[PATCH RFC v16 0/11] NFSD: Initial implementation of NFSv4 Courteous Server

[PATCH RFC v16 0/11] NFSD: Initial implementation of NFSv4 Courteous Server

[Dai Ngo]

Hi Chuck, Bruce

This series of patches implement the NFSv4 Courteous Server.

A server which does not immediately expunge the state on lease expiration
is known as a Courteous Server.  A Courteous Server continues to recognize
previously generated state tokens as valid until conflict arises between
the expired state and the requests from another client, or the server
reboots.

v2 patch includes:

. add new callback, lm_expire_lock, to lock_manager_operations to
  allow the lock manager to take appropriate action with conflict lock.

. handle conflicts of NFSv4 locks with NFSv3/NLM and local locks.

. expire courtesy client after 24hr if client has not reconnected.

. do not allow expired client to become courtesy client if there are
  waiters for client's locks.

. modify client_info_show to show courtesy client and seconds from
  last renew.

. fix a problem with NFSv4.1 server where the it keeps returning
  SEQ4_STATUS_CB_PATH_DOWN in the successful SEQUENCE reply, after
  the courtesy client reconnects, causing the client to keep sending
  BCTS requests to server.

v3 patch includes:

. modified posix_test_lock to check and resolve conflict locks
  to handle NLM TEST and NFSv4 LOCKT requests.

. separate out fix for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.

v4 patch includes:

. rework nfsd_check_courtesy to avoid dead lock of fl_lock and client_lock
  by asking the laudromat thread to destroy the courtesy client.

. handle NFSv4 share reservation conflicts with courtesy client. This
  includes conflicts between access mode and deny mode and vice versa.

. drop the patch for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.

v5 patch includes:

. fix recursive locking of file_rwsem from posix_lock_file. 

. retest with LOCKDEP enabled.

v6 patch includes:

. merge witn 5.15-rc7

. fix a bug in nfs4_check_deny_bmap that did not check for matched
  nfs4_file before checking for access/deny conflict. This bug causes
  pynfs OPEN18 to fail since the server taking too long to release
  lots of un-conflict clients' state.

. enhance share reservation conflict handler to handle case where
  a large number of conflict courtesy clients need to be expired.
  The 1st 100 clients are expired synchronously and the rest are
  expired in the background by the laundromat and NFS4ERR_DELAY
  is returned to the NFS client. This is needed to prevent the
  NFS client from timing out waiting got the reply.

v7 patch includes:

. Fix race condition in posix_test_lock and posix_lock_inode after
  dropping spinlock.

. Enhance nfsd4_fl_expire_lock to work with with new lm_expire_lock
  callback

. Always resolve share reservation conflicts asynchrously.

. Fix bug in nfs4_laundromat where spinlock is not used when
  scanning cl_ownerstr_hashtbl.

. Fix bug in nfs4_laundromat where idr_get_next was called
  with incorrect 'id'. 

. Merge nfs4_destroy_courtesy_client into nfsd4_fl_expire_lock.

v8 patch includes:

. Fix warning in nfsd4_fl_expire_lock reported by test robot.

v9 patch includes:

. Simplify lm_expire_lock API by (1) remove the 'testonly' flag
  and (2) specifying return value as true/false to indicate
  whether conflict was succesfully resolved.

. Rework nfsd4_fl_expire_lock to mark client with
  NFSD4_DESTROY_COURTESY_CLIENT then tell the laundromat to expire
  the client in the background.

. Add a spinlock in nfs4_client to synchronize access to the
  NFSD4_COURTESY_CLIENT and NFSD4_DESTROY_COURTESY_CLIENT flag to
  handle race conditions when resolving lock and share reservation
  conflict.

. Courtesy client that was marked as NFSD4_DESTROY_COURTESY_CLIENT
  are now consisdered 'dead', waiting for the laundromat to expire
  it. This client is no longer allowed to use its states if it
  reconnects before the laundromat finishes expiring the client.

  For v4.1 client, the detection is done in the processing of the
  SEQUENCE op and returns NFS4ERR_BAD_SESSION to force the client
  to re-establish new clientid and session.
  For v4.0 client, the detection is done in the processing of the
  RENEW and state-related ops and return NFS4ERR_EXPIRE to force
  the client to re-establish new clientid.

v10 patch includes:

  Resolve deadlock in v9 by avoiding getting cl_client and
  cl_cs_lock together. The laundromat needs to determine whether
  the expired client has any state and also has no blockers on
  its locks. Both of these conditions are allowed to change after
  the laundromat transits an expired client to courtesy client.
  When this happens, the laundromat will detect it on the next
  run and and expire the courtesy client.

  Remove client persistent record before marking it as COURTESY_CLIENT
  and add client persistent record before clearing the COURTESY_CLIENT
  flag to allow the courtesy client to transist to normal client to
  continue to use its state.

  Lock/delegation/share reversation conflict with courtesy client is
  resolved by marking the courtesy client as DESTROY_COURTESY_CLIENT,
  effectively disable it, then allow the current request to proceed
  immediately.
  
  Courtesy client marked as DESTROY_COURTESY_CLIENT is not allowed
  to reconnect to reuse itsstate. It is expired by the laundromat
  asynchronously in the background.

  Move processing of expired clients from nfs4_laudromat to a
  separate function, nfs4_get_client_reaplist, that creates the
  reaplist and also to process courtesy clients.

  Update Documentation/filesystems/locking.rst to include new
  lm_lock_conflict call.

  Modify leases_conflict to call lm_breaker_owns_lease only if
  there is real conflict.  This is to allow the lock manager to
  resolve the delegation conflict if possible.

v11 patch includes:

  Add comment for lm_lock_conflict callback.

  Replace static const courtesy_client_expiry with macro.

  Remove courtesy_clnt argument from find_in_sessionid_hashtbl.
  Callers use nfs4_client->cl_cs_client boolean to determined if
  it's the courtesy client and take appropriate actions.

  Rename NFSD4_COURTESY_CLIENT and NFSD4_DESTROY_COURTESY_CLIENT
  with NFSD4_CLIENT_COURTESY and NFSD4_CLIENT_DESTROY_COURTESY.

v12 patch includes:

  Remove unnecessary comment in nfs4_get_client_reaplist.

  Replace nfs4_client->cl_cs_client boolean with
  NFSD4_CLIENT_COURTESY_CLNT flag.

  Remove courtesy_clnt argument from find_client_in_id_table and
  find_clp_in_name_tree. Callers use NFSD4_CLIENT_COURTESY_CLNT to
  determined if it's the courtesy client and take appropriate actions.

v13 patch includes:

  Merge with 5.17-rc3.

  Cleanup Documentation/filesystems/locking.rst: replace i_lock
  with flc_lock, update API's that use flc_lock.

  Rename lm_lock_conflict to lm_lock_expired().

  Remove comment of lm_lock_expired API in lock_manager_operations.
  Same information is in patch description.

  Update commit messages of 4/4.

  Add some comment for NFSD4_CLIENT_COURTESY_CLNT.

  Add nfsd4_discard_courtesy_clnt() to eliminate duplicate code of
  discarding courtesy client; setting NFSD4_DESTROY_COURTESY_CLIENT.

v14 patch includes:

. merge with Chuck's public for-next branch.

. remove courtesy_client_expiry, use client's last renew time.

. simplify comment of nfs4_check_access_deny_bmap.

. add comment about race condition in nfs4_get_client_reaplist.

. add list_del when walking cslist in nfs4_get_client_reaplist.

. remove duplicate INIT_LIST_HEAD(&reaplist) from nfs4_laundromat

. Modify find_confirmed_client and find_confirmed_client_by_name
  to detect courtesy client and destroy it.

. refactor lookup_clientid to use find_client_in_id_table
  directly instead of find_confirmed_client.

. refactor nfsd4_setclientid to call find_clp_in_name_tree
  directly instead of find_confirmed_client_by_name.

. remove comment of NFSD4_CLIENT_COURTESY.

. replace NFSD4_CLIENT_DESTROY_COURTESY with NFSD4_CLIENT_EXPIRED.

. replace NFSD4_CLIENT_COURTESY_CLNT with NFSD4_CLIENT_RECONNECTED.

v14 patch includes:

. add helper locks_has_blockers_locked in fs.h to check for
  lock blockers

. rename nfs4_conflict_clients to nfs4_resolve_deny_conflicts_locked

. update nfs4_upgrade_open() to handle courtesy clients.

. add helper nfs4_check_and_expire_courtesy_client and
  nfs4_is_courtesy_client_expired to deduplicate some code.

. update nfs4_anylock_blocker:
   . replace list_for_each_entry_safe with list_for_each_entry
   . break nfs4_anylock_blocker into 2 smaller functions.

. update nfs4_get_client_reaplist:
   . remove unnecessary commets
   . acquire cl_cs_lock before setting NFSD4_CLIENT_COURTESY flag

. update client_info_show to show 'time since last renew: 00:00:38'
  instead of 'seconds from last renew: 38'.

v16 patch includes:

. update client_info_show to display 'status' as
  'confirmed/unconfirmed/courtesy'

. replace helper locks_has_blockers_locked in fs.h in v15 with new
  locks_owner_has_blockers call in fs/locks.c

. update nfs4_lockowner_has_blockers to use locks_owner_has_blockers

. move nfs4_check_and_expire_courtesy_client from 5/11 to 4/11

. remove unnecessary check for NULL clp in find_in_sessionid_hashtb

. fix typo in commit messages

[PATCH RFC v16 01/11] fs/lock: add helper locks_owner_has_blockers to check for blockers

[Dai Ngo]

Add helper locks_owner_has_blockers to check if there is any blockers
for a given lockowner.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/locks.c         | 28 ++++++++++++++++++++++++++++
 include/linux/fs.h |  7 +++++++
 2 files changed, 35 insertions(+)

diff --git a/fs/locks.c b/fs/locks.c
index 050acf8b5110..53864eb99dc5 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -300,6 +300,34 @@ void locks_release_private(struct file_lock *fl)
 }
 EXPORT_SYMBOL_GPL(locks_release_private);
 
+/**
+ * locks_owner_has_blockers - Check for blocking lock requests
+ * @flctx: file lock context
+ * @owner: lock owner
+ *
+ * Return values:
+ *   %true: @owner has at least one blocker
+ *   %false: @owner has no blockers
+ */
+bool locks_owner_has_blockers(struct file_lock_context *flctx,
+		fl_owner_t owner)
+{
+	struct file_lock *fl;
+
+	spin_lock(&flctx->flc_lock);
+	list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
+		if (fl->fl_owner != owner)
+			continue;
+		if (!list_empty(&fl->fl_blocked_requests)) {
+			spin_unlock(&flctx->flc_lock);
+			return true;
+		}
+	}
+	spin_unlock(&flctx->flc_lock);
+	return false;
+}
+EXPORT_SYMBOL_GPL(locks_owner_has_blockers);
+
 /* Free a lock which is not in use. */
 void locks_free_lock(struct file_lock *fl)
 {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 831b20430d6e..da8ae38f471c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1200,6 +1200,8 @@ extern void lease_unregister_notifier(struct notifier_block *);
 struct files_struct;
 extern void show_fd_locks(struct seq_file *f,
 			 struct file *filp, struct files_struct *files);
+extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
+			fl_owner_t owner);
 #else /* !CONFIG_FILE_LOCKING */
 static inline int fcntl_getlk(struct file *file, unsigned int cmd,
 			      struct flock __user *user)
@@ -1335,6 +1337,11 @@ static inline int lease_modify(struct file_lock *fl, int arg,
 struct files_struct;
 static inline void show_fd_locks(struct seq_file *f,
 			struct file *filp, struct files_struct *files) {}
+extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
+			fl_owner_t owner)
+{
+	return false;
+}
 #endif /* !CONFIG_FILE_LOCKING */
 
 static inline struct inode *file_inode(const struct file *f)
-- 
2.9.5

Re: [PATCH RFC v16 01/11] fs/lock: add helper locks_owner_has_blockers to check for blockers

