1 files changed, 303 insertions, 302 deletions

diff --git a/io_uring/rw.c b/io_uring/rw.c
index 47e097ab5d7e..894c43a5fc0e 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -18,6 +18,7 @@
 #include "io_uring.h"
 #include "opdef.h"
 #include "kbuf.h"
+#include "alloc_cache.h"
 #include "rsrc.h"
 #include "poll.h"
 #include "rw.h"
@@ -75,7 +76,179 @@ static int io_iov_buffer_select_prep(struct io_kiocb *req)
 	return 0;
 }
 
-int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+static int __io_import_iovec(int ddir, struct io_kiocb *req,
+			     struct io_async_rw *io,
+			     unsigned int issue_flags)
+{
+	const struct io_issue_def *def = &io_issue_defs[req->opcode];
+	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
+	struct iovec *iov;
+	void __user *buf;
+	int nr_segs, ret;
+	size_t sqe_len;
+
+	buf = u64_to_user_ptr(rw->addr);
+	sqe_len = rw->len;
+
+	if (!def->vectored || req->flags & REQ_F_BUFFER_SELECT) {
+		if (io_do_buffer_select(req)) {
+			buf = io_buffer_select(req, &sqe_len, issue_flags);
+			if (!buf)
+				return -ENOBUFS;
+			rw->addr = (unsigned long) buf;
+			rw->len = sqe_len;
+		}
+
+		return import_ubuf(ddir, buf, sqe_len, &io->iter);
+	}
+
+	if (io->free_iovec) {
+		nr_segs = io->free_iov_nr;
+		iov = io->free_iovec;
+	} else {
+		iov = &io->fast_iov;
+		nr_segs = 1;
+	}
+	ret = __import_iovec(ddir, buf, sqe_len, nr_segs, &iov, &io->iter,
+				req->ctx->compat);
+	if (unlikely(ret < 0))
+		return ret;
+	if (iov) {
+		req->flags |= REQ_F_NEED_CLEANUP;
+		io->free_iov_nr = io->iter.nr_segs;
+		kfree(io->free_iovec);
+		io->free_iovec = iov;
+	}
+	return 0;
+}
+
+static inline int io_import_iovec(int rw, struct io_kiocb *req,
+				  struct io_async_rw *io,
+				  unsigned int issue_flags)
+{
+	int ret;
+
+	ret = __io_import_iovec(rw, req, io, issue_flags);
+	if (unlikely(ret < 0))
+		return ret;
+
+	iov_iter_save_state(&io->iter, &io->iter_state);
+	return 0;
+}
+
+static void io_rw_iovec_free(struct io_async_rw *rw)
+{
+	if (rw->free_iovec) {
+		kfree(rw->free_iovec);
+		rw->free_iov_nr = 0;
+		rw->free_iovec = NULL;
+	}
+}
+
+static void io_rw_recycle(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_async_rw *rw = req->async_data;
+	struct iovec *iov;
+
+	if (unlikely(issue_flags & IO_URING_F_UNLOCKED)) {
+		io_rw_iovec_free(rw);
+		return;
+	}
+	iov = rw->free_iovec;
+	if (io_alloc_cache_put(&req->ctx->rw_cache, rw)) {
+		if (iov)
+			kasan_mempool_poison_object(iov);
+		req->async_data = NULL;
+		req->flags &= ~REQ_F_ASYNC_DATA;
+	}
+}
+
+static void io_req_rw_cleanup(struct io_kiocb *req, unsigned int issue_flags)
+{
+	/*
+	 * Disable quick recycling for anything that's gone through io-wq.
