linux-kernel - [RFC v1 2/5] locks: Split insert/delete block functions into flock/posix parts

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Date:	Fri, 20 Feb 2015 15:39:52 +0100
From:	Daniel Wagner <daniel.wagner@...-carit.de>
To:	Jeff Layton <jlayton@...chiereds.net>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	John Kacur <jkacur@...hat.com>,
	Daniel Wagner <daniel.wagner@...-carit.de>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Alexander Viro <viro@...iv.linux.org.uk>
Subject: [RFC v1 2/5] locks: Split insert/delete block functions into flock/posix parts

The locks_insert/delete_block() functions are used for flock, posix
and leases types. blocked_lock_lock is used to serialize all access to
fl_link, fl_block, fl_next and blocked_hash. Here, we prepare the
stage for using blocked_lock_lock to protect blocked_hash.

Signed-off-by: Daniel Wagner <daniel.wagner@...-carit.de>
Cc: Jeff Layton <jlayton@...chiereds.net>
Cc: "J. Bruce Fields" <bfields@...ldses.org>
Cc: Alexander Viro <viro@...iv.linux.org.uk>
---
 fs/locks.c | 48 ++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 40 insertions(+), 8 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index f63aa92..142e4fd 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -607,11 +607,20 @@ static void locks_delete_global_blocked(struct file_lock *waiter)
  */
 static void __locks_delete_block(struct file_lock *waiter)
 {
-	locks_delete_global_blocked(waiter);
 	list_del_init(&waiter->fl_block);
 	waiter->fl_next = NULL;
 }
 
+/* Posix block variant of __locks_delete_block.
+ *
+ * Must be called with blocked_lock_lock held.
+ */
+static void __locks_delete_posix_block(struct file_lock *waiter)
+{
+	locks_delete_global_blocked(waiter);
+	__locks_delete_block(waiter);
+}
+
 static void locks_delete_block(struct file_lock *waiter)
 {
 	spin_lock(&blocked_lock_lock);
@@ -619,6 +628,13 @@ static void locks_delete_block(struct file_lock *waiter)
 	spin_unlock(&blocked_lock_lock);
 }
 
+static void locks_delete_posix_block(struct file_lock *waiter)
+{
+	spin_lock(&blocked_lock_lock);
+	__locks_delete_posix_block(waiter);
+	spin_unlock(&blocked_lock_lock);
+}
+
 /* Insert waiter into blocker's block list.
  * We use a circular list so that processes can be easily woken up in
  * the order they blocked. The documentation doesn't require this but
@@ -635,7 +651,17 @@ static void __locks_insert_block(struct file_lock *blocker,
 	BUG_ON(!list_empty(&waiter->fl_block));
 	waiter->fl_next = blocker;
 	list_add_tail(&waiter->fl_block, &blocker->fl_block);
-	if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
+}
+
+/* Posix block variant of __locks_insert_block.
+ *
+ * Must be called with flc_lock and blocked_lock_lock held.
+ */
+static void __locks_insert_posix_block(struct file_lock *blocker,
+					struct file_lock *waiter)
+{
+	__locks_insert_block(blocker, waiter);
+	if (!IS_OFDLCK(blocker))
 		locks_insert_global_blocked(waiter);
 }
 
@@ -671,7 +697,10 @@ static void locks_wake_up_blocks(struct file_lock *blocker)
 
 		waiter = list_first_entry(&blocker->fl_block,
 				struct file_lock, fl_block);
-		__locks_delete_block(waiter);
+		if (IS_POSIX(blocker))
+			__locks_delete_posix_block(waiter);
+		else
+			__locks_delete_block(waiter);
 		if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
 			waiter->fl_lmops->lm_notify(waiter);
 		else
@@ -979,7 +1008,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
 			spin_lock(&blocked_lock_lock);
 			if (likely(!posix_locks_deadlock(request, fl))) {
 				error = FILE_LOCK_DEFERRED;
-				__locks_insert_block(fl, request);
+				__locks_insert_posix_block(fl, request);
 			}
 			spin_unlock(&blocked_lock_lock);
 			goto out;
@@ -1180,7 +1209,7 @@ int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
 		if (!error)
 			continue;
 
-		locks_delete_block(fl);
+		locks_delete_posix_block(fl);
 		break;
 	}
 	return error;
@@ -1277,7 +1306,7 @@ int locks_mandatory_area(int read_write, struct inode *inode,
 				continue;
 		}
 
-		locks_delete_block(&fl);
+		locks_delete_posix_block(&fl);
 		break;
 	}
 
@@ -2097,7 +2126,10 @@ static int do_lock_file_wait(struct file *filp, unsigned int cmd,
 		if (!error)
 			continue;
 
-		locks_delete_block(fl);
+		if (IS_POSIX(fl))
+			locks_delete_posix_block(fl);
+		else
+			locks_delete_block(fl);
 		break;
 	}
 
@@ -2461,7 +2493,7 @@ posix_unblock_lock(struct file_lock *waiter)
 
 	spin_lock(&blocked_lock_lock);
 	if (waiter->fl_next)
-		__locks_delete_block(waiter);
+		__locks_delete_posix_block(waiter);
 	else
 		status = -ENOENT;
 	spin_unlock(&blocked_lock_lock);
-- 
2.1.0

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