[Chuck Lever III]

> On Mar 11, 2022, at 9:13 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
> 
> Add helper locks_owner_has_blockers to check if there is any blockers
> for a given lockowner.
> 
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
> fs/locks.c         | 28 ++++++++++++++++++++++++++++
> include/linux/fs.h |  7 +++++++
> 2 files changed, 35 insertions(+)
> 
> diff --git a/fs/locks.c b/fs/locks.c
> index 050acf8b5110..53864eb99dc5 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -300,6 +300,34 @@ void locks_release_private(struct file_lock *fl)
> }
> EXPORT_SYMBOL_GPL(locks_release_private);
> 
> +/**
> + * locks_owner_has_blockers - Check for blocking lock requests
> + * @flctx: file lock context
> + * @owner: lock owner
> + *
> + * Return values:
> + *   %true: @owner has at least one blocker
> + *   %false: @owner has no blockers
> + */
> +bool locks_owner_has_blockers(struct file_lock_context *flctx,
> +		fl_owner_t owner)
> +{
> +	struct file_lock *fl;
> +
> +	spin_lock(&flctx->flc_lock);
> +	list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
> +		if (fl->fl_owner != owner)
> +			continue;
> +		if (!list_empty(&fl->fl_blocked_requests)) {
> +			spin_unlock(&flctx->flc_lock);
> +			return true;
> +		}
> +	}
> +	spin_unlock(&flctx->flc_lock);
> +	return false;
> +}
> +EXPORT_SYMBOL_GPL(locks_owner_has_blockers);
> +
> /* Free a lock which is not in use. */
> void locks_free_lock(struct file_lock *fl)
> {
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 831b20430d6e..da8ae38f471c 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1200,6 +1200,8 @@ extern void lease_unregister_notifier(struct notifier_block *);
> struct files_struct;
> extern void show_fd_locks(struct seq_file *f,
> 			 struct file *filp, struct files_struct *files);
> +extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
> +			fl_owner_t owner);
> #else /* !CONFIG_FILE_LOCKING */
> static inline int fcntl_getlk(struct file *file, unsigned int cmd,
> 			      struct flock __user *user)
> @@ -1335,6 +1337,11 @@ static inline int lease_modify(struct file_lock *fl, int arg,
> struct files_struct;
> static inline void show_fd_locks(struct seq_file *f,
> 			struct file *filp, struct files_struct *files) {}
> +extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
> +			fl_owner_t owner)

Here's the problem, Dai.

This empty function needs to be declared "static inline" not "extern".


> +{
> +	return false;
> +}
> #endif /* !CONFIG_FILE_LOCKING */
> 
> static inline struct inode *file_inode(const struct file *f)
> -- 
> 2.9.5
> 

--
Chuck Lever

Re: [PATCH RFC v16 01/11] fs/lock: add helper locks_owner_has_blockers to check for blockers

[dai.ngo]

Hi Chuck,

On 3/16/22 7:27 AM, Chuck Lever III wrote:
>
>> On Mar 11, 2022, at 9:13 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
>>
>> Add helper locks_owner_has_blockers to check if there is any blockers
>> for a given lockowner.
>>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>> fs/locks.c         | 28 ++++++++++++++++++++++++++++
>> include/linux/fs.h |  7 +++++++
>> 2 files changed, 35 insertions(+)
>>
>> diff --git a/fs/locks.c b/fs/locks.c
>> index 050acf8b5110..53864eb99dc5 100644
>> --- a/fs/locks.c
>> +++ b/fs/locks.c
>> @@ -300,6 +300,34 @@ void locks_release_private(struct file_lock *fl)
>> }
>> EXPORT_SYMBOL_GPL(locks_release_private);
>>
>> +/**
>> + * locks_owner_has_blockers - Check for blocking lock requests
>> + * @flctx: file lock context
>> + * @owner: lock owner
>> + *
>> + * Return values:
>> + *   %true: @owner has at least one blocker
>> + *   %false: @owner has no blockers
>> + */
>> +bool locks_owner_has_blockers(struct file_lock_context *flctx,
>> +		fl_owner_t owner)
>> +{
>> +	struct file_lock *fl;
>> +
>> +	spin_lock(&flctx->flc_lock);
>> +	list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
>> +		if (fl->fl_owner != owner)
>> +			continue;
>> +		if (!list_empty(&fl->fl_blocked_requests)) {
>> +			spin_unlock(&flctx->flc_lock);
>> +			return true;
>> +		}
>> +	}
>> +	spin_unlock(&flctx->flc_lock);
>> +	return false;
>> +}
>> +EXPORT_SYMBOL_GPL(locks_owner_has_blockers);
>> +
>> /* Free a lock which is not in use. */
>> void locks_free_lock(struct file_lock *fl)
>> {
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index 831b20430d6e..da8ae38f471c 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -1200,6 +1200,8 @@ extern void lease_unregister_notifier(struct notifier_block *);
>> struct files_struct;
>> extern void show_fd_locks(struct seq_file *f,
>> 			 struct file *filp, struct files_struct *files);
>> +extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
>> +			fl_owner_t owner);
>> #else /* !CONFIG_FILE_LOCKING */
>> static inline int fcntl_getlk(struct file *file, unsigned int cmd,
>> 			      struct flock __user *user)
>> @@ -1335,6 +1337,11 @@ static inline int lease_modify(struct file_lock *fl, int arg,
>> struct files_struct;
>> static inline void show_fd_locks(struct seq_file *f,
>> 			struct file *filp, struct files_struct *files) {}
>> +extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
>> +			fl_owner_t owner)
> Here's the problem, Dai.
>
> This empty function needs to be declared "static inline" not "extern".

Yes, I also found it last night with the 2nd notice from
kernel test robot. Fix in v17.

-Dai

>
>
>> +{
>> +	return false;
>> +}
>> #endif /* !CONFIG_FILE_LOCKING */
>>
>> static inline struct inode *file_inode(const struct file *f)
>> -- 
>> 2.9.5
>>
> --
> Chuck Lever
>
>
>

[PATCH RFC v16 02/11] NFSD: Add client flags, macro and spinlock to support courteous server

[Dai Ngo]

Add flags to track a client's lease state after the client fails to
renew its lease. Add macro for courtesy client expire time. Add spinlock
to synchronize access to these flags. Modify alloc_client to initialize
these fields.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 2 ++
 fs/nfsd/nfsd.h      | 1 +
 fs/nfsd/state.h     | 6 ++++++
 3 files changed, 9 insertions(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 234e852fcdfa..a65d59510681 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2009,12 +2009,14 @@ static struct nfs4_client *alloc_client(struct xdr_netobj name)
 	INIT_LIST_HEAD(&clp->cl_delegations);
 	INIT_LIST_HEAD(&clp->cl_lru);
 	INIT_LIST_HEAD(&clp->cl_revoked);
+	INIT_LIST_HEAD(&clp->cl_cs_list);
 #ifdef CONFIG_NFSD_PNFS
 	INIT_LIST_HEAD(&clp->cl_lo_states);
 #endif
 	INIT_LIST_HEAD(&clp->async_copies);
 	spin_lock_init(&clp->async_lock);
 	spin_lock_init(&clp->cl_lock);
+	spin_lock_init(&clp->cl_cs_lock);
 	rpc_init_wait_queue(&clp->cl_cb_waitq, "Backchannel slot table");
 	return clp;
 err_no_hashtbl:
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 4fc1fd639527..23996c6ca75e 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -336,6 +336,7 @@ void		nfsd_lockd_shutdown(void);
 #define COMPOUND_ERR_SLACK_SPACE	16     /* OP_SETATTR */
 
 #define NFSD_LAUNDROMAT_MINTIMEOUT      1   /* seconds */
+#define	NFSD_COURTESY_CLIENT_TIMEOUT	(24 * 60 * 60)	/* seconds */
 
 /*
  * The following attributes are currently not supported by the NFSv4 server:
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 95457cfd37fc..8cbd3b69a584 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -343,6 +343,9 @@ struct nfs4_client {
 #define NFSD4_CLIENT_RECLAIM_COMPLETE	(3)	/* reclaim_complete done */
 #define NFSD4_CLIENT_CONFIRMED		(4)	/* client is confirmed */
 #define NFSD4_CLIENT_UPCALL_LOCK	(5)	/* upcall serialization */
+#define	NFSD4_CLIENT_COURTESY		(6)
+#define	NFSD4_CLIENT_EXPIRED		(7)
+#define	NFSD4_CLIENT_RECONNECTED	(8)
 #define NFSD4_CLIENT_CB_FLAG_MASK	(1 << NFSD4_CLIENT_CB_UPDATE | \
 					 1 << NFSD4_CLIENT_CB_KILL)
 	unsigned long		cl_flags;
@@ -385,6 +388,9 @@ struct nfs4_client {
 	struct list_head	async_copies;	/* list of async copies */
 	spinlock_t		async_lock;	/* lock for async copies */
 	atomic_t		cl_cb_inflight;	/* Outstanding callbacks */
+
+	spinlock_t		cl_cs_lock;
+	struct list_head	cl_cs_list;
 };
 
 /* struct nfs4_client_reset
-- 
2.9.5

[PATCH RFC v16 03/11] NFSD: Add lm_lock_expired call out

[Dai Ngo]

Add callout function nfsd4_lm_lock_expired for lm_lock_expired.
If lock request has conflict with courtesy client then expire the
courtesy client and return no conflict to caller.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index a65d59510681..583ac807e98d 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -6578,10 +6578,47 @@ nfsd4_lm_notify(struct file_lock *fl)
 	}
 }
 
+/**
+ * nfsd4_lm_lock_expired - check if lock conflict can be resolved.
+ *
+ * @fl: pointer to file_lock with a potential conflict
+ * Return values:
+ *   %false: real conflict, lock conflict can not be resolved.
+ *   %true: no conflict, lock conflict was resolved.
+ *
+ * Note that this function is called while the flc_lock is held.
+ */
+static bool
+nfsd4_lm_lock_expired(struct file_lock *fl)
+{
+	struct nfs4_lockowner *lo;
+	struct nfs4_client *clp;
+	bool rc = false;
+
+	if (!fl)
+		return false;
+	lo = (struct nfs4_lockowner *)fl->fl_owner;
+	clp = lo->lo_owner.so_client;
+
+	/* need to sync with courtesy client trying to reconnect */
+	spin_lock(&clp->cl_cs_lock);
+	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
+		rc = true;
+	else {
+		if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
+			set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
+			rc =  true;
+		}
+	}
+	spin_unlock(&clp->cl_cs_lock);
+	return rc;
+}
+
 static const struct lock_manager_operations nfsd_posix_mng_ops  = {
 	.lm_notify = nfsd4_lm_notify,
 	.lm_get_owner = nfsd4_lm_get_owner,
 	.lm_put_owner = nfsd4_lm_put_owner,
+	.lm_lock_expired = nfsd4_lm_lock_expired,
 };
 
 static inline void
-- 
2.9.5

Re: [PATCH RFC v16 03/11] NFSD: Add lm_lock_expired call out

[J. Bruce Fields]

On Fri, Mar 11, 2022 at 06:13:27PM -0800, Dai Ngo wrote:
> Add callout function nfsd4_lm_lock_expired for lm_lock_expired.
> If lock request has conflict with courtesy client then expire the
> courtesy client and return no conflict to caller.
> 
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
> 
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index a65d59510681..583ac807e98d 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -6578,10 +6578,47 @@ nfsd4_lm_notify(struct file_lock *fl)
>  	}
>  }
>  
> +/**
> + * nfsd4_lm_lock_expired - check if lock conflict can be resolved.
> + *
> + * @fl: pointer to file_lock with a potential conflict
> + * Return values:
> + *   %false: real conflict, lock conflict can not be resolved.
> + *   %true: no conflict, lock conflict was resolved.
> + *
> + * Note that this function is called while the flc_lock is held.
> + */
> +static bool
> +nfsd4_lm_lock_expired(struct file_lock *fl)
> +{
> +	struct nfs4_lockowner *lo;
> +	struct nfs4_client *clp;
> +	bool rc = false;
> +
> +	if (!fl)
> +		return false;
> +	lo = (struct nfs4_lockowner *)fl->fl_owner;
> +	clp = lo->lo_owner.so_client;
> +
> +	/* need to sync with courtesy client trying to reconnect */
> +	spin_lock(&clp->cl_cs_lock);
> +	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
> +		rc = true;
> +	else {
> +		if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
> +			set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
> +			rc =  true;
> +		}
> +	}

I'd prefer:

	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
		rc = true;

Same result, but more compact and straightforward, I think.

