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, 28 insertions, 21 deletions

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index f5dfa128af64..816a0f77a39f 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -128,6 +128,7 @@ xfs_cleanup_inode(
 
 STATIC int
 xfs_generic_create(
+	struct user_namespace	*mnt_userns,
 	struct inode	*dir,
 	struct dentry	*dentry,
 	umode_t		mode,
@@ -161,9 +162,10 @@ xfs_generic_create(
 		goto out_free_acl;
 
 	if (!tmpfile) {
-		error = xfs_create(XFS_I(dir), &name, mode, rdev, &ip);
+		error = xfs_create(mnt_userns, XFS_I(dir), &name, mode, rdev,
+				   &ip);
 	} else {
-		error = xfs_create_tmpfile(XFS_I(dir), mode, &ip);
+		error = xfs_create_tmpfile(mnt_userns, XFS_I(dir), mode, &ip);
 	}
 	if (unlikely(error))
 		goto out_free_acl;
@@ -226,7 +228,7 @@ xfs_vn_mknod(
 	umode_t			mode,
 	dev_t			rdev)
 {
-	return xfs_generic_create(dir, dentry, mode, rdev, false);
+	return xfs_generic_create(mnt_userns, dir, dentry, mode, rdev, false);
 }
 
 STATIC int
@@ -237,7 +239,7 @@ xfs_vn_create(
 	umode_t			mode,
 	bool			flags)
 {
-	return xfs_generic_create(dir, dentry, mode, 0, false);
+	return xfs_generic_create(mnt_userns, dir, dentry, mode, 0, false);
 }
 
 STATIC int
@@ -247,7 +249,8 @@ xfs_vn_mkdir(
 	struct dentry		*dentry,
 	umode_t			mode)
 {
-	return xfs_generic_create(dir, dentry, mode | S_IFDIR, 0, false);
+	return xfs_generic_create(mnt_userns, dir, dentry, mode | S_IFDIR, 0,
+				  false);
 }
 
 STATIC struct dentry *
@@ -381,7 +384,7 @@ xfs_vn_symlink(
 	if (unlikely(error))
 		goto out;
 
-	error = xfs_symlink(XFS_I(dir), &name, symname, mode, &cip);
+	error = xfs_symlink(mnt_userns, XFS_I(dir), &name, symname, mode, &cip);
 	if (unlikely(error))
 		goto out;
 
@@ -436,8 +439,8 @@ xfs_vn_rename(
 	if (unlikely(error))
 		return error;
 
-	return xfs_rename(XFS_I(odir), &oname, XFS_I(d_inode(odentry)),
-			  XFS_I(ndir), &nname,
+	return xfs_rename(mnt_userns, XFS_I(odir), &oname,
+			  XFS_I(d_inode(odentry)), XFS_I(ndir), &nname,
 			  new_inode ? XFS_I(new_inode) : NULL, flags);
 }
 
@@ -553,8 +556,8 @@ xfs_vn_getattr(
 	stat->dev = inode->i_sb->s_dev;
 	stat->mode = inode->i_mode;
 	stat->nlink = inode->i_nlink;
-	stat->uid = inode->i_uid;
-	stat->gid = inode->i_gid;
+	stat->uid = i_uid_into_mnt(mnt_userns, inode);
+	stat->gid = i_gid_into_mnt(mnt_userns, inode);
 	stat->ino = ip->i_ino;
 	stat->atime = inode->i_atime;
 	stat->mtime = inode->i_mtime;
@@ -632,8 +635,9 @@ xfs_setattr_time(
 
 static int
 xfs_vn_change_ok(
-	struct dentry	*dentry,
-	struct iattr	*iattr)
+	struct user_namespace	*mnt_userns,
+	struct dentry		*dentry,
+	struct iattr		*iattr)
 {
 	struct xfs_mount	*mp = XFS_I(d_inode(dentry))->i_mount;
 
@@ -643,7 +647,7 @@ xfs_vn_change_ok(
 	if (XFS_FORCED_SHUTDOWN(mp))
 		return -EIO;
 
-	return setattr_prepare(&init_user_ns, dentry, iattr);
+	return setattr_prepare(mnt_userns, dentry, iattr);
 }
 
 /*
@@ -654,6 +658,7 @@ xfs_vn_change_ok(
  */
 static int
 xfs_setattr_nonsize(
+	struct user_namespace	*mnt_userns,
 	struct xfs_inode	*ip,
 	struct iattr		*iattr)
 {
@@ -813,7 +818,7 @@ xfs_setattr_nonsize(
 	 * 	     Posix ACL code seems to care about this issue either.
 	 */
 	if (mask & ATTR_MODE) {
-		error = posix_acl_chmod(&init_user_ns, inode, inode->i_mode);
+		error = posix_acl_chmod(mnt_userns, inode, inode->i_mode);
 		if (error)
 			return error;
 	}
@@ -837,6 +842,7 @@ out_dqrele:
  */
 STATIC int
 xfs_setattr_size(
+	struct user_namespace	*mnt_userns,
 	struct xfs_inode	*ip,
 	struct iattr		*iattr)
 {
@@ -868,7 +874,7 @@ xfs_setattr_size(
 		 * Use the regular setattr path to update the timestamps.
 		 */
 		iattr->ia_valid &= ~ATTR_SIZE;
-		return xfs_setattr_nonsize(ip, iattr);
+		return xfs_setattr_nonsize(mnt_userns, ip, iattr);
 	}
 
 	/*
@@ -1037,6 +1043,7 @@ out_trans_cancel:
 
 int
 xfs_vn_setattr_size(
+	struct user_namespace	*mnt_userns,
 	struct dentry		*dentry,
 	struct iattr		*iattr)
 {
@@ -1045,10 +1052,10 @@ xfs_vn_setattr_size(
 
 	trace_xfs_setattr(ip);
 
-	error = xfs_vn_change_ok(dentry, iattr);
+	error = xfs_vn_change_ok(mnt_userns, dentry, iattr);
 	if (error)
 		return error;
-	return xfs_setattr_size(ip, iattr);
+	return xfs_setattr_size(mnt_userns, ip, iattr);
 }
 
 STATIC int
@@ -1073,14 +1080,14 @@ xfs_vn_setattr(
 			return error;
 		}
 
-		error = xfs_vn_setattr_size(dentry, iattr);
+		error = xfs_vn_setattr_size(mnt_userns, dentry, iattr);
 		xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
 	} else {
 		trace_xfs_setattr(ip);
 
-		error = xfs_vn_change_ok(dentry, iattr);
+		error = xfs_vn_change_ok(mnt_userns, dentry, iattr);
 		if (!error)
-			error = xfs_setattr_nonsize(ip, iattr);
+			error = xfs_setattr_nonsize(mnt_userns, ip, iattr);
 	}
 
 	return error;
@@ -1156,7 +1163,7 @@ xfs_vn_tmpfile(
 	struct dentry		*dentry,
 	umode_t			mode)
 {
-	return xfs_generic_create(dir, dentry, mode, 0, true);
+	return xfs_generic_create(mnt_userns, dir, dentry, mode, 0, true);
 }
 
 static const struct inode_operations xfs_inode_operations = {