io_uring: retain iov_iter state over io_read/io_write calls
Instead of maintaining (and setting/remembering) iov_iter size and segment counts, just put the iov_iter in the async part of the IO structure. This is mostly a preparation patch for doing appropriate internal retries for short reads, but it also cleans up the state handling nicely and simplifies it quite a bit. Signed-off-by: Jens Axboe <axboe@kernel.dk>zero-sugar-mainline-defconfig
Jens Axboe
parent
ebf0d100df
commit
ff6165b2d7
136
fs/io_uring.c
136
fs/io_uring.c
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@ -508,9 +508,8 @@ struct io_async_msghdr {
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struct io_async_rw {
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struct iovec fast_iov[UIO_FASTIOV];
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struct iovec *iov;
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ssize_t nr_segs;
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ssize_t size;
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const struct iovec *free_iovec;
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struct iov_iter iter;
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struct wait_page_queue wpq;
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};
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@ -915,8 +914,8 @@ static void io_file_put_work(struct work_struct *work);
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static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
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struct iovec **iovec, struct iov_iter *iter,
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bool needs_lock);
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static int io_setup_async_rw(struct io_kiocb *req, ssize_t io_size,
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struct iovec *iovec, struct iovec *fast_iov,
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static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
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const struct iovec *fast_iov,
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struct iov_iter *iter);
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static struct kmem_cache *req_cachep;
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@ -2299,7 +2298,7 @@ static bool io_resubmit_prep(struct io_kiocb *req, int error)
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ret = io_import_iovec(rw, req, &iovec, &iter, false);
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if (ret < 0)
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goto end_req;
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ret = io_setup_async_rw(req, ret, iovec, inline_vecs, &iter);
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ret = io_setup_async_rw(req, iovec, inline_vecs, &iter);
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if (!ret)
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return true;
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kfree(iovec);
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@ -2820,6 +2819,13 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
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ssize_t ret;
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u8 opcode;
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if (req->io) {
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struct io_async_rw *iorw = &req->io->rw;
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*iovec = NULL;
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return iov_iter_count(&iorw->iter);
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}
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opcode = req->opcode;
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if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
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*iovec = NULL;
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@ -2845,14 +2851,6 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
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return ret < 0 ? ret : sqe_len;
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}
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if (req->io) {
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struct io_async_rw *iorw = &req->io->rw;
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iov_iter_init(iter, rw, iorw->iov, iorw->nr_segs, iorw->size);
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*iovec = NULL;
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return iorw->size;
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}
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if (req->flags & REQ_F_BUFFER_SELECT) {
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ret = io_iov_buffer_select(req, *iovec, needs_lock);
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if (!ret) {
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@ -2930,21 +2928,29 @@ static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb,
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return ret;
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}
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static void io_req_map_rw(struct io_kiocb *req, ssize_t io_size,
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struct iovec *iovec, struct iovec *fast_iov,
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struct iov_iter *iter)
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static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
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const struct iovec *fast_iov, struct iov_iter *iter)
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{
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struct io_async_rw *rw = &req->io->rw;
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rw->nr_segs = iter->nr_segs;
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rw->size = io_size;
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memcpy(&rw->iter, iter, sizeof(*iter));
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rw->free_iovec = NULL;
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/* can only be fixed buffers, no need to do anything */
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if (iter->type == ITER_BVEC)
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return;
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if (!iovec) {
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rw->iov = rw->fast_iov;
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if (rw->iov != fast_iov)
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memcpy(rw->iov, fast_iov,
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unsigned iov_off = 0;
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rw->iter.iov = rw->fast_iov;
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if (iter->iov != fast_iov) {
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iov_off = iter->iov - fast_iov;
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rw->iter.iov += iov_off;
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}
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if (rw->fast_iov != fast_iov)
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memcpy(rw->fast_iov + iov_off, fast_iov + iov_off,
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sizeof(struct iovec) * iter->nr_segs);
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} else {
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rw->iov = iovec;
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rw->free_iovec = iovec;
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req->flags |= REQ_F_NEED_CLEANUP;
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}
