[PATCH v5 06/28] btrfs: disallow NODATACOW in HMZONED 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: Naohiro Aota <naohiro.aota@wdc.com>
---
 fs/btrfs/hmzoned.c | 6 ++++++
 fs/btrfs/ioctl.c   | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/fs/btrfs/hmzoned.c b/fs/btrfs/hmzoned.c
index 1c015ed050fc..e890d2ab8cd9 100644
--- a/fs/btrfs/hmzoned.c
+++ b/fs/btrfs/hmzoned.c
@@ -269,5 +269,11 @@ int btrfs_check_mountopts_hmzoned(struct btrfs_fs_info *info)
 		return -EINVAL;
 	}
 
+	if (btrfs_test_opt(info, NODATACOW)) {
+		btrfs_err(info,
+		  "cannot enable nodatacow with HMZONED mode");
+		return -EINVAL;
+	}
+
 	return 0;
 }
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a1ee0b775e65..a67421eb8bd5 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -94,6 +94,9 @@ static int btrfs_clone(struct inode *src, struct inode *inode,
 static unsigned int btrfs_mask_fsflags_for_type(struct inode *inode,
 		unsigned int flags)
 {
+	if (btrfs_fs_incompat(btrfs_sb(inode->i_sb), HMZONED))
+		flags &= ~FS_NOCOW_FL;
+
 	if (S_ISDIR(inode->i_mode))
 		return flags;
 	else if (S_ISREG(inode->i_mode))
-- 
2.24.0