+	 * In theory, this should be fine to cleanup. However, some read or
+	 * write iter handling touches the iovec AFTER having called into the
+	 * handler, eg to reexpand or revert. This means we can have:
+	 *
+	 * task			io-wq
+	 *   issue
+	 *     punt to io-wq
+	 *			issue
+	 *			  blkdev_write_iter()
+	 *			    ->ki_complete()
+	 *			      io_complete_rw()
+	 *			        queue tw complete
+	 *  run tw
+	 *    req_rw_cleanup
+	 *			iov_iter_count() <- look at iov_iter again
+	 *
+	 * which can lead to a UAF. This is only possible for io-wq offload
+	 * as the cleanup can run in parallel. As io-wq is not the fast path,
+	 * just leave cleanup to the end.
+	 *
+	 * This is really a bug in the core code that does this, any issue
+	 * path should assume that a successful (or -EIOCBQUEUED) return can
+	 * mean that the underlying data can be gone at any time. But that
+	 * should be fixed seperately, and then this check could be killed.
+	 */
+	if (!(req->flags & REQ_F_REFCOUNT)) {
+		req->flags &= ~REQ_F_NEED_CLEANUP;
+		io_rw_recycle(req, issue_flags);
+	}
+}
+
+static int io_rw_alloc_async(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_async_rw *rw;
+
+	rw = io_alloc_cache_get(&ctx->rw_cache);
+	if (rw) {
+		if (rw->free_iovec) {
+			kasan_mempool_unpoison_object(rw->free_iovec,
+				rw->free_iov_nr * sizeof(struct iovec));
+			req->flags |= REQ_F_NEED_CLEANUP;
+		}
+		req->flags |= REQ_F_ASYNC_DATA;
+		req->async_data = rw;
+		goto done;
+	}
+
+	if (!io_alloc_async_data(req)) {
+		rw = req->async_data;
+		rw->free_iovec = NULL;
+		rw->free_iov_nr = 0;
+done:
+		rw->bytes_done = 0;
+		return 0;
+	}
+
+	return -ENOMEM;
+}
+
+static int io_prep_rw_setup(struct io_kiocb *req, int ddir, bool do_import)
+{
+	struct io_async_rw *rw;
+	int ret;
+
+	if (io_rw_alloc_async(req))
+		return -ENOMEM;
+
+	if (!do_import || io_do_buffer_select(req))
+		return 0;
+
+	rw = req->async_data;
+	ret = io_import_iovec(ddir, req, rw, 0);
+	if (unlikely(ret < 0))
+		return ret;
+
+	iov_iter_save_state(&rw->iter, &rw->iter_state);
+	return 0;
+}
+
+static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+		      int ddir, bool do_import)
 {
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 	unsigned ioprio;
@@ -100,34 +273,58 @@ int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	rw->addr = READ_ONCE(sqe->addr);
 	rw->len = READ_ONCE(sqe->len);
 	rw->flags = READ_ONCE(sqe->rw_flags);
-	return 0;
+	return io_prep_rw_setup(req, ddir, do_import);
+}
+
+int io_prep_read(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	return io_prep_rw(req, sqe, ITER_DEST, true);
+}
+
+int io_prep_write(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	return io_prep_rw(req, sqe, ITER_SOURCE, true);
 }
 
