Merge branch 'x86-microcode-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[pandora-kernel.git] / fs / direct-io.c

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 354cbdb..44a360c 100644 (file)
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -35,7 +35,7 @@
 #include <linux/buffer_head.h>
 #include <linux/rwsem.h>
 #include <linux/uio.h>
-#include <asm/atomic.h>
+#include <linux/atomic.h>
 
 /*
  * How many user pages to map in one call to get_user_pages().  This determines
@@ -293,12 +293,12 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is
        if (dio->end_io && dio->result) {
                dio->end_io(dio->iocb, offset, transferred,
                            dio->map_bh.b_private, ret, is_async);
-       } else if (is_async) {
-               aio_complete(dio->iocb, ret, 0);
+       } else {
+               if (is_async)
+                       aio_complete(dio->iocb, ret, 0);
+               inode_dio_done(dio->inode);
        }
 
-       if (dio->flags & DIO_LOCKING)
-               inode_dio_done(dio->inode);
        return ret;
 }
 
@@ -1185,14 +1185,16 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
  *    For writes this function is called under i_mutex and returns with
  *    i_mutex held, for reads, i_mutex is not held on entry, but it is
  *    taken and dropped again before returning.
- *    The i_dio_count counter keeps track of the number of outstanding
- *    direct I/O requests, and truncate waits for it to reach zero.
- *    New references to i_dio_count must only be grabbed with i_mutex
- *    held.
- *
  *  - if the flags value does NOT contain DIO_LOCKING we don't use any
  *    internal locking but rather rely on the filesystem to synchronize
  *    direct I/O reads/writes versus each other and truncate.
+ *
+ * To help with locking against truncate we incremented the i_dio_count
+ * counter before starting direct I/O, and decrement it once we are done.
+ * Truncate can wait for it to reach zero to provide exclusion.  It is
+ * expected that filesystem provide exclusion between new direct I/O
+ * and truncates.  For DIO_LOCKING filesystems this is done by i_mutex,
+ * but other filesystems need to take care of this on their own.
  */
 ssize_t
 __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
@@ -1270,13 +1272,13 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
                                goto out;
                        }
                }
-
-               /*
-                * Will be decremented at I/O completion time.
-                */
-               atomic_inc(&inode->i_dio_count);
        }
 
+       /*
+        * Will be decremented at I/O completion time.
+        */
+       atomic_inc(&inode->i_dio_count);
+
        /*
         * For file extending writes updating i_size before data
         * writeouts complete can expose uninitialized blocks. So