blktrace: add definitions for blk_user_trace_setup2

Add definitions for a version 2 of the blk_user_trace_setup ioctl. This
new ioctl will enable a different struct layout of the binary data passed
to user-space when using a new version of the blktrace utility requesting
the new struct layout.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/uapi/linux/blktrace_api.h

@@ -129,6 +129,7 @@ enum {
 };
 
 #define BLKTRACE_BDEV_SIZE	32
+#define BLKTRACE_BDEV_SIZE2	64
 
 /*
  * User setup structure passed with BLKTRACESETUP
@@ -143,4 +144,19 @@ struct blk_user_trace_setup {
 	__u32 pid;
 };
 
+/*
+ * User setup structure passed with BLKTRACESETUP2
+ */
+struct blk_user_trace_setup2 {
+	char name[BLKTRACE_BDEV_SIZE2];		/* output */
+	__u64 act_mask;				/* input */
+	__u32 buf_size;				/* input */
+	__u32 buf_nr;				/* input */
+	__u64 start_lba;
+	__u64 end_lba;
+	__u32 pid;
+	__u32 flags;		/* currently unused */
+	__u64 reserved[11];
+};
+
 #endif /* _UAPIBLKTRACE_H */

include/uapi/linux/fs.h

@@ -300,6 +300,7 @@ struct file_attr {
 #define BLKGETDISKSEQ _IOR(0x12,128,__u64)
 /* 130-136 are used by zoned block device ioctls (uapi/linux/blkzoned.h) */
 /* 137-141 are used by blk-crypto ioctls (uapi/linux/blk-crypto.h) */
+#define BLKTRACESETUP2 _IOWR(0x12, 142, struct blk_user_trace_setup2)
 
 #define BMAP_IOCTL 1		/* obsolete - kept for compatibility */
 #define FIBMAP	   _IO(0x00,1)	/* bmap access */

kernel/trace/blktrace.c

@@ -1601,6 +1601,9 @@ static int __init init_blk_tracer(void)
 		return 1;
 	}
 
+	BUILD_BUG_ON(__alignof__(struct blk_user_trace_setup2) %
+		     __alignof__(long));
+
 	return 0;
 }