// 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 <[email protected]>
*/
#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/sunrpc/svc_xprt.h>
#include <linux/lockd/lockd.h>
#include <linux/kthread.h>
#include "trace.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.
*/
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);
void nlmclnt_prepare_block(struct nlm_wait *block, struct nlm_host *host, struct file_lock *fl)
{
block->b_host = host;
block->b_lock = fl;
init_waitqueue_head(&block->b_wait);
block->b_status = nlm_lck_blocked;
}
struct rpc_clnt *nlmclnt_rpc_clnt(struct nlm_host *host)
{
return host->h_rpcclnt;
}
EXPORT_SYMBOL_GPL(nlmclnt_rpc_clnt);
/*
* Queue up a lock for blocking so that the GRANTED request can see it
*/
void nlmclnt_queue_block(struct nlm_wait *block)
{
spin_lock(&nlm_blocked_lock);
list_add(&block->b_list, &nlm_blocked);
spin_unlock(&nlm_blocked_lock);
}
/*
* Dequeue the block and return its final status
*/
__be32 nlmclnt_dequeue_block(struct nlm_wait *block)
{
__be32 status;
spin_lock(&nlm_blocked_lock);
list_del(&block->b_list);
status = block->b_status;
spin_unlock(&nlm_blocked_lock);
return status;
}
/*
* Block on a lock
*/
int nlmclnt_wait(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;
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->c.flc_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);
trace_nlmclnt_grant(lock, addr, svc_addr_len(addr), res);
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;
}
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