renameat2: add EL7 compatibility handling

EL7 has .rename2 op upper in the inode_operations_wrapper, so let's add a wrapping ifdef to dir inode_operations and ifdef the ops assignment too. Configure test lives in kernel-rename.m4 for now, as rename2/EL7 case is the only reason why we need it - for now, until support for tmpfile is needed. then it would me more logical to move this check to a separate file. Signed-off-by: Pavel Snajdr <snajpa@snajpa.net> Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
openzfs · Jun 9, 2021 · 43f2844 · 43f2844
1 parent 54f00e0
commit 43f2844
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diff --git a/config/kernel-rename.m4 b/config/kernel-rename.m4
@@ -36,6 +36,24 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_RENAME], [
 		};
 	],[])
 
+	dnl #
+	dnl # EL7 compatibility
+	dnl #
+	dnl # EL7 has backported renameat2 support, but it's done by defining a
+	dnl # separate iops wrapper structure that takes the .renameat2 function.
+	dnl #
+	ZFS_LINUX_TEST_SRC([dir_inode_operations_wrapper_rename2], [
+		#include <linux/fs.h>
+		int rename2_fn(struct inode *sip, struct dentry *sdp,
+			struct inode *tip, struct dentry *tdp,
+			unsigned int flags) { return 0; }
+
+		static const struct inode_operations_wrapper
+		    iops __attribute__ ((unused)) = {
+			.rename2 = rename2_fn,
+		};
+	],[])
+
 	dnl #
 	dnl # 5.12 API change,
 	dnl #
@@ -78,6 +96,15 @@ AC_DEFUN([ZFS_AC_KERNEL_RENAME], [
 					[iops->rename() wants flags])
 			],[
 				AC_MSG_RESULT(no)
+
+				AC_MSG_CHECKING([whether struct inode_operations_wrapper takes .rename2()])
+				ZFS_LINUX_TEST_RESULT([dir_inode_operations_wrapper_rename2], [
+					AC_MSG_RESULT(yes)
+					AC_DEFINE(HAVE_RENAME2_OPERATIONS_WRAPPER, 1,
+						[struct inode_operations_wrapper takes .rename2()])
+				],[
+					AC_MSG_RESULT(no)
+				])
 			])
 		])
 	])

diff --git a/include/os/linux/zfs/sys/zpl.h b/include/os/linux/zfs/sys/zpl.h
@@ -42,7 +42,11 @@ extern void zpl_vap_init(vattr_t *vap, struct inode *dir,
     umode_t mode, cred_t *cr);
 
 extern const struct inode_operations zpl_inode_operations;
+#ifdef HAVE_RENAME2_OPERATIONS_WRAPPER
+extern const struct inode_operations_wrapper zpl_dir_inode_operations;
+#else
 extern const struct inode_operations zpl_dir_inode_operations;
+#endif
 extern const struct inode_operations zpl_symlink_inode_operations;
 extern const struct inode_operations zpl_special_inode_operations;
 

diff --git a/module/os/linux/zfs/zfs_znode.c b/module/os/linux/zfs/zfs_znode.c
@@ -414,7 +414,12 @@ zfs_inode_set_ops(zfsvfs_t *zfsvfs, struct inode *ip)
 		break;
 
 	case S_IFDIR:
+#ifdef HAVE_RENAME2_OPERATIONS_WRAPPER
+		ip->i_flags |= S_IOPS_WRAPPER;
+		ip->i_op = &zpl_dir_inode_operations.ops;
+#else
 		ip->i_op = &zpl_dir_inode_operations;
+#endif
 		ip->i_fop = &zpl_dir_file_operations;
 		ITOZ(ip)->z_zn_prefetch = B_TRUE;
 		break;

diff --git a/module/os/linux/zfs/zpl_inode.c b/module/os/linux/zfs/zpl_inode.c
@@ -692,7 +692,12 @@ const struct inode_operations zpl_inode_operations = {
 #endif /* CONFIG_FS_POSIX_ACL */
 };
 
+#ifdef HAVE_RENAME2_OPERATIONS_WRAPPER
+const struct inode_operations_wrapper zpl_dir_inode_operations = {
+	.ops = {
+#else
 const struct inode_operations zpl_dir_inode_operations = {
+#endif
 	.create		= zpl_create,
 	.lookup		= zpl_lookup,
 	.link		= zpl_link,
@@ -725,6 +730,10 @@ const struct inode_operations zpl_dir_inode_operations = {
 #endif /* HAVE_SET_ACL */
 	.get_acl	= zpl_get_acl,
 #endif /* CONFIG_FS_POSIX_ACL */
+#ifdef HAVE_RENAME2_OPERATIONS_WRAPPER
+	},
+	.rename2	= zpl_rename2,
+#endif
 };
 
 const struct inode_operations zpl_symlink_inode_operations = {