[PATCH] netfs: make ops->init_rreq() optional

[Jeffle Xu <jefflexu@linux.alibaba.com>]

Hi, recently I'm developing erofs over fscache for implementing
on-demand read, and erofs also implements an empty .init_rreq()
callback[1].

[1] https://lkml.org/lkml/2021/12/27/224

If folks don't like this cleanup and prefer empty callback in upper fs,
I'm also fine with that.
---
There's already upper fs implementing empty .init_rreq() callback, and
thus make it optional.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
 fs/ceph/addr.c         | 5 -----
 fs/netfs/read_helper.c | 3 ++-
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index e53c8541f5b2..c3537dfd8c04 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -291,10 +291,6 @@ static void ceph_netfs_issue_op(struct netfs_read_subrequest *subreq)
 	dout("%s: result %d\n", __func__, err);
 }
 
-static void ceph_init_rreq(struct netfs_read_request *rreq, struct file *file)
-{
-}
-
 static void ceph_readahead_cleanup(struct address_space *mapping, void *priv)
 {
 	struct inode *inode = mapping->host;
@@ -306,7 +302,6 @@ static void ceph_readahead_cleanup(struct address_space *mapping, void *priv)
 }
 
 static const struct netfs_read_request_ops ceph_netfs_read_ops = {
-	.init_rreq		= ceph_init_rreq,
 	.is_cache_enabled	= ceph_is_cache_enabled,
 	.begin_cache_operation	= ceph_begin_cache_operation,
 	.issue_op		= ceph_netfs_issue_op,
diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 75c76cbb27cc..0befb0747c59 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -55,7 +55,8 @@ static struct netfs_read_request *netfs_alloc_read_request(
 		INIT_WORK(&rreq->work, netfs_rreq_work);
 		refcount_set(&rreq->usage, 1);
 		__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
-		ops->init_rreq(rreq, file);
+		if (ops->init_rreq)
+			ops->init_rreq(rreq, file);
 		netfs_stat(&netfs_n_rh_rreq);
 	}
 
-- 
2.27.0