[PATCH v4 07/39] netfs: Allow the netfs to make the io (sub)request alloc larger

[David Howells]

Allow the network filesystem to specify extra space to be allocated on the
end of the io (sub)request.  This allows cifs, for example, to use this
space rather than allocating its own cifs_readdata struct.

Signed-off-by: David Howells <dhowells at redhat.com>
cc: Jeff Layton <jlayton at kernel.org>
cc: linux-cachefs at redhat.com
cc: linux-fsdevel at vger.kernel.org
cc: linux-mm at kvack.org
---
 fs/netfs/objects.c    | 7 +++++--
 include/linux/netfs.h | 2 ++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/netfs/objects.c b/fs/netfs/objects.c
index 85f428fc52e6..c4229c5f3f54 100644
--- a/fs/netfs/objects.c
+++ b/fs/netfs/objects.c
@@ -22,7 +22,8 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
 	struct netfs_io_request *rreq;
 	int ret;
 
-	rreq = kzalloc(sizeof(struct netfs_io_request), GFP_KERNEL);
+	rreq = kzalloc(ctx->ops->io_request_size ?: sizeof(struct netfs_io_request),
+		       GFP_KERNEL);
 	if (!rreq)
 		return ERR_PTR(-ENOMEM);
 
@@ -114,7 +115,9 @@ struct netfs_io_subrequest *netfs_alloc_subrequest(struct netfs_io_request *rreq
 {
 	struct netfs_io_subrequest *subreq;
 
-	subreq = kzalloc(sizeof(struct netfs_io_subrequest), GFP_KERNEL);
+	subreq = kzalloc(rreq->netfs_ops->io_subrequest_size ?:
+			 sizeof(struct netfs_io_subrequest),
+			 GFP_KERNEL);
 	if (subreq) {
 		INIT_LIST_HEAD(&subreq->rreq_link);
 		refcount_set(&subreq->ref, 2);
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 7244ddebd974..d6f27000eeb0 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -210,6 +210,8 @@ struct netfs_io_request {
  * Operations the network filesystem can/must provide to the helpers.
  */
 struct netfs_request_ops {
+	unsigned int	io_request_size;	/* Alloc size for netfs_io_request struct */
+	unsigned int	io_subrequest_size;	/* Alloc size for netfs_io_subrequest struct */
 	int (*init_request)(struct netfs_io_request *rreq, struct file *file);
 	void (*free_request)(struct netfs_io_request *rreq);