/*
* 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_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, jiffies + 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, jiffies + 30 * HZ);
/* Call the client */
nlmclnt_async_call(&block->b_call, NLMPROC_GRANTED_MSG,
nlmsvc_grant_callback);
up(&file->f_sema);
}
/*
* Attempt to establish a lock, and if it can't be granted, block it
* if required.
*/
u32
nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
struct nlm_lock *lock, int wait, u32 cookie)
{
struct file_lock *conflock;
struct nlm_block *block;
int error;
dprintk("lockd: nlmsvc_lock(%04x/%ld, ty=%d, pi=%d, %ld-%ld, bl=%d)\n",
file->f_file.f_dentry->d_inode->i_dev,
file->f_file.f_dentry->d_inode->i_ino,
lock->fl.fl_type, lock->fl.fl_pid,
lock->fl.fl_start,
lock->fl.fl_end,
wait);
/* Lock file against concurrent access */
down(&file->f_sema);
/* Get existing block (in case client is busy-waiting) */
block = nlmsvc_lookup_block(file, lock, 0);
lock->fl.fl_flags |= FL_LOCKD;
again:
if (!(conflock = posix_test_lock(&file->f_file, &lock->fl))) {
error = posix_lock_file(&file->f_file, &lock->fl, 0);
if (block)
nlmsvc_delete_block(block, 0);
up(&file->f_sema);
dprintk("lockd: posix_lock_file returned %d\n", -error);
switch(-error) {
case 0:
return nlm_granted;
case EDEADLK: /* no applicable NLM status */
case EAGAIN:
return nlm_lck_denied;
default: /* includes ENOLCK */
return nlm_lck_denied_nolocks;
}
}
if (!wait) {
up(&file->f_sema);
return nlm_lck_denied;
}
/* If we don't have a block, create and initialize it. Then
* retry because we may have slept in kmalloc. */
if (block == NULL) {
dprintk("lockd: blocking on this lock (allocating).\n");
if (!(block = nlmsvc_create_block(rqstp, file, lock, cookie)))
return nlm_lck_denied_nolocks;
goto again;
}
/* Append to list of blocked */
nlmsvc_insert_block(block, NLM_NEVER);
/* Now add block to block list of the conflicting lock */
dprintk("lockd: blocking on this lock.\n");
posix_block_lock(conflock, &block->b_call.a_args.lock.fl);
up(&file->f_sema);
return nlm_lck_blocked;
}
/*
* Attempt to establish a lock, and if it can't be granted, block it
* if required.
*/
u32
nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
{
struct file_lock *conflock;
struct nlm_block *block, *nblock = NULL;
int error;
dprintk("lockd: nlmsvc_lock(%04x/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
file->f_file.f_dentry->d_inode->i_dev,
file->f_file.f_dentry->d_inode->i_ino,
lock->fl.fl_type, lock->fl.fl_pid,
(long long)lock->fl.fl_start,
(long long)lock->fl.fl_end,
wait);
/* Get existing block (in case client is busy-waiting) */
block = nlmsvc_lookup_block(file, lock, 0);
lock->fl.fl_flags |= FL_LOCKD;
again:
/* Lock file against concurrent access */
down(&file->f_sema);
if (!(conflock = posix_test_lock(&file->f_file, &lock->fl))) {
error = posix_lock_file(&file->f_file, &lock->fl, 0);
if (block)
nlmsvc_delete_block(block, 0);
up(&file->f_sema);
dprintk("lockd: posix_lock_file returned %d\n", -error);
switch(-error) {
case 0:
return nlm_granted;
case EDEADLK:
return nlm_deadlock;
case EAGAIN:
return nlm_lck_denied;
default: /* includes ENOLCK */
return nlm_lck_denied_nolocks;
}
}
if (!wait) {
up(&file->f_sema);
return nlm_lck_denied;
}
if (posix_locks_deadlock(&lock->fl, conflock)) {
if (nblock)
nlmsvc_delete_block(nblock, 0);
up(&file->f_sema);
return nlm_deadlock;
}
/* If we don't have a block, create and initialize it. Then
* retry because we may have slept in kmalloc. */
/* We have to release f_sema as nlmsvc_create_block may try to
* to claim it while doing host garbage collection */
if (block == NULL) {
up(&file->f_sema);
dprintk("lockd: blocking on this lock (allocating).\n");
if (!(block = nlmsvc_create_block(rqstp, file, lock, cookie)))
return nlm_lck_denied_nolocks;
nblock = block;
goto again;
}
/* Append to list of blocked */
nlmsvc_insert_block(block, NLM_NEVER);
if (list_empty(&block->b_call.a_args.lock.fl.fl_block)) {
/* Now add block to block list of the conflicting lock
if we haven't done so. */
dprintk("lockd: blocking on this lock.\n");
posix_block_lock(conflock, &block->b_call.a_args.lock.fl);
}
up(&file->f_sema);
return nlm_lck_blocked;
}