--b.

> +	spin_unlock(&clp->cl_cs_lock);
> +	return rc;
> +}
> +
>  static const struct lock_manager_operations nfsd_posix_mng_ops  = {
>  	.lm_notify = nfsd4_lm_notify,
>  	.lm_get_owner = nfsd4_lm_get_owner,
>  	.lm_put_owner = nfsd4_lm_put_owner,
> +	.lm_lock_expired = nfsd4_lm_lock_expired,
>  };
>  
>  static inline void
> -- 
> 2.9.5

Re: [PATCH RFC v16 03/11] NFSD: Add lm_lock_expired call out

[dai.ngo]

On 3/15/22 8:02 AM, J. Bruce Fields wrote:
> On Fri, Mar 11, 2022 at 06:13:27PM -0800, Dai Ngo wrote:
>> Add callout function nfsd4_lm_lock_expired for lm_lock_expired.
>> If lock request has conflict with courtesy client then expire the
>> courtesy client and return no conflict to caller.
>>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>>   fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
>>   1 file changed, 37 insertions(+)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index a65d59510681..583ac807e98d 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -6578,10 +6578,47 @@ nfsd4_lm_notify(struct file_lock *fl)
>>   	}
>>   }
>>   
>> +/**
>> + * nfsd4_lm_lock_expired - check if lock conflict can be resolved.
>> + *
>> + * @fl: pointer to file_lock with a potential conflict
>> + * Return values:
>> + *   %false: real conflict, lock conflict can not be resolved.
>> + *   %true: no conflict, lock conflict was resolved.
>> + *
>> + * Note that this function is called while the flc_lock is held.
>> + */
>> +static bool
>> +nfsd4_lm_lock_expired(struct file_lock *fl)
>> +{
>> +	struct nfs4_lockowner *lo;
>> +	struct nfs4_client *clp;
>> +	bool rc = false;
>> +
>> +	if (!fl)
>> +		return false;
>> +	lo = (struct nfs4_lockowner *)fl->fl_owner;
>> +	clp = lo->lo_owner.so_client;
>> +
>> +	/* need to sync with courtesy client trying to reconnect */
>> +	spin_lock(&clp->cl_cs_lock);
>> +	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
>> +		rc = true;
>> +	else {
>> +		if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
>> +			set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
>> +			rc =  true;
>> +		}
>> +	}
> I'd prefer:
>
> 	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
> 		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);

we also need to set rc to true here.

> 	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
> 		rc = true;

With v16 we need to check for NFSD4_CLIENT_EXPIRED first then
NFSD4_CLIENT_COURTESY because both flags can be set. In the
next patch version, we will clear NFSD4_CLIENT_COURTESY when
setting NFSD4_CLIENT_EXPIRED so the order of check does not
matter.

>
> Same result, but more compact and straightforward, I think.

Chuck wants to replace the bits used for courtesy client in
cl_flags with a  separate u8 field so it does not have to use
bit operation to set/test.

-Dai

>
> --b.
>
>> +	spin_unlock(&clp->cl_cs_lock);
>> +	return rc;
>> +}
>> +
>>   static const struct lock_manager_operations nfsd_posix_mng_ops  = {
>>   	.lm_notify = nfsd4_lm_notify,
>>   	.lm_get_owner = nfsd4_lm_get_owner,
>>   	.lm_put_owner = nfsd4_lm_put_owner,
>> +	.lm_lock_expired = nfsd4_lm_lock_expired,
>>   };
>>   
>>   static inline void
>> -- 
>> 2.9.5

Re: [PATCH RFC v16 03/11] NFSD: Add lm_lock_expired call out

[J. Bruce Fields]

On Tue, Mar 15, 2022 at 09:26:46AM -0700, dai.ngo@oracle.com wrote:
> 
> On 3/15/22 8:02 AM, J. Bruce Fields wrote:
> >On Fri, Mar 11, 2022 at 06:13:27PM -0800, Dai Ngo wrote:
> >>Add callout function nfsd4_lm_lock_expired for lm_lock_expired.
> >>If lock request has conflict with courtesy client then expire the
> >>courtesy client and return no conflict to caller.
> >>
> >>Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> >>---
> >>  fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
> >>  1 file changed, 37 insertions(+)
> >>
> >>diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> >>index a65d59510681..583ac807e98d 100644
> >>--- a/fs/nfsd/nfs4state.c
> >>+++ b/fs/nfsd/nfs4state.c
> >>@@ -6578,10 +6578,47 @@ nfsd4_lm_notify(struct file_lock *fl)
> >>  	}
> >>  }
> >>+/**
> >>+ * nfsd4_lm_lock_expired - check if lock conflict can be resolved.
> >>+ *
> >>+ * @fl: pointer to file_lock with a potential conflict
> >>+ * Return values:
> >>+ *   %false: real conflict, lock conflict can not be resolved.
> >>+ *   %true: no conflict, lock conflict was resolved.
> >>+ *
> >>+ * Note that this function is called while the flc_lock is held.
> >>+ */
> >>+static bool
> >>+nfsd4_lm_lock_expired(struct file_lock *fl)
> >>+{
> >>+	struct nfs4_lockowner *lo;
> >>+	struct nfs4_client *clp;
> >>+	bool rc = false;
> >>+
> >>+	if (!fl)
> >>+		return false;
> >>+	lo = (struct nfs4_lockowner *)fl->fl_owner;
> >>+	clp = lo->lo_owner.so_client;
> >>+
> >>+	/* need to sync with courtesy client trying to reconnect */
> >>+	spin_lock(&clp->cl_cs_lock);
> >>+	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
> >>+		rc = true;
> >>+	else {
> >>+		if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
> >>+			set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
> >>+			rc =  true;
> >>+		}
> >>+	}
> >I'd prefer:
> >
> >	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
> >		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
> 
> we also need to set rc to true here.

No, the next line does it because we set the EXPIRED bit.

--b.

> 
> >	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
> >		rc = true;
> 
> With v16 we need to check for NFSD4_CLIENT_EXPIRED first then
> NFSD4_CLIENT_COURTESY because both flags can be set. In the
> next patch version, we will clear NFSD4_CLIENT_COURTESY when
> setting NFSD4_CLIENT_EXPIRED so the order of check does not
> matter.
> 
> >
> >Same result, but more compact and straightforward, I think.
> 
> Chuck wants to replace the bits used for courtesy client in
> cl_flags with a  separate u8 field so it does not have to use
> bit operation to set/test.
> 
> -Dai
> 
> >
> >--b.
> >
> >>+	spin_unlock(&clp->cl_cs_lock);
> >>+	return rc;
> >>+}
> >>+
> >>  static const struct lock_manager_operations nfsd_posix_mng_ops  = {
> >>  	.lm_notify = nfsd4_lm_notify,
> >>  	.lm_get_owner = nfsd4_lm_get_owner,
> >>  	.lm_put_owner = nfsd4_lm_put_owner,
> >>+	.lm_lock_expired = nfsd4_lm_lock_expired,
> >>  };
> >>  static inline void
> >>-- 
> >>2.9.5

Re: [PATCH RFC v16 03/11] NFSD: Add lm_lock_expired call out

[dai.ngo]

On 3/15/22 10:20 AM, J. Bruce Fields wrote:
> On Tue, Mar 15, 2022 at 09:26:46AM -0700, dai.ngo@oracle.com wrote:
>> On 3/15/22 8:02 AM, J. Bruce Fields wrote:
>>> On Fri, Mar 11, 2022 at 06:13:27PM -0800, Dai Ngo wrote:
>>>> Add callout function nfsd4_lm_lock_expired for lm_lock_expired.
>>>> If lock request has conflict with courtesy client then expire the
>>>> courtesy client and return no conflict to caller.
>>>>
>>>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>>>> ---
>>>>   fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
>>>>   1 file changed, 37 insertions(+)
>>>>
>>>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>>>> index a65d59510681..583ac807e98d 100644
>>>> --- a/fs/nfsd/nfs4state.c
>>>> +++ b/fs/nfsd/nfs4state.c
>>>> @@ -6578,10 +6578,47 @@ nfsd4_lm_notify(struct file_lock *fl)
>>>>   	}
>>>>   }
>>>> +/**
>>>> + * nfsd4_lm_lock_expired - check if lock conflict can be resolved.
>>>> + *
>>>> + * @fl: pointer to file_lock with a potential conflict
>>>> + * Return values:
>>>> + *   %false: real conflict, lock conflict can not be resolved.
>>>> + *   %true: no conflict, lock conflict was resolved.
>>>> + *
>>>> + * Note that this function is called while the flc_lock is held.
>>>> + */
>>>> +static bool
>>>> +nfsd4_lm_lock_expired(struct file_lock *fl)
>>>> +{
>>>> +	struct nfs4_lockowner *lo;
>>>> +	struct nfs4_client *clp;
>>>> +	bool rc = false;
>>>> +
>>>> +	if (!fl)
>>>> +		return false;
>>>> +	lo = (struct nfs4_lockowner *)fl->fl_owner;
>>>> +	clp = lo->lo_owner.so_client;
>>>> +
>>>> +	/* need to sync with courtesy client trying to reconnect */
>>>> +	spin_lock(&clp->cl_cs_lock);
>>>> +	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
>>>> +		rc = true;
>>>> +	else {
>>>> +		if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
>>>> +			set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
>>>> +			rc =  true;
>>>> +		}
>>>> +	}
>>> I'd prefer:
>>>
>>> 	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
>>> 		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
>> we also need to set rc to true here.
> No, the next line does it because we set the EXPIRED bit.

ok, as mentioned below this code will be changed to use an u8
for the courtesy client state and only either CLIENT_EXPIRED or
CLIENT_COURTESY is set but not both so it might be slightly
different in v17.