-int io_prep_rwv(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+static int io_prep_rwv(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+		       int ddir)
 {
+	const bool do_import = !(req->flags & REQ_F_BUFFER_SELECT);
 	int ret;
 
-	ret = io_prep_rw(req, sqe);
+	ret = io_prep_rw(req, sqe, ddir, do_import);
 	if (unlikely(ret))
 		return ret;
+	if (do_import)
+		return 0;
 
 	/*
 	 * Have to do this validation here, as this is in io_read() rw->len
 	 * might have chanaged due to buffer selection
 	 */
-	if (req->flags & REQ_F_BUFFER_SELECT)
-		return io_iov_buffer_select_prep(req);
+	return io_iov_buffer_select_prep(req);
+}
 
-	return 0;
+int io_prep_readv(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	return io_prep_rwv(req, sqe, ITER_DEST);
 }
 
-int io_prep_rw_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+int io_prep_writev(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
+	return io_prep_rwv(req, sqe, ITER_SOURCE);
+}
+
+static int io_prep_rw_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+			    int ddir)
+{
+	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 	struct io_ring_ctx *ctx = req->ctx;
+	struct io_async_rw *io;
 	u16 index;
 	int ret;
 
-	ret = io_prep_rw(req, sqe);
+	ret = io_prep_rw(req, sqe, ddir, false);
 	if (unlikely(ret))
 		return ret;
 
@@ -136,7 +333,21 @@ int io_prep_rw_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	index = array_index_nospec(req->buf_index, ctx->nr_user_bufs);
 	req->imu = ctx->user_bufs[index];
 	io_req_set_rsrc_node(req, ctx, 0);
-	return 0;
+
+	io = req->async_data;
+	ret = io_import_fixed(ddir, &io->iter, req->imu, rw->addr, rw->len);
+	iov_iter_save_state(&io->iter, &io->iter_state);
+	return ret;
+}
+
+int io_prep_read_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	return io_prep_rw_fixed(req, sqe, ITER_DEST);
+}
+
+int io_prep_write_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	return io_prep_rw_fixed(req, sqe, ITER_SOURCE);
 }
 
 /*
@@ -152,7 +363,7 @@ int io_read_mshot_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	if (!(req->flags & REQ_F_BUFFER_SELECT))
 		return -EINVAL;
 
-	ret = io_prep_rw(req, sqe);
+	ret = io_prep_rw(req, sqe, ITER_DEST, false);
 	if (unlikely(ret))
 		return ret;
 
@@ -165,9 +376,7 @@ int io_read_mshot_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 
 void io_readv_writev_cleanup(struct io_kiocb *req)
 {
-	struct io_async_rw *io = req->async_data;
-
-	kfree(io->free_iovec);
+	io_rw_iovec_free(req->async_data);
 }
 
 static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
@@ -187,21 +396,12 @@ static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
 	return NULL;
 }
 
-static void io_req_task_queue_reissue(struct io_kiocb *req)
-{
-	req->io_task_work.func = io_queue_iowq;
-	io_req_task_work_add(req);
-}
-
 #ifdef CONFIG_BLOCK
-static bool io_resubmit_prep(struct io_kiocb *req)
+static void io_resubmit_prep(struct io_kiocb *req)
 {
 	struct io_async_rw *io = req->async_data;
 
-	if (!req_has_async_data(req))
-		return !io_req_prep_async(req);
-	iov_iter_restore(&io->s.iter, &io->s.iter_state);
-	return true;
+	iov_iter_restore(&io->iter, &io->iter_state);
 }
 
 static bool io_rw_should_reissue(struct io_kiocb *req)
@@ -230,9 +430,8 @@ static bool io_rw_should_reissue(struct io_kiocb *req)
 	return true;
 }
 #else
-static bool io_resubmit_prep(struct io_kiocb *req)
+static void io_resubmit_prep(struct io_kiocb *req)
 {
-	return false;
 }
 static bool io_rw_should_reissue(struct io_kiocb *req)
 {
@@ -311,11 +510,10 @@ void io_req_rw_complete(struct io_kiocb *req, struct io_tw_state *ts)
 
 	io_req_io_end(req);
 
-	if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) {
-		unsigned issue_flags = ts->locked ? 0 : IO_URING_F_UNLOCKED;
+	if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING))
+		req->cqe.flags |= io_put_kbuf(req, 0);
 
-		req->cqe.flags |= io_put_kbuf(req, issue_flags);
-	}
+	io_req_rw_cleanup(req, 0);
 	io_req_task_complete(req, ts);
 }
 
@@ -396,6 +594,7 @@ static int kiocb_done(struct io_kiocb *req, ssize_t ret,
 			io_req_io_end(req);
 			io_req_set_res(req, final_ret,
 				       io_put_kbuf(req, issue_flags));
+			io_req_rw_cleanup(req, issue_flags);
 			return IOU_OK;
 		}
 	} else {
@@ -404,71 +603,12 @@ static int kiocb_done(struct io_kiocb *req, ssize_t ret,
 
 	if (req->flags & REQ_F_REISSUE) {
 		req->flags &= ~REQ_F_REISSUE;
-		if (io_resubmit_prep(req))
-			io_req_task_queue_reissue(req);
-		else
-			io_req_task_queue_fail(req, final_ret);
+		io_resubmit_prep(req);
+		return -EAGAIN;
 	}
 	return IOU_ISSUE_SKIP_COMPLETE;
 }
 