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}
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@ -2963,8 +2969,8 @@ static int io_alloc_async_ctx(struct io_kiocb *req)
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return __io_alloc_async_ctx(req);
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}
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static int io_setup_async_rw(struct io_kiocb *req, ssize_t io_size,
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struct iovec *iovec, struct iovec *fast_iov,
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static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
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const struct iovec *fast_iov,
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struct iov_iter *iter)
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{
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if (!io_op_defs[req->opcode].async_ctx)
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@ -2973,7 +2979,7 @@ static int io_setup_async_rw(struct io_kiocb *req, ssize_t io_size,
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if (__io_alloc_async_ctx(req))
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return -ENOMEM;
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io_req_map_rw(req, io_size, iovec, fast_iov, iter);
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io_req_map_rw(req, iovec, fast_iov, iter);
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}
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return 0;
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}
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@ -2981,18 +2987,19 @@ static int io_setup_async_rw(struct io_kiocb *req, ssize_t io_size,
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static inline int io_rw_prep_async(struct io_kiocb *req, int rw,
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bool force_nonblock)
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{
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struct io_async_ctx *io = req->io;
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struct iov_iter iter;
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struct io_async_rw *iorw = &req->io->rw;
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ssize_t ret;
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io->rw.iov = io->rw.fast_iov;
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iorw->iter.iov = iorw->fast_iov;
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/* reset ->io around the iovec import, we don't want to use it */
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req->io = NULL;
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ret = io_import_iovec(rw, req, &io->rw.iov, &iter, !force_nonblock);
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req->io = io;
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ret = io_import_iovec(rw, req, (struct iovec **) &iorw->iter.iov,
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&iorw->iter, !force_nonblock);
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req->io = container_of(iorw, struct io_async_ctx, rw);
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if (unlikely(ret < 0))
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return ret;
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io_req_map_rw(req, ret, io->rw.iov, io->rw.fast_iov, &iter);
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io_req_map_rw(req, iorw->iter.iov, iorw->fast_iov, &iorw->iter);
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return 0;
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}
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@ -3090,7 +3097,8 @@ static inline int kiocb_wait_page_queue_init(struct kiocb *kiocb,
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* succeed, or in rare cases where it fails, we then fall back to using the
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* async worker threads for a blocking retry.
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*/
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static bool io_rw_should_retry(struct io_kiocb *req)
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static bool io_rw_should_retry(struct io_kiocb *req, struct iovec *iovec,
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struct iovec *fast_iov, struct iov_iter *iter)
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{
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struct kiocb *kiocb = &req->rw.kiocb;
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int ret;
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@ -3113,8 +3121,11 @@ static bool io_rw_should_retry(struct io_kiocb *req)
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* If request type doesn't require req->io to defer in general,
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* we need to allocate it here
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*/
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if (!req->io && __io_alloc_async_ctx(req))
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return false;
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if (!req->io) {
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if (__io_alloc_async_ctx(req))
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return false;
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io_req_map_rw(req, iovec, fast_iov, iter);
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}
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ret = kiocb_wait_page_queue_init(kiocb, &req->io->rw.wpq,
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io_async_buf_func, req);
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@ -3141,12 +3152,14 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
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{
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struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
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struct kiocb *kiocb = &req->rw.kiocb;
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struct iov_iter iter;
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struct iov_iter __iter, *iter = &__iter;
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size_t iov_count;
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ssize_t io_size, ret, ret2;
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unsigned long nr_segs;
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ssize_t io_size, ret, ret2 = 0;
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ret = io_import_iovec(READ, req, &iovec, &iter, !force_nonblock);
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if (req->io)
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iter = &req->io->rw.iter;
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ret = io_import_iovec(READ, req, &iovec, iter, !force_nonblock);
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if (ret < 0)
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return ret;
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io_size = ret;
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@ -3160,30 +3173,26 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
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if (force_nonblock && !io_file_supports_async(req->file, READ))
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goto copy_iov;
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iov_count = iov_iter_count(&iter);
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nr_segs = iter.nr_segs;
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iov_count = iov_iter_count(iter);
