Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 5ca1d21..3ee0678 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -269,6 +269,7 @@
 #define BTRFS_FEATURE_INCOMPAT_RAID56		(1ULL << 7)
 #define BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA	(1ULL << 8)
 #define BTRFS_FEATURE_INCOMPAT_NO_HOLES		(1ULL << 9)
+#define BTRFS_FEATURE_INCOMPAT_METADATA_UUID	(1ULL << 10)
 
 struct btrfs_ioctl_feature_flags {
 	__u64 compat_flags;
@@ -664,7 +665,12 @@
 	/* out values: */
 	__u64 values[BTRFS_DEV_STAT_VALUES_MAX];
 
-	__u64 unused[128 - 2 - BTRFS_DEV_STAT_VALUES_MAX]; /* pad to 1k */
+	/*
+	 * This pads the struct to 1032 bytes. It was originally meant to pad to
+	 * 1024 bytes, but when adding the flags field, the padding calculation
+	 * was not adjusted.
+	 */
+	__u64 unused[128 - 2 - BTRFS_DEV_STAT_VALUES_MAX];
 };
 
 #define BTRFS_QUOTA_CTL_ENABLE	1
@@ -836,6 +842,8 @@
 				   struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_SCAN_DEV _IOW(BTRFS_IOCTL_MAGIC, 4, \
 				   struct btrfs_ioctl_vol_args)
+#define BTRFS_IOC_FORGET_DEV _IOW(BTRFS_IOCTL_MAGIC, 5, \
+				   struct btrfs_ioctl_vol_args)
 /* trans start and trans end are dangerous, and only for
  * use by applications that know how to avoid the
  * resulting deadlocks
@@ -914,10 +922,8 @@
 #define BTRFS_IOC_QUOTA_RESCAN_STATUS _IOR(BTRFS_IOCTL_MAGIC, 45, \
 			       struct btrfs_ioctl_quota_rescan_args)
 #define BTRFS_IOC_QUOTA_RESCAN_WAIT _IO(BTRFS_IOCTL_MAGIC, 46)
-#define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 49, \
-				   char[BTRFS_LABEL_SIZE])
-#define BTRFS_IOC_SET_FSLABEL _IOW(BTRFS_IOCTL_MAGIC, 50, \
-				   char[BTRFS_LABEL_SIZE])
+#define BTRFS_IOC_GET_FSLABEL 	FS_IOC_GETFSLABEL
+#define BTRFS_IOC_SET_FSLABEL	FS_IOC_SETFSLABEL
 #define BTRFS_IOC_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \
 				      struct btrfs_ioctl_get_dev_stats)
 #define BTRFS_IOC_DEV_REPLACE _IOWR(BTRFS_IOCTL_MAGIC, 53, \