diff mbox series

[2/4] fuse: {io-uring} Access entries with queue lock in fuse_uring_entry_teardown

Message ID 20250124-optimize-fuse-uring-req-timeouts-v1-2-b834b5f32e85@ddn.com (mailing list archive)
State New
Headers show
Series fuse: {io-uring} Ensure fuse requests are set/read with locks | expand

Commit Message

Bernd Schubert Jan. 24, 2025, 4:46 p.m. UTC
This ensures that ent->cmd and ent->fuse_req are accessed in
fuse_uring_entry_teardown while holding the queue lock.

Fixes: a4bdb3d786c0 ("fuse: enable fuse-over-io-uring")
Signed-off-by: Bernd Schubert <bschubert@ddn.com>
---
 fs/fuse/dev_uring.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

Comments

Joanne Koong Jan. 25, 2025, 12:37 a.m. UTC | #1
On Fri, Jan 24, 2025 at 8:47 AM Bernd Schubert <bschubert@ddn.com> wrote:
>
> This ensures that ent->cmd and ent->fuse_req are accessed in
> fuse_uring_entry_teardown while holding the queue lock.
>
> Fixes: a4bdb3d786c0 ("fuse: enable fuse-over-io-uring")
> Signed-off-by: Bernd Schubert <bschubert@ddn.com>
> ---
>  fs/fuse/dev_uring.c | 27 +++++++++++++++++++--------
>  1 file changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> index 1834c1933d2bbab0342257fde4b030f06506c55d..87bb89994c311f435c370f78984be060fcb8036f 100644
> --- a/fs/fuse/dev_uring.c
> +++ b/fs/fuse/dev_uring.c
> @@ -315,14 +315,20 @@ static void fuse_uring_stop_fuse_req_end(struct fuse_ring_ent *ent)
>   */
>  static void fuse_uring_entry_teardown(struct fuse_ring_ent *ent)
>  {
> -       struct fuse_ring_queue *queue = ent->queue;
> -       if (ent->cmd) {
> -               io_uring_cmd_done(ent->cmd, -ENOTCONN, 0, IO_URING_F_UNLOCKED);
> -               ent->cmd = NULL;
> -       }
> +       struct fuse_req *req;
> +       struct io_uring_cmd *cmd;
>
> -       if (ent->fuse_req)
> -               fuse_uring_stop_fuse_req_end(ent);
> +       struct fuse_ring_queue *queue = ent->queue;
> +
> +       spin_lock(&queue->lock);
> +       ent->fuse_req = NULL;
> +
> +       req = ent->fuse_req;

I think you meant here to switch these two lines? otherwise i think
req will alwyas be null here.

