1. test_bit was used to return true boolean value, if
   BIO_UPTODATE bit of bio->bi_flags is set. But the same
   job can be done by checking bio->bi_error, implemented in
   linux kernel 4.3 and above. If bio->bi_error is set, then 
   it denotes error.

Ref: https://github.com/torvalds/linux/commit/4246a0b63bd8f56a1469b12eafeb875b1041a451

It solves below build error:
-- snip --
iscsitarget-1.4.20.3+svn502/kernel/block-io.c:40:19: error: 'BIO_UPTODATE' undeclared (first use in this function)
   error = test_bit(BIO_UPTODATE, &bio->bi_flags) ? error : -EIO;
-- CUT --

2. bio can always be filled to a maximum value of BIO_MAX_PAGES, 
   so no need to check for min value for linux kernel 4.3 and above.

Ref: https://github.com/torvalds/linux/commit/b54ffb73cadcdcff9cc1ae0e11f502407e3e2e4c

It solves below build error:
-- snip --
iscsitarget-1.4.20.3+svn502/kernel/block-io.c:80:15: error: implicit declaration of function 'bio_get_nr_vecs' [-Werror=implicit-function-declaration]
    max_pages = bio_get_nr_vecs(bio_data->bdev);
-- CUT --

Upstream-Status: Pending

Signed-off-by: Jagadeesh Krishnanjanappa <jkrishnanjanappa@mvista.com>

diff -Naurp iscsitarget-1.4.20.3+svn502_org/kernel/block-io.c iscsitarget-1.4.20.3+svn502/kernel/block-io.c
--- iscsitarget-1.4.20.3+svn502_org/kernel/block-io.c	2016-04-01 09:07:12.891810059 +0530
+++ iscsitarget-1.4.20.3+svn502/kernel/block-io.c	2016-04-01 09:15:59.076469313 +0530
@@ -33,7 +33,11 @@ static void blockio_bio_endio(struct bio
 {
 	struct tio_work *tio_work = bio->bi_private;
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 3, 0)
+	error = bio->bi_error ? -EIO : error;
+#else
 	error = test_bit(BIO_UPTODATE, &bio->bi_flags) ? error : -EIO;
+#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 3, 0) */	
 
 	if (error)
 		atomic_set(&tio_work->error, error);
@@ -61,6 +65,10 @@ blockio_make_request(struct iet_volume *
 	u32 size = tio->size;
 	u32 tio_index = 0;
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 3, 0)
+	int err = 0;
+	loff_t ppos = tio->offset;	
+#else	
 	int max_pages = 1;
 	int err = 0;
 
@@ -69,6 +77,7 @@ blockio_make_request(struct iet_volume *
 	/* Calculate max_pages for bio_alloc (memory saver) */
 	if (bdev_q)
 		max_pages = bio_get_nr_vecs(bio_data->bdev);
+#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 3, 0) */
 
 	tio_work = kzalloc(sizeof (*tio_work), GFP_KERNEL);
 	if (!tio_work)
@@ -80,7 +89,11 @@ blockio_make_request(struct iet_volume *
 
 	/* Main processing loop, allocate and fill all bios */
 	while (size && tio_index < tio->pg_cnt) {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 3, 0)
+		bio = bio_alloc(GFP_KERNEL, BIO_MAX_PAGES);
+#else    		
 		bio = bio_alloc(GFP_KERNEL, min(max_pages, BIO_MAX_PAGES));
+#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 3, 0) */		
 		if (!bio) {
 			err = -ENOMEM;
 			goto out;