-static struct iovec *__io_import_iovec(int ddir, struct io_kiocb *req,
-				       struct io_rw_state *s,
-				       unsigned int issue_flags)
-{
-	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
-	struct iov_iter *iter = &s->iter;
-	u8 opcode = req->opcode;
-	struct iovec *iovec;
-	void __user *buf;
-	size_t sqe_len;
-	ssize_t ret;
-
-	if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
-		ret = io_import_fixed(ddir, iter, req->imu, rw->addr, rw->len);
-		if (ret)
-			return ERR_PTR(ret);
-		return NULL;
-	}
-
-	buf = u64_to_user_ptr(rw->addr);
-	sqe_len = rw->len;
-
-	if (!io_issue_defs[opcode].vectored || req->flags & REQ_F_BUFFER_SELECT) {
-		if (io_do_buffer_select(req)) {
-			buf = io_buffer_select(req, &sqe_len, issue_flags);
-			if (!buf)
-				return ERR_PTR(-ENOBUFS);
-			rw->addr = (unsigned long) buf;
-			rw->len = sqe_len;
-		}
-
-		ret = import_ubuf(ddir, buf, sqe_len, iter);
-		if (ret)
-			return ERR_PTR(ret);
-		return NULL;
-	}
-
-	iovec = s->fast_iov;
-	ret = __import_iovec(ddir, buf, sqe_len, UIO_FASTIOV, &iovec, iter,
-			      req->ctx->compat);
-	if (unlikely(ret < 0))
-		return ERR_PTR(ret);
-	return iovec;
-}
-
-static inline int io_import_iovec(int rw, struct io_kiocb *req,
-				  struct iovec **iovec, struct io_rw_state *s,
-				  unsigned int issue_flags)
-{
-	*iovec = __io_import_iovec(rw, req, s, issue_flags);
-	if (IS_ERR(*iovec))
-		return PTR_ERR(*iovec);
-
-	iov_iter_save_state(&s->iter, &s->iter_state);
-	return 0;
-}
-
 static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb)
 {
 	return (kiocb->ki_filp->f_mode & FMODE_STREAM) ? NULL : &kiocb->ki_pos;
@@ -540,89 +680,6 @@ static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter)
 	return ret;
 }
 