Thanks,
Joanne

> +       if (req)
> +               list_del_init(&req->list);
> +
> +       cmd = ent->cmd;
> +       ent->cmd = NULL;
>
>         /*
>          * The entry must not be freed immediately, due to access of direct
> @@ -330,10 +336,15 @@ static void fuse_uring_entry_teardown(struct fuse_ring_ent *ent)
>          * of race between daemon termination (which triggers IO_URING_F_CANCEL
>          * and accesses entries without checking the list state first
>          */
> -       spin_lock(&queue->lock);
>         list_move(&ent->list, &queue->ent_released);
>         ent->state = FRRS_RELEASED;
>         spin_unlock(&queue->lock);
> +
> +       if (cmd)
> +               io_uring_cmd_done(cmd, -ENOTCONN, 0, IO_URING_F_UNLOCKED);
> +
> +       if (req)
> +               fuse_uring_stop_fuse_req_end(req);
>  }
>
>  static void fuse_uring_stop_list_entries(struct list_head *head,
>
> --
> 2.43.0
>
Bernd Schubert Jan. 25, 2025, 9:46 a.m. UTC | #2
On 1/25/25 01:37, Joanne Koong wrote:
> On Fri, Jan 24, 2025 at 8:47 AM Bernd Schubert <bschubert@ddn.com> wrote:
>>
>> This ensures that ent->cmd and ent->fuse_req are accessed in
>> fuse_uring_entry_teardown while holding the queue lock.
>>
>> Fixes: a4bdb3d786c0 ("fuse: enable fuse-over-io-uring")
>> Signed-off-by: Bernd Schubert <bschubert@ddn.com>
>> ---
>>  fs/fuse/dev_uring.c | 27 +++++++++++++++++++--------
>>  1 file changed, 19 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
>> index 1834c1933d2bbab0342257fde4b030f06506c55d..87bb89994c311f435c370f78984be060fcb8036f 100644
>> --- a/fs/fuse/dev_uring.c
>> +++ b/fs/fuse/dev_uring.c
>> @@ -315,14 +315,20 @@ static void fuse_uring_stop_fuse_req_end(struct fuse_ring_ent *ent)
>>   */
>>  static void fuse_uring_entry_teardown(struct fuse_ring_ent *ent)
>>  {
>> -       struct fuse_ring_queue *queue = ent->queue;
>> -       if (ent->cmd) {
>> -               io_uring_cmd_done(ent->cmd, -ENOTCONN, 0, IO_URING_F_UNLOCKED);
>> -               ent->cmd = NULL;
>> -       }
>> +       struct fuse_req *req;
>> +       struct io_uring_cmd *cmd;
>>
>> -       if (ent->fuse_req)
>> -               fuse_uring_stop_fuse_req_end(ent);
>> +       struct fuse_ring_queue *queue = ent->queue;
>> +
>> +       spin_lock(&queue->lock);
>> +       ent->fuse_req = NULL;
>> +
>> +       req = ent->fuse_req;
> 
> I think you meant here to switch these two lines? otherwise i think
> req will alwyas be null here.
> 

Ah yes, thanks for spotting it, it is for extra safety, so bypassed my
basic testing.


Thanks,
Bernd
diff mbox series

Patch

diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index 1834c1933d2bbab0342257fde4b030f06506c55d..87bb89994c311f435c370f78984be060fcb8036f 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -315,14 +315,20 @@  static void fuse_uring_stop_fuse_req_end(struct fuse_ring_ent *ent)
  */
 static void fuse_uring_entry_teardown(struct fuse_ring_ent *ent)
 {
-	struct fuse_ring_queue *queue = ent->queue;
-	if (ent->cmd) {
-		io_uring_cmd_done(ent->cmd, -ENOTCONN, 0, IO_URING_F_UNLOCKED);
-		ent->cmd = NULL;
-	}
+	struct fuse_req *req;
+	struct io_uring_cmd *cmd;
 
-	if (ent->fuse_req)
-		fuse_uring_stop_fuse_req_end(ent);
+	struct fuse_ring_queue *queue = ent->queue;
+
+	spin_lock(&queue->lock);
+	ent->fuse_req = NULL;
+
+	req = ent->fuse_req;
+	if (req)
+		list_del_init(&req->list);
+
+	cmd = ent->cmd;
+	ent->cmd = NULL;
 
 	/*
 	 * The entry must not be freed immediately, due to access of direct
@@ -330,10 +336,15 @@  static void fuse_uring_entry_teardown(struct fuse_ring_ent *ent)
 	 * of race between daemon termination (which triggers IO_URING_F_CANCEL
 	 * and accesses entries without checking the list state first
 	 */
-	spin_lock(&queue->lock);
 	list_move(&ent->list, &queue->ent_released);
 	ent->state = FRRS_RELEASED;
 	spin_unlock(&queue->lock);
+
+	if (cmd)
+		io_uring_cmd_done(cmd, -ENOTCONN, 0, IO_URING_F_UNLOCKED);
+
+	if (req)
+		fuse_uring_stop_fuse_req_end(req);
 }
 
 static void fuse_uring_stop_list_entries(struct list_head *head,