Linux-libre 4.7.1-gnupck-4.7.1-gnu

1 files changed, 11 insertions, 1 deletions

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 61205e3bb..4919aedb5 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -196,6 +196,16 @@ struct btrfs_inode {
 	struct list_head delayed_iput;
 	long delayed_iput_count;
 
+	/*
+	 * To avoid races between lockless (i_mutex not held) direct IO writes
+	 * and concurrent fsync requests. Direct IO writes must acquire read
+	 * access on this semaphore for creating an extent map and its
+	 * corresponding ordered extent. The fast fsync path must acquire write
+	 * access on this semaphore before it collects ordered extents and
+	 * extent maps.
+	 */
+	struct rw_semaphore dio_sem;
+
 	struct inode vfs_inode;
 };
 
@@ -303,7 +313,7 @@ struct btrfs_dio_private {
 	struct bio *dio_bio;
 
 	/*
-	 * The original bio may be splited to several sub-bios, this is
+	 * The original bio may be split to several sub-bios, this is
 	 * done during endio of sub-bios
 	 */
 	int (*subio_endio)(struct inode *, struct btrfs_io_bio *, int);