Alexey,
I gave no access to sources but batch looks strange for me,
please take look at my comment in end of this letter
Thank you,
Vasily Averin
On 11/12/24 18:12, Alexey Kuznetsov wrote:
> Obvious leak, which cannot detected unless you try to unload
> fuse module. Found accidentally searching for reasons why
> fuse_dev_find_request take 7% of cpu in profiles.
>
> Also, make it in more optimal way, fget() is too expensive and
> well seen on profiles.
>
> NOTE: this place also needs rcufication. I did that, it is simple
> but patch is too intrusive and suprizingly does not show too
> much of win. It looks like cache bouncing between krpc thread
> and client thread sending request is dominating rather
> than spinlock contention/bouncing.
>
> Signed-off-by: Alexey Kuznetsov <kuz...@virtuozzo.com>
> ---
> fs/fuse/dev.c | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> index f5594e4..5967248 100644
> --- a/fs/fuse/dev.c
> +++ b/fs/fuse/dev.c
> @@ -2678,16 +2678,28 @@ int fuse_dev_release(struct inode *inode, struct file
> *file)
>
> struct fuse_req *fuse_dev_find_request(int fd, u64 unique)
> {
> - struct file *f = fget(fd);
> - struct fuse_dev *fud = fuse_get_dev(f);
> - struct fuse_pqueue *fpq = &fud->pq;
> + struct file * file;
> + struct fuse_dev *fud;
> + struct fuse_pqueue *fpq;
> struct fuse_req *req = NULL;
>
> spin_lock(&fpq->lock);
> + file = files_lookup_fd_rcu(current->files, fd);
> + if (!file)
> + return NULL;
> +
> + if (file->f_op != &fuse_dev_operations)
> + return NULL;
> +
> + fud = fuse_get_dev(file);
> + fpq = &fud->pq;
> +
> if (fpq->connected)
> req = request_find(&fud->pq, unique);
> - spin_unlock(&fpq->lock);
>
> + if (req && hlist_unhashed_lockless(&req->hlist))
> + req = NULL;
> + spin_lock(&fpq->lock);
<<<<<< unlock should be here perhaps? before patch function was returned
without taken lock..
> return req;
> }
> EXPORT_SYMBOL_GPL(fuse_dev_find_request);
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