[PATCH v4 06/14] locks: encapsulate the fl_link list handling

From: Jeff Layton
Date: Fri Jun 21 2013 - 09:02:20 EST


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@xxxxxxxxxx>
---
fs/locks.c | 45 ++++++++++++++++++++++++++++++++++++---------
1 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 1d6cb28..89d898b 100644
--- 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);
--
1.7.1

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