[PATCH 5.10 05/54] io_uring: always batch cancel in *cancel_files()

Greg Kroah-Hartman
2021-02-11T15:38:49Z

From: Pavel Begunkov <asml.silence@gmail.com>

[ Upstream commit f6edbabb8359798c541b0776616c5eab3a840d3d ]

Instead of iterating over each request and cancelling it individually in
io_uring_cancel_files(), try to cancel all matching requests and use
->inflight_list only to check if there anything left.

In many cases it should be faster, and we can reuse a lot of code from
task cancellation.

Signed-off-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-wq.c | 10 ----
fs/io-wq.h | 1
fs/io_uring.c | 139 ++++++++--------------------------------------------------
3 files changed, 20 insertions(+), 130 deletions(-)

--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -1078,16 +1078,6 @@ enum io_wq_cancel io_wq_cancel_cb(struct
return IO_WQ_CANCEL_NOTFOUND;
}

-static bool io_wq_io_cb_cancel_data(struct io_wq_work *work, void *data)
-{
- return work == data;
-}
-
-enum io_wq_cancel io_wq_cancel_work(struct io_wq *wq, struct io_wq_work *cwork)
-{
- return io_wq_cancel_cb(wq, io_wq_io_cb_cancel_data, (void *)cwork, false);
-}
-
struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
{
int ret = -ENOMEM, node;
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -130,7 +130,6 @@ static inline bool io_wq_is_hashed(struc
}

void io_wq_cancel_all(struct io_wq *wq);
-enum io_wq_cancel io_wq_cancel_work(struct io_wq *wq, struct io_wq_work *cwork);

typedef bool (work_cancel_fn)(struct io_wq_work *, void *);

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1496,15 +1496,6 @@ static void io_kill_timeout(struct io_ki
}
}

-static bool io_task_match(struct io_kiocb *req, struct task_struct *tsk)
-{
- struct io_ring_ctx *ctx = req->ctx;
-
- if (!tsk || req->task == tsk)
- return true;
- return (ctx->flags & IORING_SETUP_SQPOLL);
-}
-
/*
* Returns true if we found and killed one or more timeouts
*/
@@ -8524,112 +8515,31 @@ static int io_uring_release(struct inode
return 0;
}

-/*
- * Returns true if 'preq' is the link parent of 'req'
- */
-static bool io_match_link(struct io_kiocb *preq, struct io_kiocb *req)
-{
- struct io_kiocb *link;
-
- if (!(preq->flags & REQ_F_LINK_HEAD))
- return false;
-
- list_for_each_entry(link, &preq->link_list, link_list) {
- if (link == req)
- return true;
- }
-
- return false;
-}
-
-/*
- * We're looking to cancel 'req' because it's holding on to our files, but
- * 'req' could be a link to another request. See if it is, and cancel that
- * parent request if so.
- */
-static bool io_poll_remove_link(struct io_ring_ctx *ctx, struct io_kiocb *req)
-{
- struct hlist_node *tmp;
- struct io_kiocb *preq;
- bool found = false;
- int i;
-
- spin_lock_irq(&ctx->completion_lock);
- for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
- struct hlist_head *list;
-
- list = &ctx->cancel_hash[i];
- hlist_for_each_entry_safe(preq, tmp, list, hash_node) {
- found = io_match_link(preq, req);
- if (found) {
- io_poll_remove_one(preq);
- break;
- }
- }
- }
- spin_unlock_irq(&ctx->completion_lock);
- return found;
-}
-
-static bool io_timeout_remove_link(struct io_ring_ctx *ctx,
- struct io_kiocb *req)
-{
- struct io_kiocb *preq;
- bool found = false;
-
- spin_lock_irq(&ctx->completion_lock);
- list_for_each_entry(preq, &ctx->timeout_list, timeout.list) {
- found = io_match_link(preq, req);
- if (found) {
- __io_timeout_cancel(preq);
- break;
- }
- }
- spin_unlock_irq(&ctx->completion_lock);
- return found;
-}
+struct io_task_cancel {
+ struct task_struct *task;
+ struct files_struct *files;
+};

