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Subject[PATCH 4/4] io_wq: add per-wq work handler instead of per work
Date
io_uring is the only user of io-wq, and now it uses only io-wq callback
for all its requests, namely io_wq_submit_work(). Instead of storing
work->runner callback in each instance of io_wq_work, keep it in io-wq
itself.

pros:
- reduces io_wq_work size
- more robust -- ->func won't be invalidated with mem{cpy,set}(req)
- helps other work

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io-wq.c | 10 ++++++----
fs/io-wq.h | 7 ++++---
fs/io_uring.c | 3 ++-
3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 2bfa9117bc28..a44ad3b98886 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -112,6 +112,7 @@ struct io_wq {
unsigned long state;

free_work_fn *free_work;
+ io_wq_work_fn *do_work;

struct task_struct *manager;
struct user_struct *user;
@@ -528,7 +529,7 @@ static void io_worker_handle_work(struct io_worker *worker)

hash = io_get_work_hash(work);
linked = old_work = work;
- linked->func(&linked);
+ wq->do_work(&linked);
linked = (old_work == linked) ? NULL : linked;

work = next_hashed;
@@ -785,7 +786,7 @@ static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe)
struct io_wq_work *old_work = work;

work->flags |= IO_WQ_WORK_CANCEL;
- work->func(&work);
+ wq->do_work(&work);
work = (work == old_work) ? NULL : work;
wq->free_work(old_work);
} while (work);
@@ -1027,7 +1028,7 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
int ret = -ENOMEM, node;
struct io_wq *wq;

- if (WARN_ON_ONCE(!data->free_work))
+ if (WARN_ON_ONCE(!data->free_work || !data->do_work))
return ERR_PTR(-EINVAL);

wq = kzalloc(sizeof(*wq), GFP_KERNEL);
@@ -1041,6 +1042,7 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
}

wq->free_work = data->free_work;
+ wq->do_work = data->do_work;

/* caller must already hold a reference to this */
wq->user = data->user;
@@ -1097,7 +1099,7 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)

bool io_wq_get(struct io_wq *wq, struct io_wq_data *data)
{
- if (data->free_work != wq->free_work)
+ if (data->free_work != wq->free_work || data->do_work != wq->do_work)
return false;

return refcount_inc_not_zero(&wq->use_refs);
diff --git a/fs/io-wq.h b/fs/io-wq.h
index df8a4cd3236d..f3bb596f5a3f 100644
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -85,7 +85,6 @@ static inline void wq_list_del(struct io_wq_work_list *list,

struct io_wq_work {
struct io_wq_work_node list;
- void (*func)(struct io_wq_work **);
struct files_struct *files;
struct mm_struct *mm;
const struct cred *creds;
@@ -94,9 +93,9 @@ struct io_wq_work {
pid_t task_pid;
};

-#define INIT_IO_WORK(work, _func) \
+#define INIT_IO_WORK(work) \
do { \
- *(work) = (struct io_wq_work){ .func = _func }; \
+ *(work) = (struct io_wq_work){}; \
} while (0) \

static inline struct io_wq_work *wq_next_work(struct io_wq_work *work)
@@ -108,10 +107,12 @@ static inline struct io_wq_work *wq_next_work(struct io_wq_work *work)
}

typedef void (free_work_fn)(struct io_wq_work *);
+typedef void (io_wq_work_fn)(struct io_wq_work **);

struct io_wq_data {
struct user_struct *user;

+ io_wq_work_fn *do_work;
free_work_fn *free_work;
};

diff --git a/fs/io_uring.c b/fs/io_uring.c
index adf18ff9fdb9..b4ca6026269c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5880,7 +5880,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
refcount_set(&req->refs, 2);
req->task = NULL;
req->result = 0;
- INIT_IO_WORK(&req->work, io_wq_submit_work);
+ INIT_IO_WORK(&req->work);

if (unlikely(req->opcode >= IORING_OP_LAST))
return -EINVAL;
@@ -6896,6 +6896,7 @@ static int io_init_wq_offload(struct io_ring_ctx *ctx,

data.user = ctx->user;
data.free_work = io_free_work;
+ data.do_work = io_wq_submit_work;

if (!(p->flags & IORING_SETUP_ATTACH_WQ)) {
/* Do QD, or 4 * CPUS, whatever is smallest */
--
2.24.0
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