--- /dev/null
+/*
+ * 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);
+ 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);
+ if (host == NULL)
+ goto out_nohost;
+ if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL)
+ goto out_nobind;
+
+ 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(file_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) {
+ printk(KERN_ERR "lockd: reclaimer unable to alloc memory."
+ " Locks for %s won't be reclaimed!\n",
+ host->h_name);
+ return 0;
+ }
+
+ allow_signal(SIGKILL);
+
+ down_write(&host->h_rwsem);
+ lockd_up(net); /* 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;
+}
Code Review / kvmfornfv.git / blobdiff