-Dai

>
> --b.
>
>>> 	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
>>> 		rc = true;
>> With v16 we need to check for NFSD4_CLIENT_EXPIRED first then
>> NFSD4_CLIENT_COURTESY because both flags can be set. In the
>> next patch version, we will clear NFSD4_CLIENT_COURTESY when
>> setting NFSD4_CLIENT_EXPIRED so the order of check does not
>> matter.
>>
>>> Same result, but more compact and straightforward, I think.
>> Chuck wants to replace the bits used for courtesy client in
>> cl_flags with a  separate u8 field so it does not have to use
>> bit operation to set/test.
>>
>> -Dai
>>
>>> --b.
>>>
>>>> +	spin_unlock(&clp->cl_cs_lock);
>>>> +	return rc;
>>>> +}
>>>> +
>>>>   static const struct lock_manager_operations nfsd_posix_mng_ops  = {
>>>>   	.lm_notify = nfsd4_lm_notify,
>>>>   	.lm_get_owner = nfsd4_lm_get_owner,
>>>>   	.lm_put_owner = nfsd4_lm_put_owner,
>>>> +	.lm_lock_expired = nfsd4_lm_lock_expired,
>>>>   };
>>>>   static inline void
>>>> -- 
>>>> 2.9.5

Re: [PATCH RFC v16 03/11] NFSD: Add lm_lock_expired call out

[Chuck Lever III]

> On Mar 15, 2022, at 12:26 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
> 
> 
> On 3/15/22 8:02 AM, J. Bruce Fields wrote:
>> On Fri, Mar 11, 2022 at 06:13:27PM -0800, Dai Ngo wrote:
>>> Add callout function nfsd4_lm_lock_expired for lm_lock_expired.
>>> If lock request has conflict with courtesy client then expire the
>>> courtesy client and return no conflict to caller.
>>> 
>>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>>> ---
>>>  fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
>>>  1 file changed, 37 insertions(+)
>>> 
>>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>>> index a65d59510681..583ac807e98d 100644
>>> --- a/fs/nfsd/nfs4state.c
>>> +++ b/fs/nfsd/nfs4state.c
>>> @@ -6578,10 +6578,47 @@ nfsd4_lm_notify(struct file_lock *fl)
>>>  	}
>>>  }
>>>  +/**
>>> + * nfsd4_lm_lock_expired - check if lock conflict can be resolved.
>>> + *
>>> + * @fl: pointer to file_lock with a potential conflict
>>> + * Return values:
>>> + *   %false: real conflict, lock conflict can not be resolved.
>>> + *   %true: no conflict, lock conflict was resolved.
>>> + *
>>> + * Note that this function is called while the flc_lock is held.
>>> + */
>>> +static bool
>>> +nfsd4_lm_lock_expired(struct file_lock *fl)
>>> +{
>>> +	struct nfs4_lockowner *lo;
>>> +	struct nfs4_client *clp;
>>> +	bool rc = false;
>>> +
>>> +	if (!fl)
>>> +		return false;
>>> +	lo = (struct nfs4_lockowner *)fl->fl_owner;
>>> +	clp = lo->lo_owner.so_client;
>>> +
>>> +	/* need to sync with courtesy client trying to reconnect */
>>> +	spin_lock(&clp->cl_cs_lock);
>>> +	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
>>> +		rc = true;
>>> +	else {
>>> +		if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
>>> +			set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
>>> +			rc =  true;
>>> +		}
>>> +	}
>> I'd prefer:
>> 
>> 	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
>> 		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
> 
> we also need to set rc to true here.
> 
>> 	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
>> 		rc = true;
> 
> With v16 we need to check for NFSD4_CLIENT_EXPIRED first then
> NFSD4_CLIENT_COURTESY because both flags can be set. In the
> next patch version, we will clear NFSD4_CLIENT_COURTESY when
> setting NFSD4_CLIENT_EXPIRED so the order of check does not
> matter.
> 
>> 
>> Same result, but more compact and straightforward, I think.
> 
> Chuck wants to replace the bits used for courtesy client in
> cl_flags with a  separate u8 field so it does not have to use
> bit operation to set/test.

Code audit suggested there are really only four unique
combinations of the bit flags that are used.

Plus, taking a spin_lock and using bitops seems like overkill.

The rules for transitioning between the courtesy states are
straightforward, but need to be done in a critical section.
So I suggested storing the courtesy state in a lock-protected
unsigned int instead of using bit flags.

If we hate it, we can go back to bit flags.


>>> +	spin_unlock(&clp->cl_cs_lock);
>>> +	return rc;
>>> +}
>>> +
>>>  static const struct lock_manager_operations nfsd_posix_mng_ops  = {
>>>  	.lm_notify = nfsd4_lm_notify,
>>>  	.lm_get_owner = nfsd4_lm_get_owner,
>>>  	.lm_put_owner = nfsd4_lm_put_owner,
>>> +	.lm_lock_expired = nfsd4_lm_lock_expired,
>>>  };
>>>    static inline void
>>> -- 
>>> 2.9.5

--
Chuck Lever

Re: [PATCH RFC v16 03/11] NFSD: Add lm_lock_expired call out

[dai.ngo]

On 3/15/22 10:39 AM, Chuck Lever III wrote:
>
>> On Mar 15, 2022, at 12:26 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
>>
>>
>> On 3/15/22 8:02 AM, J. Bruce Fields wrote:
>>> On Fri, Mar 11, 2022 at 06:13:27PM -0800, Dai Ngo wrote:
>>>> Add callout function nfsd4_lm_lock_expired for lm_lock_expired.
>>>> If lock request has conflict with courtesy client then expire the
>>>> courtesy client and return no conflict to caller.
>>>>
>>>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>>>> ---
>>>>   fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
>>>>   1 file changed, 37 insertions(+)
>>>>
>>>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>>>> index a65d59510681..583ac807e98d 100644
>>>> --- a/fs/nfsd/nfs4state.c
>>>> +++ b/fs/nfsd/nfs4state.c
>>>> @@ -6578,10 +6578,47 @@ nfsd4_lm_notify(struct file_lock *fl)
>>>>   	}
>>>>   }
>>>>   +/**
>>>> + * nfsd4_lm_lock_expired - check if lock conflict can be resolved.
>>>> + *
>>>> + * @fl: pointer to file_lock with a potential conflict
>>>> + * Return values:
>>>> + *   %false: real conflict, lock conflict can not be resolved.
>>>> + *   %true: no conflict, lock conflict was resolved.
>>>> + *
>>>> + * Note that this function is called while the flc_lock is held.
>>>> + */
>>>> +static bool
>>>> +nfsd4_lm_lock_expired(struct file_lock *fl)
>>>> +{
>>>> +	struct nfs4_lockowner *lo;
>>>> +	struct nfs4_client *clp;
>>>> +	bool rc = false;
>>>> +
>>>> +	if (!fl)
>>>> +		return false;
>>>> +	lo = (struct nfs4_lockowner *)fl->fl_owner;
>>>> +	clp = lo->lo_owner.so_client;
>>>> +
>>>> +	/* need to sync with courtesy client trying to reconnect */
>>>> +	spin_lock(&clp->cl_cs_lock);
>>>> +	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
>>>> +		rc = true;
>>>> +	else {
>>>> +		if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
>>>> +			set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
>>>> +			rc =  true;
>>>> +		}
>>>> +	}
>>> I'd prefer:
>>>
>>> 	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
>>> 		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
>> we also need to set rc to true here.
>>
>>> 	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
>>> 		rc = true;
>> With v16 we need to check for NFSD4_CLIENT_EXPIRED first then
>> NFSD4_CLIENT_COURTESY because both flags can be set. In the
>> next patch version, we will clear NFSD4_CLIENT_COURTESY when
>> setting NFSD4_CLIENT_EXPIRED so the order of check does not
>> matter.
>>
>>> Same result, but more compact and straightforward, I think.
>> Chuck wants to replace the bits used for courtesy client in
>> cl_flags with a  separate u8 field so it does not have to use
>> bit operation to set/test.
> Code audit suggested there are really only four unique
> combinations of the bit flags that are used.
>
> Plus, taking a spin_lock and using bitops seems like overkill.
>
> The rules for transitioning between the courtesy states are
> straightforward, but need to be done in a critical section.
> So I suggested storing the courtesy state in a lock-protected
> unsigned int instead of using bit flags.

I will try what Chuck suggested.

>
> If we hate it, we can go back to bit flags.

ok.

-Dai


>>>> +	spin_unlock(&clp->cl_cs_lock);
>>>> +	return rc;
>>>> +}
>>>> +
>>>>   static const struct lock_manager_operations nfsd_posix_mng_ops  = {
>>>>   	.lm_notify = nfsd4_lm_notify,
>>>>   	.lm_get_owner = nfsd4_lm_get_owner,
>>>>   	.lm_put_owner = nfsd4_lm_put_owner,
>>>> +	.lm_lock_expired = nfsd4_lm_lock_expired,
>>>>   };
>>>>     static inline void
>>>> -- 
>>>> 2.9.5
> --
> Chuck Lever
>
>
>

[PATCH RFC v16 04/11] NFSD: Update nfsd_breaker_owns_lease() to handle courtesy clients

[Dai Ngo]

Update nfsd_breaker_owns_lease() to handle delegation conflict
with courtesy clients. If conflict was caused by courtesy client
then discard the courtesy client by setting CLIENT_EXPIRED and
return conflict resolved. Client with CLIENT_EXPIRED is expired
by the laundromat.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 583ac807e98d..2beb0972de88 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4713,6 +4713,28 @@ nfsd_break_deleg_cb(struct file_lock *fl)
 	return ret;
 }
 
+static bool
+nfs4_check_and_expire_courtesy_client(struct nfs4_client *clp)
+{
+	/*
+	 * need to sync with courtesy client trying to reconnect using
+	 * the cl_cs_lock, nn->client_lock can not be used since this
+	 * function is called with the fl_lck held.
+	 */
+	spin_lock(&clp->cl_cs_lock);
+	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags)) {
+		spin_unlock(&clp->cl_cs_lock);
+		return true;
+	}
+	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
+		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
+		spin_unlock(&clp->cl_cs_lock);
+		return true;
+	}
+	spin_unlock(&clp->cl_cs_lock);
+	return false;
+}
+
 /**
  * nfsd_breaker_owns_lease - Check if lease conflict was resolved
  * @fl: Lock state to check
@@ -4727,6 +4749,10 @@ static bool nfsd_breaker_owns_lease(struct file_lock *fl)
 	struct svc_rqst *rqst;
 	struct nfs4_client *clp;
 
+	clp = dl->dl_stid.sc_client;
+	if (nfs4_check_and_expire_courtesy_client(clp))
+		return true;
+
 	if (!i_am_nfsd())
 		return false;
 	rqst = kthread_data(current);
-- 
2.9.5

Re: [PATCH RFC v16 04/11] NFSD: Update nfsd_breaker_owns_lease() to handle courtesy clients

[Chuck Lever III]

> On Mar 11, 2022, at 9:13 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
> 
> Update nfsd_breaker_owns_lease() to handle delegation conflict
> with courtesy clients. If conflict was caused by courtesy client
> then discard the courtesy client by setting CLIENT_EXPIRED and
> return conflict resolved. Client with CLIENT_EXPIRED is expired
> by the laundromat.
> 
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
> fs/nfsd/nfs4state.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
> 
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 583ac807e98d..2beb0972de88 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -4713,6 +4713,28 @@ nfsd_break_deleg_cb(struct file_lock *fl)
> 	return ret;
> }
> 
> +static bool
> +nfs4_check_and_expire_courtesy_client(struct nfs4_client *clp)
> +{
> +	/*
> +	 * need to sync with courtesy client trying to reconnect using
> +	 * the cl_cs_lock, nn->client_lock can not be used since this
> +	 * function is called with the fl_lck held.
> +	 */
> +	spin_lock(&clp->cl_cs_lock);
> +	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags)) {
> +		spin_unlock(&clp->cl_cs_lock);
> +		return true;
> +	}
> +	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
> +		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
> +		spin_unlock(&clp->cl_cs_lock);
> +		return true;
> +	}
> +	spin_unlock(&clp->cl_cs_lock);
> +	return false;
> +}
> +
> /**
>  * nfsd_breaker_owns_lease - Check if lease conflict was resolved
>  * @fl: Lock state to check
> @@ -4727,6 +4749,10 @@ static bool nfsd_breaker_owns_lease(struct file_lock *fl)
> 	struct svc_rqst *rqst;
> 	struct nfs4_client *clp;
> 
> +	clp = dl->dl_stid.sc_client;
> +	if (nfs4_check_and_expire_courtesy_client(clp))

Since you'll need to fix the kernel robot issue in 1/11, when you
repost, can you also just pass dl->dl_stid.sc_client directly to
nfs4_check_and_expire_courtesy_client() here?


