kernel/linux.git/fs/lockd/svcproc.c, branch v7.1

lockd: fix TEST handling when not all permissions are available.

2026-05-21T21:08:47+00:00

The F_GETLK fcntl can work with either read access or write access or both. It can query F_RDLCK and F_WRLCK locks in either case. However lockd currently treats F_GETLK similar to F_SETLK in that read access is required to query an F_RDLCK lock and write access is required to query a F_WRLCK lock. This is wrong and can cause problems - e.g. when qemu accesses a read-only (e.g. iso) filesystem image over NFS (though why it queries if it can get a write lock - I don't know. But it does, and this works with local filesystems). So we need TEST requests to be handled differently. To do this: - change nlm_do_fopen() to accept O_RDWR as a mode and in that case succeed if either a O_RDONLY or O_WRONLY file can be opened. - change nlm_lookup_file() to accept a mode argument from caller, instead of deducing base on lock time, and pass that on to nlm_do_fopen() - change nlm4svc_retrieve_args() and nlmsvc_retrieve_args() to detect TEST requests and pass O_RDWR as a mode to nlm_lookup_file, passing the same mode as before for other requests. Also set lock->fl.c.flc_file to whichever file is available for TEST requests. - change nlmsvc_testlock() to also not calculate the mode, but to use whatever was stored in lock->fl.c.flc_file. This behaviour of lockd - requesting O_WRONLY access to TEST for exclusive locks - has been present at least since git history began. However it was hidden until recently because knfsd ignored the access requested by lockd and required only READ access for all locking requests (unless the underlying filesystem provided an f_op->open function which checked access permissions). The commit mentioned in Fixes: below changed nfsd_permission() to NOT override the access request for LOCK requests and this exposed the bug that we are now fixing. Note that there is another issue that this patch does not address. The flock(.., LOCK_EX) call is permitted on a read-only file descriptor. Linux NFS maps this to NLM locking as whole-file byte-range locks. nfsd will see this as though it were fcntl( F_SETLK (F_WRLCK)) and will now require write access, which it might not be able to get. It is not clear if this is a problem in practice, or what the best solution might be. So no attempt is made to address it. Reported-by: Tj Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1128861 Fixes: 4cc9b9f2bf4d ("nfsd: refine and rename NFSD_MAY_LOCK") Reviewed-by: Jeff Layton Signed-off-by: NeilBrown Signed-off-by: Chuck Lever

lockd: Prepare share helpers for xdrgen conversion

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

In order to convert the NLMv4 server-side XDR functions to use xdrgen, the internal share helpers need to be decoupled from the NLMv3-specific struct nlm_args. NLMv4 procedures will use different argument structures once they are converted. Refactor nlmsvc_share_file() and nlmsvc_unshare_file() to accept individual arguments (oh, access, mode) instead of the common struct nlm_args. This allows both protocol versions to call these helpers without forcing a common argument structure. While here, add kdoc comments to both functions and fix a comment typo in the unshare path. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

lockd: Relocate svc_version definitions to XDR layer

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

Public RPC server interfaces become cluttered when internal XDR implementation details leak into them. The procedure count, maximum XDR buffer size, and per-CPU call counters serve no purpose outside the code that encodes and decodes NLM protocol messages. Exposing these values through global headers creates unnecessary coupling between the RPC dispatch logic and the XDR layer. Relocating the svc_version structure definitions confines this implementation information to the files where XDR encoding and decoding occur. In svc.c, the buffer size computation now reads vs_xdrsize from the version structures rather than relying on a preprocessor constant. This calculation occurs at service initialization, after the linker has resolved the version structure definitions. The dispatch function becomes non-static because both the version structures and the dispatcher reside in different translation units. The NLMSVC_XDRSIZE macro is removed from xdr.h because buffer size is now computed from the union of XDR argument and result structures, matching the pattern used in other RPC services. Version 1 and 3 share the same procedure table but maintain separate counter arrays. Version 4 remains separate due to its distinct procedure definitions. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

lockd: Relocate include/linux/lockd/lockd.h

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

Headers placed in include/linux/ form part of the kernel's internal API and signal to subsystem maintainers that other parts of the kernel may depend on them. By moving lockd.h into fs/lockd/, lockd becomes a more self-contained module whose internal interfaces are clearly distinguished from its public contract with the rest of the kernel. This relocation addresses a long-standing XXX comment in the header itself that acknowledged the file's misplacement. Future changes to lockd internals can now proceed with confidence that external consumers are not inadvertently coupled to implementation details. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

