/*
* 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/time.h>
#include <linux/nfs_fs.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/lockd/lockd.h>
#include <linux/smp_lock.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 */
u32 b_status; /* grant callback status */
};
static LIST_HEAD(nlm_blocked);
/*
* 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;
list_add(&block->b_list, &nlm_blocked);
}
return block;
}
void nlmclnt_finish_block(struct nlm_wait *block)
{
if (block == NULL)
return;
list_del(&block->b_list);
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;
req->a_res.status = block->b_status;
return 0;
}
/*
* The server lockd has called us back to tell us the lock was granted
*/
u32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
{
const struct file_lock *fl = &lock->fl;
const struct nfs_fh *fh = &lock->fh;
struct nlm_wait *block;
u32 res = nlm_lck_denied;
/*
* Look up blocked request based on arguments.
* Warning: must not use cookie to match it!
*/
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 (!nlm_cmp_addr(&block->b_host->h_addr, addr))
continue;
if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_dentry->d_inode) ,fh) != 0)
continue;
/* Alright, we found a lock. Set the return status
* and wake up the caller
*/
block->b_status = NLM_LCK_GRANTED;
wake_up(&block->b_wait);
res = nlm_granted;
}
return res;
}
/*
* The following procedures deal with the recovery of locks after a
* server crash.
*/
/*
* Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
* that we mark locks for reclaiming, and that we bump the pseudo NSM state.
*/
static void nlmclnt_prepare_reclaim(struct nlm_host *host)
{
down_write(&host->h_rwsem);
host->h_monitored = 0;
host->h_state++;
host->h_nextrebind = 0;
nlm_rebind_host(host);
/*
* Mark the locks for reclaiming.
*/
list_splice_init(&host->h_granted, &host->h_reclaim);
dprintk("NLM: reclaiming locks for host %s\n", host->h_name);
}
static void nlmclnt_finish_reclaim(struct nlm_host *host)
{
host->h_reclaiming = 0;
up_write(&host->h_rwsem);
dprintk("NLM: done reclaiming locks for host %s", host->h_name);
}
/*
* Reclaim all locks on server host. We do this by spawning a separate
* reclaimer thread.
*/
void
nlmclnt_recovery(struct nlm_host *host, u32 newstate)
{
if (host->h_nsmstate == newstate)
return;
host->h_nsmstate = newstate;
if (!host->h_reclaiming++) {
nlm_get_host(host);
__module_get(THIS_MODULE);
if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
module_put(THIS_MODULE);
}
}
static int
reclaimer(void *ptr)
{
struct nlm_host *host = (struct nlm_host *) ptr;
struct nlm_wait *block;
struct file_lock *fl, *next;
u32 nsmstate;
daemonize("%s-reclaim", host->h_name);
allow_signal(SIGKILL);
/* This one ensures that our parent doesn't terminate while the
* reclaim is in progress */
lock_kernel();
lockd_up(0); /* note: this cannot fail as lockd is already running */
nlmclnt_prepare_reclaim(host);
/* First, reclaim all locks that have been marked. */
restart:
nsmstate = host->h_nsmstate;
list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
list_del_init(&fl->fl_u.nfs_fl.list);
if (signalled())
continue;
if (nlmclnt_reclaim(host, fl) != 0)
continue;
list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
if (host->h_nsmstate != nsmstate) {
/* Argh! The server rebooted again! */
list_splice_init(&host->h_granted, &host->h_reclaim);
goto restart;
}
}
nlmclnt_finish_reclaim(host);
/* Now, wake up all processes that sleep on a 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);
}
}
/* Release host handle after use */
nlm_release_host(host);
lockd_down();
unlock_kernel();
module_put_and_exit(0);
}