> +		return true;
> +
> 	if (!i_am_nfsd())
> 		return false;
> 	rqst = kthread_data(current);
> -- 
> 2.9.5
> 

--
Chuck Lever

Re: [PATCH RFC v16 04/11] NFSD: Update nfsd_breaker_owns_lease() to handle courtesy clients

[Bruce Fields]

On Sun, Mar 13, 2022 at 04:04:21PM +0000, Chuck Lever III wrote:
> 
> 
> > On Mar 11, 2022, at 9:13 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
> > 
> > Update nfsd_breaker_owns_lease() to handle delegation conflict
> > with courtesy clients. If conflict was caused by courtesy client
> > then discard the courtesy client by setting CLIENT_EXPIRED and
> > return conflict resolved. Client with CLIENT_EXPIRED is expired
> > by the laundromat.
> > 
> > Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> > ---
> > fs/nfsd/nfs4state.c | 26 ++++++++++++++++++++++++++
> > 1 file changed, 26 insertions(+)
> > 
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index 583ac807e98d..2beb0972de88 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -4713,6 +4713,28 @@ nfsd_break_deleg_cb(struct file_lock *fl)
> > 	return ret;
> > }
> > 
> > +static bool
> > +nfs4_check_and_expire_courtesy_client(struct nfs4_client *clp)
> > +{
> > +	/*
> > +	 * need to sync with courtesy client trying to reconnect using
> > +	 * the cl_cs_lock, nn->client_lock can not be used since this
> > +	 * function is called with the fl_lck held.
> > +	 */
> > +	spin_lock(&clp->cl_cs_lock);
> > +	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags)) {
> > +		spin_unlock(&clp->cl_cs_lock);
> > +		return true;
> > +	}
> > +	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
> > +		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
> > +		spin_unlock(&clp->cl_cs_lock);
> > +		return true;
> > +	}
> > +	spin_unlock(&clp->cl_cs_lock);

Same comment as on the previous patch.  ALso, this is the second time
we've used this logic, please define a

	static bool expire_client_if_courtesy(struct nfs4_client *clp)

and call it from both places.

> > +	return false;
> > +}
> > +
> > /**
> >  * nfsd_breaker_owns_lease - Check if lease conflict was resolved
> >  * @fl: Lock state to check
> > @@ -4727,6 +4749,10 @@ static bool nfsd_breaker_owns_lease(struct file_lock *fl)
> > 	struct svc_rqst *rqst;
> > 	struct nfs4_client *clp;
> > 
> > +	clp = dl->dl_stid.sc_client;
> > +	if (nfs4_check_and_expire_courtesy_client(clp))
> 
> Since you'll need to fix the kernel robot issue in 1/11, when you
> repost, can you also just pass dl->dl_stid.sc_client directly to
> nfs4_check_and_expire_courtesy_client() here?

Agreed.

This client is quite different from the one we look up from the task a
little later, and I'd just rather not have both represented by the same
variable.

--b.

Re: [PATCH RFC v16 04/11] NFSD: Update nfsd_breaker_owns_lease() to handle courtesy clients

[dai.ngo]

On 3/15/22 8:13 AM, Bruce Fields wrote:
> On Sun, Mar 13, 2022 at 04:04:21PM +0000, Chuck Lever III wrote:
>>
>>> On Mar 11, 2022, at 9:13 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
>>>
>>> Update nfsd_breaker_owns_lease() to handle delegation conflict
>>> with courtesy clients. If conflict was caused by courtesy client
>>> then discard the courtesy client by setting CLIENT_EXPIRED and
>>> return conflict resolved. Client with CLIENT_EXPIRED is expired
>>> by the laundromat.
>>>
>>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>>> ---
>>> fs/nfsd/nfs4state.c | 26 ++++++++++++++++++++++++++
>>> 1 file changed, 26 insertions(+)
>>>
>>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>>> index 583ac807e98d..2beb0972de88 100644
>>> --- a/fs/nfsd/nfs4state.c
>>> +++ b/fs/nfsd/nfs4state.c
>>> @@ -4713,6 +4713,28 @@ nfsd_break_deleg_cb(struct file_lock *fl)
>>> 	return ret;
>>> }
>>>
>>> +static bool
>>> +nfs4_check_and_expire_courtesy_client(struct nfs4_client *clp)
>>> +{
>>> +	/*
>>> +	 * need to sync with courtesy client trying to reconnect using
>>> +	 * the cl_cs_lock, nn->client_lock can not be used since this
>>> +	 * function is called with the fl_lck held.
>>> +	 */
>>> +	spin_lock(&clp->cl_cs_lock);
>>> +	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags)) {
>>> +		spin_unlock(&clp->cl_cs_lock);
>>> +		return true;
>>> +	}
>>> +	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
>>> +		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
>>> +		spin_unlock(&clp->cl_cs_lock);
>>> +		return true;
>>> +	}
>>> +	spin_unlock(&clp->cl_cs_lock);
> Same comment as on the previous patch.  ALso, this is the second time
> we've used this logic, please define a
>
> 	static bool expire_client_if_courtesy(struct nfs4_client *clp)
>
> and call it from both places.

I will replace the similar code in nfsd4_lm_lock_expired with
a call to nfs4_check_and_expire_courtesy_client.

>
>>> +	return false;
>>> +}
>>> +
>>> /**
>>>   * nfsd_breaker_owns_lease - Check if lease conflict was resolved
>>>   * @fl: Lock state to check
>>> @@ -4727,6 +4749,10 @@ static bool nfsd_breaker_owns_lease(struct file_lock *fl)
>>> 	struct svc_rqst *rqst;
>>> 	struct nfs4_client *clp;
>>>
>>> +	clp = dl->dl_stid.sc_client;
>>> +	if (nfs4_check_and_expire_courtesy_client(clp))
>> Since you'll need to fix the kernel robot issue in 1/11, when you
>> repost, can you also just pass dl->dl_stid.sc_client directly to
>> nfs4_check_and_expire_courtesy_client() here?
> Agreed.
>
> This client is quite different from the one we look up from the task a
> little later, and I'd just rather not have both represented by the same
> variable.

fix in v17.

-Dai

>
> --b.

[PATCH RFC v16 05/11] NFSD: Update nfs4_get_vfs_file() to handle courtesy clients

[Dai Ngo]

Update nfs4_get_vfs_file and nfs4_upgrade_open to handle share
reservation conflict with courtesy client.

If share/access check fails with share denied then check if the
the conflict was caused by courtesy clients. If that's the case
then set CLIENT_EXPIRED flag to expire the courtesy clients and
allow nfs4_get_vfs_file to continue. Client with CLIENT_EXPIRED
is expired by the laundromat.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 91 insertions(+), 8 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 2beb0972de88..b16f689f34c3 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4973,9 +4973,75 @@ nfsd4_truncate(struct svc_rqst *rqstp, struct svc_fh *fh,
 	return nfsd_setattr(rqstp, fh, &iattr, 0, (time64_t)0);
 }
 
+static bool
+nfs4_check_access_deny_bmap(struct nfs4_ol_stateid *stp, u32 access,
+			bool share_access)
+{
+	if (share_access) {
+		if (!stp->st_deny_bmap)
+			return false;
+
+		if ((stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_BOTH)) ||
+			(access & NFS4_SHARE_ACCESS_READ &&
+				stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_READ)) ||
+			(access & NFS4_SHARE_ACCESS_WRITE &&
+				stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_WRITE))) {
+			return true;
+		}
+		return false;
+	}
+	if ((access & NFS4_SHARE_DENY_BOTH) ||
+		(access & NFS4_SHARE_DENY_READ &&
+			stp->st_access_bmap & (1 << NFS4_SHARE_ACCESS_READ)) ||
+		(access & NFS4_SHARE_DENY_WRITE &&
+			stp->st_access_bmap & (1 << NFS4_SHARE_ACCESS_WRITE))) {
+		return true;
+	}
+	return false;
+}
+
+/*
+ * Check whether courtesy clients have conflicting access
+ *
+ * access:  is op_share_access if share_access is true.
+ *	    Check if access mode, op_share_access, would conflict with
+ *	    the current deny mode of the file 'fp'.
+ * access:  is op_share_deny if share_access is false.
+ *	    Check if the deny mode, op_share_deny, would conflict with
+ *	    current access of the file 'fp'.
+ * stp:     skip checking this entry.
+ * new_stp: normal open, not open upgrade.
+ *
+ * Function returns:
+ *	true   - access/deny mode conflict with normal client.
+ *	false  - no conflict or conflict with courtesy client(s) is resolved.
+ */
+static bool
+nfs4_resolve_deny_conflicts_locked(struct nfs4_file *fp, bool new_stp,
+		struct nfs4_ol_stateid *stp, u32 access, bool share_access)
+{
+	struct nfs4_ol_stateid *st;
+	struct nfs4_client *clp;
+	bool conflict = false;
+
+	lockdep_assert_held(&fp->fi_lock);
+	list_for_each_entry(st, &fp->fi_stateids, st_perfile) {
+		if (st->st_openstp || (st == stp && new_stp) ||
+			(!nfs4_check_access_deny_bmap(st,
+					access, share_access)))
+			continue;
+		clp = st->st_stid.sc_client;
+		if (nfs4_check_and_expire_courtesy_client(clp))
+			continue;
+		conflict = true;
+		break;
+	}
+	return conflict;
+}
+
 static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
 		struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp,
-		struct nfsd4_open *open)
+		struct nfsd4_open *open, bool new_stp)
 {
 	struct nfsd_file *nf = NULL;
 	__be32 status;
@@ -4991,15 +5057,29 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
 	 */
 	status = nfs4_file_check_deny(fp, open->op_share_deny);
 	if (status != nfs_ok) {
-		spin_unlock(&fp->fi_lock);
-		goto out;
+		if (status != nfserr_share_denied) {
+			spin_unlock(&fp->fi_lock);
+			goto out;
+		}
+		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
+				stp, open->op_share_deny, false)) {
+			spin_unlock(&fp->fi_lock);
+			goto out;
+		}
 	}
 
 	/* set access to the file */
 	status = nfs4_file_get_access(fp, open->op_share_access);
 	if (status != nfs_ok) {
-		spin_unlock(&fp->fi_lock);
-		goto out;
+		if (status != nfserr_share_denied) {
+			spin_unlock(&fp->fi_lock);
+			goto out;
+		}
+		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
+				stp, open->op_share_access, true)) {
+			spin_unlock(&fp->fi_lock);
+			goto out;
+		}
 	}
 
 	/* Set access bits in stateid */
@@ -5050,7 +5130,7 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *c
 	unsigned char old_deny_bmap = stp->st_deny_bmap;
 
 	if (!test_access(open->op_share_access, stp))
-		return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open);
+		return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open, false);
 
 	/* test and set deny mode */
 	spin_lock(&fp->fi_lock);
@@ -5059,7 +5139,10 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *c
 		set_deny(open->op_share_deny, stp);
 		fp->fi_share_deny |=
 				(open->op_share_deny & NFS4_SHARE_DENY_BOTH);
-	}
+	} else if (status == nfserr_share_denied &&
+		!nfs4_resolve_deny_conflicts_locked(fp, false, stp,
+			open->op_share_deny, false))
+		status = nfs_ok;
 	spin_unlock(&fp->fi_lock);
 
 	if (status != nfs_ok)
@@ -5399,7 +5482,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
 			goto out;
 		}
 	} else {
-		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);
+		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open, true);
 		if (status) {
 			stp->st_stid.sc_type = NFS4_CLOSED_STID;
 			release_open_stateid(stp);
-- 
2.9.5

Re: [PATCH RFC v16 05/11] NFSD: Update nfs4_get_vfs_file() to handle courtesy clients

[J. Bruce Fields]

On Fri, Mar 11, 2022 at 06:13:29PM -0800, Dai Ngo wrote:
> Update nfs4_get_vfs_file and nfs4_upgrade_open to handle share
> reservation conflict with courtesy client.
> 
> If share/access check fails with share denied then check if the
> the conflict was caused by courtesy clients. If that's the case
> then set CLIENT_EXPIRED flag to expire the courtesy clients and
> allow nfs4_get_vfs_file to continue. Client with CLIENT_EXPIRED
> is expired by the laundromat.