-static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
-			  const struct iovec *fast_iov, struct iov_iter *iter)
-{
-	struct io_async_rw *io = req->async_data;
-
-	memcpy(&io->s.iter, iter, sizeof(*iter));
-	io->free_iovec = iovec;
-	io->bytes_done = 0;
-	/* can only be fixed buffers, no need to do anything */
-	if (iov_iter_is_bvec(iter) || iter_is_ubuf(iter))
-		return;
-	if (!iovec) {
-		unsigned iov_off = 0;
-
-		io->s.iter.__iov = io->s.fast_iov;
-		if (iter->__iov != fast_iov) {
-			iov_off = iter_iov(iter) - fast_iov;
-			io->s.iter.__iov += iov_off;
-		}
-		if (io->s.fast_iov != fast_iov)
-			memcpy(io->s.fast_iov + iov_off, fast_iov + iov_off,
-			       sizeof(struct iovec) * iter->nr_segs);
-	} else {
-		req->flags |= REQ_F_NEED_CLEANUP;
-	}
-}
-
-static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
-			     struct io_rw_state *s, bool force)
-{
-	if (!force && !io_cold_defs[req->opcode].prep_async)
-		return 0;
-	/* opcode type doesn't need async data */
-	if (!io_cold_defs[req->opcode].async_size)
-		return 0;
-	if (!req_has_async_data(req)) {
-		struct io_async_rw *iorw;
-
-		if (io_alloc_async_data(req)) {
-			kfree(iovec);
-			return -ENOMEM;
-		}
-
-		io_req_map_rw(req, iovec, s->fast_iov, &s->iter);
-		iorw = req->async_data;
-		/* we've copied and mapped the iter, ensure state is saved */
-		iov_iter_save_state(&iorw->s.iter, &iorw->s.iter_state);
-	}
-	return 0;
-}
-
-static inline int io_rw_prep_async(struct io_kiocb *req, int rw)
-{
-	struct io_async_rw *iorw = req->async_data;
-	struct iovec *iov;
-	int ret;
-
-	iorw->bytes_done = 0;
-	iorw->free_iovec = NULL;
-
-	/* submission path, ->uring_lock should already be taken */
-	ret = io_import_iovec(rw, req, &iov, &iorw->s, 0);
-	if (unlikely(ret < 0))
-		return ret;
-
-	if (iov) {
-		iorw->free_iovec = iov;
-		req->flags |= REQ_F_NEED_CLEANUP;
-	}
-
-	return 0;
-}
-
-int io_readv_prep_async(struct io_kiocb *req)
-{
-	return io_rw_prep_async(req, ITER_DEST);
-}
-
-int io_writev_prep_async(struct io_kiocb *req)
-{
-	return io_rw_prep_async(req, ITER_SOURCE);
-}
-
 /*
  * This is our waitqueue callback handler, registered through __folio_lock_async()
  * when we initially tried to do the IO with the iocb armed our waitqueue.
@@ -683,7 +740,8 @@ static bool io_rw_should_retry(struct io_kiocb *req)
 	 * just use poll if we can, and don't attempt if the fs doesn't
 	 * support callback based unlocks
 	 */
-	if (io_file_can_poll(req) || !(req->file->f_mode & FMODE_BUF_RASYNC))
+	if (io_file_can_poll(req) ||
+	    !(req->file->f_op->fop_flags & FOP_BUFFER_RASYNC))
 		return false;
 
 	wait->wait.func = io_async_buf_func;
@@ -762,54 +820,28 @@ static int io_rw_init_file(struct io_kiocb *req, fmode_t mode)
 
 static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
 {
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
-	struct io_rw_state __s, *s = &__s;
-	struct iovec *iovec;
+	struct io_async_rw *io = req->async_data;
 	struct kiocb *kiocb = &rw->kiocb;
-	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
-	struct io_async_rw *io;
-	ssize_t ret, ret2;
+	ssize_t ret;
 	loff_t *ppos;
 
-	if (!req_has_async_data(req)) {
-		ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
+	if (io_do_buffer_select(req)) {
+		ret = io_import_iovec(ITER_DEST, req, io, issue_flags);
 		if (unlikely(ret < 0))
 			return ret;
-	} else {
-		io = req->async_data;
-		s = &io->s;
-
-		/*
-		 * Safe and required to re-import if we're using provided
-		 * buffers, as we dropped the selected one before retry.
-		 */
-		if (io_do_buffer_select(req)) {
-			ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
-			if (unlikely(ret < 0))
-				return ret;
-		}
-
-		/*
-		 * We come here from an earlier attempt, restore our state to
-		 * match in case it doesn't. It's cheap enough that we don't
-		 * need to make this conditional.
-		 */
-		iov_iter_restore(&s->iter, &s->iter_state);
-		iovec = NULL;
 	}
+
 	ret = io_rw_init_file(req, FMODE_READ);
-	if (unlikely(ret)) {
-		kfree(iovec);
+	if (unlikely(ret))
 		return ret;
-	}
-	req->cqe.res = iov_iter_count(&s->iter);
+	req->cqe.res = iov_iter_count(&io->iter);
 
 	if (force_nonblock) {
 		/* If the file doesn't support async, just async punt */
-		if (unlikely(!io_file_supports_nowait(req))) {
-			ret = io_setup_async_rw(req, iovec, s, true);
-			return ret ?: -EAGAIN;
-		}
+		if (unlikely(!io_file_supports_nowait(req)))
+			return -EAGAIN;
 		kiocb->ki_flags |= IOCB_NOWAIT;
 	} else {
 		/* Ensure we clear previously set non-block flag */
@@ -819,20 +851,15 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
 	ppos = io_kiocb_update_pos(req);
 
 	ret = rw_verify_area(READ, req->file, ppos, req->cqe.res);
-	if (unlikely(ret)) {
-		kfree(iovec);
+	if (unlikely(ret))
 		return ret;
-	}
 
