* [PATCH 5.11] io_uring: share fixed_file_refs b/w multiple rsrcs
[not found] <[email protected]>
@ 2020-11-18 19:57 ` Pavel Begunkov
2020-11-18 21:11 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: Pavel Begunkov @ 2020-11-18 19:57 UTC (permalink / raw)
To: Jens Axboe, io-uring, bijan.mottahedeh
Double fixed files for splice/tee are done in a nasty way, it takes 2
ref_node refs, and during the second time it blindly overrides
req->fixed_file_refs hoping that it haven't changed. That works because
all that is done under iouring_lock in a single go but is error-prone.
Bind everything explicitly to a single ref_node and take only one ref,
with current ref_node ordering it's guaranteed to keep all files valid
awhile the request is inflight.
That's mainly a cleanup + preparation for generic resource handling,
but also saves pcpu_ref get/put for splice/tee with 2 fixed files.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6e052011a186..8e769d3f96ca 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1039,6 +1039,16 @@ static inline void io_clean_op(struct io_kiocb *req)
__io_clean_op(req);
}
+static inline void io_set_resource_node(struct io_kiocb *req)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+
+ if (!req->fixed_file_refs) {
+ req->fixed_file_refs = &ctx->file_data->node->refs;
+ percpu_ref_get(req->fixed_file_refs);
+ }
+}
+
static bool io_match_task(struct io_kiocb *head,
struct task_struct *task,
struct files_struct *files)
@@ -1927,9 +1937,7 @@ static struct io_kiocb *io_alloc_req(struct io_ring_ctx *ctx,
static inline void io_put_file(struct io_kiocb *req, struct file *file,
bool fixed)
{
- if (fixed)
- percpu_ref_put(req->fixed_file_refs);
- else
+ if (!fixed)
fput(file);
}
@@ -1941,7 +1949,8 @@ static void io_dismantle_req(struct io_kiocb *req)
kfree(req->async_data);
if (req->file)
io_put_file(req, req->file, (req->flags & REQ_F_FIXED_FILE));
-
+ if (req->fixed_file_refs)
+ percpu_ref_put(req->fixed_file_refs);
io_req_clean_work(req);
}
@@ -6344,10 +6353,7 @@ static struct file *io_file_get(struct io_submit_state *state,
return NULL;
fd = array_index_nospec(fd, ctx->nr_user_files);
file = io_file_from_index(ctx, fd);
- if (file) {
- req->fixed_file_refs = &ctx->file_data->node->refs;
- percpu_ref_get(req->fixed_file_refs);
- }
+ io_set_resource_node(req);
} else {
trace_io_uring_file_get(ctx, fd);
file = __io_file_get(state, fd);
@@ -6725,6 +6731,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
req->ctx = ctx;
req->flags = 0;
req->link = NULL;
+ req->fixed_file_refs = NULL;
/* one is dropped after submission, the other at completion */
refcount_set(&req->refs, 2);
req->task = current;
--
2.24.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 5.11] io_uring: share fixed_file_refs b/w multiple rsrcs
2020-11-18 19:57 ` [PATCH 5.11] io_uring: share fixed_file_refs b/w multiple rsrcs Pavel Begunkov
@ 2020-11-18 21:11 ` Jens Axboe
0 siblings, 0 replies; 2+ messages in thread
From: Jens Axboe @ 2020-11-18 21:11 UTC (permalink / raw)
To: Pavel Begunkov, io-uring, bijan.mottahedeh
On 11/18/20 12:57 PM, Pavel Begunkov wrote:
> Double fixed files for splice/tee are done in a nasty way, it takes 2
> ref_node refs, and during the second time it blindly overrides
> req->fixed_file_refs hoping that it haven't changed. That works because
> all that is done under iouring_lock in a single go but is error-prone.
>
> Bind everything explicitly to a single ref_node and take only one ref,
> with current ref_node ordering it's guaranteed to keep all files valid
> awhile the request is inflight.
>
> That's mainly a cleanup + preparation for generic resource handling,
> but also saves pcpu_ref get/put for splice/tee with 2 fixed files.
LGTM, applied, thanks.
--
Jens Axboe
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