From 5379a405ab4a8a99b520348ac6d3f3d2a7e7ca69 Mon Sep 17 00:00:00 2001
From: Coleman Kane <ckane@colemankane.org>
Date: Sun, 30 Jul 2023 15:50:27 -0400
Subject: [PATCH] Add blk_mode_is_open_write() to test FMODE_WRITE /
 BLK_OPEN_WRITE

The wrapper function is now used for testing using the appropriate
method for the kernel, whether the open mode is writeable or not.

Signed-off-by: Coleman Kane <ckane@colemankane.org>
---
 include/os/linux/kernel/linux/blkdev_compat.h |  6 ++++++
 module/os/linux/zfs/zfs_vnops_os.c            |  2 +-
 module/os/linux/zfs/zpl_ctldir.c              |  2 +-
 module/os/linux/zfs/zvol_os.c                 | 13 +++----------
 4 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/include/os/linux/kernel/linux/blkdev_compat.h b/include/os/linux/kernel/linux/blkdev_compat.h
index e0f20ba32008..05112d699610 100644
--- a/include/os/linux/kernel/linux/blkdev_compat.h
+++ b/include/os/linux/kernel/linux/blkdev_compat.h
@@ -397,6 +397,12 @@ vdev_lookup_bdev(const char *path, dev_t *dev)
 #endif
 }
 
+#if defined(HAVE_BLK_MODE_T)
+#define	blk_mode_is_open_write(flag)	((flag) & BLK_OPEN_WRITE)
+#else
+#define	blk_mode_is_open_write(flag)	((flag) & FMODE_WRITE)
+#endif
+
 /*
  * Kernels without bio_set_op_attrs use bi_rw for the bio flags.
  */
diff --git a/module/os/linux/zfs/zfs_vnops_os.c b/module/os/linux/zfs/zfs_vnops_os.c
index 234c4d5ef0e0..33baac9db06b 100644
--- a/module/os/linux/zfs/zfs_vnops_os.c
+++ b/module/os/linux/zfs/zfs_vnops_os.c
@@ -186,7 +186,7 @@ zfs_open(struct inode *ip, int mode, int flag, cred_t *cr)
 		return (error);
 
 	/* Honor ZFS_APPENDONLY file attribute */
-	if ((mode & FMODE_WRITE) && (zp->z_pflags & ZFS_APPENDONLY) &&
+	if (blk_mode_is_open_write(mode) && (zp->z_pflags & ZFS_APPENDONLY) &&
 	    ((flag & O_APPEND) == 0)) {
 		zfs_exit(zfsvfs, FTAG);
 		return (SET_ERROR(EPERM));
diff --git a/module/os/linux/zfs/zpl_ctldir.c b/module/os/linux/zfs/zpl_ctldir.c
index 68a7de78f471..7786444fea35 100644
--- a/module/os/linux/zfs/zpl_ctldir.c
+++ b/module/os/linux/zfs/zpl_ctldir.c
@@ -42,7 +42,7 @@
 static int
 zpl_common_open(struct inode *ip, struct file *filp)
 {
-	if (filp->f_mode & FMODE_WRITE)
+	if (blk_mode_is_open_write(filp->f_mode))
 		return (-EACCES);
 
 	return (generic_file_open(ip, filp));
diff --git a/module/os/linux/zfs/zvol_os.c b/module/os/linux/zfs/zvol_os.c
index 7089890ca598..ff34d8120e97 100644
--- a/module/os/linux/zfs/zvol_os.c
+++ b/module/os/linux/zfs/zvol_os.c
@@ -777,22 +777,15 @@ zvol_open(struct block_device *bdev, fmode_t flag)
 			}
 		}
 
-#ifdef HAVE_BLK_MODE_T
-		error = -zvol_first_open(zv, !(flag & BLK_OPEN_WRITE));
-#else
-		error = -zvol_first_open(zv, !(flag & FMODE_WRITE));
-#endif
+		error = -zvol_first_open(zv, !(blk_mode_is_open_write(flag)));
 
 		if (drop_namespace)
 			mutex_exit(&spa_namespace_lock);
 	}
 
 	if (error == 0) {
-#ifdef HAVE_BLK_MODE_T
-		if ((flag & BLK_OPEN_WRITE) && (zv->zv_flags & ZVOL_RDONLY)) {
-#else
-		if ((flag & FMODE_WRITE) && (zv->zv_flags & ZVOL_RDONLY)) {
-#endif
+		if ((blk_mode_is_open_write(flag)) &&
+		    (zv->zv_flags & ZVOL_RDONLY)) {
 			if (zv->zv_open_count == 0)
 				zvol_last_close(zv);