-	ret = io_iter_do_read(rw, &s->iter);
+	ret = io_iter_do_read(rw, &io->iter);
 
 	if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
 		req->flags &= ~REQ_F_REISSUE;
-		/*
-		 * If we can poll, just do that. For a vectored read, we'll
-		 * need to copy state first.
-		 */
-		if (io_file_can_poll(req) && !io_issue_defs[req->opcode].vectored)
+		/* If we can poll, just do that. */
+		if (io_file_can_poll(req))
 			return -EAGAIN;
 		/* IOPOLL retry should happen for io-wq threads */
 		if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
@@ -842,8 +869,6 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
 			goto done;
 		ret = 0;
 	} else if (ret == -EIOCBQUEUED) {
-		if (iovec)
-			kfree(iovec);
 		return IOU_ISSUE_SKIP_COMPLETE;
 	} else if (ret == req->cqe.res || ret <= 0 || !force_nonblock ||
 		   (req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) {
@@ -856,21 +881,7 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
 	 * untouched in case of error. Restore it and we'll advance it
 	 * manually if we need to.
 	 */
-	iov_iter_restore(&s->iter, &s->iter_state);
-
-	ret2 = io_setup_async_rw(req, iovec, s, true);
-	iovec = NULL;
-	if (ret2) {
-		ret = ret > 0 ? ret : ret2;
-		goto done;
-	}
-
-	io = req->async_data;
-	s = &io->s;
-	/*
-	 * Now use our persistent iterator and state, if we aren't already.
-	 * We've restored and mapped the iter to match.
-	 */
+	iov_iter_restore(&io->iter, &io->iter_state);
 
 	do {
 		/*
@@ -878,11 +889,11 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
 		 * above or inside this loop. Advance the iter by the bytes
 		 * that were consumed.
 		 */
-		iov_iter_advance(&s->iter, ret);
-		if (!iov_iter_count(&s->iter))
+		iov_iter_advance(&io->iter, ret);
+		if (!iov_iter_count(&io->iter))
 			break;
 		io->bytes_done += ret;
-		iov_iter_save_state(&s->iter, &s->iter_state);
+		iov_iter_save_state(&io->iter, &io->iter_state);
 
 		/* if we can retry, do so with the callbacks armed */
 		if (!io_rw_should_retry(req)) {
@@ -890,24 +901,22 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
 			return -EAGAIN;
 		}
 
-		req->cqe.res = iov_iter_count(&s->iter);
+		req->cqe.res = iov_iter_count(&io->iter);
 		/*
 		 * Now retry read with the IOCB_WAITQ parts set in the iocb. If
 		 * we get -EIOCBQUEUED, then we'll get a notification when the
 		 * desired page gets unlocked. We can also get a partial read
 		 * here, and if we do, then just retry at the new offset.
 		 */
-		ret = io_iter_do_read(rw, &s->iter);
+		ret = io_iter_do_read(rw, &io->iter);
 		if (ret == -EIOCBQUEUED)
 			return IOU_ISSUE_SKIP_COMPLETE;
 		/* we got some bytes, but not all. retry. */
 		kiocb->ki_flags &= ~IOCB_WAITQ;
-		iov_iter_restore(&s->iter, &s->iter_state);
+		iov_iter_restore(&io->iter, &io->iter_state);
 	} while (ret > 0);
 done:
 	/* it's faster to check here then delegate to kfree */
-	if (iovec)
-		kfree(iovec);
 	return ret;
 }
 
