diff --git a/fs/io_uring.c b/fs/io_uring.c
index 3077f85a2638142f2518a3f200b75cfc386e706c..e372d5b9f6dc04ce31b39d4499602d54815867f6 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -712,6 +712,7 @@ struct io_async_rw {
struct iovec fast_iov[UIO_FASTIOV];
const struct iovec *free_iovec;
struct iov_iter iter;
+ struct iov_iter_state iter_state;
size_t bytes_done;
struct wait_page_queue wpq;
};
@@ -735,7 +736,6 @@ enum {
REQ_F_BUFFER_SELECTED_BIT,
REQ_F_COMPLETE_INLINE_BIT,
REQ_F_REISSUE_BIT,
- REQ_F_DONT_REISSUE_BIT,
REQ_F_CREDS_BIT,
REQ_F_REFCOUNT_BIT,
REQ_F_ARM_LTIMEOUT_BIT,
@@ -782,8 +782,6 @@ enum {
REQ_F_COMPLETE_INLINE = BIT(REQ_F_COMPLETE_INLINE_BIT),
/* caller should reissue async */
REQ_F_REISSUE = BIT(REQ_F_REISSUE_BIT),
- /* don't attempt request reissue, see io_rw_reissue() */
- REQ_F_DONT_REISSUE = BIT(REQ_F_DONT_REISSUE_BIT),
/* supports async reads */
REQ_F_NOWAIT_READ = BIT(REQ_F_NOWAIT_READ_BIT),
/* supports async writes */
@@ -2444,13 +2442,6 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
req = list_first_entry(done, struct io_kiocb, inflight_entry);
list_del(&req->inflight_entry);
- if (READ_ONCE(req->result) == -EAGAIN &&
- !(req->flags & REQ_F_DONT_REISSUE)) {
- req->iopoll_completed = 0;
- io_req_task_queue_reissue(req);
- continue;
- }
-
__io_cqring_fill_event(ctx, req->user_data, req->result,
io_put_rw_kbuf(req));
(*nr_events)++;
@@ -2613,8 +2604,7 @@ static bool io_resubmit_prep(struct io_kiocb *req)
if (!rw)
return !io_req_prep_async(req);
- /* may have left rw->iter inconsistent on -EIOCBQUEUED */
- iov_iter_revert(&rw->iter, req->result - iov_iter_count(&rw->iter));
+ iov_iter_restore(&rw->iter, &rw->iter_state);
return true;
}
@@ -2714,10 +2704,9 @@ static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
if (kiocb->ki_flags & IOCB_WRITE)
kiocb_end_write(req);
if (unlikely(res != req->result)) {
- if (!(res == -EAGAIN && io_rw_should_reissue(req) &&
- io_resubmit_prep(req))) {
- req_set_fail(req);
- req->flags |= REQ_F_DONT_REISSUE;
+ if (res == -EAGAIN && io_rw_should_reissue(req)) {
+ req->flags |= REQ_F_REISSUE;
+ return;
}
}
@@ -2937,7 +2926,6 @@ static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
{
struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
struct io_async_rw *io = req->async_data;
- bool check_reissue = kiocb->ki_complete == io_complete_rw;
/* add previously done IO, if any */
if (io && io->bytes_done > 0) {
@@ -2949,19 +2937,27 @@ static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
if (req->flags & REQ_F_CUR_POS)
req->file->f_pos = kiocb->ki_pos;
- if (ret >= 0 && check_reissue)
+ if (ret >= 0 && (kiocb->ki_complete == io_complete_rw))
__io_complete_rw(req, ret, 0, issue_flags);
else
io_rw_done(kiocb, ret);
- if (check_reissue && (req->flags & REQ_F_REISSUE)) {
+ if (req->flags & REQ_F_REISSUE) {
req->flags &= ~REQ_F_REISSUE;
if (io_resubmit_prep(req)) {
io_req_task_queue_reissue(req);
} else {
+ unsigned int cflags = io_put_rw_kbuf(req);
+ struct io_ring_ctx *ctx = req->ctx;
+
req_set_fail(req);
- __io_req_complete(req, issue_flags, ret,
- io_put_rw_kbuf(req));
+ if (issue_flags & IO_URING_F_NONBLOCK) {
+ mutex_lock(&ctx->uring_lock);
+ __io_req_complete(req, issue_flags, ret, cflags);
+ mutex_unlock(&ctx->uring_lock);
+ } else {
