lockd: stop abusing file_lock_list

Currently lockd directly access the file_lock_list from fs/locks.c.
It does so to mark locks granted or reclaimable.  This is very
suboptimal, because a) lockd needs to poke into locks.c internals, and
b) it needs to iterate over all locks in the system for marking locks
granted or reclaimable.

This patch adds lists for granted and reclaimable locks to the nlm_host
structure instead, and adds locks to those.

nlmclnt_lock:
	now adds the lock to h_granted instead of setting the
	NFS_LCK_GRANTED, still O(1)

nlmclnt_mark_reclaim:
	goes away completely, replaced by a list_splice_init.
	Complexity reduced from O(locks in the system) to O(1)

reclaimer:
	iterates over h_reclaim now, complexity reduced from
	O(locks in the system) to O(locks per nlm_host)

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

4 files changed, 18 insertions, 54 deletions

diff --git a/fs/lockd/clntlock.c b/fs/lockd/clntlock.c
index 8ae79ae..0fc0ee2 100644
--- a/fs/lockd/clntlock.c
+++ b/fs/lockd/clntlock.c
@@ -155,34 +155,6 @@ u32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
  */
 
 /*
- * Mark the locks for reclaiming.
- * FIXME: In 2.5 we don't want to iterate through any global file_lock_list.
- *        Maintain NLM lock reclaiming lists in the nlm_host instead.
- */
-static
-void nlmclnt_mark_reclaim(struct nlm_host *host)
-{
-	struct file_lock *fl;
-	struct inode *inode;
-	struct list_head *tmp;
-
-	list_for_each(tmp, &file_lock_list) {
-		fl = list_entry(tmp, struct file_lock, fl_link);
-
-		inode = fl->fl_file->f_dentry->d_inode;
-		if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
-			continue;
-		if (fl->fl_u.nfs_fl.owner == NULL)
-			continue;
-		if (fl->fl_u.nfs_fl.owner->host != host)
-			continue;
-		if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED))
-			continue;
-		fl->fl_u.nfs_fl.flags |= NFS_LCK_RECLAIM;
-	}
-}
-
-/*
  * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
  * that we mark locks for reclaiming, and that we bump the pseudo NSM state.
  */
@@ -194,7 +166,12 @@ void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate)
 	host->h_state++;
 	host->h_nextrebind = 0;
 	nlm_rebind_host(host);
-	nlmclnt_mark_reclaim(host);
+
+	/*
+	 * Mark the locks for reclaiming.
+	 */
+	list_splice_init(&host->h_granted, &host->h_reclaim);
+
 	dprintk("NLM: reclaiming locks for host %s", host->h_name);
 }
 
@@ -223,9 +200,7 @@ reclaimer(void *ptr)
 {
 	struct nlm_host	  *host = (struct nlm_host *) ptr;
 	struct nlm_wait	  *block;
-	struct list_head *tmp;
-	struct file_lock *fl;
-	struct inode *inode;
+	struct file_lock *fl, *next;
 
 	daemonize("%s-reclaim", host->h_name);
 	allow_signal(SIGKILL);
@@ -237,20 +212,9 @@ reclaimer(void *ptr)
 
 	/* First, reclaim all locks that have been marked. */
 restart:
-	list_for_each(tmp, &file_lock_list) {
-		fl = list_entry(tmp, struct file_lock, fl_link);
-
-		inode = fl->fl_file->f_dentry->d_inode;
-		if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
-			continue;
-		if (fl->fl_u.nfs_fl.owner == NULL)
-			continue;
-		if (fl->fl_u.nfs_fl.owner->host != host)
-			continue;
-		if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM))
-			continue;
+	list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
+		list_del(&fl->fl_u.nfs_fl.list);
 
-		fl->fl_u.nfs_fl.flags &= ~NFS_LCK_RECLAIM;
 		nlmclnt_reclaim(host, fl);
 		if (signalled())
 			break;
diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
index 80ae312..cb46943 100644
--- a/fs/lockd/clntproc.c
+++ b/fs/lockd/clntproc.c
@@ -465,7 +465,6 @@ static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *ho
 {
 	BUG_ON(fl->fl_ops != NULL);
 	fl->fl_u.nfs_fl.state = 0;
-	fl->fl_u.nfs_fl.flags = 0;
 	fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
 	fl->fl_ops = &nlmclnt_lock_ops;
 }
@@ -552,8 +551,8 @@ nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 
 	if (resp->status == NLM_LCK_GRANTED) {
 		fl->fl_u.nfs_fl.state = host->h_state;
-		fl->fl_u.nfs_fl.flags |= NFS_LCK_GRANTED;
 		fl->fl_flags |= FL_SLEEP;
+		list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
 		do_vfs_lock(fl);
 	}
 	status = nlm_stat_to_errno(resp->status);
@@ -619,9 +618,11 @@ nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 	struct nlm_res	*resp = &req->a_res;
 	int		status;
 
-	/* Clean the GRANTED flag now so the lock doesn't get
-	 * reclaimed while we're stuck in the unlock call. */
-	fl->fl_u.nfs_fl.flags &= ~NFS_LCK_GRANTED;
+	/*
+	 * Remove from the granted list now so the lock doesn't get
+	 * reclaimed while we're stuck in the unlock call.
+	 */
+	list_del(&fl->fl_u.nfs_fl.list);
 
 	/*
 	 * Note: the server is supposed to either grant us the unlock
diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index 100e782..f456f8e 100644
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -123,6 +123,8 @@ nlm_lookup_host(int server, struct sockaddr_in *sin,
 	nlm_hosts[hash]    = host;
 	INIT_LIST_HEAD(&host->h_lockowners);
 	spin_lock_init(&host->h_lock);
+	INIT_LIST_HEAD(&host->h_granted);
+	INIT_LIST_HEAD(&host->h_reclaim);
 
 	if (++nrhosts > NLM_HOST_MAX)
 		next_gc = 0;
diff --git a/fs/locks.c b/fs/locks.c
index c83b5db..56f996e 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -139,10 +139,7 @@ int lease_break_time = 45;
 #define for_each_lock(inode, lockp) \
 	for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
 
-LIST_HEAD(file_lock_list);
-
-EXPORT_SYMBOL(file_lock_list);
-
+static LIST_HEAD(file_lock_list);
 static LIST_HEAD(blocked_list);
 
 static kmem_cache_t *filelock_cache;