Linux 4.3 compat: bio_end_io_t / BIO_UPTODATE

Commit torvalds/linux@4246a0b ("block:
add a bi_error field to struct bio") dropped the error argument from
bio_end_io in favor of newly introduced bio->bi_error. This also
replaces bio->bi_flags value BIO_UPTODATE.

bio_end_io was a 3 argument function until Linux 2.6.24, which made it
a 2 argument function, and now the prototype has changed yet again now
to a 1 argument function.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Fixes openzfs#3799

config/kernel-bio-end-io-t-args.m4

@@ -7,6 +7,11 @@ dnl # that partial IO's are no longer possibe and the end_io callback
 dnl # should not check bi->bi_size.  Finally, the return type was updated
 dnl # to void.
 dnl #
+dnl # 4.3 API change
+dnl # Error argument dropped from bio_end_io in favor of newly introduced
+dnl # bio->bi_error. This also replaces bio->bi_flags value BIO_UPTODATE.
+dnl # Introduced by torvalds/linux@4246a0b63bd8f56a1469b12eafeb875b1041a451
+dnl #
 AC_DEFUN([ZFS_AC_KERNEL_BIO_END_IO_T_ARGS], [
 	AC_MSG_CHECKING([whether bio_end_io_t wants 2 args])
 	ZFS_LINUX_TRY_COMPILE([
@@ -22,5 +27,20 @@ AC_DEFUN([ZFS_AC_KERNEL_BIO_END_IO_T_ARGS], [
 		          [bio_end_io_t wants 2 args])
 	],[
 		AC_MSG_RESULT(no)
+		AC_MSG_CHECKING([whether bio_end_io_t wants 1 args])
+		ZFS_LINUX_TRY_COMPILE([
+			#include <linux/bio.h>
+
+			void wanted_end_io(struct bio *bio) { return; }
+
+			bio_end_io_t *end_io __attribute__ ((unused)) =
+				wanted_end_io;
+		],[
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_1ARGS_BIO_END_IO_T, 1,
+		          [bio_end_io_t wants 1 args])
+		],[
+			AC_MSG_RESULT(no)
+		])
 	])
 ])

include/linux/blkdev_compat.h

@@ -182,11 +182,14 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
 #endif /* DISK_NAME_LEN */
 
 /*
- * 2.6.24 API change,
+ * 2.6.24 and 4.3 API change,
  * The bio_end_io() prototype changed slightly.  These are helper
  * macro's to ensure the prototype and return value are handled.
  */
-#ifdef HAVE_2ARGS_BIO_END_IO_T
+#ifdef HAVE_1ARGS_BIO_END_IO_T
+#define	BIO_END_IO_PROTO(fn, x, y, z)	static void fn(struct bio *x)
+#define	BIO_END_IO_RETURN(rc)		return
+#elif  HAVE_2ARGS_BIO_END_IO_T
 #define	BIO_END_IO_PROTO(fn, x, y, z)	static void fn(struct bio *x, int z)
 #define	BIO_END_IO_RETURN(rc)		return
 #else
@@ -195,7 +198,7 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
 					    unsigned int y, \
 					    int z)
 #define	BIO_END_IO_RETURN(rc)		return rc
-#endif /* HAVE_2ARGS_BIO_END_IO_T */
+#endif /* HAVE_1ARGS_BIO_END_IO_T */
 
 /*
  * 2.6.38 - 2.6.x API,

module/zfs/vdev_disk.c

@@ -428,14 +428,19 @@ BIO_END_IO_PROTO(vdev_disk_physio_completion, bio, size, error)
 {
 	dio_request_t *dr = bio->bi_private;
 	int rc;
+#ifdef HAVE_1ARGS_BIO_END_IO_T
+	int error = bio->bi_error;
+#endif
 
-#ifndef HAVE_2ARGS_BIO_END_IO_T
+#if !defined(HAVE_2ARGS_BIO_END_IO_T) && !defined(HAVE_1ARGS_BIO_END_IO_T)
 	if (BIO_BI_SIZE(bio))
 		return (1);
-#endif /* HAVE_2ARGS_BIO_END_IO_T */
+#endif
 
+#if !defined(HAVE_1ARGS_BIO_END_IO_T)
 	if (error == 0 && !test_bit(BIO_UPTODATE, &bio->bi_flags))
 		error = (-EIO);
+#endif
 
 	if (dr->dr_error == 0)
 		dr->dr_error = -error;