From: Christian Brauner <redacted>

Setting flags on subvolumes or snapshots are core features of btrfs. The
BTRFS_IOC_SUBVOL_SETFLAGS ioctl is especially important as it allows to make
subvolumes and snapshots read-only or read-write. Allow setting flags on btrfs
subvolumes and snapshots on idmapped mounts. This is a fairly straightforward
operation since all the permission checking helpers are already capable of
handling idmapped mounts. So we just need to pass down the mount's userns.

Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Sterba <dsterba@suse.com>
Cc: linux-btrfs@vger.kernel.org
Signed-off-by: Christian Brauner <redacted>
---
 fs/btrfs/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9e6c9dfae981..8c1ca9f05f4f 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c

@@ -1981,7 +1981,7 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
 	u64 flags;
 	int ret = 0;
 
-	if (!inode_owner_or_capable(&init_user_ns, inode))
+	if (!inode_owner_or_capable(file_mnt_user_ns(file), inode))
 		return -EPERM;
 
 	ret = mnt_want_write_file(file);

-- 
2.30.2