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io_uring: allow buffer recycling in READV

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In commit 934447a603 ("io_uring: do not recycle buffer in READV") a
temporary fix was put in io_kbuf_recycle to simply never recycle READV
buffers.

Instead of that, rather treat READV with REQ_F_BUFFER_SELECTED the same as
a READ with REQ_F_BUFFER_SELECTED. Since READV requires iov_len of 1 they
are essentially the same.
In order to do this inside io_prep_rw() add some validation to check that
it is in fact only length 1, and also extract the length of the buffer at
prep time.

This allows removal of the io_iov_buffer_select codepaths as they are only
used from the READV op.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220907165152.994979-1-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Dylan Yudaken
2022-09-07 09:51:52 -07:00
committed by Jens Axboe
parent de97fcb303
commit 4ab9d46507
2 changed files with 52 additions and 94 deletions
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12
io_uring/kbuf.h
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@@ -86,18 +86,6 @@ static inline bool io_do_buffer_select(struct io_kiocb *req)
static inline void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
{
/*
* READV uses fields in `struct io_rw` (len/addr) to stash the selected
* buffer data. However if that buffer is recycled the original request
* data stored in addr is lost. Therefore forbid recycling for now.
*/
if (req->opcode == IORING_OP_READV) {
if ((req->flags & REQ_F_BUFFER_RING) && req->buf_list) {
req->buf_list->head++;
req->buf_list = NULL;
}
return;
}
if (req->flags & REQ_F_BUFFER_SELECTED)
io_kbuf_recycle_legacy(req, issue_flags);
if (req->flags & REQ_F_BUFFER_RING)