linux/fs/lockd, branch v6.7

SUNRPC: change how svc threads are asked to exit.

2023-10-16T16:44:04Z

svc threads are currently stopped using kthread_stop(). This requires identifying a specific thread. However we don't care which thread stops, just as long as one does. So instead, set a flag in the svc_pool to say that a thread needs to die, and have each thread check this flag instead of calling kthread_should_stop(). The first thread to find and clear this flag then moves towards exiting. This removes an explicit dependency on sp_all_threads which will make a future patch simpler. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever

lockd: hold a reference to nlmsvc_serv while stopping the thread.

2023-10-16T16:44:04Z

Both nfsd and nfsv4-callback take a temporary reference to the svc_serv while calling svc_set_num_threads() to stop the last thread. lockd does not. This extra reference prevents the scv_serv from being freed when the last thread drops its reference count. This is not currently needed for lockd as the svc_serv is not accessed after the last thread is told to exit. However a future patch will require svc_exit_thread() to access the svc_serv after the svc_put() so it will need the code that calls svc_set_num_threads() to keep a reference and keep the svc_serv active. So copy the pattern from nfsd and nfsv4-cb to lockd, and take a reference around svc_set_num_threads(.., 0) Reviewed-by: Jeff Layton Tested-by: Jeff Layton Signed-off-by: NeilBrown Signed-off-by: Chuck Lever

lockd: fix race in async lock request handling

2023-10-16T16:44:02Z

This patch fixes a race in async lock request handling between adding the relevant struct nlm_block to nlm_blocked list after the request was sent by vfs_lock_file() and nlmsvc_grant_deferred() does a lookup of the nlm_block in the nlm_blocked list. It could be that the async request is completed before the nlm_block was added to the list. This would end in a -ENOENT and a kernel log message of "lockd: grant for unknown block". To solve this issue we add the nlm_block before the vfs_lock_file() call to be sure it has been added when a possible nlmsvc_grant_deferred() is called. If the vfs_lock_file() results in an case when it wouldn't be added to nlm_blocked list, the nlm_block struct will be removed from this list again. Reviewed-by: Jeff Layton Signed-off-by: Alexander Aring Signed-off-by: Chuck Lever

lockd: don't call vfs_lock_file() for pending requests

2023-10-16T16:44:01Z

This patch returns nlm_lck_blocked in nlmsvc_lock() when an asynchronous lock request is pending. During testing I ran into the case with the side-effects that lockd is waiting for only one lm_grant() callback because it's already part of the nlm_blocked list. If another asynchronous for the same nlm_block is triggered two lm_grant() callbacks will occur but lockd was only waiting for one. To avoid any change of existing users this handling will only being made when export_op_support_safe_async_lock() returns true. Reviewed-by: Jeff Layton Signed-off-by: Alexander Aring Signed-off-by: Chuck Lever

lockd: introduce safe async lock op

2023-10-16T16:44:01Z

This patch reverts mostly commit 40595cdc93ed ("nfs: block notification on fs with its own ->lock") and introduces an EXPORT_OP_ASYNC_LOCK export flag to signal that the "own ->lock" implementation supports async lock requests. The only main user is DLM that is used by GFS2 and OCFS2 filesystem. Those implement their own lock() implementation and return FILE_LOCK_DEFERRED as return value. Since commit 40595cdc93ed ("nfs: block notification on fs with its own ->lock") the DLM implementation were never updated. This patch should prepare for DLM to set the EXPORT_OP_ASYNC_LOCK export flag and update the DLM plock implementation regarding to it. Acked-by: Jeff Layton Signed-off-by: Alexander Aring Signed-off-by: Chuck Lever

SUNRPC: Add enum svc_auth_status

2023-08-29T21:45:22Z

In addition to the benefits of using an enum rather than a set of macros, we now have a named type that can improve static type checking of function return values. As part of this change, I removed a stale comment from svcauth.h; the return values from current implementations of the auth_ops::release method are all zero/negative errno, not the SVC_OK enum values as the old comment suggested. Suggested-by: NeilBrown Signed-off-by: Chuck Lever

SUNRPC: remove timeout arg from svc_recv()

2023-08-29T21:45:22Z

Most svc threads have no interest in a timeout. nfsd sets it to 1 hour, but this is a wart of no significance. lockd uses the timeout so that it can call nlmsvc_retry_blocked(). It also sometimes calls svc_wake_up() to ensure this is called. So change lockd to be consistent and always use svc_wake_up() to trigger nlmsvc_retry_blocked() - using a timer instead of a timeout to svc_recv(). And change svc_recv() to not take a timeout arg. This makes the sp_threads_timedout counter always zero. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever

SUNRPC: change svc_recv() to return void.

2023-08-29T21:45:22Z

svc_recv() currently returns a 0 on success or one of two errors: - -EAGAIN means no message was successfully received - -EINTR means the thread has been told to stop Previously nfsd would stop as the result of a signal as well as following kthread_stop(). In that case the difference was useful: EINTR means stop unconditionally. EAGAIN means stop if kthread_should_stop(), continue otherwise. Now threads only exit when kthread_should_stop() so we don't need the distinction. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever

SUNRPC: call svc_process() from svc_recv().

2023-08-29T21:45:22Z

All callers of svc_recv() go on to call svc_process() on success. Simplify callers by having svc_recv() do that for them. This loses one call to validate_process_creds() in nfsd. That was debugging code added 14 years ago. I don't think we need to keep it. Signed-off-by: NeilBrown Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever

lockd: remove SIGKILL handling

2023-08-29T21:45:22Z

lockd allows SIGKILL and responds by dropping all locks and restarting the grace period. This functionality has been present since 2.1.32 when lockd was added to Linux. This functionality is undocumented and most likely added as a useful debug aid. When there is a need to drop locks, the better approach is to use /proc/fs/nfsd/unlock_*. This patch removes SIGKILL handling as part of preparation for removing all signal handling from sunrpc service threads. Signed-off-by: NeilBrown Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever