[PATCH 5.9 08/74] io_uring: enable task/files specific overflow flushing

Greg Kroah-Hartman
2020-10-31T11:44:12Z

From: Jens Axboe <axboe@kernel.dk>

commit e6c8aa9ac33bd7c968af7816240fc081401fddcd upstream.

This allows us to selectively flush out pending overflows, depending on
the task and/or files_struct being passed in.

No intended functional changes in this patch.

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/io_uring.c | 41 +++++++++++++++++++++++++----------------
1 file changed, 25 insertions(+), 16 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1344,12 +1344,24 @@ static void io_cqring_mark_overflow(stru
}
}

+static inline bool io_match_files(struct io_kiocb *req,
+ struct files_struct *files)
+{
+ if (!files)
+ return true;
+ if (req->flags & REQ_F_WORK_INITIALIZED)
+ return req->work.files == files;
+ return false;
+}
+
/* Returns true if there are no backlogged entries after the flush */
-static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force)
+static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
+ struct task_struct *tsk,
+ struct files_struct *files)
{
struct io_rings *rings = ctx->rings;
+ struct io_kiocb *req, *tmp;
struct io_uring_cqe *cqe;
- struct io_kiocb *req;
unsigned long flags;
LIST_HEAD(list);

@@ -1368,13 +1380,16 @@ static bool io_cqring_overflow_flush(str
ctx->cq_overflow_flushed = 1;

cqe = NULL;
- while (!list_empty(&ctx->cq_overflow_list)) {
+ list_for_each_entry_safe(req, tmp, &ctx->cq_overflow_list, compl.list) {
+ if (tsk && req->task != tsk)
+ continue;
+ if (!io_match_files(req, files))
+ continue;
+
cqe = io_get_cqring(ctx);
if (!cqe && !force)
break;

- req = list_first_entry(&ctx->cq_overflow_list, struct io_kiocb,
- compl.list);
list_move(&req->compl.list, &list);
if (cqe) {
WRITE_ONCE(cqe->user_data, req->user_data);
@@ -1988,7 +2003,7 @@ static unsigned io_cqring_events(struct
if (noflush && !list_empty(&ctx->cq_overflow_list))
return -1U;

- io_cqring_overflow_flush(ctx, false);
+ io_cqring_overflow_flush(ctx, false, NULL, NULL);
}

/* See comment at the top of this file */
@@ -6489,7 +6504,7 @@ static int io_submit_sqes(struct io_ring
/* if we have a backlog and couldn't flush it all, return BUSY */
if (test_bit(0, &ctx->sq_check_overflow)) {
if (!list_empty(&ctx->cq_overflow_list) &&
- !io_cqring_overflow_flush(ctx, false))
+ !io_cqring_overflow_flush(ctx, false, NULL, NULL))
return -EBUSY;
}

@@ -7993,7 +8008,7 @@ static void io_ring_exit_work(struct wor
*/
do {
if (ctx->rings)
- io_cqring_overflow_flush(ctx, true);
+ io_cqring_overflow_flush(ctx, true, NULL, NULL);
io_iopoll_try_reap_events(ctx);
} while (!wait_for_completion_timeout(&ctx->ref_comp, HZ/20));
io_ring_ctx_free(ctx);
@@ -8013,7 +8028,7 @@ static void io_ring_ctx_wait_and_kill(st

/* if we failed setting up the ctx, we might not have any rings */
if (ctx->rings)
- io_cqring_overflow_flush(ctx, true);
+ io_cqring_overflow_flush(ctx, true, NULL, NULL);
io_iopoll_try_reap_events(ctx);
idr_for_each(&ctx->personality_idr, io_remove_personalities, ctx);

@@ -8069,12 +8084,6 @@ static bool io_match_link(struct io_kioc
return false;
}

-static inline bool io_match_files(struct io_kiocb *req,
- struct files_struct *files)
-{
- return (req->flags & REQ_F_WORK_INITIALIZED) && req->work.files == files;
-}
-
static bool io_match_link_files(struct io_kiocb *req,
struct files_struct *files)
{
@@ -8365,7 +8374,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned
ret = 0;
if (ctx->flags & IORING_SETUP_SQPOLL) {
if (!list_empty_careful(&ctx->cq_overflow_list))
- io_cqring_overflow_flush(ctx, false);
+ io_cqring_overflow_flush(ctx, false, NULL, NULL);
if (flags & IORING_ENTER_SQ_WAKEUP)
wake_up(&ctx->sqo_wait);
submitted = to_submit;