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Subject[PATCH 5.9 002/152] io_uring: order refnode recycling
Date
From: Pavel Begunkov <asml.silence@gmail.com>

commit e297822b20e7fe683e107aea46e6402adcf99c70 upstream.

Don't recycle a refnode until we're done with all requests of nodes
ejected before.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/io_uring.c | 34 ++++++++++++++++++++++++----------
1 file changed, 24 insertions(+), 10 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -200,6 +200,7 @@ struct fixed_file_ref_node {
struct list_head file_list;
struct fixed_file_data *file_data;
struct llist_node llist;
+ bool done;
};

struct fixed_file_data {
@@ -7106,10 +7107,6 @@ static void __io_file_put_work(struct fi
kfree(pfile);
}

- spin_lock(&file_data->lock);
- list_del(&ref_node->node);
- spin_unlock(&file_data->lock);
-
percpu_ref_exit(&ref_node->refs);
kfree(ref_node);
percpu_ref_put(&file_data->refs);
@@ -7136,17 +7133,33 @@ static void io_file_put_work(struct work
static void io_file_data_ref_zero(struct percpu_ref *ref)
{
struct fixed_file_ref_node *ref_node;
+ struct fixed_file_data *data;
struct io_ring_ctx *ctx;
- bool first_add;
+ bool first_add = false;
int delay = HZ;

ref_node = container_of(ref, struct fixed_file_ref_node, refs);
- ctx = ref_node->file_data->ctx;
+ data = ref_node->file_data;
+ ctx = data->ctx;
+
+ spin_lock(&data->lock);
+ ref_node->done = true;
+
+ while (!list_empty(&data->ref_list)) {
+ ref_node = list_first_entry(&data->ref_list,
+ struct fixed_file_ref_node, node);
+ /* recycle ref nodes in order */
+ if (!ref_node->done)
+ break;
+ list_del(&ref_node->node);
+ first_add |= llist_add(&ref_node->llist, &ctx->file_put_llist);
+ }
+ spin_unlock(&data->lock);
+

- if (percpu_ref_is_dying(&ctx->file_data->refs))
+ if (percpu_ref_is_dying(&data->refs))
delay = 0;

- first_add = llist_add(&ref_node->llist, &ctx->file_put_llist);
if (!delay)
mod_delayed_work(system_wq, &ctx->file_put_work, 0);
else if (first_add)
@@ -7170,6 +7183,7 @@ static struct fixed_file_ref_node *alloc
INIT_LIST_HEAD(&ref_node->node);
INIT_LIST_HEAD(&ref_node->file_list);
ref_node->file_data = ctx->file_data;
+ ref_node->done = false;
return ref_node;
}

@@ -7297,7 +7311,7 @@ static int io_sqe_files_register(struct

ctx->file_data->cur_refs = &ref_node->refs;
spin_lock(&ctx->file_data->lock);
- list_add(&ref_node->node, &ctx->file_data->ref_list);
+ list_add_tail(&ref_node->node, &ctx->file_data->ref_list);
spin_unlock(&ctx->file_data->lock);
percpu_ref_get(&ctx->file_data->refs);
return ret;
@@ -7442,7 +7456,7 @@ static int __io_sqe_files_update(struct
if (needs_switch) {
percpu_ref_kill(data->cur_refs);
spin_lock(&data->lock);
- list_add(&ref_node->node, &data->ref_list);
+ list_add_tail(&ref_node->node, &data->ref_list);
data->cur_refs = &ref_node->refs;
spin_unlock(&data->lock);
percpu_ref_get(&ctx->file_data->refs);

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