splice: add helpers for locking pipe inode

There are lots of sequences like this, especially in splice code:

	if (pipe->inode)
		mutex_lock(&pipe->inode->i_mutex);
	/* do something */
	if (pipe->inode)
		mutex_unlock(&pipe->inode->i_mutex);

so introduce helpers which do the conditional locking and unlocking.
Also replace the inode_double_lock() call with a pipe_double_lock()
helper to avoid spreading the use of this functionality beyond the
pipe code.

This patch is just a cleanup, and should cause no behavioral changes.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/fs/inode.c b/fs/inode.c
index d06d6d268de9a12c5fbe9d66bd618c293729e8e9..6ad14a1cd8c9ce6fd7d9b68a3e21d696fbe884c5 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1470,42 +1470,6 @@ static void __wait_on_freeing_inode(struct inode *inode)
        spin_lock(&inode_lock);
 }
 
-/*
- * We rarely want to lock two inodes that do not have a parent/child
- * relationship (such as directory, child inode) simultaneously. The
- * vast majority of file systems should be able to get along fine
- * without this. Do not use these functions except as a last resort.
- */
-void inode_double_lock(struct inode *inode1, struct inode *inode2)
-{
-       if (inode1 == NULL || inode2 == NULL || inode1 == inode2) {
-               if (inode1)
-                       mutex_lock(&inode1->i_mutex);
-               else if (inode2)
-                       mutex_lock(&inode2->i_mutex);
-               return;
-       }
-
-       if (inode1 < inode2) {
-               mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
-               mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
-       } else {
-               mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
-               mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
-       }
-}
-EXPORT_SYMBOL(inode_double_lock);
-
-void inode_double_unlock(struct inode *inode1, struct inode *inode2)
-{
-       if (inode1)
-               mutex_unlock(&inode1->i_mutex);
-
-       if (inode2 && inode2 != inode1)
-               mutex_unlock(&inode2->i_mutex);
-}
-EXPORT_SYMBOL(inode_double_unlock);
-
 static __initdata unsigned long ihash_entries;
 static int __init set_ihash_entries(char *str)
 {

diff --git a/fs/pipe.c b/fs/pipe.c
index 4af7aa521813e89a256016329d306f8a4f6f59ec..13414ec45b8d5b42012d8c5fbd56d54df5a96749 100644 (file)
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -37,6 +37,42 @@
  * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
  */
 
+static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
+{
+       if (pipe->inode)
+               mutex_lock_nested(&pipe->inode->i_mutex, subclass);
+}
+
+void pipe_lock(struct pipe_inode_info *pipe)
+{
+       /*
+        * pipe_lock() nests non-pipe inode locks (for writing to a file)
+        */
+       pipe_lock_nested(pipe, I_MUTEX_PARENT);
+}
+EXPORT_SYMBOL(pipe_lock);
+
+void pipe_unlock(struct pipe_inode_info *pipe)
+{
+       if (pipe->inode)
+               mutex_unlock(&pipe->inode->i_mutex);
+}
+EXPORT_SYMBOL(pipe_unlock);
+
+void pipe_double_lock(struct pipe_inode_info *pipe1,
+                     struct pipe_inode_info *pipe2)
+{
+       BUG_ON(pipe1 == pipe2);
+
+       if (pipe1 < pipe2) {
+               pipe_lock_nested(pipe1, I_MUTEX_PARENT);
+               pipe_lock_nested(pipe2, I_MUTEX_CHILD);
+       } else {
+               pipe_lock_nested(pipe2, I_MUTEX_CHILD);
+               pipe_lock_nested(pipe1, I_MUTEX_PARENT);
+       }
+}
+
 /* Drop the inode semaphore and wait for a pipe event, atomically */
 void pipe_wait(struct pipe_inode_info *pipe)
 {
@@ -47,12 +83,10 @@ void pipe_wait(struct pipe_inode_info *pipe)
         * is considered a noninteractive wait:
         */
        prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
-       if (pipe->inode)
-               mutex_unlock(&pipe->inode->i_mutex);
+       pipe_unlock(pipe);
        schedule();
        finish_wait(&pipe->wait, &wait);
-       if (pipe->inode)
-               mutex_lock(&pipe->inode->i_mutex);
+       pipe_lock(pipe);
 }
 
 static int

diff --cc fs/splice.c
Simple merge

diff --cc include/linux/fs.h
Simple merge

diff --cc include/linux/pipe_fs_i.h
Simple merge