lockd: Convert NLM service fl_owner to nlm_lockowner

Do as the NLM client: allocate and track a struct nlm_lockowner for use as
the fl_owner for locks created by the NLM sever.  This allows us to keep
the svid within this structure for matching locks, and will allow us to
track the pid of lockd in a future patch.  It should also allow easier
reference of the nlm_host in conflicting locks, and simplify lock hashing
and comparison.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
[bfields@redhat.com: fix type of some error returns]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index ea719cdd6a36..34c6ee85274e 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -332,6 +332,93 @@ restart:
 	mutex_unlock(&file->f_mutex);
 }
 
+static struct nlm_lockowner *
+nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
+{
+	refcount_inc(&lockowner->count);
+	return lockowner;
+}
+
+static void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
+{
+	if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
+		return;
+	list_del(&lockowner->list);
+	spin_unlock(&lockowner->host->h_lock);
+	nlmsvc_release_host(lockowner->host);
+	kfree(lockowner);
+}
+
+static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
+{
+	struct nlm_lockowner *lockowner;
+	list_for_each_entry(lockowner, &host->h_lockowners, list) {
+		if (lockowner->pid != pid)
+			continue;
+		return nlmsvc_get_lockowner(lockowner);
+	}
+	return NULL;
+}
+
+static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
+{
+	struct nlm_lockowner *res, *new = NULL;
+
+	spin_lock(&host->h_lock);
+	res = __nlmsvc_find_lockowner(host, pid);
+
+	if (res == NULL) {
+		spin_unlock(&host->h_lock);
+		new = kmalloc(sizeof(*res), GFP_KERNEL);
+		spin_lock(&host->h_lock);
+		res = __nlmsvc_find_lockowner(host, pid);
+		if (res == NULL && new != NULL) {
+			res = new;
+			/* fs/locks.c will manage the refcount through lock_ops */
+			refcount_set(&new->count, 1);
+			new->pid = pid;
+			new->host = nlm_get_host(host);
+			list_add(&new->list, &host->h_lockowners);
+			new = NULL;
+		}
+	}
+
+	spin_unlock(&host->h_lock);
+	kfree(new);
+	return res;
+}
+
+void
+nlmsvc_release_lockowner(struct nlm_lock *lock)
+{
+	if (lock->fl.fl_owner)
+		nlmsvc_put_lockowner(lock->fl.fl_owner);
+}
+
+static void nlmsvc_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
+{
+	struct nlm_lockowner *nlm_lo = (struct nlm_lockowner *)fl->fl_owner;
+	new->fl_owner = nlmsvc_get_lockowner(nlm_lo);
+}
+
+static void nlmsvc_locks_release_private(struct file_lock *fl)
+{
+	nlmsvc_put_lockowner((struct nlm_lockowner *)fl->fl_owner);
+}
+
+const struct file_lock_operations nlmsvc_lock_ops = {
+	.fl_copy_lock = nlmsvc_locks_copy_lock,
+	.fl_release_private = nlmsvc_locks_release_private,
+};
+
+void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
+						pid_t pid)
+{
+	fl->fl_owner = nlmsvc_find_lockowner(host, pid);
+	if (fl->fl_owner != NULL)
+		fl->fl_ops = &nlmsvc_lock_ops;
+}
+
 /*
  * Initialize arguments for GRANTED call. The nlm_rqst structure
  * has been cleared already.
@@ -509,6 +596,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 {
 	int			error;
 	__be32			ret;
+	struct nlm_lockowner	*test_owner;
 
 	dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
 				locks_inode(file->f_file)->i_sb->s_id,
@@ -522,6 +610,9 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 		goto out;
 	}
 
+	/* If there's a conflicting lock, remember to clean up the test lock */
+	test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
+
 	error = vfs_test_lock(file->f_file, &lock->fl);
 	if (error) {
 		/* We can't currently deal with deferred test requests */
@@ -548,6 +639,11 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 	conflock->fl.fl_start = lock->fl.fl_start;
 	conflock->fl.fl_end = lock->fl.fl_end;
 	locks_release_private(&lock->fl);
+
+	/* Clean up the test lock */
+	lock->fl.fl_owner = NULL;
+	nlmsvc_put_lockowner(test_owner);
+
 	ret = nlm_lck_denied;
 out:
 	return ret;