xfs: support idmapped mounts

Enable idmapped mounts for xfs. This basically just means passing down
the user_namespace argument from the VFS methods down to where it is
passed to the relevant helpers.

Note that full-filesystem bulkstat is not supported from inside idmapped
mounts as it is an administrative operation that acts on the whole file
system. The limitation is not applied to the bulkstat single operation
that just operates on a single inode.

Link: https://lore.kernel.org/r/20210121131959.646623-40-christian.brauner@ubuntu.com
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

1 files changed, 18 insertions, 8 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index b7352bc4c815..95b7f2ba4e06 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -766,6 +766,7 @@ xfs_inode_inherit_flags2(
  */
 static int
 xfs_init_new_inode(
+	struct user_namespace	*mnt_userns,
 	struct xfs_trans	*tp,
 	struct xfs_inode	*pip,
 	xfs_ino_t		ino,
@@ -806,7 +807,7 @@ xfs_init_new_inode(
 	inode = VFS_I(ip);
 	inode->i_mode = mode;
 	set_nlink(inode, nlink);
-	inode->i_uid = current_fsuid();
+	inode->i_uid = fsuid_into_mnt(mnt_userns);
 	inode->i_rdev = rdev;
 	ip->i_d.di_projid = prid;
 
@@ -815,7 +816,7 @@ xfs_init_new_inode(
 		if ((VFS_I(pip)->i_mode & S_ISGID) && S_ISDIR(mode))
 			inode->i_mode |= S_ISGID;
 	} else {
-		inode->i_gid = current_fsgid();
+		inode->i_gid = fsgid_into_mnt(mnt_userns);
 	}
 
 	/*
@@ -824,7 +825,8 @@ xfs_init_new_inode(
 	 * (and only if the irix_sgid_inherit compatibility variable is set).
 	 */
 	if (irix_sgid_inherit &&
-	    (inode->i_mode & S_ISGID) && !in_group_p(inode->i_gid))
+	    (inode->i_mode & S_ISGID) &&
+	    !in_group_p(i_gid_into_mnt(mnt_userns, inode)))
 		inode->i_mode &= ~S_ISGID;
 
 	ip->i_d.di_size = 0;
@@ -901,6 +903,7 @@ xfs_init_new_inode(
  */
 int
 xfs_dir_ialloc(
+	struct user_namespace	*mnt_userns,
 	struct xfs_trans	**tpp,
 	struct xfs_inode	*dp,
 	umode_t			mode,
@@ -933,7 +936,8 @@ xfs_dir_ialloc(
 		return error;
 	ASSERT(ino != NULLFSINO);
 
-	return xfs_init_new_inode(*tpp, dp, ino, mode, nlink, rdev, prid, ipp);
+	return xfs_init_new_inode(mnt_userns, *tpp, dp, ino, mode, nlink, rdev,
+				  prid, ipp);
 }
 
 /*
@@ -973,6 +977,7 @@ xfs_bumplink(
 
 int
 xfs_create(
+	struct user_namespace	*mnt_userns,
 	xfs_inode_t		*dp,
 	struct xfs_name		*name,
 	umode_t			mode,
@@ -1047,7 +1052,8 @@ xfs_create(
 	 * entry pointing to them, but a directory also the "." entry
 	 * pointing to itself.
 	 */
-	error = xfs_dir_ialloc(&tp, dp, mode, is_dir ? 2 : 1, rdev, prid, &ip);
+	error = xfs_dir_ialloc(mnt_userns, &tp, dp, mode, is_dir ? 2 : 1, rdev,
+			       prid, &ip);
 	if (error)
 		goto out_trans_cancel;
 
@@ -1128,6 +1134,7 @@ xfs_create(
 
 int
 xfs_create_tmpfile(
+	struct user_namespace	*mnt_userns,
 	struct xfs_inode	*dp,
 	umode_t			mode,
 	struct xfs_inode	**ipp)
@@ -1169,7 +1176,7 @@ xfs_create_tmpfile(
 	if (error)
 		goto out_trans_cancel;
 
-	error = xfs_dir_ialloc(&tp, dp, mode, 0, 0, prid, &ip);
+	error = xfs_dir_ialloc(mnt_userns, &tp, dp, mode, 0, 0, prid, &ip);
 	if (error)
 		goto out_trans_cancel;
 
@@ -2977,13 +2984,15 @@ out_trans_abort:
  */
 static int
 xfs_rename_alloc_whiteout(
+	struct user_namespace	*mnt_userns,
 	struct xfs_inode	*dp,
 	struct xfs_inode	**wip)
 {
 	struct xfs_inode	*tmpfile;
 	int			error;
 
-	error = xfs_create_tmpfile(dp, S_IFCHR | WHITEOUT_MODE, &tmpfile);
+	error = xfs_create_tmpfile(mnt_userns, dp, S_IFCHR | WHITEOUT_MODE,
+				   &tmpfile);
 	if (error)
 		return error;
 
@@ -3005,6 +3014,7 @@ xfs_rename_alloc_whiteout(
  */
 int
 xfs_rename(
+	struct user_namespace	*mnt_userns,
 	struct xfs_inode	*src_dp,
 	struct xfs_name		*src_name,
 	struct xfs_inode	*src_ip,
@@ -3036,7 +3046,7 @@ xfs_rename(
 	 */
 	if (flags & RENAME_WHITEOUT) {
 		ASSERT(!(flags & (RENAME_NOREPLACE | RENAME_EXCHANGE)));
-		error = xfs_rename_alloc_whiteout(target_dp, &wip);
+		error = xfs_rename_alloc_whiteout(mnt_userns, target_dp, &wip);
 		if (error)
 			return error;