kernel/linux.git/include/linux/lockd/bind.h, branch v7.3-rc1

lockd, nfsd: RCU-protect nlmsvc_ops dispatch

2026-08-10T13:54:35+00:00

nlmsvc_ops is published by nfsd_lockd_init() and cleared by nfsd_lockd_shutdown() with plain stores, while lockd dereferences it unguarded from dispatch sites in fs/lockd/svcsubs.c. The pointer targets nfsd's .rodata and the fopen/fclose callbacks live in nfsd's .text, so a stale load after rmmod nfsd results in either a NULL deref or a module-text use-after-free. Declare nlmsvc_ops as __rcu, publish via rcu_assign_pointer(), clear via RCU_INIT_POINTER() + synchronize_rcu(). Add a struct module *owner field to nlmsvc_binding and pin the module across indirect calls with try_module_get/module_put. When the binding is torn down, fall back to fput() to avoid leaking struct file references. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260611-nfsd-testing-v2-16-5b90e276f2d9@kernel.org Signed-off-by: Chuck Lever

lockd: Make linux/lockd/nlm.h an internal header

2026-03-30T01:25:09+00:00

The NLM protocol constants and status codes in nlm.h are needed only by lockd's internal implementation. NFS client code and NFSD interact with lockd through the stable API in bind.h and have no direct use for protocol-level definitions. Exposing these definitions globally via bind.h creates unnecessary coupling between lockd internals and its consumers. Moving nlm.h from include/linux/lockd/ to fs/lockd/ clarifies the API boundary: bind.h provides the lockd service interface, while nlm.h remains available only to code within fs/lockd/ that implements the protocol. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

lockd: Move xdr.h from include/linux/lockd/ to fs/lockd/

2026-03-30T01:25:09+00:00

The lockd subsystem unnecessarily exposes internal NLM XDR type definitions through the global include path. These definitions are not used by any code outside fs/lockd/, making them inappropriate for include/linux/lockd/. Moving xdr.h to fs/lockd/ narrows the API surface and clarifies that these types are internal implementation details. The comment in linux/lockd/bind.h stating xdr.h was needed for "xdr-encoded error codes" is stale: no lockd API consumers use those codes. Forward declarations for struct nfs_fh and struct file_lock are added to bind.h because their definitions were previously pulled in transitively through xdr.h. Additionally, nfs3proc.c and proc.c need explicit includes of filelock.h for FL_CLOSE and for accessing struct file_lock members, respectively. Built and tested with lockd client/server operations. No functional change. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

lockd: Move xdr4.h from include/linux/lockd/ to fs/lockd/

2026-03-30T01:25:09+00:00

The xdr4.h header declares NLMv4-specific XDR encoder/decoder functions and error codes that are used exclusively within the lockd subsystem. Moving it from include/linux/lockd/ to fs/lockd/ clarifies the intended scope of these declarations and prevents external code from depending on lockd-internal interfaces. This change reduces the public API surface of the lockd module and makes it easier to refactor NLMv4 internals without risk of breaking out-of-tree consumers. The header's contents are implementation details of the NLMv4 wire protocol handling, not a contract with other kernel subsystems. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

NFS: Use nlmclnt_shutdown_rpc_clnt() to safely shut down NLM

2026-03-30T01:25:09+00:00

A race condition exists in shutdown_store() when writing to the sysfs "shutdown" file concurrently with nlm_shutdown_hosts_net(). Without synchronization, the following sequence can occur: 1. shutdown_store() reads server->nlm_host (non-NULL) 2. nlm_shutdown_hosts_net() acquires nlm_host_mutex, calls rpc_shutdown_client(), sets h_rpcclnt to NULL, and potentially frees the host via nlm_gc_hosts() 3. shutdown_store() dereferences the now-stale or freed host Introduce nlmclnt_shutdown_rpc_clnt(), which acquires nlm_host_mutex before accessing h_rpcclnt. This synchronizes with nlm_shutdown_hosts_net() and ensures the rpc_clnt pointer remains valid during the shutdown operation. This change also improves API layering: NFS client code no longer needs to include the internal lockd header to access nlm_host fields. The new helper resides in bind.h alongside other public lockd interfaces. Reported-by: Jeff Layton Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

lockd: Relocate nlmsvc_unlock API declarations

2026-03-30T01:25:09+00:00

The nlmsvc_unlock_all_by_sb() and nlmsvc_unlock_all_by_ip() functions are part of lockd's external API, consumed by other kernel subsystems. Their declarations currently reside in linux/lockd/lockd.h alongside internal implementation details, which blurs the boundary between lockd's public interface and its private internals. Moving these declarations to linux/lockd/bind.h groups them with other external API functions and makes the separation explicit. This clarifies which functions are intended for external use and reduces the risk of internal implementation details leaking into the public API surface. Build-tested with allyesconfig; no functional changes. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

lockd: Have nlm_fopen() return errno values

2026-03-30T01:25:09+00:00

The nlm_fopen() function is part of the API between nfsd and lockd. Currently its return value is an on-the-wire NLM status code. But that forces NFSD to include NLM wire protocol definitions despite having no other dependency on the NLM wire protocol. In addition, a CONFIG_LOCKD_V4 Kconfig symbol appears in the middle of NFSD source code. Refactor: Let's not use on-the-wire values as part of a high-level API between two Linux kernel modules. That's what we have errno for, right? And, instead of simply moving the CONFIG_LOCKD_V4 check, we can get rid of it entirely and let the decision of what actual NLM status code goes on the wire to be left up to NLM version-specific code. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

NFS: add a sysfs link to the lockd rpc_client

2023-06-19T19:06:07+00:00

After lockd is started, add a symlink for lockd's rpc_client under NFS' superblock sysfs. Signed-off-by: Benjamin Coddington Signed-off-by: Trond Myklebust

Keep read and write fds with each nlm_file

2021-08-23T22:05:31+00:00

We shouldn't really be using a read-only file descriptor to take a write lock. Most filesystems will put up with it. But NFS, for example, won't. Signed-off-by: J. Bruce Fields Signed-off-by: Chuck Lever

lockd: Pass the user cred from knfsd when starting the lockd server

2019-04-24T13:46:35+00:00

When starting up a new knfsd server, pass the user cred to the supporting lockd server. Signed-off-by: Trond Myklebust Signed-off-by: J. Bruce Fields