+ __io_req_complete(req, issue_flags, ret, cflags);
+ }
}
}
}
@@ -3324,12 +3320,17 @@ static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
if (!force && !io_op_defs[req->opcode].needs_async_setup)
return 0;
if (!req->async_data) {
+ struct io_async_rw *iorw;
+
if (io_alloc_async_data(req)) {
kfree(iovec);
return -ENOMEM;
}
io_req_map_rw(req, iovec, fast_iov, iter);
+ iorw = req->async_data;
+ /* we've copied and mapped the iter, ensure state is saved */
+ iov_iter_save_state(&iorw->iter, &iorw->iter_state);
}
return 0;
}
@@ -3348,6 +3349,7 @@ static inline int io_rw_prep_async(struct io_kiocb *req, int rw)
iorw->free_iovec = iov;
if (iov)
req->flags |= REQ_F_NEED_CLEANUP;
+ iov_iter_save_state(&iorw->iter, &iorw->iter_state);
return 0;
}
@@ -3451,19 +3453,28 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
struct kiocb *kiocb = &req->rw.kiocb;
struct iov_iter __iter, *iter = &__iter;
struct io_async_rw *rw = req->async_data;
- ssize_t io_size, ret, ret2;
bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+ struct iov_iter_state __state, *state;
+ ssize_t ret, ret2;
if (rw) {
iter = &rw->iter;
+ state = &rw->iter_state;
+ /*
+ * 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(iter, state);
iovec = NULL;
} else {
ret = io_import_iovec(READ, req, &iovec, iter, !force_nonblock);
if (ret < 0)
return ret;
+ state = &__state;
+ iov_iter_save_state(iter, state);
}
- io_size = iov_iter_count(iter);
- req->result = io_size;
+ req->result = iov_iter_count(iter);
/* Ensure we clear previously set non-block flag */
if (!force_nonblock)
@@ -3477,7 +3488,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
return ret ?: -EAGAIN;
}
- ret = rw_verify_area(READ, req->file, io_kiocb_ppos(kiocb), io_size);
+ ret = rw_verify_area(READ, req->file, io_kiocb_ppos(kiocb), req->result);
if (unlikely(ret)) {
kfree(iovec);
return ret;
@@ -3493,30 +3504,49 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
/* no retry on NONBLOCK nor RWF_NOWAIT */
if (req->flags & REQ_F_NOWAIT)
goto done;
- /* some cases will consume bytes even on error returns */
- iov_iter_reexpand(iter, iter->count + iter->truncated);
- iov_iter_revert(iter, io_size - iov_iter_count(iter));
ret = 0;
} else if (ret == -EIOCBQUEUED) {
goto out_free;
- } else if (ret <= 0 || ret == io_size || !force_nonblock ||
+ } else if (ret <= 0 || ret == req->result || !force_nonblock ||
(req->flags & REQ_F_NOWAIT) || !need_read_all(req)) {
/* read all, failed, already did sync or don't want to retry */
goto done;
}
+ /*
+ * Don't depend on the iter state matching what was consumed, or being
+ * untouched in case of error. Restore it and we'll advance it
+ * manually if we need to.
+ */
+ iov_iter_restore(iter, state);
+
ret2 = io_setup_async_rw(req, iovec, inline_vecs, iter, true);
if (ret2)
return ret2;
iovec = NULL;
rw = req->async_data;
- /* now use our persistent iterator, if we aren't already */
- iter = &rw->iter;
+ /*
+ * Now use our persistent iterator and state, if we aren't already.
+ * We've restored and mapped the iter to match.
+ */
+ if (iter != &rw->iter) {
+ iter = &rw->iter;
+ state = &rw->iter_state;
+ }
do {
- io_size -= ret;
+ /*
+ * We end up here because of a partial read, either from
+ * above or inside this loop. Advance the iter by the bytes
+ * that were consumed.