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

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

The share.h header defines struct nlm_share and declares the DOS share management functions used by the NLM server to implement NLM_SHARE and NLM_UNSHARE operations. These interfaces are used exclusively within the lockd subsystem. A git grep search confirms no external code references them. Relocating this header from include/linux/lockd/ to fs/lockd/ narrows the public API surface of the lockd module. Out-of-tree code cannot depend on these internal interfaces after this change. Future refactoring of the share management implementation thus requires no consideration of external consumers. 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

lockd: Introduce nlmintdeadlock

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

The use of CONFIG_LOCKD_V4 in combination with a later cast_status() in the NLMv3 code is difficult to reason about. Instead, replace the use of nlm_deadlock with an implementation-defined status value that version-specific code translates appropriately. The new approach establishes a translation boundary: generic lockd code returns nlm__int__deadlock when posix_lock_file() yields -EDEADLK. Version-specific handlers (svc4proc.c for NLMv4, svcproc.c for NLMv3) translate this internal status to the appropriate wire protocol value. NLMv4 maps to nlm4_deadlock; NLMv3 maps to nlm_lck_denied (since NLMv3 lacks a deadlock-specific status code). Later this modification will also remove the need to include NLMv4 headers in NLMv3 and generic code. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

lockd: Relocate and rename nlm_drop_reply

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

The nlm_drop_reply status code is internal to the kernel's lockd implementation and must never appear on the wire. Its previous location in xdr.h grouped it with legitimate NLM protocol status codes, obscuring this critical distinction. Relocate the definition to lockd.h with a comment block for internal status codes, and rename to nlm__int__drop_reply to make its internal-only nature explicit. This prepares for adding additional internal status codes in subsequent patches. Signed-off-by: Chuck Lever

lockd: Simplify cast_status() in svcproc.c

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

Clean up: The svcproc.c file handles only NLM v1 and v3 requests. NLMv4 requests are routed to a separate procedure table in svc4proc.c, so rqstp->rq_vers can never be 4 in this context. Remove the unused vers parameter and the dead "vers != 4" check from cast_to_nlm(). This eliminates the need for the macro wrapper. Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

lockd: fix vfs_test_lock() calls

2025-12-25T02:18:46+00:00

Usage of vfs_test_lock() is somewhat confused. Documentation suggests it is given a "lock" but this is not the case. It is given a struct file_lock which contains some details of the sort of lock it should be looking for. In particular passing a "file_lock" containing fl_lmops or fl_ops is meaningless and possibly confusing. This is particularly problematic in lockd. nlmsvc_testlock() receives an initialised "file_lock" from xdr-decode, including manager ops and an owner. It then mistakenly passes this to vfs_test_lock() which might replace the owner and the ops. This can lead to confusion when freeing the lock. The primary role of the 'struct file_lock' passed to vfs_test_lock() is to report a conflicting lock that was found, so it makes more sense for nlmsvc_testlock() to pass "conflock", which it uses for returning the conflicting lock. With this change, freeing of the lock is not confused and code in __nlm4svc_proc_test() and __nlmsvc_proc_test() can be simplified. Documentation for vfs_test_lock() is improved to reflect its real purpose, and a WARN_ON_ONCE() is added to avoid a similar problem in the future. Reported-by: Olga Kornievskaia Closes: https://lore.kernel.org/all/20251021130506.45065-1-okorniev@redhat.com Signed-off-by: NeilBrown Fixes: 20fa19027286 ("nfs: add export operations") Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

kernel/linux.git/fs/lockd/svcproc.c, branch v7.1

lockd: fix TEST handling when not all permissions are available.

lockd: Prepare share helpers for xdrgen conversion

lockd: Relocate svc_version definitions to XDR layer

lockd: Relocate include/linux/lockd/lockd.h

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

lockd: Have nlm_fopen() return errno values

lockd: Introduce nlm__int__deadlock

lockd: Relocate and rename nlm_drop_reply

lockd: Simplify cast_status() in svcproc.c

lockd: fix vfs_test_lock() calls

lockd: Introduce nlmintdeadlock