I'm not following this code.  I'll see if I can give it another shot
tomorrow, but are you sure it can't be simplified somehow?

Keep in mind, we really don't care about share conflicts much.  I'm not
sure whether anyone actually uses open deny modes, so there's no need to
optimize that case.  I'd be totally fine with expiring things
unnecessarily in the deny mode case, for example.

--b.

> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfsd/nfs4state.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 91 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 2beb0972de88..b16f689f34c3 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -4973,9 +4973,75 @@ nfsd4_truncate(struct svc_rqst *rqstp, struct svc_fh *fh,
>  	return nfsd_setattr(rqstp, fh, &iattr, 0, (time64_t)0);
>  }
>  
> +static bool
> +nfs4_check_access_deny_bmap(struct nfs4_ol_stateid *stp, u32 access,
> +			bool share_access)
> +{
> +	if (share_access) {
> +		if (!stp->st_deny_bmap)
> +			return false;
> +
> +		if ((stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_BOTH)) ||
> +			(access & NFS4_SHARE_ACCESS_READ &&
> +				stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_READ)) ||
> +			(access & NFS4_SHARE_ACCESS_WRITE &&
> +				stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_WRITE))) {
> +			return true;
> +		}
> +		return false;
> +	}
> +	if ((access & NFS4_SHARE_DENY_BOTH) ||
> +		(access & NFS4_SHARE_DENY_READ &&
> +			stp->st_access_bmap & (1 << NFS4_SHARE_ACCESS_READ)) ||
> +		(access & NFS4_SHARE_DENY_WRITE &&
> +			stp->st_access_bmap & (1 << NFS4_SHARE_ACCESS_WRITE))) {
> +		return true;
> +	}
> +	return false;
> +}
> +
> +/*
> + * Check whether courtesy clients have conflicting access
> + *
> + * access:  is op_share_access if share_access is true.
> + *	    Check if access mode, op_share_access, would conflict with
> + *	    the current deny mode of the file 'fp'.
> + * access:  is op_share_deny if share_access is false.
> + *	    Check if the deny mode, op_share_deny, would conflict with
> + *	    current access of the file 'fp'.
> + * stp:     skip checking this entry.
> + * new_stp: normal open, not open upgrade.
> + *
> + * Function returns:
> + *	true   - access/deny mode conflict with normal client.
> + *	false  - no conflict or conflict with courtesy client(s) is resolved.
> + */
> +static bool
> +nfs4_resolve_deny_conflicts_locked(struct nfs4_file *fp, bool new_stp,
> +		struct nfs4_ol_stateid *stp, u32 access, bool share_access)
> +{
> +	struct nfs4_ol_stateid *st;
> +	struct nfs4_client *clp;
> +	bool conflict = false;
> +
> +	lockdep_assert_held(&fp->fi_lock);
> +	list_for_each_entry(st, &fp->fi_stateids, st_perfile) {
> +		if (st->st_openstp || (st == stp && new_stp) ||
> +			(!nfs4_check_access_deny_bmap(st,
> +					access, share_access)))
> +			continue;
> +		clp = st->st_stid.sc_client;
> +		if (nfs4_check_and_expire_courtesy_client(clp))
> +			continue;
> +		conflict = true;
> +		break;
> +	}
> +	return conflict;
> +}
> +
>  static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
>  		struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp,
> -		struct nfsd4_open *open)
> +		struct nfsd4_open *open, bool new_stp)
>  {
>  	struct nfsd_file *nf = NULL;
>  	__be32 status;
> @@ -4991,15 +5057,29 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
>  	 */
>  	status = nfs4_file_check_deny(fp, open->op_share_deny);
>  	if (status != nfs_ok) {
> -		spin_unlock(&fp->fi_lock);
> -		goto out;
> +		if (status != nfserr_share_denied) {
> +			spin_unlock(&fp->fi_lock);
> +			goto out;
> +		}
> +		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
> +				stp, open->op_share_deny, false)) {
> +			spin_unlock(&fp->fi_lock);
> +			goto out;
> +		}
>  	}
>  
>  	/* set access to the file */
>  	status = nfs4_file_get_access(fp, open->op_share_access);
>  	if (status != nfs_ok) {
> -		spin_unlock(&fp->fi_lock);
> -		goto out;
> +		if (status != nfserr_share_denied) {
> +			spin_unlock(&fp->fi_lock);
> +			goto out;
> +		}
> +		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
> +				stp, open->op_share_access, true)) {
> +			spin_unlock(&fp->fi_lock);
> +			goto out;
> +		}
>  	}
>  
>  	/* Set access bits in stateid */
> @@ -5050,7 +5130,7 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *c
>  	unsigned char old_deny_bmap = stp->st_deny_bmap;
>  
>  	if (!test_access(open->op_share_access, stp))
> -		return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open);
> +		return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open, false);
>  
>  	/* test and set deny mode */
>  	spin_lock(&fp->fi_lock);
> @@ -5059,7 +5139,10 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *c
>  		set_deny(open->op_share_deny, stp);
>  		fp->fi_share_deny |=
>  				(open->op_share_deny & NFS4_SHARE_DENY_BOTH);
> -	}
> +	} else if (status == nfserr_share_denied &&
> +		!nfs4_resolve_deny_conflicts_locked(fp, false, stp,
> +			open->op_share_deny, false))
> +		status = nfs_ok;
>  	spin_unlock(&fp->fi_lock);
>  
>  	if (status != nfs_ok)
> @@ -5399,7 +5482,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
>  			goto out;
>  		}
>  	} else {
> -		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);
> +		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open, true);
>  		if (status) {
>  			stp->st_stid.sc_type = NFS4_CLOSED_STID;
>  			release_open_stateid(stp);
> -- 
> 2.9.5

Re: [PATCH RFC v16 05/11] NFSD: Update nfs4_get_vfs_file() to handle courtesy clients

[dai.ngo]

On 3/15/22 8:39 AM, J. Bruce Fields wrote:
> On Fri, Mar 11, 2022 at 06:13:29PM -0800, Dai Ngo wrote:
>> Update nfs4_get_vfs_file and nfs4_upgrade_open to handle share
>> reservation conflict with courtesy client.
>>
>> If share/access check fails with share denied then check if the
>> the conflict was caused by courtesy clients. If that's the case
>> then set CLIENT_EXPIRED flag to expire the courtesy clients and
>> allow nfs4_get_vfs_file to continue. Client with CLIENT_EXPIRED
>> is expired by the laundromat.
> I'm not following this code.  I'll see if I can give it another shot
> tomorrow, but are you sure it can't be simplified somehow?

When we have deny/access conflict we walk the fi_stateids of the
file in question, looking for open stateid and check the deny/access
of that stateid against the one from the open request. If there is
a conflict then we check if the client that owns that stateid is
a courtesy client. If it is then we set the client state to
CLIENT_EXPIRED and allow the open request to continue. We have
to scan all the stateid's of the file since the conflict can be
caused by multiple open stateid's.

>
> Keep in mind, we really don't care about share conflicts much.  I'm not
> sure whether anyone actually uses open deny modes, so there's no need to
> optimize that case.

Yes, but we have to pass pynfs 4.0 tests.

>   I'd be totally fine with expiring things
> unnecessarily in the deny mode case, for example.

I have not been able to come up with a simpler solution.

