Linux 5.7 compat: blk_alloc_queue()

Commit https://github.com/torvalds/linux/commit/3d745ea5 simplified
the blk_alloc_queue() interface by updating it to take the request
queue as an argument.  Add a wrapper function which accepts the new
arguments and internally uses the available interfaces.

Other minor changes include increasing the Linux-Maximum to 5.6 now
that 5.6 has been released.  It was not bumped to 5.7 because this
release has not yet been finalized and is still subject to change.

Added local 'struct zvol_state_os *zso' variable to zvol_alloc.

Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Tony Hutter <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #10181
Closes #10187

4 files changed, 57 insertions, 11 deletions

diff --git a/META b/META
index 4871ede9c..357539128 100644
--- a/META
+++ b/META
@@ -6,5 +6,5 @@ Release:       1
 Release-Tags:  relext
 License:       CDDL
 Author:        OpenZFS on Linux
-Linux-Maximum: 5.4
+Linux-Maximum: 5.6
 Linux-Minimum: 2.6.32
diff --git a/config/kernel-make-request-fn.m4 b/config/kernel-make-request-fn.m4
index 86339aa04..d26e12f99 100644
--- a/config/kernel-make-request-fn.m4
+++ b/config/kernel-make-request-fn.m4
@@ -25,20 +25,36 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_MAKE_REQUEST_FN], [
 	],[
 		blk_queue_make_request(NULL, &make_request);
 	])
+
+	ZFS_LINUX_TEST_SRC([blk_alloc_queue_request_fn], [
+		#include <linux/blkdev.h>
+		blk_qc_t make_request(struct request_queue *q,
+		    struct bio *bio) { return (BLK_QC_T_NONE); }
+	],[
+		struct request_queue *q __attribute__ ((unused));
+		q = blk_alloc_queue(make_request, NUMA_NO_NODE);
+	])
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_MAKE_REQUEST_FN], [
 	dnl #
-	dnl # Legacy API
-	dnl # make_request_fn returns int.
+	dnl # Linux 5.7 API Change
+	dnl # blk_alloc_queue() expects request function.
 	dnl #
-	AC_MSG_CHECKING([whether make_request_fn() returns int])
-	ZFS_LINUX_TEST_RESULT([make_request_fn_int], [
+	AC_MSG_CHECKING([whether blk_alloc_queue() expects request function])
+	ZFS_LINUX_TEST_RESULT([blk_alloc_queue_request_fn], [
+		AC_MSG_RESULT(yes)
+
+		dnl # Checked as part of the blk_alloc_queue_request_fn test
+		AC_MSG_CHECKING([whether make_request_fn() returns blk_qc_t])
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(MAKE_REQUEST_FN_RET, int,
+
+		AC_DEFINE(HAVE_BLK_ALLOC_QUEUE_REQUEST_FN, 1,
+		    [blk_alloc_queue() expects request function])
+		AC_DEFINE(MAKE_REQUEST_FN_RET, blk_qc_t,
 		    [make_request_fn() return type])
-		AC_DEFINE(HAVE_MAKE_REQUEST_FN_RET_INT, 1,
-		    [Noting that make_request_fn() returns int])
+		AC_DEFINE(HAVE_MAKE_REQUEST_FN_RET_QC, 1,
+		    [Noting that make_request_fn() returns blk_qc_t])
 	],[
 		AC_MSG_RESULT(no)
 
@@ -70,7 +86,24 @@ AC_DEFUN([ZFS_AC_KERNEL_MAKE_REQUEST_FN], [
 				    [Noting that make_request_fn() ]
 				    [returns blk_qc_t])
 			],[
-				ZFS_LINUX_TEST_ERROR([make_request_fn])
+				AC_MSG_RESULT(no)
+
+				dnl #
+				dnl # Legacy API
+				dnl # make_request_fn returns int.
+				dnl #
+				AC_MSG_CHECKING(
+				    [whether make_request_fn() returns int])
+				ZFS_LINUX_TEST_RESULT([make_request_fn_int], [
+					AC_MSG_RESULT(yes)
+					AC_DEFINE(MAKE_REQUEST_FN_RET, int,
+					    [make_request_fn() return type])
+					AC_DEFINE(HAVE_MAKE_REQUEST_FN_RET_INT,
+					    1, [Noting that make_request_fn() ]
+					    [returns int])
+				],[
+					ZFS_LINUX_TEST_ERROR([make_request_fn])
+				])
 			])
 		])
 	])
diff --git a/include/linux/blkdev_compat.h b/include/linux/blkdev_compat.h
index ace461dc9..f3e97b77b 100644
--- a/include/linux/blkdev_compat.h
+++ b/include/linux/blkdev_compat.h
@@ -669,4 +669,18 @@ blk_generic_end_io_acct(struct request_queue *q, int rw,
 #endif
 }
 
+static inline struct request_queue *
+blk_generic_alloc_queue(make_request_fn make_request, int node_id)
+{
+#if defined(HAVE_BLK_ALLOC_QUEUE_REQUEST_FN)
+	return (blk_alloc_queue(make_request, node_id));
+#else
+	struct request_queue *q = blk_alloc_queue(GFP_KERNEL);
+	if (q != NULL)
+		blk_queue_make_request(q, make_request);
+
+	return (q);
+#endif
+}
+
 #endif /* _ZFS_BLKDEV_H */
diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
index 2d16c4482..7a55403e2 100644
--- a/module/zfs/zvol.c
+++ b/module/zfs/zvol.c
@@ -1703,11 +1703,10 @@ zvol_alloc(dev_t dev, const char *name)
 
 	mutex_init(&zv->zv_state_lock, NULL, MUTEX_DEFAULT, NULL);
 
-	zv->zv_queue = blk_alloc_queue(GFP_ATOMIC);
+	zv->zv_queue = blk_generic_alloc_queue(zvol_request, NUMA_NO_NODE);
 	if (zv->zv_queue == NULL)
 		goto out_kmem;
 
-	blk_queue_make_request(zv->zv_queue, zvol_request);
 	blk_queue_set_write_cache(zv->zv_queue, B_TRUE, B_TRUE);
 
 	/* Limit read-ahead to a single page to prevent over-prefetching. */