Linux 5.7 compat: blk_alloc_queue()

Commit torvalds/linux@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 <mail@gmelikov.ru>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes openzfs#10181
Closes openzfs#10187

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

config/kernel-make-request-fn.m4

@@ -25,23 +25,37 @@ 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)
-
 		dnl #
 		dnl # Linux 3.2 API Change
 		dnl # make_request_fn returns void.
@@ -70,7 +84,20 @@ AC_DEFUN([ZFS_AC_KERNEL_MAKE_REQUEST_FN], [
 				    [Noting that make_request_fn() ]
 				    [returns blk_qc_t])
 			],[
-				ZFS_LINUX_TEST_ERROR([make_request_fn])
+				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])
+				])
 			])
 		])
 	])

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 */

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. */