ceph: add additional size check in ceph_setattr()

ceph_setattr() finally calls vfs function inode_newsize_ok()
to do offset validation and that is based on sb->s_maxbytes.
Because we set sb->s_maxbytes to MAX_LFS_FILESIZE to through
VFS check and do proper offset validation in cephfs level,
we need adding proper offset validation before calling
inode_newsize_ok().

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/inode.c

@@ -2157,6 +2157,7 @@ int __ceph_setattr(struct inode *inode, struct iattr *attr)
 int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 	int err;
 
 	if (ceph_snap(inode) != CEPH_NOSNAP)
@@ -2166,6 +2167,10 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	if (err != 0)
 		return err;
 
+	if ((attr->ia_valid & ATTR_SIZE) &&
+	    attr->ia_size > max(inode->i_size, fsc->max_file_size))
+		return -EFBIG;
+
 	if ((attr->ia_valid & ATTR_SIZE) &&
 	    ceph_quota_is_max_bytes_exceeded(inode, attr->ia_size))
 		return -EDQUOT;