netfs: Change ->init_request() to return an error code

Change the request initialisation function to return an error code so that
the network filesystem can return a failure (ENOMEM, for example).

This will also allow ceph to abort a ->readahead() op if the server refuses
to give it a cap allowing local caching from within the netfslib framework
(errors aren't passed back through ->readahead(), so returning, say,
-ENOBUFS will cause the op to be aborted).

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164678212401.1200972.16537041523832944934.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692905398.2099075.5238033621684646524.stgit@warthog.procyon.org.uk/ # v3

1 files changed, 24 insertions, 17 deletions

diff --git a/fs/netfs/objects.c b/fs/netfs/objects.c
index 986d7a9d25dd..ae18827e156b 100644
--- a/fs/netfs/objects.c
+++ b/fs/netfs/objects.c
@@ -20,27 +20,34 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
 {
 	static atomic_t debug_ids;
 	struct netfs_io_request *rreq;
+	int ret;
 
 	rreq = kzalloc(sizeof(struct netfs_io_request), GFP_KERNEL);
-	if (rreq) {
-		rreq->start	= start;
-		rreq->len	= len;
-		rreq->origin	= origin;
-		rreq->netfs_ops	= ops;
-		rreq->netfs_priv = netfs_priv;
-		rreq->mapping	= mapping;
-		rreq->inode	= file_inode(file);
-		rreq->i_size	= i_size_read(rreq->inode);
-		rreq->debug_id	= atomic_inc_return(&debug_ids);
-		INIT_LIST_HEAD(&rreq->subrequests);
-		INIT_WORK(&rreq->work, netfs_rreq_work);
-		refcount_set(&rreq->ref, 1);
-		__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
-		if (ops->init_request)
-			ops->init_request(rreq, file);
-		netfs_stat(&netfs_n_rh_rreq);
+	if (!rreq)
+		return ERR_PTR(-ENOMEM);
+
+	rreq->start	= start;
+	rreq->len	= len;
+	rreq->origin	= origin;
+	rreq->netfs_ops	= ops;
+	rreq->netfs_priv = netfs_priv;
+	rreq->mapping	= mapping;
+	rreq->inode	= file_inode(file);
+	rreq->i_size	= i_size_read(rreq->inode);
+	rreq->debug_id	= atomic_inc_return(&debug_ids);
+	INIT_LIST_HEAD(&rreq->subrequests);
+	INIT_WORK(&rreq->work, netfs_rreq_work);
+	refcount_set(&rreq->ref, 1);
+	__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
+	if (rreq->netfs_ops->init_request) {
+		ret = rreq->netfs_ops->init_request(rreq, file);
+		if (ret < 0) {
+			kfree(rreq);
+			return ERR_PTR(ret);
+		}
 	}
 
+	netfs_stat(&netfs_n_rh_rreq);
 	return rreq;
 }