ext3: Don't update superblock write time when filesystem is read-only

[safe/jmp/linux-2.6] / fs / pipe.c

diff --git a/fs/pipe.c b/fs/pipe.c
index 6ddf052..52c4151 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_PARENT);
+               pipe_lock_nested(pipe1, I_MUTEX_CHILD);
+       }
+}
+
 /* 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
@@ -268,6 +302,20 @@ int generic_pipe_buf_confirm(struct pipe_inode_info *info,
        return 0;
 }
 
+/**
+ * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
+ * @pipe:      the pipe that the buffer belongs to
+ * @buf:       the buffer to put a reference to
+ *
+ * Description:
+ *     This function releases a reference to @buf.
+ */
+void generic_pipe_buf_release(struct pipe_inode_info *pipe,
+                             struct pipe_buffer *buf)
+{
+       page_cache_release(buf->page);
+}
+
 static const struct pipe_buf_operations anon_pipe_buf_ops = {
        .can_merge = 1,
        .map = generic_pipe_buf_map,
@@ -667,10 +715,7 @@ pipe_read_fasync(int fd, struct file *filp, int on)
        retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers);
        mutex_unlock(&inode->i_mutex);
 
-       if (retval < 0)
-               return retval;
-
-       return 0;
+       return retval;
 }
 
 
@@ -684,10 +729,7 @@ pipe_write_fasync(int fd, struct file *filp, int on)
        retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers);
        mutex_unlock(&inode->i_mutex);
 
-       if (retval < 0)
-               return retval;
-
-       return 0;
+       return retval;
 }
 
 
@@ -706,11 +748,7 @@ pipe_rdwr_fasync(int fd, struct file *filp, int on)
                        fasync_helper(-1, filp, 0, &pipe->fasync_readers);
        }
        mutex_unlock(&inode->i_mutex);
-
-       if (retval < 0)
-               return retval;
-
-       return 0;
+       return retval;
 }