On Mon, Oct 26, 2020 at 04:05:30PM +0100, Roberto Bergantinos Corpas wrote:
> RPC channel buffer size for slow case (user buffer bigger than
> one page) can be converted into dymanic and also allows us to
> prescind from queue_io_mutex
Sorry for the slow response.
Let's just remove cache_slow_downcall and the find_or_create_page()
thing and just do a kvmalloc() from the start. I don't understand why
we need to be more complicated.
--b.
>
> Signed-off-by: Roberto Bergantinos Corpas <rbergant@xxxxxxxxxx>
> ---
> net/sunrpc/cache.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
> index baef5ee43dbb..325393f75e17 100644
> --- a/net/sunrpc/cache.c
> +++ b/net/sunrpc/cache.c
> @@ -777,7 +777,6 @@ void cache_clean_deferred(void *owner)
> */
>
> static DEFINE_SPINLOCK(queue_lock);
> -static DEFINE_MUTEX(queue_io_mutex);
>
> struct cache_queue {
> struct list_head list;
> @@ -908,14 +907,18 @@ static ssize_t cache_do_downcall(char *kaddr, const char __user *buf,
> static ssize_t cache_slow_downcall(const char __user *buf,
> size_t count, struct cache_detail *cd)
> {
> - static char write_buf[8192]; /* protected by queue_io_mutex */
> + char *write_buf;
> ssize_t ret = -EINVAL;
>
> - if (count >= sizeof(write_buf))
> + if (count >= 32768) /* 32k is max userland buffer, lets check anyway */
> goto out;
> - mutex_lock(&queue_io_mutex);
> +
> + write_buf = kvmalloc(count + 1, GFP_KERNEL);
> + if (!write_buf)
> + return -ENOMEM;
> +
> ret = cache_do_downcall(write_buf, buf, count, cd);
> - mutex_unlock(&queue_io_mutex);
> + kvfree(write_buf);
> out:
> return ret;
> }
> --
> 2.21.0
