Revert "io_uring: don't take fs for recvmsg/sendmsg"

This reverts commit 10cad2c4.

Petr reports that with this commit in place, io_uring fails the chroot
test (CVE-202-29373). We do need to retain ->fs for send/recvmsg, so
revert this commit.
Reported-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -857,7 +857,8 @@ static const struct io_op_def io_op_defs[] = {
 		.pollout		= 1,
 		.needs_async_data	= 1,
 		.async_size		= sizeof(struct io_async_msghdr),
-		.work_flags		= IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG,
+		.work_flags		= IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG |
+						IO_WQ_WORK_FS,
 	},
 	[IORING_OP_RECVMSG] = {
 		.needs_file		= 1,
@@ -866,7 +867,8 @@ static const struct io_op_def io_op_defs[] = {
 		.buffer_select		= 1,
 		.needs_async_data	= 1,
 		.async_size		= sizeof(struct io_async_msghdr),
-		.work_flags		= IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG,
+		.work_flags		= IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG |
+						IO_WQ_WORK_FS,
 	},
 	[IORING_OP_TIMEOUT] = {
 		.needs_async_data	= 1,