1 files changed, 299 insertions, 0 deletions
diff --git a/fs/lockd/clntlock.c b/fs/lockd/clntlock.c
new file mode 100644
index 000000000..a5bb3f721
--- /dev/null
+++ b/fs/lockd/clntlock.c
@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/lockd/clntlock.c
+ *
+ * Lock handling for the client side NLM implementation
+ *
+ * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/nfs_fs.h>
+#include <linux/sunrpc/addr.h>
+#include <linux/sunrpc/svc.h>
+#include <linux/lockd/lockd.h>
+#include <linux/kthread.h>
+
+#define NLMDBG_FACILITY		NLMDBG_CLIENT
+
+/*
+ * Local function prototypes
+ */
+static int			reclaimer(void *ptr);
+
+/*
+ * The following functions handle blocking and granting from the
+ * client perspective.
+ */
+
+/*
+ * This is the representation of a blocked client lock.
+ */
+struct nlm_wait {
+	struct list_head	b_list;		/* linked list */
+	wait_queue_head_t	b_wait;		/* where to wait on */
+	struct nlm_host *	b_host;
+	struct file_lock *	b_lock;		/* local file lock */
+	unsigned short		b_reclaim;	/* got to reclaim lock */
+	__be32			b_status;	/* grant callback status */
+};
+
+static LIST_HEAD(nlm_blocked);
+static DEFINE_SPINLOCK(nlm_blocked_lock);
+
+/**
+ * nlmclnt_init - Set up per-NFS mount point lockd data structures
+ * @nlm_init: pointer to arguments structure
+ *
+ * Returns pointer to an appropriate nlm_host struct,
+ * or an ERR_PTR value.
+ */
+struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
+{
+	struct nlm_host *host;
+	u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
+	int status;
+
+	status = lockd_up(nlm_init->net, nlm_init->cred);
+	if (status < 0)
+		return ERR_PTR(status);
+
+	host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
+				   nlm_init->protocol, nlm_version,
+				   nlm_init->hostname, nlm_init->noresvport,
+				   nlm_init->net, nlm_init->cred);
+	if (host == NULL)
+		goto out_nohost;
+	if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL)
+		goto out_nobind;
+
+	host->h_nlmclnt_ops = nlm_init->nlmclnt_ops;
+	return host;
+out_nobind:
+	nlmclnt_release_host(host);
+out_nohost:
+	lockd_down(nlm_init->net);
+	return ERR_PTR(-ENOLCK);
+}
+EXPORT_SYMBOL_GPL(nlmclnt_init);
+
+/**
+ * nlmclnt_done - Release resources allocated by nlmclnt_init()
+ * @host: nlm_host structure reserved by nlmclnt_init()
+ *
+ */
+void nlmclnt_done(struct nlm_host *host)
+{
+	struct net *net = host->net;
+
+	nlmclnt_release_host(host);
+	lockd_down(net);
+}
+EXPORT_SYMBOL_GPL(nlmclnt_done);
+
+/*
+ * Queue up a lock for blocking so that the GRANTED request can see it
+ */
+struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
+{
+	struct nlm_wait *block;
+
+	block = kmalloc(sizeof(*block), GFP_KERNEL);
+	if (block != NULL) {
+		block->b_host = host;
+		block->b_lock = fl;
+		init_waitqueue_head(&block->b_wait);
+		block->b_status = nlm_lck_blocked;
+
+		spin_lock(&nlm_blocked_lock);
+		list_add(&block->b_list, &nlm_blocked);
+		spin_unlock(&nlm_blocked_lock);
+	}
+	return block;
+}
+
+void nlmclnt_finish_block(struct nlm_wait *block)
+{
+	if (block == NULL)
+		return;
+	spin_lock(&nlm_blocked_lock);
+	list_del(&block->b_list);
+	spin_unlock(&nlm_blocked_lock);
+	kfree(block);
+}
+
+/*
+ * Block on a lock
+ */
+int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
+{
+	long ret;
+
+	/* A borken server might ask us to block even if we didn't
+	 * request it. Just say no!
+	 */
+	if (block == NULL)
+		return -EAGAIN;
+
+	/* Go to sleep waiting for GRANT callback. Some servers seem
+	 * to lose callbacks, however, so we're going to poll from
+	 * time to time just to make sure.
+	 *
+	 * For now, the retry frequency is pretty high; normally 
+	 * a 1 minute timeout would do. See the comment before
+	 * nlmclnt_lock for an explanation.
