/*
* This is the generic lockd callback for async RPC calls
*/
static u32
nlm4svc_callback(struct svc_rqst *rqstp, u32 proc, struct nlm_res *resp)
{
struct nlm_host *host;
struct nlm_rqst *call;
if (!(call = nlmclnt_alloc_call()))
return rpc_system_err;
host = nlmclnt_lookup_host(&rqstp->rq_addr,
rqstp->rq_prot, rqstp->rq_vers);
if (!host) {
kfree(call);
return rpc_system_err;
}
call->a_flags = RPC_TASK_ASYNC;
call->a_host = host;
memcpy(&call->a_args, resp, sizeof(*resp));
if (nlmsvc_async_call(call, proc, nlm4svc_callback_exit) < 0)
goto error;
return rpc_success;
error:
kfree(call);
nlm_release_host(host);
return rpc_system_err;
}
/*
* Try to claim a lock that was previously blocked.
*
* Note that we use both the RPC_GRANTED_MSG call _and_ an async
* RPC thread when notifying the client. This seems like overkill...
* Here's why:
* - we don't want to use a synchronous RPC thread, otherwise
* we might find ourselves hanging on a dead portmapper.
* - Some lockd implementations (e.g. HP) don't react to
* RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
*/
static void
nlmsvc_grant_blocked(struct nlm_block *block)
{
struct nlm_file *file = block->b_file;
struct nlm_lock *lock = &block->b_call.a_args.lock;
struct file_lock *conflock;
int error;
dprintk("lockd: grant blocked lock %p\n", block);
/* First thing is lock the file */
down(&file->f_sema);
/* Unlink block request from list */
nlmsvc_remove_block(block);
/* If b_granted is true this means we've been here before.
* Just retry the grant callback, possibly refreshing the RPC
* binding */
if (block->b_granted) {
nlm_rebind_host(block->b_call.a_host);
goto callback;
}
/* Try the lock operation again */
if ((conflock = posix_test_lock(&file->f_file, &lock->fl)) != NULL) {
/* Bummer, we blocked again */
dprintk("lockd: lock still blocked\n");
nlmsvc_insert_block(block, NLM_NEVER);
posix_block_lock(conflock, &lock->fl);
up(&file->f_sema);
return;
}
/* Alright, no conflicting lock. Now lock it for real. If the
* following yields an error, this is most probably due to low
* memory. Retry the lock in a few seconds.
*/
if ((error = posix_lock_file(&file->f_file, &lock->fl, 0)) < 0) {
printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
-error, __FUNCTION__);
nlmsvc_insert_block(block, 10 * HZ);
up(&file->f_sema);
return;
}
callback:
/* Lock was granted by VFS. */
dprintk("lockd: GRANTing blocked lock.\n");
block->b_granted = 1;
block->b_incall = 1;
/* Schedule next grant callback in 30 seconds */
nlmsvc_insert_block(block, 30 * HZ);
/* Call the client */
nlm_get_host(block->b_call.a_host);
if (nlmsvc_async_call(&block->b_call, NLMPROC_GRANTED_MSG,
nlmsvc_grant_callback) < 0)
nlm_release_host(block->b_call.a_host);
up(&file->f_sema);
}