+ */
+ iov_iter_advance(iter, ret);
+ if (!iov_iter_count(iter))
+ break;
rw->bytes_done += ret;
+ iov_iter_save_state(iter, state);
+
/* if we can retry, do so with the callbacks armed */
if (!io_rw_should_retry(req)) {
kiocb->ki_flags &= ~IOCB_WAITQ;
@@ -3534,7 +3564,8 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
return 0;
/* we got some bytes, but not all. retry. */
kiocb->ki_flags &= ~IOCB_WAITQ;
- } while (ret > 0 && ret < io_size);
+ iov_iter_restore(iter, state);
+ } while (ret > 0);
done:
kiocb_done(kiocb, ret, issue_flags);
out_free:
@@ -3557,19 +3588,24 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
struct kiocb *kiocb = &req->rw.kiocb;
struct iov_iter __iter, *iter = &__iter;
struct io_async_rw *rw = req->async_data;
- ssize_t ret, ret2, io_size;
bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+ struct iov_iter_state __state, *state;
+ ssize_t ret, ret2;
if (rw) {
iter = &rw->iter;
+ state = &rw->iter_state;
+ iov_iter_restore(iter, state);
iovec = NULL;
} else {
ret = io_import_iovec(WRITE, req, &iovec, iter, !force_nonblock);
if (ret < 0)
return ret;
+ state = &__state;
+ iov_iter_save_state(iter, state);
}
- io_size = iov_iter_count(iter);
- req->result = io_size;
+ req->result = iov_iter_count(iter);
+ ret2 = 0;
/* Ensure we clear previously set non-block flag */
if (!force_nonblock)
@@ -3586,7 +3622,7 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
(req->flags & REQ_F_ISREG))
goto copy_iov;
- ret = rw_verify_area(WRITE, req->file, io_kiocb_ppos(kiocb), io_size);
+ ret = rw_verify_area(WRITE, req->file, io_kiocb_ppos(kiocb), req->result);
if (unlikely(ret))
goto out_free;
@@ -3633,9 +3669,9 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
kiocb_done(kiocb, ret2, issue_flags);
} else {
copy_iov:
- /* some cases will consume bytes even on error returns */
- iov_iter_reexpand(iter, iter->count + iter->truncated);
- iov_iter_revert(iter, io_size - iov_iter_count(iter));
+ iov_iter_restore(iter, state);
+ if (ret2 > 0)
+ iov_iter_advance(iter, ret2);
ret = io_setup_async_rw(req, iovec, inline_vecs, iter, false);
return ret ?: -EAGAIN;
}
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 5265024e8b9094cae8b211928e030980f7ec7d12..207101a9c5c326958eaae5b4be2208f0b6e2028e 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -27,6 +27,12 @@ enum iter_type {
ITER_DISCARD,
};
+struct iov_iter_state {
+ size_t iov_offset;
+ size_t count;
+ unsigned long nr_segs;
+};
+
struct iov_iter {
u8 iter_type;
bool data_source;
@@ -47,7 +53,6 @@ struct iov_iter {
};
loff_t xarray_start;
};
- size_t truncated;
};
static inline enum iter_type iov_iter_type(const struct iov_iter *i)
@@ -55,6 +60,14 @@ static inline enum iter_type iov_iter_type(const struct iov_iter *i)
return i->iter_type;
}
+static inline void iov_iter_save_state(struct iov_iter *iter,
+ struct iov_iter_state *state)
+{
+ state->iov_offset = iter->iov_offset;
+ state->count = iter->count;
+ state->nr_segs = iter->nr_segs;
+}
+
static inline bool iter_is_iovec(const struct iov_iter *i)
{
return iov_iter_type(i) == ITER_IOVEC;
@@ -233,6 +246,7 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
size_t maxsize, size_t *start);
int iov_iter_npages(const struct iov_iter *i, int maxpages);
+void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
@@ -255,10 +269,8 @@ static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
* conversion in assignement is by definition greater than all
* values of size_t, including old i->count.
*/
- if (i->count > count) {
- i->truncated += i->count - count;
+ if (i->count > count)
i->count = count;
- }
}
/*
@@ -267,7 +279,6 @@ static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
*/
static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
{
- i->truncated -= count - i->count;
i->count = count;
}
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index f2d50d69a6c364c06b9e7fa4f37527224dd712c6..755c10c5138cdb51d5da166ee2900565dfdfde38 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1972,3 +1972,39 @@ int import_single_range(int rw, void __user *buf, size_t len,
return 0;
}
EXPORT_SYMBOL(import_single_range);
+
+/**
+ * iov_iter_restore() - Restore a &struct iov_iter to the same state as when
+ * iov_iter_save_state() was called.
+ *
+ * @i: &struct iov_iter to restore
+ * @state: state to restore from
+ *
+ * Used after iov_iter_save_state() to bring restore @i, if operations may
+ * have advanced it.
+ *
+ * Note: only works on ITER_IOVEC, ITER_BVEC, and ITER_KVEC
+ */
+void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state)
+{
+ if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i)) &&
+ !iov_iter_is_kvec(i))
+ return;
+ i->iov_offset = state->iov_offset;
+ i->count = state->count;
+ /*
+ * For the *vec iters, nr_segs + iov is constant - if we increment
+ * the vec, then we also decrement the nr_segs count. Hence we don't
+ * need to track both of these, just one is enough and we can deduct
+ * the other from that. ITER_KVEC and ITER_IOVEC are the same struct
+ * size, so we can just increment the iov pointer as they are unionzed.
+ * ITER_BVEC _may_ be the same size on some archs, but on others it is
+ * not. Be safe and handle it separately.
+ */
+ BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
+ if (iov_iter_is_bvec(i))
+ i->bvec -= state->nr_segs - i->nr_segs;
+ else
+ i->iov -= state->nr_segs - i->nr_segs;
+ i->nr_segs = state->nr_segs;
+}