-Dai

>
> --b.
>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>>   fs/nfsd/nfs4state.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++-----
>>   1 file changed, 91 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index 2beb0972de88..b16f689f34c3 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -4973,9 +4973,75 @@ nfsd4_truncate(struct svc_rqst *rqstp, struct svc_fh *fh,
>>   	return nfsd_setattr(rqstp, fh, &iattr, 0, (time64_t)0);
>>   }
>>   
>> +static bool
>> +nfs4_check_access_deny_bmap(struct nfs4_ol_stateid *stp, u32 access,
>> +			bool share_access)
>> +{
>> +	if (share_access) {
>> +		if (!stp->st_deny_bmap)
>> +			return false;
>> +
>> +		if ((stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_BOTH)) ||
>> +			(access & NFS4_SHARE_ACCESS_READ &&
>> +				stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_READ)) ||
>> +			(access & NFS4_SHARE_ACCESS_WRITE &&
>> +				stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_WRITE))) {
>> +			return true;
>> +		}
>> +		return false;
>> +	}
>> +	if ((access & NFS4_SHARE_DENY_BOTH) ||
>> +		(access & NFS4_SHARE_DENY_READ &&
>> +			stp->st_access_bmap & (1 << NFS4_SHARE_ACCESS_READ)) ||
>> +		(access & NFS4_SHARE_DENY_WRITE &&
>> +			stp->st_access_bmap & (1 << NFS4_SHARE_ACCESS_WRITE))) {
>> +		return true;
>> +	}
>> +	return false;
>> +}
>> +
>> +/*
>> + * Check whether courtesy clients have conflicting access
>> + *
>> + * access:  is op_share_access if share_access is true.
>> + *	    Check if access mode, op_share_access, would conflict with
>> + *	    the current deny mode of the file 'fp'.
>> + * access:  is op_share_deny if share_access is false.
>> + *	    Check if the deny mode, op_share_deny, would conflict with
>> + *	    current access of the file 'fp'.
>> + * stp:     skip checking this entry.
>> + * new_stp: normal open, not open upgrade.
>> + *
>> + * Function returns:
>> + *	true   - access/deny mode conflict with normal client.
>> + *	false  - no conflict or conflict with courtesy client(s) is resolved.
>> + */
>> +static bool
>> +nfs4_resolve_deny_conflicts_locked(struct nfs4_file *fp, bool new_stp,
>> +		struct nfs4_ol_stateid *stp, u32 access, bool share_access)
>> +{
>> +	struct nfs4_ol_stateid *st;
>> +	struct nfs4_client *clp;
>> +	bool conflict = false;
>> +
>> +	lockdep_assert_held(&fp->fi_lock);
>> +	list_for_each_entry(st, &fp->fi_stateids, st_perfile) {
>> +		if (st->st_openstp || (st == stp && new_stp) ||
>> +			(!nfs4_check_access_deny_bmap(st,
>> +					access, share_access)))
>> +			continue;
>> +		clp = st->st_stid.sc_client;
>> +		if (nfs4_check_and_expire_courtesy_client(clp))
>> +			continue;
>> +		conflict = true;
>> +		break;
>> +	}
>> +	return conflict;
>> +}
>> +
>>   static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
>>   		struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp,
>> -		struct nfsd4_open *open)
>> +		struct nfsd4_open *open, bool new_stp)
>>   {
>>   	struct nfsd_file *nf = NULL;
>>   	__be32 status;
>> @@ -4991,15 +5057,29 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
>>   	 */
>>   	status = nfs4_file_check_deny(fp, open->op_share_deny);
>>   	if (status != nfs_ok) {
>> -		spin_unlock(&fp->fi_lock);
>> -		goto out;
>> +		if (status != nfserr_share_denied) {
>> +			spin_unlock(&fp->fi_lock);
>> +			goto out;
>> +		}
>> +		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
>> +				stp, open->op_share_deny, false)) {
>> +			spin_unlock(&fp->fi_lock);
>> +			goto out;
>> +		}
>>   	}
>>   
>>   	/* set access to the file */
>>   	status = nfs4_file_get_access(fp, open->op_share_access);
>>   	if (status != nfs_ok) {
>> -		spin_unlock(&fp->fi_lock);
>> -		goto out;
>> +		if (status != nfserr_share_denied) {
>> +			spin_unlock(&fp->fi_lock);
>> +			goto out;
>> +		}
>> +		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
>> +				stp, open->op_share_access, true)) {
>> +			spin_unlock(&fp->fi_lock);
>> +			goto out;
>> +		}
>>   	}
>>   
>>   	/* Set access bits in stateid */
>> @@ -5050,7 +5130,7 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *c
>>   	unsigned char old_deny_bmap = stp->st_deny_bmap;
>>   
>>   	if (!test_access(open->op_share_access, stp))
>> -		return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open);
>> +		return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open, false);
>>   
>>   	/* test and set deny mode */
>>   	spin_lock(&fp->fi_lock);
>> @@ -5059,7 +5139,10 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *c
>>   		set_deny(open->op_share_deny, stp);
>>   		fp->fi_share_deny |=
>>   				(open->op_share_deny & NFS4_SHARE_DENY_BOTH);
>> -	}
>> +	} else if (status == nfserr_share_denied &&
>> +		!nfs4_resolve_deny_conflicts_locked(fp, false, stp,
>> +			open->op_share_deny, false))
>> +		status = nfs_ok;
>>   	spin_unlock(&fp->fi_lock);
>>   
>>   	if (status != nfs_ok)
>> @@ -5399,7 +5482,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
>>   			goto out;
>>   		}
>>   	} else {
>> -		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);
>> +		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open, true);
>>   		if (status) {
>>   			stp->st_stid.sc_type = NFS4_CLOSED_STID;
>>   			release_open_stateid(stp);
>> -- 
>> 2.9.5

[PATCH RFC v16 06/11] NFSD: Update find_clp_in_name_tree() to handle courtesy clients

[Dai Ngo]

Update find_clp_in_name_tree:
 . skip client with CLIENT_EXPIRED flag; discarded courtesy client.
 . if courtesy client was found then clear CLIENT_COURTESY and
   set CLIENT_RECONNECTED so callers can take appropriate action.

Update find_confirmed_client_by_name to discard the courtesy
client; set CLIENT_EXPIRED.

Update nfsd4_setclientid to expire the confirmed courtesy client
to prevent multiple confirmed clients with the same name on the
the conf_id_hashtbl list.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 51 insertions(+), 3 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index b16f689f34c3..2f19aaaf6a66 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1929,6 +1929,33 @@ __find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid, struct net *net)
 	return NULL;
 }
 
+static void
+nfsd4_discard_courtesy_clnt(struct nfs4_client *clp)
+{
+	spin_lock(&clp->cl_cs_lock);
+	set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
+	spin_unlock(&clp->cl_cs_lock);
+}
+
+static bool
+nfs4_is_courtesy_client_expired(struct nfs4_client *clp)
+{
+	spin_lock(&clp->cl_cs_lock);
+	clear_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags);
+	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags)) {
+		spin_unlock(&clp->cl_cs_lock);
+		return true;
+	}
+	/*
+	 * clear CLIENT_COURTESY flag to prevent it from being
+	 * destroyed by thread trying to resolve conflicts.
+	 */
+	if (test_and_clear_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
+		set_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags);
+	spin_unlock(&clp->cl_cs_lock);
+	return false;
+}
+
 static struct nfsd4_session *
 find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid, struct net *net,
 		__be32 *ret)
@@ -2834,8 +2861,11 @@ find_clp_in_name_tree(struct xdr_netobj *name, struct rb_root *root)
 			node = node->rb_left;
 		else if (cmp < 0)
 			node = node->rb_right;
-		else
+		else {
+			if (nfs4_is_courtesy_client_expired(clp))
+				return NULL;
 			return clp;
+		}
 	}
 	return NULL;
 }
@@ -2914,8 +2944,15 @@ static bool clp_used_exchangeid(struct nfs4_client *clp)
 static struct nfs4_client *
 find_confirmed_client_by_name(struct xdr_netobj *name, struct nfsd_net *nn)
 {
+	struct nfs4_client *clp;
+
 	lockdep_assert_held(&nn->client_lock);
-	return find_clp_in_name_tree(name, &nn->conf_name_tree);
+	clp = find_clp_in_name_tree(name, &nn->conf_name_tree);
+	if (clp && test_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags)) {
+		nfsd4_discard_courtesy_clnt(clp);
+		clp = NULL;
+	}
+	return clp;
 }
 
 static struct nfs4_client *
@@ -4032,12 +4069,19 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	struct nfs4_client	*unconf = NULL;
 	__be32 			status;
 	struct nfsd_net		*nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+	struct nfs4_client	*cclient = NULL;
 
 	new = create_client(clname, rqstp, &clverifier);
 	if (new == NULL)
 		return nfserr_jukebox;
 	spin_lock(&nn->client_lock);
-	conf = find_confirmed_client_by_name(&clname, nn);
+	/* find confirmed client by name */
+	conf = find_clp_in_name_tree(&clname, &nn->conf_name_tree);
+	if (conf && test_bit(NFSD4_CLIENT_RECONNECTED, &conf->cl_flags)) {
+		cclient = conf;
+		conf = NULL;
+	}
+
 	if (conf && client_has_state(conf)) {
 		status = nfserr_clid_inuse;
 		if (clp_used_exchangeid(conf))
@@ -4068,7 +4112,11 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	new = NULL;
 	status = nfs_ok;
 out:
+	if (cclient)
+		unhash_client_locked(cclient);
 	spin_unlock(&nn->client_lock);
+	if (cclient)
+		expire_client(cclient);
 	if (new)
 		free_client(new);
 	if (unconf) {
-- 
2.9.5

[PATCH RFC v16 07/11] NFSD: Update find_in_sessionid_hashtbl() to handle courtesy clients

[Dai Ngo]

Update find_in_sessionid_hashtbl to:
 . skip client with CLIENT_EXPIRED flag; discarded courtesy client.
 . if courtesy client was found then clear CLIENT_COURTESY and
   set CLIENT_RECONNECTED so callers can take appropriate action.

Update nfsd4_sequence and nfsd4_bind_conn_to_session to create client
record for client with CLIENT_RECONNECTED set.

Update nfsd4_destroy_session to discard client with CLIENT_RECONNECTED
set.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 2f19aaaf6a66..c917b6372a92 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1962,13 +1962,22 @@ find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid, struct net *net,
 {
 	struct nfsd4_session *session;
 	__be32 status = nfserr_badsession;
+	struct nfs4_client *clp;
 
 	session = __find_in_sessionid_hashtbl(sessionid, net);
 	if (!session)
 		goto out;
+	clp = session->se_client;
+	if (nfs4_is_courtesy_client_expired(clp)) {
+		session = NULL;
+		goto out;
+	}
 	status = nfsd4_get_session_locked(session);
-	if (status)
+	if (status) {
 		session = NULL;
+		if (test_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags))
+			nfsd4_discard_courtesy_clnt(clp);
+	}
 out:
 	*ret = status;
 	return session;
@@ -3670,6 +3679,7 @@ __be32 nfsd4_bind_conn_to_session(struct svc_rqst *rqstp,
 	struct nfsd4_session *session;
 	struct net *net = SVC_NET(rqstp);
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+	struct nfs4_client *clp;
 
 	if (!nfsd4_last_compound_op(rqstp))
 		return nfserr_not_only_op;
@@ -3702,6 +3712,13 @@ __be32 nfsd4_bind_conn_to_session(struct svc_rqst *rqstp,
 	nfsd4_init_conn(rqstp, conn, session);
 	status = nfs_ok;
 out:
+	clp = session->se_client;
+	if (test_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags)) {
+		if (status == nfs_ok)
+			nfsd4_client_record_create(clp);
+		else
+			nfsd4_discard_courtesy_clnt(clp);
+	}
 	nfsd4_put_session(session);
 out_no_session:
 	return status;
@@ -3724,6 +3741,7 @@ nfsd4_destroy_session(struct svc_rqst *r, struct nfsd4_compound_state *cstate,
 	int ref_held_by_me = 0;
 	struct net *net = SVC_NET(r);
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+	struct nfs4_client *clp;
 
 	status = nfserr_not_only_op;
 	if (nfsd4_compound_in_session(cstate, sessionid)) {
@@ -3736,6 +3754,12 @@ nfsd4_destroy_session(struct svc_rqst *r, struct nfsd4_compound_state *cstate,
 	ses = find_in_sessionid_hashtbl(sessionid, net, &status);
 	if (!ses)
 		goto out_client_lock;
+	clp = ses->se_client;
+	if (test_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags)) {
+		status = nfserr_badsession;
+		nfsd4_discard_courtesy_clnt(clp);
+		goto out_put_session;
+	}
 	status = nfserr_wrong_cred;
 	if (!nfsd4_mach_creds_match(ses->se_client, r))
 		goto out_put_session;
@@ -3840,7 +3864,7 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	struct nfsd4_compoundres *resp = rqstp->rq_resp;
 	struct xdr_stream *xdr = resp->xdr;
 	struct nfsd4_session *session;
-	struct nfs4_client *clp;
+	struct nfs4_client *clp = NULL;
 	struct nfsd4_slot *slot;
 	struct nfsd4_conn *conn;
 	__be32 status;
@@ -3950,6 +3974,12 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	if (conn)
 		free_conn(conn);
 	spin_unlock(&nn->client_lock);
+	if (clp && test_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags)) {
+		if (status == nfs_ok)
+			nfsd4_client_record_create(clp);
+		else
+			nfsd4_discard_courtesy_clnt(clp);
+	}
 	return status;
 out_put_session:
 	nfsd4_put_session_locked(session);
-- 
2.9.5

[PATCH RFC v16 08/11] NFSD: Update find_client_in_id_table() to handle courtesy clients

[Dai Ngo]

Update find_client_in_id_table to:
 . skip client with CLIENT_EXPIRED; discarded courtesy client
 . if courtesy client was found then clear CLIENT_COURTESY and set
   CLIENT_RECONNECTED flag so callers can take appropriate action.

