When an NFSv3/NLM client issues multiple NLM_SHARE calls from a single
host for the same (file, owner) tuple, the current implementation
overwrites the recorded access and deny modes with the latest pair.
A subsequent NLM_UNSHARE then drops the entire entry, even if other
grants were implicitly subsumed by the most recent SHARE. This is
particularly visible to Windows-style clients that map each open of
a file to a distinct NLM_SHARE, all carrying the same NLM owner
handle. For example:
1. SHARE(access=RW, deny=W) -> entry [RW, deny W]
2. SHARE(access=R, deny=N) -> entry [R, deny N] (RW/W overwritten)
3. UNSHARE(access=R, deny=N) -> entry freed
4. UNSHARE(access=RW, deny=W) -> nothing to release
NLM has no duplicate reply cache, so both SHARE and UNSHARE handlers
must be idempotent under UDP retransmit.
Track each (access, deny) pair with a single bit in a u16 bitmap.
fsh_access and fsh_mode are each in {0..3}, so there are 16 possible
pairs; index = (access << 2) | deny. SHARE sets the bit, UNSHARE
clears it, both via idempotent bit operations. s_access and s_mode
are recomputed as the union of the (access, deny) values whose bit
is set, and the entry is freed once s_access_deny_bmap reaches zero.
NLM_UNSHARE gains the access and deny modes as arguments so the
correct bit can be cleared. The two callers in svcproc.c and
svc4proc.c are updated to forward the decoded values.
Signed-off-by: Oscar Ou <oscarou@synology.com>
Link: https://patch.msgid.link/20260703063856.2423734-1-oscarou@synology.com
Signed-off-by: Chuck Lever <cel@kernel.org>
As part of the effort to enable lockd's server-side XDR functions to
be generated from the NLM protocol specification (using xdrgen), the
internal type names must be changed to avoid conflicts with the
machine-generated type names.
Rename struct nlm_share to struct lockd_share to avoid conflicts with
the NLMv3 XDR type definitions that will be introduced when svcproc.c
is converted to use xdrgen.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Replace the magic value ~(u32)0 with a named constant. This value
is used as a synthetic svid when looking up lockowners for DOS
share operations, which have no real process ID associated with
them.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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 <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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 <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2026-03-29 21:25:09 -04:00
Renamed from include/linux/lockd/share.h (Browse further)
