ext4: add a new spinlock i_raw_lock to protect the ext4's raw inode

To avoid potential data races, use a spinlock which protects the raw
(on-disk) inode.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

fs/ext4/ext4.h

@@ -875,6 +875,8 @@ struct ext4_inode_info {
 	struct inode vfs_inode;
 	struct jbd2_inode *jinode;
 
+	spinlock_t i_raw_lock;	/* protects updates to the raw inode */
+
 	/*
 	 * File creation time. Its function is same as that of
 	 * struct timespec i_{a,c,m}time in the generic inode.