-static bool io_cancel_link_cb(struct io_wq_work *work, void *data)
+static bool io_cancel_task_cb(struct io_wq_work *work, void *data)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+ struct io_task_cancel *cancel = data;
bool ret;

- if (req->flags & REQ_F_LINK_TIMEOUT) {
+ if (cancel->files && (req->flags & REQ_F_LINK_TIMEOUT)) {
unsigned long flags;
struct io_ring_ctx *ctx = req->ctx;

/* protect against races with linked timeouts */
spin_lock_irqsave(&ctx->completion_lock, flags);
- ret = io_match_link(req, data);
+ ret = io_match_task(req, cancel->task, cancel->files);
spin_unlock_irqrestore(&ctx->completion_lock, flags);
} else {
- ret = io_match_link(req, data);
+ ret = io_match_task(req, cancel->task, cancel->files);
}
return ret;
}

-static void io_attempt_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req)
-{
- enum io_wq_cancel cret;
-
- /* cancel this particular work, if it's running */
- cret = io_wq_cancel_work(ctx->io_wq, &req->work);
- if (cret != IO_WQ_CANCEL_NOTFOUND)
- return;
-
- /* find links that hold this pending, cancel those */
- cret = io_wq_cancel_cb(ctx->io_wq, io_cancel_link_cb, req, true);
- if (cret != IO_WQ_CANCEL_NOTFOUND)
- return;
-
- /* if we have a poll link holding this pending, cancel that */
- if (io_poll_remove_link(ctx, req))
- return;
-
- /* final option, timeout link is holding this req pending */
- io_timeout_remove_link(ctx, req);
-}
-
static void io_cancel_defer_files(struct io_ring_ctx *ctx,
struct task_struct *task,
struct files_struct *files)
@@ -8661,8 +8571,10 @@ static void io_uring_cancel_files(struct
struct files_struct *files)
{
while (!list_empty_careful(&ctx->inflight_list)) {
- struct io_kiocb *cancel_req = NULL, *req;
+ struct io_task_cancel cancel = { .task = task, .files = NULL, };
+ struct io_kiocb *req;
DEFINE_WAIT(wait);
+ bool found = false;

spin_lock_irq(&ctx->inflight_lock);
list_for_each_entry(req, &ctx->inflight_list, inflight_entry) {
@@ -8670,25 +8582,21 @@ static void io_uring_cancel_files(struct
(req->work.flags & IO_WQ_WORK_FILES) &&
req->work.identity->files != files)
continue;
- /* req is being completed, ignore */
- if (!refcount_inc_not_zero(&req->refs))
- continue;
- cancel_req = req;
+ found = true;
break;
}
- if (cancel_req)
+ if (found)
prepare_to_wait(&ctx->inflight_wait, &wait,
TASK_UNINTERRUPTIBLE);
spin_unlock_irq(&ctx->inflight_lock);

/* We need to keep going until we don't find a matching req */
- if (!cancel_req)
+ if (!found)
break;
- /* cancel this request, or head link requests */
- io_attempt_cancel(ctx, cancel_req);
- io_cqring_overflow_flush(ctx, true, task, files);

- io_put_req(cancel_req);
+ io_wq_cancel_cb(ctx->io_wq, io_cancel_task_cb, &cancel, true);
+ io_poll_remove_all(ctx, task, files);
+ io_kill_timeouts(ctx, task, files);
/* cancellations _may_ trigger task work */
io_run_task_work();
schedule();
@@ -8696,22 +8604,15 @@ static void io_uring_cancel_files(struct
}
}

-static bool io_cancel_task_cb(struct io_wq_work *work, void *data)
-{
- struct io_kiocb *req = container_of(work, struct io_kiocb, work);
- struct task_struct *task = data;
-
- return io_task_match(req, task);
-}
-
static void __io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
struct task_struct *task)
{
while (1) {
+ struct io_task_cancel cancel = { .task = task, .files = NULL, };
enum io_wq_cancel cret;
bool ret = false;

- cret = io_wq_cancel_cb(ctx->io_wq, io_cancel_task_cb, task, true);
+ cret = io_wq_cancel_cb(ctx->io_wq, io_cancel_task_cb, &cancel, true);
if (cret != IO_WQ_CANCEL_NOTFOUND)
ret = true;