Update find_confirmed_client to discard courtesy client.
Update lookup_clientid to call find_client_in_id_table directly.
Update set_client to create client record for courtesy client.
Update find_cpntf_state to discard courtesy client.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index c917b6372a92..2ff80999b243 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2920,6 +2920,8 @@ find_client_in_id_table(struct list_head *tbl, clientid_t *clid, bool sessions)
 		if (same_clid(&clp->cl_clientid, clid)) {
 			if ((bool)clp->cl_minorversion != sessions)
 				return NULL;
+			if (nfs4_is_courtesy_client_expired(clp))
+				continue;
 			renew_client_locked(clp);
 			return clp;
 		}
@@ -2931,9 +2933,15 @@ static struct nfs4_client *
 find_confirmed_client(clientid_t *clid, bool sessions, struct nfsd_net *nn)
 {
 	struct list_head *tbl = nn->conf_id_hashtbl;
+	struct nfs4_client *clp;
 
 	lockdep_assert_held(&nn->client_lock);
-	return find_client_in_id_table(tbl, clid, sessions);
+	clp = find_client_in_id_table(tbl, clid, sessions);
+	if (clp && test_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags)) {
+		nfsd4_discard_courtesy_clnt(clp);
+		clp = NULL;
+	}
+	return clp;
 }
 
 static struct nfs4_client *
@@ -4872,9 +4880,10 @@ static struct nfs4_client *lookup_clientid(clientid_t *clid, bool sessions,
 						struct nfsd_net *nn)
 {
 	struct nfs4_client *found;
+	struct list_head *tbl = nn->conf_id_hashtbl;
 
 	spin_lock(&nn->client_lock);
-	found = find_confirmed_client(clid, sessions, nn);
+	found = find_client_in_id_table(tbl, clid, sessions);
 	if (found)
 		atomic_inc(&found->cl_rpc_users);
 	spin_unlock(&nn->client_lock);
@@ -4899,6 +4908,8 @@ static __be32 set_client(clientid_t *clid,
 	cstate->clp = lookup_clientid(clid, false, nn);
 	if (!cstate->clp)
 		return nfserr_expired;
+	if (test_bit(NFSD4_CLIENT_RECONNECTED, &cstate->clp->cl_flags))
+		nfsd4_client_record_create(cstate->clp);
 	return nfs_ok;
 }
 
@@ -6218,6 +6229,13 @@ static __be32 find_cpntf_state(struct nfsd_net *nn, stateid_t *st,
 	found = lookup_clientid(&cps->cp_p_clid, true, nn);
 	if (!found)
 		goto out;
+	if (test_bit(NFSD4_CLIENT_RECONNECTED, &found->cl_flags)) {
+		nfsd4_discard_courtesy_clnt(found);
+		if (atomic_dec_and_lock(&found->cl_rpc_users,
+				&nn->client_lock))
+			spin_unlock(&nn->client_lock);
+		goto out;
+	}
 
 	*stid = find_stateid_by_type(found, &cps->cp_p_stateid,
 			NFS4_DELEG_STID|NFS4_OPEN_STID|NFS4_LOCK_STID);
-- 
2.9.5

[PATCH RFC v16 09/11] NFSD: Refactor nfsd4_laundromat()

[Dai Ngo]

Extract a bit of logic that is about to be expanded to handle
courtesy clients.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 2ff80999b243..034161a28bd1 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -5805,6 +5805,26 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
 }
 #endif
 
+static void
+nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
+				struct laundry_time *lt)
+{
+	struct list_head *pos, *next;
+	struct nfs4_client *clp;
+
+	INIT_LIST_HEAD(reaplist);
+	spin_lock(&nn->client_lock);
+	list_for_each_safe(pos, next, &nn->client_lru) {
+		clp = list_entry(pos, struct nfs4_client, cl_lru);
+		if (!state_expired(lt, clp->cl_time))
+			break;
+		if (mark_client_expired_locked(clp))
+			continue;
+		list_add(&clp->cl_lru, reaplist);
+	}
+	spin_unlock(&nn->client_lock);
+}
+
 static time64_t
 nfs4_laundromat(struct nfsd_net *nn)
 {
@@ -5827,7 +5847,6 @@ nfs4_laundromat(struct nfsd_net *nn)
 		goto out;
 	}
 	nfsd4_end_grace(nn);
-	INIT_LIST_HEAD(&reaplist);
 
 	spin_lock(&nn->s2s_cp_lock);
 	idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) {
@@ -5837,17 +5856,7 @@ nfs4_laundromat(struct nfsd_net *nn)
 			_free_cpntf_state_locked(nn, cps);
 	}
 	spin_unlock(&nn->s2s_cp_lock);
-
-	spin_lock(&nn->client_lock);
-	list_for_each_safe(pos, next, &nn->client_lru) {
-		clp = list_entry(pos, struct nfs4_client, cl_lru);
-		if (!state_expired(&lt, clp->cl_time))
-			break;
-		if (mark_client_expired_locked(clp))
-			continue;
-		list_add(&clp->cl_lru, &reaplist);
-	}
-	spin_unlock(&nn->client_lock);
+	nfs4_get_client_reaplist(nn, &reaplist, &lt);
 	list_for_each_safe(pos, next, &reaplist) {
 		clp = list_entry(pos, struct nfs4_client, cl_lru);
 		trace_nfsd_clid_purged(&clp->cl_clientid);
-- 
2.9.5

[PATCH RFC v16 10/11] NFSD: Update laundromat to handle courtesy clients

[Dai Ngo]

Add nfs4_anylock_blocker and nfs4_lockowner_has_blockers to check
if an expired client has any lock blockers

Update nfs4_get_client_reaplist to:
 . add discarded courtesy client; client marked with CLIENT_EXPIRED,
   to reaplist.
 . detect if expired client still has state and no blockers then
   transit it to courtesy client by setting CLIENT_COURTESY flag
   and removing the client record.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 92 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 034161a28bd1..17b5d5b202c1 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -5805,24 +5805,107 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
 }
 #endif
 
+/* Check if any lock belonging to this lockowner has any blockers */
+static bool
+nfs4_lockowner_has_blockers(struct nfs4_lockowner *lo)
+{
+	struct file_lock_context *ctx;
+	struct nfs4_ol_stateid *stp;
+	struct nfs4_file *nf;
+
+	list_for_each_entry(stp, &lo->lo_owner.so_stateids, st_perstateowner) {
+		nf = stp->st_stid.sc_file;
+		ctx = nf->fi_inode->i_flctx;
+		if (!ctx)
+			continue;
+		if (locks_owner_has_blockers(ctx, lo))
+			return true;
+	}
+	return false;
+}
+
+static bool
+nfs4_anylock_blockers(struct nfs4_client *clp)
+{
+	int i;
+	struct nfs4_stateowner *so;
+	struct nfs4_lockowner *lo;
+
+	spin_lock(&clp->cl_lock);
+	for (i = 0; i < OWNER_HASH_SIZE; i++) {
+		list_for_each_entry(so, &clp->cl_ownerstr_hashtbl[i],
+				so_strhash) {
+			if (so->so_is_open_owner)
+				continue;
+			lo = lockowner(so);
+			if (nfs4_lockowner_has_blockers(lo)) {
+				spin_unlock(&clp->cl_lock);
+				return true;
+			}
+		}
+	}
+	spin_unlock(&clp->cl_lock);
+	return false;
+}
+
 static void
 nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
 				struct laundry_time *lt)
 {
 	struct list_head *pos, *next;
 	struct nfs4_client *clp;
+	bool cour;
+	struct list_head cslist;
 
 	INIT_LIST_HEAD(reaplist);
+	INIT_LIST_HEAD(&cslist);
 	spin_lock(&nn->client_lock);
 	list_for_each_safe(pos, next, &nn->client_lru) {
 		clp = list_entry(pos, struct nfs4_client, cl_lru);
 		if (!state_expired(lt, clp->cl_time))
 			break;
-		if (mark_client_expired_locked(clp))
+
+		if (!client_has_state(clp))
+			goto exp_client;
+
+		if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
+			goto exp_client;
+		cour = test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags);
+		if (cour && ktime_get_boottime_seconds() >=
+				(clp->cl_time + NFSD_COURTESY_CLIENT_TIMEOUT))
+			goto exp_client;
+		if (nfs4_anylock_blockers(clp)) {
+exp_client:
+			if (mark_client_expired_locked(clp))
+				continue;
+			list_add(&clp->cl_lru, reaplist);
 			continue;
-		list_add(&clp->cl_lru, reaplist);
+		}
+		if (!cour) {
+			spin_lock(&clp->cl_cs_lock);
+			set_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags);
+			spin_unlock(&clp->cl_cs_lock);
+			list_add(&clp->cl_cs_list, &cslist);
+		}
 	}
 	spin_unlock(&nn->client_lock);
+
+	while (!list_empty(&cslist)) {
+		clp = list_first_entry(&cslist, struct nfs4_client, cl_cs_list);
+		list_del_init(&clp->cl_cs_list);
+		spin_lock(&clp->cl_cs_lock);
+		/*
+		 * Client might have re-connected. Make sure it's
+		 * still in courtesy state before removing its record.
+		 */
+		if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags) ||
+			!test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
+			spin_unlock(&clp->cl_cs_lock);
+			continue;
+		}
+		spin_unlock(&clp->cl_cs_lock);
+		nfsd4_client_record_remove(clp);
+	}
 }
 
 static time64_t
@@ -5868,6 +5951,13 @@ nfs4_laundromat(struct nfsd_net *nn)
 		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
 		if (!state_expired(&lt, dp->dl_time))
 			break;
+		spin_lock(&clp->cl_cs_lock);
+		if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
+			set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
+			spin_unlock(&clp->cl_cs_lock);
+			continue;
+		}
+		spin_unlock(&clp->cl_cs_lock);
 		WARN_ON(!unhash_delegation_locked(dp));
 		list_add(&dp->dl_recall_lru, &reaplist);
 	}
-- 
2.9.5

[PATCH RFC v16 11/11] NFSD: Show state of courtesy clients in client info

[Dai Ngo]

Update client_info_show to show state of courtesy client
and time since last renew.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 17b5d5b202c1..79f60bb7be76 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2438,7 +2438,8 @@ static int client_info_show(struct seq_file *m, void *v)
 {
 	struct inode *inode = m->private;
 	struct nfs4_client *clp;
-	u64 clid;
+	u64 clid, hrs;
+	u32 mins, secs;
 
 	clp = get_nfsdfs_clp(inode);
 	if (!clp)
@@ -2446,10 +2447,16 @@ static int client_info_show(struct seq_file *m, void *v)
 	memcpy(&clid, &clp->cl_clientid, sizeof(clid));
 	seq_printf(m, "clientid: 0x%llx\n", clid);
 	seq_printf(m, "address: \"%pISpc\"\n", (struct sockaddr *)&clp->cl_addr);
-	if (test_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags))
+	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
+		seq_puts(m, "status: courtesy\n");
+	else if (test_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags))
 		seq_puts(m, "status: confirmed\n");
 	else
 		seq_puts(m, "status: unconfirmed\n");
+	hrs = div_u64_rem(ktime_get_boottime_seconds() - clp->cl_time,
+				3600, &secs);
+	mins = div_u64_rem((u64)secs, 60, &secs);
+	seq_printf(m, "time since last renew: %llu:%02u:%02u\n", hrs, mins, secs);
 	seq_printf(m, "name: ");
 	seq_quote_mem(m, clp->cl_name.data, clp->cl_name.len);
 	seq_printf(m, "\nminor version: %d\n", clp->cl_minorversion);
-- 
2.9.5