On Sat, Nov 21, 2020 at 11:54:30AM +0100, Roberto Bergantinos Corpas wrote:
> Hi Bruce,
>
> Sorry for late response as well.
>
> Ok, here's a possible patch, let me know your thoughts
Looks good to me! Could you just submit with changelog and
Signed-off-by?
--b.
>
> diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
> index baef5ee43dbb..1347ecae9c84 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;
> @@ -905,44 +904,26 @@ static ssize_t cache_do_downcall(char *kaddr,
> const char __user *buf,
> return ret;
> }
>
> -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 */
> - ssize_t ret = -EINVAL;
> -
> - if (count >= sizeof(write_buf))
> - goto out;
> - mutex_lock(&queue_io_mutex);
> - ret = cache_do_downcall(write_buf, buf, count, cd);
> - mutex_unlock(&queue_io_mutex);
> -out:
> - return ret;
> -}
> -
> static ssize_t cache_downcall(struct address_space *mapping,
> const char __user *buf,
> size_t count, struct cache_detail *cd)
> {
> - struct page *page;
> - char *kaddr;
> + char *write_buf;
> ssize_t ret = -ENOMEM;
>
> - if (count >= PAGE_SIZE)
> - goto out_slow;
> + if (count >= 32768) { /* 32k is max userland buffer, lets
> check anyway */
> + ret = -EINVAL;
> + goto out;
> + }
>
> - page = find_or_create_page(mapping, 0, GFP_KERNEL);
> - if (!page)
> - goto out_slow;
> + write_buf = kvmalloc(count + 1, GFP_KERNEL);
> + if (!write_buf)
> + goto out;
>
> - kaddr = kmap(page);
> - ret = cache_do_downcall(kaddr, buf, count, cd);
> - kunmap(page);
> - unlock_page(page);
> - put_page(page);
> + ret = cache_do_downcall(write_buf, buf, count, cd);
> + kvfree(write_buf);
> +out:
> return ret;
> -out_slow:
> - return cache_slow_downcall(buf, count, cd);
> }
>
> static ssize_t cache_write(struct file *filp, const char __user *buf,
>
> On Fri, Nov 6, 2020 at 10:51 PM J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
> >
> > 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
> >
