/*
* 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);
}
/*
* Delete a block. If the lock was cancelled or the grant callback
* failed, unlock is set to 1.
* It is the caller's responsibility to check whether the file
* can be closed hereafter.
*/
static void
nlmsvc_delete_block(struct nlm_block *block, int unlock)
{
struct file_lock *fl = &block->b_call.a_args.lock.fl;
struct nlm_file *file = block->b_file;
struct nlm_block **bp;
dprintk("lockd: deleting block %p...\n", block);
/* Remove block from list */
nlmsvc_remove_block(block);
posix_unblock_lock(&file->f_file, fl);
block->b_granted = 0;
/* If the block is in the middle of a GRANT callback,
* don't kill it yet. */
if (block->b_incall) {
nlmsvc_insert_block(block, NLM_NEVER);
block->b_done = 1;
return;
}
/* Remove block from file's list of blocks */
for (bp = &file->f_blocks; *bp; bp = &(*bp)->b_fnext) {
if (*bp == block) {
*bp = block->b_fnext;
break;
}
}
if (block->b_host)
nlm_release_host(block->b_host);
nlmclnt_freegrantargs(&block->b_call);
kfree(block);
}
/*
* Insert a blocked lock into the global list
*/
static void
nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
{
struct nlm_block **bp, *b;
dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
if (block->b_queued)
nlmsvc_remove_block(block);
for (bp = &nlm_blocked; (b = *bp); bp = &b->b_next)
if (when < b->b_when)
break;
block->b_queued = 1;
block->b_when = when;
block->b_next = b;
*bp = block;
}
/*
* Insert a blocked lock into the global list
*/
static void
nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
{
struct nlm_block **bp, *b;
dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
if (block->b_queued)
nlmsvc_remove_block(block);
bp = &nlm_blocked;
if (when != NLM_NEVER) {
if ((when += jiffies) > NLM_NEVER)
when = NLM_NEVER;
while ((b = *bp) && time_before_eq(b->b_when,when) && b->b_when != NLM_NEVER)
bp = &b->b_next;
} else
while ((b = *bp))
bp = &b->b_next;
block->b_queued = 1;
block->b_when = when;
block->b_next = b;
*bp = block;
}