[PATCH v9 08/41] btrfs: disallow NODATACOW in ZONED mode

[Naohiro Aota <naohiro.aota@wdc.com>]

NODATACOW implies overwriting the file data on a device, which is
impossible in sequential required zones. Disable NODATACOW globally with
mount option and per-file NODATACOW attribute by masking FS_NOCOW_FL.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
 fs/btrfs/ioctl.c | 16 ++++++++++++++++
 fs/btrfs/zoned.c |  6 ++++++
 2 files changed, 22 insertions(+)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index ab408a23ba32..e1036a9ce881 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -193,6 +193,18 @@ static int check_fsflags(unsigned int old_flags, unsigned int flags)
 	return 0;
 }
 
+static int check_fsflags_compatible(struct btrfs_fs_info *fs_info,
+				    unsigned int flags)
+{
+	bool zoned = btrfs_is_zoned(fs_info);
+
+	if (zoned && (flags & FS_NOCOW_FL))
+		return -EPERM;
+
+	return 0;
+}
+
+
 static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 {
 	struct inode *inode = file_inode(file);
@@ -230,6 +242,10 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 	if (ret)
 		goto out_unlock;
 
+	ret = check_fsflags_compatible(fs_info, fsflags);
+	if (ret)
+		goto out_unlock;
+
 	binode_flags = binode->flags;
 	if (fsflags & FS_SYNC_FL)
 		binode_flags |= BTRFS_INODE_SYNC;
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 3885fa327049..1939b3ee6c10 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -281,5 +281,11 @@ int btrfs_check_mountopts_zoned(struct btrfs_fs_info *info)
 		return -EOPNOTSUPP;
 	}
 
+	if (btrfs_test_opt(info, NODATACOW)) {
+		btrfs_err(info,
+		  "cannot enable nodatacow with ZONED mode");
+		return -EOPNOTSUPP;
+	}
+
 	return 0;
 }
-- 
2.27.0