6.8-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
commit 2a975d426c82ff05ec1f0b773798d909fe4a3105 upstream.
Supporting multishot reads requires support for NOWAIT, as the alternative would be always having io-wq execute the work item whenever the poll readiness triggered. Any fast file type will have NOWAIT support (eg it understands both O_NONBLOCK and IOCB_NOWAIT). If the given file type does not, then simply resort to single shot execution.
Cc: stable@vger.kernel.org Fixes: fc68fcda04910 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT") Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/rw.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -938,6 +938,13 @@ int io_read_mshot(struct io_kiocb *req, 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. */ @@ -956,7 +963,7 @@ int io_read_mshot(struct io_kiocb *req, /* * 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.