@@ -937,6 +946,13 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 	ret = __io_read(req, issue_flags);
 
 	/*
+	 * If the file doesn't support proper NOWAIT, then disable multishot
+	 * and stay in single shot mode.
+	 */
+	if (!io_file_supports_nowait(req))
+		req->flags &= ~REQ_F_APOLL_MULTISHOT;
+
+	/*
 	 * If we get -EAGAIN, recycle our buffer and just let normal poll
 	 * handling arm it.
 	 */
@@ -947,13 +963,15 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 		 */
 		if (io_kbuf_recycle(req, issue_flags))
 			rw->len = 0;
+		if (issue_flags & IO_URING_F_MULTISHOT)
+			return IOU_ISSUE_SKIP_COMPLETE;
 		return -EAGAIN;
 	}
 
 	/*
 	 * Any successful return value will keep the multishot read armed.
 	 */
-	if (ret > 0) {
+	if (ret > 0 && req->flags & REQ_F_APOLL_MULTISHOT) {
 		/*
 		 * Put our buffer and post a CQE. If we fail to post a CQE, then
 		 * jump to the termination path. This request is then done.
@@ -961,9 +979,7 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 		cflags = io_put_kbuf(req, issue_flags);
 		rw->len = 0; /* similarly to above, reset len to 0 */
 
-		if (io_fill_cqe_req_aux(req,
-					issue_flags & IO_URING_F_COMPLETE_DEFER,
-					ret, cflags | IORING_CQE_F_MORE)) {
+		if (io_req_post_cqe(req, ret, cflags | IORING_CQE_F_MORE)) {
 			if (issue_flags & IO_URING_F_MULTISHOT) {
 				/*
 				 * Force retry, as we might have more data to
@@ -982,6 +998,7 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 	 * multishot request, hitting overflow will terminate it.
 	 */
 	io_req_set_res(req, ret, cflags);
+	io_req_rw_cleanup(req, issue_flags);
 	if (issue_flags & IO_URING_F_MULTISHOT)
 		return IOU_STOP_MULTISHOT;
 	return IOU_OK;
@@ -989,42 +1006,28 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 
 int io_write(struct io_kiocb *req, unsigned int issue_flags)
 {
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
-	struct io_rw_state __s, *s = &__s;
-	struct iovec *iovec;
+	struct io_async_rw *io = req->async_data;
 	struct kiocb *kiocb = &rw->kiocb;
-	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
 	ssize_t ret, ret2;
 	loff_t *ppos;
 
-	if (!req_has_async_data(req)) {
-		ret = io_import_iovec(ITER_SOURCE, req, &iovec, s, issue_flags);
-		if (unlikely(ret < 0))
-			return ret;
-	} else {
-		struct io_async_rw *io = req->async_data;
-
-		s = &io->s;
-		iov_iter_restore(&s->iter, &s->iter_state);
-		iovec = NULL;
-	}
 	ret = io_rw_init_file(req, FMODE_WRITE);
-	if (unlikely(ret)) {
-		kfree(iovec);
+	if (unlikely(ret))
 		return ret;
-	}
-	req->cqe.res = iov_iter_count(&s->iter);
+	req->cqe.res = iov_iter_count(&io->iter);
 
 	if (force_nonblock) {
 		/* If the file doesn't support async, just async punt */
 		if (unlikely(!io_file_supports_nowait(req)))
-			goto copy_iov;
+			goto ret_eagain;
 
