From c88598a92a587109d915b4d97831bcea774c8b6f Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Thu, 14 Oct 2021 16:10:16 +0100
Subject: [PATCH] io_uring: optimise read/write iov state storing
Git-commit: c88598a92a587109d915b4d97831bcea774c8b6f
Patch-mainline: v5.16-rc1
References: bsc#1205205
Currently io_read() and io_write() keep separate pointers to an iter and
to struct iov_iter_state, which is not great for register spilling and
requires more on-stack copies. They are both either on-stack or in
req->async_data at the same time, so use struct io_rw_state and keep a
pointer only to it, so having all the state with just one pointer.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5c5e7ffd7dc25fc35075c70411ba99df72f237fa.1634144845.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
---
fs/io_uring.c | 79 ++++++++++++++++++++++++---------------------------
1 file changed, 37 insertions(+), 42 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 47365610de5d..bb5cd8715f61 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -695,9 +695,9 @@ struct io_async_msghdr {
};
struct io_rw_state {
- struct iovec fast_iov[UIO_FASTIOV];
struct iov_iter iter;
struct iov_iter_state iter_state;
+ struct iovec fast_iov[UIO_FASTIOV];
};
struct io_async_rw {
@@ -3297,8 +3297,7 @@ static inline bool io_alloc_async_data(struct io_kiocb *req)
}
static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
- const struct iovec *fast_iov,
- struct iov_iter *iter, bool force)
+ struct io_rw_state *s, bool force)
{
if (!force && !io_op_defs[req->opcode].needs_async_setup)
return 0;
@@ -3310,7 +3309,7 @@ static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
return -ENOMEM;
}
- io_req_map_rw(req, iovec, fast_iov, iter);
+ 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);
@@ -3432,33 +3431,33 @@ static bool need_read_all(struct io_kiocb *req)
static int io_read(struct io_kiocb *req, unsigned int issue_flags)
{
- struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+ struct io_rw_state __s, *s;
+ struct iovec *iovec;
struct kiocb *kiocb = &req->rw.kiocb;
- struct iov_iter __iter, *iter = &__iter;
bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
- struct iov_iter_state __state, *state;
struct io_async_rw *rw;
ssize_t ret, ret2;
if (req_has_async_data(req)) {
rw = req->async_data;
- iter = &rw->s.iter;
- state = &rw->s.iter_state;
+ s = &rw->s;
/*
* 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);
+ iov_iter_restore(&s->iter, &s->iter_state);
iovec = NULL;
} else {
- ret = io_import_iovec(READ, req, &iovec, iter, !force_nonblock);
+ s = &__s;
+ iovec = s->fast_iov;
+ ret = io_import_iovec(READ, req, &iovec, &s->iter, !force_nonblock);
if (ret < 0)
return ret;
- state = &__state;
- iov_iter_save_state(iter, state);
+
+ iov_iter_save_state(&s->iter, &s->iter_state);
}
- req->result = iov_iter_count(iter);
+ req->result = iov_iter_count(&s->iter);
/* Ensure we clear previously set non-block flag */
if (!force_nonblock)
@@ -3468,7 +3467,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
/* If the file doesn't support async, just async punt */
if (force_nonblock && !io_file_supports_nowait(req, READ)) {
- ret = io_setup_async_rw(req, iovec, inline_vecs, iter, true);
+ ret = io_setup_async_rw(req, iovec, s, true);
return ret ?: -EAGAIN;
}
@@ -3478,7 +3477,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
return ret;
}
- ret = io_iter_do_read(req, iter);
+ ret = io_iter_do_read(req, &s->iter);
if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
req->flags &= ~REQ_F_REISSUE;
@@ -3502,22 +3501,19 @@ 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(iter, state);
+ iov_iter_restore(&s->iter, &s->iter_state);
- ret2 = io_setup_async_rw(req, iovec, inline_vecs, iter, true);
+ ret2 = io_setup_async_rw(req, iovec, s, true);
if (ret2)
return ret2;
iovec = NULL;
rw = req->async_data;
+ s = &rw->s;
/*
* Now use our persistent iterator and state, if we aren't already.
* We've restored and mapped the iter to match.
*/
- if (iter != &rw->s.iter) {
- iter = &rw->s.iter;
- state = &rw->s.iter_state;
- }
do {
/*
@@ -3525,11 +3521,11 @@ 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(iter, ret);
- if (!iov_iter_count(iter))
+ iov_iter_advance(&s->iter, ret);
+ if (!iov_iter_count(&s->iter))
break;
rw->bytes_done += ret;
- iov_iter_save_state(iter, state);
+ iov_iter_save_state(&s->iter, &s->iter_state);
/* if we can retry, do so with the callbacks armed */
if (!io_rw_should_retry(req)) {
@@ -3543,12 +3539,12 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
* 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(req, iter);
+ ret = io_iter_do_read(req, &s->iter);
if (ret == -EIOCBQUEUED)
return 0;
/* we got some bytes, but not all. retry. */
kiocb->ki_flags &= ~IOCB_WAITQ;
- iov_iter_restore(iter, state);
+ iov_iter_restore(&s->iter, &s->iter_state);
} while (ret > 0);
done:
kiocb_done(kiocb, ret, issue_flags);
@@ -3568,28 +3564,27 @@ static int io_write_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
static int io_write(struct io_kiocb *req, unsigned int issue_flags)
{
- struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+ struct io_rw_state __s, *s;
+ struct io_async_rw *rw;
+ struct iovec *iovec;
struct kiocb *kiocb = &req->rw.kiocb;
- struct iov_iter __iter, *iter = &__iter;
bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
- struct iov_iter_state __state, *state;
- struct io_async_rw *rw;
ssize_t ret, ret2;
if (req_has_async_data(req)) {
rw = req->async_data;
- iter = &rw->s.iter;
- state = &rw->s.iter_state;
- iov_iter_restore(iter, state);
+ s = &rw->s;
+ iov_iter_restore(&s->iter, &s->iter_state);
iovec = NULL;
} else {
- ret = io_import_iovec(WRITE, req, &iovec, iter, !force_nonblock);
+ s = &__s;
+ iovec = s->fast_iov;
+ ret = io_import_iovec(WRITE, req, &iovec, &s->iter, !force_nonblock);
if (ret < 0)
return ret;
- state = &__state;
- iov_iter_save_state(iter, state);
+ iov_iter_save_state(&s->iter, &s->iter_state);
}
- req->result = iov_iter_count(iter);
+ req->result = iov_iter_count(&s->iter);
/* Ensure we clear previously set non-block flag */
if (!force_nonblock)
@@ -3625,9 +3620,9 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
kiocb->ki_flags |= IOCB_WRITE;
if (req->file->f_op->write_iter)
- ret2 = call_write_iter(req->file, kiocb, iter);
+ ret2 = call_write_iter(req->file, kiocb, &s->iter);
else if (req->file->f_op->write)
- ret2 = loop_rw_iter(WRITE, req, iter);
+ ret2 = loop_rw_iter(WRITE, req, &s->iter);
else
ret2 = -EINVAL;
@@ -3653,8 +3648,8 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
kiocb_done(kiocb, ret2, issue_flags);
} else {
copy_iov:
- iov_iter_restore(iter, state);
- ret = io_setup_async_rw(req, iovec, inline_vecs, iter, false);
+ iov_iter_restore(&s->iter, &s->iter_state);
+ ret = io_setup_async_rw(req, iovec, s, false);
return ret ?: -EAGAIN;
}
out_free:
--
2.35.3