nixpkgs/pkgs/os-specific/linux/zfs/BACKPORT-Linux-5.8-compat-__vmalloc.patch

From 6cc95288ccea12ad7b67b2b5b3997dfad8e5b5c9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20Niew=C3=B6hner?=
 <c0d3z3r0@users.noreply.github.com>
Date: Tue, 9 Jun 2020 01:32:02 +0200
Subject: [PATCH] BACKPORT: Linux 5.8 compat: __vmalloc()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The `pgprot` argument has been removed from `__vmalloc` in Linux 5.8,
being `PAGE_KERNEL` always now [1].

Detect this during configure and define a wrapper for older kernels.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/mm/vmalloc.c?h=next-20200605&id=88dca4ca5a93d2c09e5bbc6a62fbfc3af83c4fca

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Co-authored-by: Michael Niewöhner <foss@mniewoehner.de>
Signed-off-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Closes #10422
---
 config/kernel-kmem.m4       | 26 ++++++++++++++++++++++++++
 config/kernel.m4            |  2 ++
 include/spl/sys/kmem.h      |  9 +++++++++
 module/spl/spl-kmem-cache.c |  4 ++--
 module/spl/spl-kmem.c       |  9 ++++-----
 5 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/config/kernel-kmem.m4 b/config/kernel-kmem.m4
index cc055e530..f1c0d2412 100644
--- a/config/kernel-kmem.m4
+++ b/config/kernel-kmem.m4
@@ -56,3 +56,29 @@ AC_DEFUN([SPL_AC_DEBUG_KMEM_TRACKING], [
 	AC_MSG_CHECKING([whether detailed kmem tracking is enabled])
 	AC_MSG_RESULT([$enable_debug_kmem_tracking])
 ])
+
+dnl #
+dnl # 5.8 API,
+dnl # __vmalloc PAGE_KERNEL removal
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_VMALLOC_PAGE_KERNEL], [
+	ZFS_LINUX_TEST_SRC([__vmalloc], [
+		#include <linux/mm.h>
+		#include <linux/vmalloc.h>
+	],[
+		void *p __attribute__ ((unused));
+
+		p = __vmalloc(0, GFP_KERNEL, PAGE_KERNEL);
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_VMALLOC_PAGE_KERNEL], [
+	AC_MSG_CHECKING([whether __vmalloc(ptr, flags, pageflags) is available])
+	ZFS_LINUX_TEST_RESULT([__vmalloc], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_VMALLOC_PAGE_KERNEL, 1, [__vmalloc page flags exists])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+-
diff --git a/config/kernel.m4 b/config/kernel.m4
index b67fcef8c..23edfdcd8 100644
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -45,6 +45,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
 	ZFS_AC_KERNEL_SRC_SCHED
 	ZFS_AC_KERNEL_SRC_USLEEP_RANGE
 	ZFS_AC_KERNEL_SRC_KMEM_CACHE
+	ZFS_AC_KERNEL_SRC_VMALLOC_PAGE_KERNEL
 	ZFS_AC_KERNEL_SRC_WAIT
 	ZFS_AC_KERNEL_SRC_INODE_TIMES
 	ZFS_AC_KERNEL_SRC_INODE_LOCK
@@ -163,6 +164,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
 	ZFS_AC_KERNEL_SCHED
 	ZFS_AC_KERNEL_USLEEP_RANGE
 	ZFS_AC_KERNEL_KMEM_CACHE
+	ZFS_AC_KERNEL_VMALLOC_PAGE_KERNEL
 	ZFS_AC_KERNEL_WAIT
 	ZFS_AC_KERNEL_INODE_TIMES
 	ZFS_AC_KERNEL_INODE_LOCK
diff --git a/include/spl/sys/kmem.h b/include/spl/sys/kmem.h
index 72d3a7765..ca15bfe7f 100644
--- a/include/spl/sys/kmem.h
+++ b/include/spl/sys/kmem.h
@@ -169,6 +169,15 @@ extern void *spl_kmem_alloc(size_t sz, int fl, const char *func, int line);
 extern void *spl_kmem_zalloc(size_t sz, int fl, const char *func, int line);
 extern void spl_kmem_free(const void *ptr, size_t sz);
 
+/*
+ * 5.8 API change, pgprot_t argument removed.
+ */
+#ifdef HAVE_VMALLOC_PAGE_KERNEL
+#define	spl_vmalloc(size, flags)	__vmalloc(size, flags, PAGE_KERNEL)
+#else
+#define	spl_vmalloc(size, flags)	__vmalloc(size, flags)
+#endif
+
 /*
  * The following functions are only available for internal use.
  */
diff --git a/module/spl/spl-kmem-cache.c b/module/spl/spl-kmem-cache.c
index d71b4b348..4866b2993 100644
--- a/module/spl/spl-kmem-cache.c
+++ b/module/spl/spl-kmem-cache.c
@@ -203,7 +203,7 @@ kv_alloc(spl_kmem_cache_t *skc, int size, int flags)
 		ASSERT(ISP2(size));
 		ptr = (void *)__get_free_pages(lflags, get_order(size));
 	} else {
-		ptr = __vmalloc(size, lflags | __GFP_HIGHMEM, PAGE_KERNEL);
+		ptr = spl_vmalloc(size, lflags | __GFP_HIGHMEM);
 	}
 
 	/* Resulting allocated memory will be page aligned */
@@ -1242,7 +1242,7 @@ spl_cache_grow(spl_kmem_cache_t *skc, int flags, void **obj)
 	 * allocation.
 	 *
 	 * However, this can't be applied to KVM_VMEM due to a bug that
-	 * __vmalloc() doesn't honor gfp flags in page table allocation.
+	 * spl_vmalloc() doesn't honor gfp flags in page table allocation.
 	 */
 	if (!(skc->skc_flags & KMC_VMEM)) {
 		rc = __spl_cache_grow(skc, flags | KM_NOSLEEP);
diff --git a/module/spl/spl-kmem.c b/module/spl/spl-kmem.c
index cee69ad43..ca1fc145f 100644
--- a/module/spl/spl-kmem.c
+++ b/module/spl/spl-kmem.c
@@ -172,16 +172,15 @@ spl_kmem_alloc_impl(size_t size, int flags, int node)
 		 * kmem_zalloc() callers.
 		 *
 		 * For vmem_alloc() and vmem_zalloc() callers it is permissible
-		 * to use __vmalloc().  However, in general use of __vmalloc()
-		 * is strongly discouraged because a global lock must be
-		 * acquired.  Contention on this lock can significantly
+		 * to use spl_vmalloc().  However, in general use of
+		 * spl_vmalloc() is strongly discouraged because a global lock
+		 * must be acquired.  Contention on this lock can significantly
 		 * impact performance so frequently manipulating the virtual
 		 * address space is strongly discouraged.
 		 */
 		if ((size > spl_kmem_alloc_max) || use_vmem) {
 			if (flags & KM_VMEM) {
-				ptr = __vmalloc(size, lflags | __GFP_HIGHMEM,
-				    PAGE_KERNEL);
+				ptr = spl_vmalloc(size, lflags | __GFP_HIGHMEM);
 			} else {
 				return (NULL);
 			}
-- 
2.25.1