Coach Mike Woodson called Rasheed Wallace’s ongoing foot surgery “a blow,” but he hasn’t given up on the defensive forward making a return for the playoffs. The Knicks’ fears regarding Wallace were realized before Wednesday night’s 109-105 win over the Warriors at the Garden. The team announced “new X-rays’’ had shown Wallace’s injury had progressed from a stress reaction to a fractured bone at the outside of his left foot, otherwise known as a Jones fracture. Wallace, 38, will require surgery that will keep him out eight weeks and for the remainder of the regular season. According to a source, the Knicks were aware of the new X-rays last week, showing Wallace’s stress reaction had turned into a stress fracture after he returned to practice following the All-Star break. The delay in the announcement was to decide whether Wallace would have surgery that would get him back for the playoffs or if he would call it a career. He has chosen surgery, and the Knicks have decided not to waive him and sign another player to fill his roster spot. The Knicks did get some good news on the aging big-man front. Center Marcus Camby, out since Jan. 10 with a strained plantar fascia, likely is to make his return tomorrow in Washington. “He’s on the mend,” Woodson said. As for Wallace, Woodson said, “We rehabbed him. We tried to rehab him back. It’s something of a blow because he put in so much work trying to get back on the floor. Now this happens. One thing we can do now is think positive on how his surgery was going to turn out. He’s got to rehab back.’’ It seems a long shot Wallace will be ready in the second round of the playoffs after being out so long. His comeback from a two-year retirement has been a major disappointment. He could have been the missing piece for a title push had he stayed healthy, but his foot gave out in mid-December and the Knicks have been a .500 club since.