Subject: [Saphira] Linux 7.3: iops->create() without flag arg (2.4.4 port)

Saphira-Port-By: Muse Spark 1.3 Contributor for AKADATA LIMITED
(Andrew Smalley, Director)
Note: The API moved; the data must not. Re-derived hunk by hunk
for 2.4.4 and proven by boot, not by inspection.

Ports robn/zfs@d01c2c7fdef8 onto OpenZFS 2.4.4: the new autoconf test is
appended to the existing kernel-inode-create.m4 (2.4.4 already ships one
for the 6.3 idmap change), registered in kernel.m4 like upstream, the
decision checks no-flag FIRST so the old chain never errors on 7.3, and
zpl_create gains the 3-arg branch in 2.4.4 spelling (param keeps the
user_ns name so the body is untouched) plus the shadow-guard extension
upstream master does not need (its refactor removed the fallback).

--- a/config/kernel-inode-create.m4
+++ b/config/kernel-inode-create.m4
@@ -54,6 +54,13 @@
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_CREATE], [
+	AC_MSG_CHECKING([whether iops->create() takes a flag arg])
+	ZFS_LINUX_TEST_RESULT([iops_create_no_flag], [
+		AC_MSG_RESULT(no)
+		AC_DEFINE(HAVE_IOPS_CREATE_NO_FLAG_ARG, 1,
+		    [iops->create() does not take a flag arg])
+	],[
+		AC_MSG_RESULT(yes)
 	AC_MSG_CHECKING([whether iops->create() takes struct mnt_idmap*])
 	ZFS_LINUX_TEST_RESULT([create_mnt_idmap], [
 		AC_MSG_RESULT(yes)
@@ -78,4 +85,31 @@
 			])
 		])
 	])
+	])
 ])
+
+AC_DEFUN([ZFS_AC_KERNEL_SRC_IOPS_CREATE_NO_FLAG], [
+	ZFS_LINUX_TEST_SRC([iops_create_no_flag], [
+		#include <linux/fs.h>
+
+		static int test_iops_create(struct mnt_idmap *idmap,
+		    struct inode *inode, struct dentry *dentry,
+		    umode_t mode) { return 0; }
+
+		static const struct inode_operations test_iops
+		    __attribute__ ((unused)) = {
+			.create = test_iops_create
+		};
+	],[])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_IOPS_CREATE_NO_FLAG], [
+	AC_MSG_CHECKING([whether iops->create() takes a flag arg])
+	ZFS_LINUX_TEST_RESULT([iops_create_no_flag], [
+		AC_MSG_RESULT(no)
+		AC_DEFINE(HAVE_IOPS_CREATE_NO_FLAG_ARG, 1,
+		    [iops->create() does not take a flag arg])
+	],[
+		AC_MSG_RESULT(yes)
+	])
+])
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -63,6 +63,7 @@
 	ZFS_AC_KERNEL_SRC_INODE_STATE_READ_ONCE
 	ZFS_AC_KERNEL_SRC_SHOW_OPTIONS
 	ZFS_AC_KERNEL_SRC_SHRINKER
+	ZFS_AC_KERNEL_SRC_IOPS_CREATE_NO_FLAG
 	ZFS_AC_KERNEL_SRC_MKDIR
 	ZFS_AC_KERNEL_SRC_LOOKUP_FLAGS
 	ZFS_AC_KERNEL_SRC_IDMAP
@@ -188,6 +189,7 @@
 	ZFS_AC_KERNEL_INODE_STATE_READ_ONCE
 	ZFS_AC_KERNEL_SHOW_OPTIONS
 	ZFS_AC_KERNEL_SHRINKER
+	ZFS_AC_KERNEL_IOPS_CREATE_NO_FLAG
 	ZFS_AC_KERNEL_MKDIR
 	ZFS_AC_KERNEL_LOOKUP_FLAGS
 	ZFS_AC_KERNEL_IDMAP
--- a/module/os/linux/zfs/zpl_inode.c
+++ b/module/os/linux/zfs/zpl_inode.c
@@ -165,7 +165,10 @@
 }
 
 static int
-#ifdef HAVE_IOPS_CREATE_USERNS
+#ifdef HAVE_IOPS_CREATE_NO_FLAG_ARG
+zpl_create(struct mnt_idmap *user_ns, struct inode *dir,
+    struct dentry *dentry, umode_t mode)
+#elif defined(HAVE_IOPS_CREATE_USERNS)
 zpl_create(struct user_namespace *user_ns, struct inode *dir,
     struct dentry *dentry, umode_t mode, bool flag)
 #elif defined(HAVE_IOPS_CREATE_IDMAP)
@@ -180,7 +183,7 @@
 	vattr_t *vap;
 	int error;
 	fstrans_cookie_t cookie;
-#if !(defined(HAVE_IOPS_CREATE_USERNS) || defined(HAVE_IOPS_CREATE_IDMAP))
+#if !(defined(HAVE_IOPS_CREATE_USERNS) || defined(HAVE_IOPS_CREATE_IDMAP) || defined(HAVE_IOPS_CREATE_NO_FLAG_ARG))
 	zidmap_t *user_ns = kcred->user_ns;
 #endif