Linux 4.8 compat

config/kernel-submit_bio.m4

@@ -0,0 +1,20 @@
+dnl #
+dnl # 4.8 API change
+dnl # The rw argument has been removed from submit_bio/submit_bio_wait.
+dnl # Callers are now expected to set bio->bi_rw instead of passing it in.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SUBMIT_BIO], [
+	AC_MSG_CHECKING([whether submit_bio() wants 1 arg])
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/bio.h>
+	],[
+		blk_qc_t blk_qc;
+		struct bio *bio = NULL;
+		blk_qc = submit_bio(bio);
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_1ARG_SUBMIT_BIO, 1, [submit_bio() wants 1 arg])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])

config/kernel.m4

@@ -8,6 +8,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
 	ZFS_AC_KERNEL_CONFIG
 	ZFS_AC_KERNEL_DECLARE_EVENT_CLASS
 	ZFS_AC_KERNEL_CURRENT_BIO_TAIL
+	ZFS_AC_KERNEL_SUBMIT_BIO
 	ZFS_AC_KERNEL_BDEV_BLOCK_DEVICE_OPERATIONS
 	ZFS_AC_KERNEL_BLOCK_DEVICE_OPERATIONS_RELEASE_VOID
 	ZFS_AC_KERNEL_TYPE_FMODE_T

include/linux/blkdev_compat.h

@@ -305,12 +305,23 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
  * The existence of these flags implies that REQ_FLUSH an REQ_FUA are
  * defined.  Thus we can safely define VDEV_REQ_FLUSH and VDEV_REQ_FUA
  * compatibility macros.
+ *
+ * Linux 4.8 renamed the REQ_FLUSH to REQ_PREFLUSH but there was no
+ * functional change in behavior.
  */
 #ifdef WRITE_FLUSH_FUA
+
 #define	VDEV_WRITE_FLUSH_FUA		WRITE_FLUSH_FUA
+#ifdef REQ_PREFLUSH
+#define	VDEV_REQ_FLUSH			REQ_PREFLUSH
+#define	VDEV_REQ_FUA			REQ_FUA
+#else
 #define	VDEV_REQ_FLUSH			REQ_FLUSH
 #define	VDEV_REQ_FUA			REQ_FUA
+#endif
+
 #else
+
 #define	VDEV_WRITE_FLUSH_FUA		WRITE_BARRIER
 #ifdef HAVE_BIO_RW_BARRIER
 #define	VDEV_REQ_FLUSH			(1 << BIO_RW_BARRIER)
@@ -319,18 +330,34 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
 #define	VDEV_REQ_FLUSH			REQ_HARDBARRIER
 #define	VDEV_REQ_FUA			REQ_FUA
 #endif
+
 #endif
 
 /*
- * 2.6.32 API change
- * Use the normal I/O patch for discards.
+ * 2.6.28 - 2.6.35 API,
+ *   BIO_RW_DISCARD
+ *
+ * 2.6.36 - 4.7 API,
+ *   REQ_DISCARD
+ *
+ * 4.8 - 4.x API,
+ *   REQ_OP_DISCARD
+ *
+ * In all cases the normal I/O path is used for discards.  The only
+ * difference is how the kernel tags individual I/Os as discards.
  */
 #ifdef QUEUE_FLAG_DISCARD
-#ifdef HAVE_BIO_RW_DISCARD
-#define	VDEV_REQ_DISCARD		(1 << BIO_RW_DISCARD)
+static inline boolean_t
+bio_is_discard(struct bio *bio)
+{
+#if defined(HAVE_BIO_RW_DISCARD)
+	return (bio->bi_rw & (1 << BIO_RW_DISCARD));
+#elif defined(REQ_DISCARD)
+	return (bio->bi_rw & REQ_DISCARD);
 #else
-#define	VDEV_REQ_DISCARD		REQ_DISCARD
+	return (bio_op(bio) == REQ_OP_DISCARD);
 #endif
+}
 #else
 #error	"Allowing the build will cause discard requests to become writes "
 	"potentially triggering the DMU_MAX_ACCESS assertion. Please file a "

module/zfs/vdev_disk.c

@@ -484,18 +484,29 @@ bio_map(struct bio *bio, void *bio_ptr, unsigned int bio_size)
 	return (bio_size);
 }
 
+static inline void
+vdev_submit_bio_impl(int rw, struct bio *bio)
+{
+#ifdef HAVE_1ARG_SUBMIT_BIO
+	bio->bi_rw |= rw;
+	submit_bio(bio);
+#else
+	submit_bio(rw, bio);
+#endif
+}
+
 static inline void
 vdev_submit_bio(int rw, struct bio *bio)
 {
 #ifdef HAVE_CURRENT_BIO_TAIL
 	struct bio **bio_tail = current->bio_tail;
 	current->bio_tail = NULL;
-	submit_bio(rw, bio);
+	vdev_submit_bio_impl(rw, bio);
 	current->bio_tail = bio_tail;
 #else
 	struct bio_list *bio_list = current->bio_list;
 	current->bio_list = NULL;
-	submit_bio(rw, bio);
+	vdev_submit_bio_impl(rw, bio);
 	current->bio_list = bio_list;
 #endif
 }

module/zfs/zvol.c

@@ -812,7 +812,7 @@ zvol_request(struct request_queue *q, struct bio *bio)
 			goto out2;
 		}
 
-		if (bio->bi_rw & VDEV_REQ_DISCARD) {
+		if (bio_is_discard(bio)) {
 			error = zvol_discard(bio);
 			goto out2;
 		}