On Fri, 2022-10-21 at 16:49 +0800, Jingbo Xu wrote:
> Use netfs_put_subrequest() and netfs_rreq_completed() completing request
> and subrequest.
>
> It is worth noting that a noop netfs_request_ops is introduced for erofs
> since some netfs routine, e.g. netfs_free_request(), will call into
> this ops.
>
> Signed-off-by: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx>
> ---
> fs/erofs/fscache.c | 47 ++++++++++------------------------------------
> 1 file changed, 10 insertions(+), 37 deletions(-)
>
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index fe05bc51f9f2..fa3f4ab5e3b6 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -4,6 +4,7 @@
> * Copyright (C) 2022, Bytedance Inc. All rights reserved.
> */
> #include <linux/fscache.h>
> +#include <trace/events/netfs.h>
> #include "internal.h"
>
> static DEFINE_MUTEX(erofs_domain_list_lock);
> @@ -11,6 +12,8 @@ static DEFINE_MUTEX(erofs_domain_cookies_lock);
> static LIST_HEAD(erofs_domain_list);
> static struct vfsmount *erofs_pseudo_mnt;
>
> +static const struct netfs_request_ops erofs_noop_req_ops;
> +
> static struct netfs_io_request *erofs_fscache_alloc_request(struct address_space *mapping,
> loff_t start, size_t len)
> {
> @@ -24,40 +27,12 @@ static struct netfs_io_request *erofs_fscache_alloc_request(struct address_space
> rreq->len = len;
> rreq->mapping = mapping;
> rreq->inode = mapping->host;
> + rreq->netfs_ops = &erofs_noop_req_ops;
> INIT_LIST_HEAD(&rreq->subrequests);
> refcount_set(&rreq->ref, 1);
> return rreq;
> }
>
Why is erofs allocating its own netfs structures? This seems quite
fragile, and a layering violation too.
> -static void erofs_fscache_put_request(struct netfs_io_request *rreq)
> -{
> - if (!refcount_dec_and_test(&rreq->ref))
> - return;
> - if (rreq->cache_resources.ops)
> - rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
> - kfree(rreq);
> -}
> -
> -static void erofs_fscache_put_subrequest(struct netfs_io_subrequest *subreq)
> -{
> - if (!refcount_dec_and_test(&subreq->ref))
> - return;
> - erofs_fscache_put_request(subreq->rreq);
> - kfree(subreq);
> -}
> -
> -static void erofs_fscache_clear_subrequests(struct netfs_io_request *rreq)
> -{
> - struct netfs_io_subrequest *subreq;
> -
> - while (!list_empty(&rreq->subrequests)) {
> - subreq = list_first_entry(&rreq->subrequests,
> - struct netfs_io_subrequest, rreq_link);
> - list_del(&subreq->rreq_link);
> - erofs_fscache_put_subrequest(subreq);
> - }
> -}
> -
> static void erofs_fscache_rreq_unlock_folios(struct netfs_io_request *rreq)
> {
> struct netfs_io_subrequest *subreq;
> @@ -114,11 +89,10 @@ static void erofs_fscache_rreq_unlock_folios(struct netfs_io_request *rreq)
> static void erofs_fscache_rreq_complete(struct netfs_io_request *rreq)
> {
> erofs_fscache_rreq_unlock_folios(rreq);
> - erofs_fscache_clear_subrequests(rreq);
> - erofs_fscache_put_request(rreq);
> + netfs_rreq_completed(rreq, false);
> }
>
> -static void erofc_fscache_subreq_complete(void *priv,
> +static void erofs_fscache_subreq_complete(void *priv,
> ssize_t transferred_or_error, bool was_async)
> {
> struct netfs_io_subrequest *subreq = priv;
> @@ -130,7 +104,7 @@ static void erofc_fscache_subreq_complete(void *priv,
> if (atomic_dec_and_test(&rreq->nr_outstanding))
> erofs_fscache_rreq_complete(rreq);
>
> - erofs_fscache_put_subrequest(subreq);
> + netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_terminated);
> }
>
> /*
> @@ -171,9 +145,8 @@ static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
> }
>
> subreq->start = pstart + done;
> - subreq->len = len - done;
> + subreq->len = len - done;
> subreq->flags = 1 << NETFS_SREQ_ONDEMAND;
> -
> list_add_tail(&subreq->rreq_link, &rreq->subrequests);
>
> source = cres->ops->prepare_read(subreq, LLONG_MAX);
> @@ -184,7 +157,7 @@ static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
> source);
> ret = -EIO;
> subreq->error = ret;
> - erofs_fscache_put_subrequest(subreq);
> + netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_failed);
> goto out;
> }
>
> @@ -195,7 +168,7 @@ static int erofs_fscache_read_folios_async(struct fscache_cookie *cookie,
>
> ret = fscache_read(cres, subreq->start, &iter,
> NETFS_READ_HOLE_FAIL,
> - erofc_fscache_subreq_complete, subreq);
> + erofs_fscache_subreq_complete, subreq);
> if (ret == -EIOCBQUEUED)
> ret = 0;
> if (ret) {
I'd rather see this done differently. Either change erofs to use the
netfs infrastructure in a more standard fashion, or maybe consider
teaching erofs to talk to cachefiles directly?
IDK, but this sort of mucking around in the low level netfs objects
seems wrong to me.
--
Jeff Layton <jlayton@xxxxxxxxxx>