-		/* File path supports NOWAIT for non-direct_IO only for block devices. */
+		/* Check if we can support NOWAIT. */
 		if (!(kiocb->ki_flags & IOCB_DIRECT) &&
-			!(kiocb->ki_filp->f_mode & FMODE_BUF_WASYNC) &&
-			(req->flags & REQ_F_ISREG))
-			goto copy_iov;
+		    !(req->file->f_op->fop_flags & FOP_BUFFER_WASYNC) &&
+		    (req->flags & REQ_F_ISREG))
+			goto ret_eagain;
 
 		kiocb->ki_flags |= IOCB_NOWAIT;
 	} else {
@@ -1035,19 +1038,17 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags)
 	ppos = io_kiocb_update_pos(req);
 
 	ret = rw_verify_area(WRITE, req->file, ppos, req->cqe.res);
-	if (unlikely(ret)) {
-		kfree(iovec);
+	if (unlikely(ret))
 		return ret;
-	}
 
 	if (req->flags & REQ_F_ISREG)
 		kiocb_start_write(kiocb);
 	kiocb->ki_flags |= IOCB_WRITE;
 
 	if (likely(req->file->f_op->write_iter))
-		ret2 = call_write_iter(req->file, kiocb, &s->iter);
+		ret2 = call_write_iter(req->file, kiocb, &io->iter);
 	else if (req->file->f_op->write)
-		ret2 = loop_rw_iter(WRITE, rw, &s->iter);
+		ret2 = loop_rw_iter(WRITE, rw, &io->iter);
 	else
 		ret2 = -EINVAL;
 
@@ -1068,11 +1069,9 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags)
 	if (!force_nonblock || ret2 != -EAGAIN) {
 		/* IOPOLL retry should happen for io-wq threads */
 		if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL))
-			goto copy_iov;
+			goto ret_eagain;
 
 		if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) {
-			struct io_async_rw *io;
-
 			trace_io_uring_short_write(req->ctx, kiocb->ki_pos - ret2,
 						req->cqe.res, ret2);
 
@@ -1081,34 +1080,22 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags)
 			 * in the worker. Also update bytes_done to account for
 			 * the bytes already written.
 			 */
-			iov_iter_save_state(&s->iter, &s->iter_state);
-			ret = io_setup_async_rw(req, iovec, s, true);
-
-			io = req->async_data;
-			if (io)
-				io->bytes_done += ret2;
+			iov_iter_save_state(&io->iter, &io->iter_state);
+			io->bytes_done += ret2;
 
 			if (kiocb->ki_flags & IOCB_WRITE)
 				io_req_end_write(req);
-			return ret ? ret : -EAGAIN;
+			return -EAGAIN;
 		}
 done:
-		ret = kiocb_done(req, ret2, issue_flags);
+		return kiocb_done(req, ret2, issue_flags);
 	} else {
-copy_iov:
-		iov_iter_restore(&s->iter, &s->iter_state);
-		ret = io_setup_async_rw(req, iovec, s, false);
-		if (!ret) {
-			if (kiocb->ki_flags & IOCB_WRITE)
-				io_req_end_write(req);
-			return -EAGAIN;
-		}
-		return ret;
+ret_eagain:
+		iov_iter_restore(&io->iter, &io->iter_state);
+		if (kiocb->ki_flags & IOCB_WRITE)
+			io_req_end_write(req);
+		return -EAGAIN;
 	}
-	/* it's reportedly faster than delegating the null check to kfree() */
-	if (iovec)
-		kfree(iovec);
-	return ret;
 }
 
 void io_rw_fail(struct io_kiocb *req)
@@ -1182,6 +1169,8 @@ int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
 			break;
 		nr_events++;
 		req->cqe.flags = io_put_kbuf(req, 0);
+		if (req->opcode != IORING_OP_URING_CMD)
+			io_req_rw_cleanup(req, 0);
 	}
 	if (unlikely(!nr_events))
 		return 0;
@@ -1195,3 +1184,15 @@ int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
 	__io_submit_flush_completions(ctx);
 	return nr_events;
 }
+
+void io_rw_cache_free(const void *entry)
+{
+	struct io_async_rw *rw = (struct io_async_rw *) entry;
+
+	if (rw->free_iovec) {
+		kasan_mempool_unpoison_object(rw->free_iovec,
+				rw->free_iov_nr * sizeof(struct iovec));
+		io_rw_iovec_free(rw);
+	}
+	kfree(rw);
+}