locks: encapsulate the fl_link list handling

Move the fl_link list handling routines into a separate set of helpers.
Also ensure that locks and requests are always put on global lists
last (after fully initializing them) and are taken off before unintializing
them.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/locks.c b/fs/locks.c
index 1d6cb28..89d898b 100644 (file)
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -153,13 +153,15 @@ int lease_break_time = 45;
 #define for_each_lock(inode, lockp) \
        for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
 
+/* The global file_lock_list is only used for displaying /proc/locks. */
 static LIST_HEAD(file_lock_list);
+
+/* The blocked_list is used to find POSIX lock loops for deadlock detection. */
 static LIST_HEAD(blocked_list);
+
+/* Protects the two list heads above, plus the inode->i_flock list */
 static DEFINE_SPINLOCK(file_lock_lock);
 
-/*
- * Protects the two list heads above, plus the inode->i_flock list
- */
 void lock_flocks(void)
 {
        spin_lock(&file_lock_lock);
@@ -484,13 +486,37 @@ static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
        return fl1->fl_owner == fl2->fl_owner;
 }
 
+static inline void
+locks_insert_global_locks(struct file_lock *fl)
+{
+       list_add_tail(&fl->fl_link, &file_lock_list);
+}
+
+static inline void
+locks_delete_global_locks(struct file_lock *fl)
+{
+       list_del_init(&fl->fl_link);
+}
+
+static inline void
+locks_insert_global_blocked(struct file_lock *waiter)
+{
+       list_add(&waiter->fl_link, &blocked_list);
+}
+
+static inline void
+locks_delete_global_blocked(struct file_lock *waiter)
+{
+       list_del_init(&waiter->fl_link);
+}
+
 /* Remove waiter from blocker's block list.
  * When blocker ends up pointing to itself then the list is empty.
  */
 static void __locks_delete_block(struct file_lock *waiter)
 {
+       locks_delete_global_blocked(waiter);
        list_del_init(&waiter->fl_block);
-       list_del_init(&waiter->fl_link);
        waiter->fl_next = NULL;
 }
 
@@ -512,10 +538,10 @@ static void locks_insert_block(struct file_lock *blocker,
                               struct file_lock *waiter)
 {
        BUG_ON(!list_empty(&waiter->fl_block));
-       list_add_tail(&waiter->fl_block, &blocker->fl_block);
        waiter->fl_next = blocker;
+       list_add_tail(&waiter->fl_block, &blocker->fl_block);
        if (IS_POSIX(blocker))
-               list_add(&waiter->fl_link, &blocked_list);
+               locks_insert_global_blocked(request);
 }
 
 /*
@@ -543,13 +569,13 @@ static void locks_wake_up_blocks(struct file_lock *blocker)
  */
 static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
 {
-       list_add(&fl->fl_link, &file_lock_list);
-
        fl->fl_nspid = get_pid(task_tgid(current));
 
        /* insert into file's list */
        fl->fl_next = *pos;
        *pos = fl;
+
+       locks_insert_global_locks(fl);
 }
 
 /*
@@ -562,9 +588,10 @@ static void locks_delete_lock(struct file_lock **thisfl_p)
 {
        struct file_lock *fl = *thisfl_p;
 
+       locks_delete_global_locks(fl);
+
        *thisfl_p = fl->fl_next;
        fl->fl_next = NULL;
-       list_del_init(&fl->fl_link);
 
        if (fl->fl_nspid) {
                put_pid(fl->fl_nspid);