[PATCH v4 16/21] btrfs/ioctl: allow idmapped BTRFS_IOC_SET_RECEIVED_SUBVOL{_32} ioctl

[Christian Brauner <brauner@kernel.org>]

From: Christian Brauner <christian.brauner@ubuntu.com>

The BTRFS_IOC_SET_RECEIVED_SUBVOL{_32} are used to set information about a
received subvolume. Make it possible to set information about a received
subvolume 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
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
unchanged

/* v3 */
unchanged

/* v4 */
unchanged
---
 fs/btrfs/ioctl.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 5a8df000cc41..c330b1b252a1 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4464,6 +4464,7 @@ static long btrfs_ioctl_quota_rescan_wait(struct btrfs_fs_info *fs_info,
 }
 
 static long _btrfs_ioctl_set_received_subvol(struct file *file,
+					    struct user_namespace *mnt_userns,
 					    struct btrfs_ioctl_received_subvol_args *sa)
 {
 	struct inode *inode = file_inode(file);
@@ -4475,7 +4476,7 @@ static long _btrfs_ioctl_set_received_subvol(struct file *file,
 	int ret = 0;
 	int received_uuid_changed;
 
-	if (!inode_owner_or_capable(&init_user_ns, inode))
+	if (!inode_owner_or_capable(mnt_userns, inode))
 		return -EPERM;
 
 	ret = mnt_want_write_file(file);
@@ -4580,7 +4581,7 @@ static long btrfs_ioctl_set_received_subvol_32(struct file *file,
 	args64->rtime.nsec = args32->rtime.nsec;
 	args64->flags = args32->flags;
 
-	ret = _btrfs_ioctl_set_received_subvol(file, args64);
+	ret = _btrfs_ioctl_set_received_subvol(file, file_mnt_user_ns(file), args64);
 	if (ret)
 		goto out;
 
@@ -4614,7 +4615,7 @@ static long btrfs_ioctl_set_received_subvol(struct file *file,
 	if (IS_ERR(sa))
 		return PTR_ERR(sa);
 
-	ret = _btrfs_ioctl_set_received_subvol(file, sa);
+	ret = _btrfs_ioctl_set_received_subvol(file, file_mnt_user_ns(file), sa);
 
 	if (ret)
 		goto out;
-- 
2.30.2