes nfsd_file_get to nfsd_file_get_local and has it increase the ref count on the nfsd net and it replaces all calls to ->nfsd_put_file to ->nfsd_put_file_local. It also changes ->nfsd_open_local_fh to return with the refcount on the net elevated precisely when a valid nfsd_file is returned. This means that whenever the client holds a valid nfsd_file, there will be an associated count on the nfsd net, and so the count can only reach zero when all nfsd_files have been returned. nfs_local_file_put() is changed to call nfs_to_nfsd_file_put_local() instead of replacing calls to one with calls to the other because this will help a later patch which changes nfs_to_nfsd_file_put_local() to take an __rcu pointer while nfs_local_file_put() doesn't. Fixes: 86e00412254a ("nfs: cache all open LOCALIO nfsd_file(s) in client") Signed-off-by: NeilBrown Signed-off-by: Anna Schumaker

nfs: probe for LOCALIO when v3 client reconnects to server

2025-01-14T22:05:10+00:00

Re-enabling NFSv3 LOCALIO is made more complex (than NFSv4) because v3 is stateless. As such, the hueristic used to identify a LOCALIO probe point is more adhoc by nature: if/when NFSv3 client IO begins to complete again in terms of normal RPC-based NFSv3 server IO, attempt nfs_local_probe_async(). Care is taken to throttle the frequency of nfs_local_probe_async(), otherwise there could be a flood of repeat calls to nfs_local_probe_async(). The throttle is admin controlled using a new module parameter for nfsv3, e.g.: echo 512 > /sys/module/nfsv3/parameters/nfs3_localio_probe_throttle Probe for NFSv3 LOCALIO every N IO requests (512 in this case). Must be power-of-2, defaults to 0 (probing disabled). On systems that expect to use LOCALIO with NFSv3 the admin should configure the 'nfs3_localio_probe_throttle' module parameter. This commit backfills module parameter documentation in localio.rst Signed-off-by: Mike Snitzer Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker

nfs/localio: remove redundant code and simplify LOCALIO enablement

2025-01-14T22:05:10+00:00

Remove nfs_local_enable and nfs_local_disable, instead use nfs_localio_enable_client and nfs_localio_disable_client. Discontinue use of the NFS_CS_LOCAL_IO bit in the nfs_client struct's cl_flags to reflect that LOCALIO is enabled; instead just test if the net member of the nfs_uuid_t struct is set. Also remove NFS_CS_LOCAL_IO. Lastly, remove trace_nfs_local_enable and trace_nfs_local_disable because comparable traces are available from nfs_localio.ko. Suggested-by: NeilBrown Signed-off-by: Mike Snitzer Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker

nfs_common: track all open nfsd_files per LOCALIO nfs_client

2025-01-14T22:05:10+00:00

This tracking enables __nfsd_file_cache_purge() to call nfs_localio_invalidate_clients(), upon shutdown or export change, to nfs_close_local_fh() all open nfsd_files that are still cached by the LOCALIO nfs clients associated with nfsd_net that is being shutdown. Now that the client must track all open nfsd_files there was more work than necessary being done with the global nfs_uuids_lock contended. This manifested in various RCU issues, e.g.: hrtimer: interrupt took 47969440 ns rcu: INFO: rcu_sched detected stalls on CPUs/tasks: Use nfs_uuid->lock to protect all nfs_uuid_t members, instead of nfs_uuids_lock, once nfs_uuid_is_local() adds the client to nn->local_clients. Also add 'local_clients_lock' to 'struct nfsd_net' to protect nn->local_clients. And store a pointer to spinlock in the 'list_lock' member of nfs_uuid_t so nfs_localio_disable_client() can use it to avoid taking the global nfs_uuids_lock. In combination, these split out locks eliminate the use of the single nfslocalio.c global nfs_uuids_lock in the IO paths (open and close). Also refactored associated fs/nfs_common/nfslocalio.c methods' locking to reduce work performed with spinlocks held in general. Signed-off-by: Mike Snitzer Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker

nfsd: rename nfsd_serv_ prefixed methods and variables with nfsd_net_

2025-01-14T22:05:07+00:00

Also update Documentation/filesystems/nfs/localio.rst accordingly and reduce the technical documentation debt that was previously captured in that document. Signed-off-by: Mike Snitzer Reviewed-by: Jeff Layton Acked-by: Chuck Lever Signed-off-by: Anna Schumaker

nfs: cache all open LOCALIO nfsd_file(s) in client

2025-01-14T22:04:05+00:00

This commit switches from leaning heavily on NFSD's filecache (in terms of GC'd nfsd_files) back to caching nfsd_files in the client. A later commit will add the callback mechanism needed to allow NFSD to force the NFS client to cleanup all cached nfsd_files. Add nfs_fh_localio_init() and 'struct nfs_fh_localio' to cache opened nfsd_file(s) (both a RO and RW nfsd_file is able to be opened and cached for a given nfs_fh). Update nfs_local_open_fh() to cache the nfsd_file once it is opened using __nfs_local_open_fh(). Introduce nfs_close_local_fh() to clear the cached open nfsd_files and call nfs_to_nfsd_file_put_local(). Refcounting is such that: - nfs_local_open_fh() is paired with nfs_close_local_fh(). - __nfs_local_open_fh() is paired with nfs_to_nfsd_file_put_local(). - nfs_local_file_get() is paired with nfs_local_file_put(). Signed-off-by: Mike Snitzer Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker