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/*
* linux/fs/lockd/clntlock.c
*
* Lock handling for the client side NLM implementation
*
* Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
*/
#define __KERNEL_SYSCALLS__
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/nfs_fs.h>
#include <linux/unistd.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_CIENT
/*
* 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 nlm_wait * b_next; /* 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 struct nlm_wait * nlm_blocked;
/*
* Block on a lock
*/
int
nlmclnt_block(struct nlm_host *host, struct file_lock *fl, u32 *statp)
{
struct nlm_wait block, **head;
int err;
u32 pstate;
block.b_host = host;
block.b_lock = fl;
init_waitqueue_head(&block.b_wait);
block.b_status = NLM_LCK_BLOCKED;
block.b_next = nlm_blocked;
nlm_blocked = █
/* Remember pseudo nsm state */
pstate = host->h_state;
/* 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.
*/
sleep_on_timeout(&block.b_wait, 30*HZ);
for (head = &nlm_blocked; *head; head = &(*head)->b_next) {
if (*head == &block) {
*head = block.b_next;
break;
}
}
if (!signalled()) {
*statp = block.b_status;
return 0;
}
/* Okay, we were interrupted. Cancel the pending request
* unless the server has rebooted.
*/
if (pstate == host->h_state && (err = nlmclnt_cancel(host, fl)) < 0)
printk(KERN_NOTICE
"lockd: CANCEL call failed (errno %d)\n", -err);
return -ERESTARTSYS;
}
/*
* The server lockd has called us back to tell us the lock was granted
*/
u32
nlmclnt_grant(struct nlm_lock *lock)
{
struct nlm_wait *block;
/*
* Look up blocked request based on arguments.
* Warning: must not use cookie to match it!
*/
for (block = nlm_blocked; block; block = block->b_next) {
if (nlm_compare_locks(block->b_lock, &lock->fl))
break;
}
/* Ooops, no blocked request found. */
if (block == NULL)
return nlm_lck_denied;
/* Alright, we found the lock. Set the return status and
* wake up the caller.
*/
block->b_status = NLM_LCK_GRANTED;
wake_up(&block->b_wait);
return nlm_granted;
}
/*
* 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.
* FIXME: should bump MOD_USE_COUNT while reclaiming
*/
void
nlmclnt_recovery(struct nlm_host *host, u32 newstate)
{
if (!host->h_reclaiming++) {
if (host->h_nsmstate == newstate)
return;
printk(KERN_WARNING
"lockd: Uh-oh! Interfering reclaims for host %s",
host->h_name);
host->h_monitored = 0;
host->h_nsmstate = newstate;
host->h_state++;
nlm_release_host(host);
} else {
host->h_monitored = 0;
host->h_nsmstate = newstate;
host->h_state++;
nlm_get_host(host);
kernel_thread(reclaimer, host, 0);
}
}
static int
reclaimer(void *ptr)
{
struct nlm_host *host = (struct nlm_host *) ptr;
struct nlm_wait *block;
struct list_head *tmp;
/* This one ensures that our parent doesn't terminate while the
* reclaim is in progress */
lock_kernel();
lockd_up();
/* First, reclaim all locks that have been granted previously. */
restart:
tmp = file_lock_list.next;
while (tmp != &file_lock_list) {
struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link);
struct inode *inode = fl->fl_file->f_dentry->d_inode;
if (inode->i_sb->s_magic == NFS_SUPER_MAGIC &&
nlm_cmp_addr(NFS_ADDR(inode), &host->h_addr) &&
fl->fl_u.nfs_fl.state != host->h_state &&
(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED)) {
fl->fl_u.nfs_fl.flags &= ~ NFS_LCK_GRANTED;
nlmclnt_reclaim(host, fl); /* This sleeps */
goto restart;
}
tmp = tmp->next;
}
host->h_reclaiming = 0;
wake_up(&host->h_gracewait);
/* Now, wake up all processes that sleep on a blocked lock */
for (block = nlm_blocked; block; block = block->b_next) {
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();
return 0;
}
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