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From:   Dai Ngo <dai.ngo@oracle.com>
To:     chuck.lever@oracle.com, bfields@fieldses.org
Cc:     jlayton@redhat.com, viro@zeniv.linux.org.uk,
        linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH RFC v19 02/11] NFSD: Add courtesy client state, macro and spinlock to support courteous server
Date:   Thu, 31 Mar 2022 09:02:00 -0700
Message-Id: <1648742529-28551-3-git-send-email-dai.ngo@oracle.com>
In-Reply-To: <1648742529-28551-1-git-send-email-dai.ngo@oracle.com>
References: <1648742529-28551-1-git-send-email-dai.ngo@oracle.com>
Precedence: bulk

Update nfs4_client to add:
 . cl_cs_client_state: courtesy client state
 . cl_cs_lock: spinlock to synchronize access to cl_cs_client_state
 . cl_cs_list: list used by laundromat to process courtesy clients

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     | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 36 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..7f78da5d1408 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -283,6 +283,35 @@ struct nfsd4_sessionid {
 #define HEXDIR_LEN     33 /* hex version of 16 byte md5 of cl_name plus '\0' */
 
 /*
+ *       State                Meaning                  Where set
+ * --------------------------------------------------------------------------
+ * | CLIENT_ACTIVE     | Confirmed, active    | Default                     |
+ * |------------------- ----------------------------------------------------|
+ * | CLIENT_COURTESY   | Courtesy state.      | nfs4_get_client_reaplist    |
+ * |                   | Lease/lock/share     |                             |
+ * |                   | reservation conflict |                             |
+ * |                   | can cause Courtesy   |                             |
+ * |                   | client to be expired |                             |
+ * |------------------------------------------------------------------------|
+ * | CLIENT_EXPIRED    | Courtesy client to be| nfs4_laundromat             |
+ * |                   | expired by Laundromat| nfsd4_lm_lock_expired       |
+ * |                   | due to conflict      | nfsd4_discard_courtesy_clnt |
+ * |                   |                      | nfsd4_expire_courtesy_clnt  |
+ * |------------------------------------------------------------------------|
+ * | CLIENT_RECONNECT  | Courtesy client      | nfsd4_courtesy_clnt_expired |
+ * |                   | reconnected,         |                             |
+ * |                   | becoming active      |                             |
+ * --------------------------------------------------------------------------
+ */
+
+enum courtesy_client_state {
+	NFSD4_CLIENT_ACTIVE = 0,
+	NFSD4_CLIENT_COURTESY,
+	NFSD4_CLIENT_EXPIRED,
+	NFSD4_CLIENT_RECONNECTED,
+};
+
+/*
  * struct nfs4_client - one per client.  Clientids live here.
  *
  * The initial object created by an NFS client using SETCLIENTID (for NFSv4.0)
@@ -385,6 +414,10 @@ 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 */
+
+	enum courtesy_client_state	cl_cs_client_state;
+	spinlock_t		cl_cs_lock;
+	struct list_head	cl_cs_list;
 };
 
 /* struct nfs4_client_reset
-- 
2.9.5