Bend zpl_set_acl to permit the new userns* parameter

Just like #12087, the set_acl signature changed with all the bolted-on
*userns parameters, which disabled set_acl usage, and caused #12076.

Turn zpl_set_acl into zpl_set_acl and zpl_set_acl_impl, and add a
new configure test for the new version.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #12076
Closes #12093 

3 files changed, 51 insertions, 14 deletions

diff --git a/config/kernel-acl.m4 b/config/kernel-acl.m4
index e02ce6653..c6da4df24 100644
--- a/config/kernel-acl.m4
+++ b/config/kernel-acl.m4
@@ -189,7 +189,22 @@ dnl #
 dnl # 3.14 API change,
 dnl # Check if inode_operations contains the function set_acl
 dnl #
+dnl # 5.12 API change,
+dnl # set_acl() added a user_namespace* parameter first
+dnl #
 AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_OPERATIONS_SET_ACL], [
+	ZFS_LINUX_TEST_SRC([inode_operations_set_acl_userns], [
+		#include <linux/fs.h>
+
+		int set_acl_fn(struct user_namespace *userns,
+		    struct inode *inode, struct posix_acl *acl,
+		    int type) { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.set_acl = set_acl_fn,
+		};
+	],[])
 	ZFS_LINUX_TEST_SRC([inode_operations_set_acl], [
 		#include <linux/fs.h>
 
@@ -205,11 +220,17 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_OPERATIONS_SET_ACL], [
 
 AC_DEFUN([ZFS_AC_KERNEL_INODE_OPERATIONS_SET_ACL], [
 	AC_MSG_CHECKING([whether iops->set_acl() exists])
-	ZFS_LINUX_TEST_RESULT([inode_operations_set_acl], [
+	ZFS_LINUX_TEST_RESULT([inode_operations_set_acl_userns], [
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_SET_ACL, 1, [iops->set_acl() exists])
+		AC_DEFINE(HAVE_SET_ACL_USERNS, 1, [iops->set_acl() takes 4 args])
 	],[
-		AC_MSG_RESULT(no)
+		ZFS_LINUX_TEST_RESULT([inode_operations_set_acl], [
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_SET_ACL, 1, [iops->set_acl() exists, takes 3 args])
+		],[
+			AC_MSG_RESULT(no)
+		])
 	])
 ])
 
diff --git a/include/os/linux/zfs/sys/zpl.h b/include/os/linux/zfs/sys/zpl.h
index 21825d1f3..54f3fa0fd 100644
--- a/include/os/linux/zfs/sys/zpl.h
+++ b/include/os/linux/zfs/sys/zpl.h
@@ -63,7 +63,12 @@ extern int zpl_xattr_security_init(struct inode *ip, struct inode *dip,
     const struct qstr *qstr);
 #if defined(CONFIG_FS_POSIX_ACL)
 #if defined(HAVE_SET_ACL)
+#if defined(HAVE_SET_ACL_USERNS)
+extern int zpl_set_acl(struct user_namespace *userns, struct inode *ip,
+    struct posix_acl *acl, int type);
+#else
 extern int zpl_set_acl(struct inode *ip, struct posix_acl *acl, int type);
+#endif /* HAVE_SET_ACL_USERNS */
 #endif /* HAVE_SET_ACL */
 extern struct posix_acl *zpl_get_acl(struct inode *ip, int type);
 extern int zpl_init_acl(struct inode *ip, struct inode *dir);
diff --git a/module/os/linux/zfs/zpl_xattr.c b/module/os/linux/zfs/zpl_xattr.c
index 5e35f90df..89ba9de14 100644
--- a/module/os/linux/zfs/zpl_xattr.c
+++ b/module/os/linux/zfs/zpl_xattr.c
@@ -926,11 +926,8 @@ xattr_handler_t zpl_xattr_security_handler = {
  * attribute implemented by filesystems in the kernel." - xattr(7)
  */
 #ifdef CONFIG_FS_POSIX_ACL
-#ifndef HAVE_SET_ACL
-static
-#endif
-int
-zpl_set_acl(struct inode *ip, struct posix_acl *acl, int type)
+static int
+zpl_set_acl_impl(struct inode *ip, struct posix_acl *acl, int type)
 {
 	char *name, *value = NULL;
 	int error = 0;
@@ -1002,6 +999,19 @@ zpl_set_acl(struct inode *ip, struct posix_acl *acl, int type)
 	return (error);
 }
 
+#ifdef HAVE_SET_ACL
+int
+#ifdef HAVE_SET_ACL_USERNS
+zpl_set_acl(struct user_namespace *userns, struct inode *ip,
+    struct posix_acl *acl, int type)
+#else
+zpl_set_acl(struct inode *ip, struct posix_acl *acl, int type)
+#endif /* HAVE_SET_ACL_USERNS */
+{
+	return (zpl_set_acl_impl(ip, acl, type));
+}
+#endif /* HAVE_SET_ACL */
+
 struct posix_acl *
 zpl_get_acl(struct inode *ip, int type)
 {
@@ -1083,7 +1093,7 @@ zpl_init_acl(struct inode *ip, struct inode *dir)
 		umode_t mode;
 
 		if (S_ISDIR(ip->i_mode)) {
-			error = zpl_set_acl(ip, acl, ACL_TYPE_DEFAULT);
+			error = zpl_set_acl_impl(ip, acl, ACL_TYPE_DEFAULT);
 			if (error)
 				goto out;
 		}
@@ -1093,8 +1103,10 @@ zpl_init_acl(struct inode *ip, struct inode *dir)
 		if (error >= 0) {
 			ip->i_mode = mode;
 			zfs_mark_inode_dirty(ip);
-			if (error > 0)
-				error = zpl_set_acl(ip, acl, ACL_TYPE_ACCESS);
+			if (error > 0) {
+				error = zpl_set_acl_impl(ip, acl,
+				    ACL_TYPE_ACCESS);
+			}
 		}
 	}
 out:
@@ -1121,7 +1133,7 @@ zpl_chmod_acl(struct inode *ip)
 
 	error = __posix_acl_chmod(&acl, GFP_KERNEL, ip->i_mode);
 	if (!error)
-		error = zpl_set_acl(ip, acl, ACL_TYPE_ACCESS);
+		error = zpl_set_acl_impl(ip, acl, ACL_TYPE_ACCESS);
 
 	zpl_posix_acl_release(acl);
 
@@ -1250,8 +1262,7 @@ __zpl_xattr_acl_set_access(struct inode *ip, const char *name,
 	} else {
 		acl = NULL;
 	}
-
-	error = zpl_set_acl(ip, acl, type);
+	error = zpl_set_acl_impl(ip, acl, type);
 	zpl_posix_acl_release(acl);
 
 	return (error);
@@ -1291,7 +1302,7 @@ __zpl_xattr_acl_set_default(struct inode *ip, const char *name,
 		acl = NULL;
 	}
 
-	error = zpl_set_acl(ip, acl, type);
+	error = zpl_set_acl_impl(ip, acl, type);
 	zpl_posix_acl_release(acl);
 
 	return (error);