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

[David Howells <dhowells@redhat.com>]

Hi Jeffle,

I've altered your patch commit message, if you could take a look?

David
---
From: Jeffle Xu <jefflexu@linux.alibaba.com>

netfs: Make ops->init_rreq() optional

Make the ops->init_rreq() callback optional.  This isn't required for the
erofs changes I'm implementing to do on-demand read through fscache[1].
Further, ceph has an empty init_rreq method that can then be removed and
it's marked optional in the documentation.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20211227125444.21187-1-jefflexu@linux.alibaba.com/ [1]
Link: https://lore.kernel.org/r/20211228124419.103020-1-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 b3d9459c9bbd..c98e5238a1b6 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -297,10 +297,6 @@ 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;
@@ -312,7 +308,6 @@ 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 6169659857b3..501da990c259 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);
 	}