io_uring: Fix use of XArray in __io_uring_files_cancel

We have to drop the lock during each iteration, so there's no advantage
to using the advanced API.  Convert this to a standard xa_for_each() loop.

Reported-by: syzbot+27c12725d8ff0bfe1a13@syzkaller.appspotmail.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 299c530c66f9c0548bc25e38c100e2d335ce9e54..2978cc78538adec1078d605a21c702031a4feb66 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8665,28 +8665,19 @@ static void io_uring_attempt_task_drop(struct file *file, bool exiting)
 void __io_uring_files_cancel(struct files_struct *files)
 {
        struct io_uring_task *tctx = current->io_uring;
-       XA_STATE(xas, &tctx->xa, 0);
+       struct file *file;
+       unsigned long index;
 
        /* make sure overflow events are dropped */
        tctx->in_idle = true;
 
-       do {
-               struct io_ring_ctx *ctx;
-               struct file *file;
-
-               xas_lock(&xas);
-               file = xas_next_entry(&xas, ULONG_MAX);
-               xas_unlock(&xas);
-
-               if (!file)
-                       break;
-
-               ctx = file->private_data;
+       xa_for_each(&tctx->xa, index, file) {
+               struct io_ring_ctx *ctx = file->private_data;
 
                io_uring_cancel_task_requests(ctx, files);
                if (files)
                        io_uring_del_task_file(file);
-       } while (1);
+       }
 }
 
 static inline bool io_uring_task_idle(struct io_uring_task *tctx)