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Commit 5ea0d750 authored by Marc Eshel's avatar Marc Eshel Committed by J. Bruce Fields
Browse files

lockd: handle test_lock deferrals 



Rewrite nlmsvc_testlock() to use the new asynchronous interface: instead of
immediately doing a posix_test_lock(), we first look for a matching block.
If the subsequent test_lock returns anything other than -EINPROGRESS, we
then remove the block we've found and return the results.

If it returns -EINPROGRESS, then we defer the lock request.

In the case where the block we find in the first step has B_QUEUED set,
we bypass the vfs_test_lock entirely, instead using the block to decide how
to respond:
	with nlm_lck_denied if B_TIMED_OUT is set.
	with nlm_granted if B_GOT_CALLBACK is set.
	by dropping if neither B_TIMED_OUT nor B_GOT_CALLBACK is set

Signed-off-by: default avatarMarc Eshel <eshel@almaden.ibm.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
parent 85f3f1b3

fs/lockd/svc4proc.c

+2 −0
Original line number Diff line number Diff line
@@ -100,6 +100,8 @@ nlm4svc_proc_test(struct svc_rqst *rqstp, struct nlm_args *argp, 


	/* Now check for conflicting locks */

	resp->status = nlmsvc_testlock(rqstp, file, &argp->lock, &resp->lock, &resp->cookie);

	if (resp->status == nlm_drop_reply)

		return rpc_drop_reply;



	dprintk("lockd: TEST4          status %d\n", ntohl(resp->status));

	nlm_release_host(host);

fs/lockd/svclock.c

+68 −16
Original line number Diff line number Diff line
@@ -210,6 +210,7 @@ nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file, 
	block->b_daemon = rqstp->rq_server;

	block->b_host   = host;

	block->b_file   = file;

	block->b_fl = NULL;

	file->f_count++;



	/* Add to file's list of blocks */
@@ -446,6 +447,10 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file, 
		struct nlm_lock *lock, struct nlm_lock *conflock,

		struct nlm_cookie *cookie)

{

	struct nlm_block 	*block = NULL;

	int			error;

	__be32			ret;



	dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",

				file->f_file->f_path.dentry->d_inode->i_sb->s_id,

				file->f_file->f_path.dentry->d_inode->i_ino,
@@ -453,10 +458,57 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file, 
				(long long)lock->fl.fl_start,

				(long long)lock->fl.fl_end);



	if (posix_test_lock(file->f_file, &lock->fl)) {

	/* Get existing block (in case client is busy-waiting) */

	block = nlmsvc_lookup_block(file, lock);



	if (block == NULL) {

		struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);



		if (conf == NULL)

			return nlm_granted;

		block = nlmsvc_create_block(rqstp, file, lock, cookie);

		if (block == NULL) {

			kfree(conf);

			return nlm_granted;

		}

		block->b_fl = conf;

	}

	if (block->b_flags & B_QUEUED) {

		dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",

			block, block->b_flags, block->b_fl);

		if (block->b_flags & B_TIMED_OUT) {

			nlmsvc_unlink_block(block);

			return nlm_lck_denied;

		}

		if (block->b_flags & B_GOT_CALLBACK) {

			if (block->b_fl != NULL

					&& block->b_fl->fl_type != F_UNLCK) {

				lock->fl = *block->b_fl;

				goto conf_lock;

			}

			else {

				nlmsvc_unlink_block(block);

				return nlm_granted;

			}

		}

		return nlm_drop_reply;

	}



	error = vfs_test_lock(file->f_file, &lock->fl);

	if (error == -EINPROGRESS)

		return nlmsvc_defer_lock_rqst(rqstp, block);

	if (error) {

		ret = nlm_lck_denied_nolocks;

		goto out;

	}

	if (lock->fl.fl_type == F_UNLCK) {

		ret = nlm_granted;

		goto out;

	}



conf_lock:

	dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",

				lock->fl.fl_type,

				(long long)lock->fl.fl_start,

		lock->fl.fl_type, (long long)lock->fl.fl_start,

		(long long)lock->fl.fl_end);

	conflock->caller = "somehost";	/* FIXME */

	conflock->len = strlen(conflock->caller);
@@ -465,10 +517,11 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file, 
	conflock->fl.fl_type = lock->fl.fl_type;

	conflock->fl.fl_start = lock->fl.fl_start;

	conflock->fl.fl_end = lock->fl.fl_end;

		return nlm_lck_denied;

	}



	return nlm_granted;

	ret = nlm_lck_denied;

out:

	if (block)

		nlmsvc_release_block(block);

	return ret;

}



/*
@@ -549,7 +602,6 @@ nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf, 
	else

		block->b_flags |= B_TIMED_OUT;

	if (conf) {

		block->b_fl = kzalloc(sizeof(struct file_lock), GFP_KERNEL);

		if (block->b_fl)

			locks_copy_lock(block->b_fl, conf);

	}

fs/lockd/svcproc.c

+3 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ cast_to_nlm(__be32 status, u32 vers) 
		case nlm_lck_denied_nolocks:

		case nlm_lck_blocked:

		case nlm_lck_denied_grace_period:

		case nlm_drop_reply:

			break;

		case nlm4_deadlock:

			status = nlm_lck_denied;
@@ -128,6 +129,8 @@ nlmsvc_proc_test(struct svc_rqst *rqstp, struct nlm_args *argp, 


	/* Now check for conflicting locks */

	resp->status = cast_status(nlmsvc_testlock(rqstp, file, &argp->lock, &resp->lock, &resp->cookie));

	if (resp->status == nlm_drop_reply)

		return rpc_drop_reply;



	dprintk("lockd: TEST          status %d vers %d\n",

		ntohl(resp->status), rqstp->rq_vers);