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ret = rw_verify_area(READ, req->file, &kiocb->ki_pos, iov_count);
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if (unlikely(ret))
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goto out_free;
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ret2 = io_iter_do_read(req, &iter);
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ret2 = io_iter_do_read(req, iter);
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/* Catch -EAGAIN return for forced non-blocking submission */
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if (!force_nonblock || (ret2 != -EAGAIN && ret2 != -EIO)) {
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kiocb_done(kiocb, ret2, cs);
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} else {
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iter.count = iov_count;
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iter.nr_segs = nr_segs;
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copy_iov:
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ret = io_setup_async_rw(req, io_size, iovec, inline_vecs,
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&iter);
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ret = io_setup_async_rw(req, iovec, inline_vecs, iter);
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if (ret)
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goto out_free;
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/* it's copied and will be cleaned with ->io */
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iovec = NULL;
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/* if we can retry, do so with the callbacks armed */
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if (io_rw_should_retry(req)) {
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ret2 = io_iter_do_read(req, &iter);
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if (io_rw_should_retry(req, iovec, inline_vecs, iter)) {
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ret2 = io_iter_do_read(req, iter);
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if (ret2 == -EIOCBQUEUED) {
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goto out_free;
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} else if (ret2 != -EAGAIN) {
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@ -3223,12 +3232,14 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
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{
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struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
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struct kiocb *kiocb = &req->rw.kiocb;
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struct iov_iter iter;
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struct iov_iter __iter, *iter = &__iter;
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size_t iov_count;
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ssize_t ret, ret2, io_size;
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unsigned long nr_segs;
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ret = io_import_iovec(WRITE, req, &iovec, &iter, !force_nonblock);
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if (req->io)
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iter = &req->io->rw.iter;
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ret = io_import_iovec(WRITE, req, &iovec, iter, !force_nonblock);
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if (ret < 0)
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return ret;
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io_size = ret;
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@ -3247,8 +3258,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
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(req->flags & REQ_F_ISREG))
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goto copy_iov;
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iov_count = iov_iter_count(&iter);
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nr_segs = iter.nr_segs;
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iov_count = iov_iter_count(iter);
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ret = rw_verify_area(WRITE, req->file, &kiocb->ki_pos, iov_count);
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if (unlikely(ret))
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goto out_free;
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@ -3269,9 +3279,9 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
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kiocb->ki_flags |= IOCB_WRITE;
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if (req->file->f_op->write_iter)
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ret2 = call_write_iter(req->file, kiocb, &iter);
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ret2 = call_write_iter(req->file, kiocb, iter);
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else if (req->file->f_op->write)
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ret2 = loop_rw_iter(WRITE, req->file, kiocb, &iter);
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ret2 = loop_rw_iter(WRITE, req->file, kiocb, iter);
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else
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ret2 = -EINVAL;
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@ -3284,16 +3294,10 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
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if (!force_nonblock || ret2 != -EAGAIN) {
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kiocb_done(kiocb, ret2, cs);
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} else {
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iter.count = iov_count;
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iter.nr_segs = nr_segs;
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copy_iov:
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ret = io_setup_async_rw(req, io_size, iovec, inline_vecs,
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&iter);
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if (ret)
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goto out_free;
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/* it's copied and will be cleaned with ->io */
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iovec = NULL;
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return -EAGAIN;
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ret = io_setup_async_rw(req, iovec, inline_vecs, iter);
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if (!ret)
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return -EAGAIN;
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}
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out_free:
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if (iovec)
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@ -5583,8 +5587,8 @@ static void __io_clean_op(struct io_kiocb *req)
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case IORING_OP_WRITEV:
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case IORING_OP_WRITE_FIXED:
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case IORING_OP_WRITE:
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if (io->rw.iov != io->rw.fast_iov)
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kfree(io->rw.iov);
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if (io->rw.free_iovec)
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kfree(io->rw.free_iovec);
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break;
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case IORING_OP_RECVMSG:
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case IORING_OP_SENDMSG:
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