+	 */
+	ret = wait_event_interruptible_timeout(block->b_wait,
+			block->b_status != nlm_lck_blocked,
+			timeout);
+	if (ret < 0)
+		return -ERESTARTSYS;
+	/* Reset the lock status after a server reboot so we resend */
+	if (block->b_status == nlm_lck_denied_grace_period)
+		block->b_status = nlm_lck_blocked;
+	req->a_res.status = block->b_status;
+	return 0;
+}
+
+/*
+ * The server lockd has called us back to tell us the lock was granted
+ */
+__be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
+{
+	const struct file_lock *fl = &lock->fl;
+	const struct nfs_fh *fh = &lock->fh;
+	struct nlm_wait	*block;
+	__be32 res = nlm_lck_denied;
+
+	/*
+	 * Look up blocked request based on arguments. 
+	 * Warning: must not use cookie to match it!
+	 */
+	spin_lock(&nlm_blocked_lock);
+	list_for_each_entry(block, &nlm_blocked, b_list) {
+		struct file_lock *fl_blocked = block->b_lock;
+
+		if (fl_blocked->fl_start != fl->fl_start)
+			continue;
+		if (fl_blocked->fl_end != fl->fl_end)
+			continue;
+		/*
+		 * Careful! The NLM server will return the 32-bit "pid" that
+		 * we put on the wire: in this case the lockowner "pid".
+		 */
+		if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
+			continue;
+		if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
+			continue;
+		if (nfs_compare_fh(NFS_FH(locks_inode(fl_blocked->fl_file)), fh) != 0)
+			continue;
+		/* Alright, we found a lock. Set the return status
+		 * and wake up the caller
+		 */
+		block->b_status = nlm_granted;
+		wake_up(&block->b_wait);
+		res = nlm_granted;
+	}
+	spin_unlock(&nlm_blocked_lock);
+	return res;
+}
+
+/*
+ * The following procedures deal with the recovery of locks after a
+ * server crash.
+ */
+
+/*
+ * Reclaim all locks on server host. We do this by spawning a separate
+ * reclaimer thread.
+ */
+void
+nlmclnt_recovery(struct nlm_host *host)
+{
+	struct task_struct *task;
+
+	if (!host->h_reclaiming++) {
+		nlm_get_host(host);
+		task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
+		if (IS_ERR(task))
+			printk(KERN_ERR "lockd: unable to spawn reclaimer "
+				"thread. Locks for %s won't be reclaimed! "
+				"(%ld)\n", host->h_name, PTR_ERR(task));
+	}
+}
+
+static int
+reclaimer(void *ptr)
+{
+	struct nlm_host	  *host = (struct nlm_host *) ptr;
+	struct nlm_wait	  *block;
+	struct nlm_rqst   *req;
+	struct file_lock *fl, *next;
+	u32 nsmstate;
+	struct net *net = host->net;
+
+	req = kmalloc(sizeof(*req), GFP_KERNEL);
+	if (!req)
+		return 0;
+
+	allow_signal(SIGKILL);
+
+	down_write(&host->h_rwsem);
+	lockd_up(net, NULL);	/* note: this cannot fail as lockd is already running */
+
+	dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
+
+restart:
+	nsmstate = host->h_nsmstate;
+
+	/* Force a portmap getport - the peer's lockd will
+	 * most likely end up on a different port.
+	 */
+	host->h_nextrebind = jiffies;
+	nlm_rebind_host(host);
+
+	/* First, reclaim all locks that have been granted. */
+	list_splice_init(&host->h_granted, &host->h_reclaim);
+	list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
+		list_del_init(&fl->fl_u.nfs_fl.list);
+
+		/*
+		 * sending this thread a SIGKILL will result in any unreclaimed
+		 * locks being removed from the h_granted list. This means that
+		 * the kernel will not attempt to reclaim them again if a new
+		 * reclaimer thread is spawned for this host.
+		 */
+		if (signalled())
+			continue;
+		if (nlmclnt_reclaim(host, fl, req) != 0)
+			continue;
+		list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
+		if (host->h_nsmstate != nsmstate) {
+			/* Argh! The server rebooted again! */
+			goto restart;
+		}
+	}
+
+	host->h_reclaiming = 0;
+	up_write(&host->h_rwsem);
+	dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
+
+	/* Now, wake up all processes that sleep on a blocked lock */
+	spin_lock(&nlm_blocked_lock);
+	list_for_each_entry(block, &nlm_blocked, b_list) {
+		if (block->b_host == host) {
+			block->b_status = nlm_lck_denied_grace_period;
+			wake_up(&block->b_wait);
+		}
+	}
+	spin_unlock(&nlm_blocked_lock);
+
+	/* Release host handle after use */
+	nlmclnt_release_host(host);
+	lockd_down(net);
+	kfree(req);
+	return 0;
+}