block: reorder the REQ_ flags

Keep the op-specific flag last so that they are clearly separate from
the generic flags.  Various recent commits just kept adding new flags
at the end.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220512061408.1826595-1-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

include/linux/blk_types.h

@@ -408,16 +408,17 @@ enum req_flag_bits {
 	 * work item to avoid such priority inversions.
 	 */
 	__REQ_CGROUP_PUNT,
-
-	/* command specific flags for REQ_OP_WRITE_ZEROES: */
-	__REQ_NOUNMAP,		/* do not free blocks when zeroing */
-
 	__REQ_POLLED,		/* caller polls for completion using bio_poll */
 	__REQ_ALLOC_CACHE,	/* allocate IO from cache if available */
+	__REQ_SWAP,		/* swap I/O */
+	__REQ_DRV,		/* for driver use */
+
+	/*
+	 * Command specific flags, keep last:
+	 */
+	/* for REQ_OP_WRITE_ZEROES: */
+	__REQ_NOUNMAP,		/* do not free blocks when zeroing */
 
-	/* for driver use */
-	__REQ_DRV,
-	__REQ_SWAP,		/* swapping request. */
 	__REQ_NR_BITS,		/* stops here */
 };