Provide and use folio_queue allocation and free functions to combine the
allocation, initialisation and stat (un)accounting steps that are repeated
in several places.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
---
 fs/netfs/buffered_read.c | 12 +++---------
 fs/netfs/misc.c          | 38 ++++++++++++++++++++++++++++++++++----
 include/linux/netfs.h    |  5 +++++
 3 files changed, 42 insertions(+), 13 deletions(-)

diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c
index 7ac34550c403..b5a7beb9d01b 100644
--- a/fs/netfs/buffered_read.c
+++ b/fs/netfs/buffered_read.c
@@ -131,11 +131,9 @@ static ssize_t netfs_prepare_read_iterator(struct netfs_io_subrequest *subreq)
 			struct folio_queue *tail = rreq->buffer_tail, *new;
 			size_t added;
 
-			new = kmalloc(sizeof(*new), GFP_NOFS);
+			new = netfs_folioq_alloc(GFP_NOFS);
 			if (!new)
 				return -ENOMEM;
-			netfs_stat(&netfs_n_folioq);
-			folioq_init(new);
 			new->prev = tail;
 			tail->next = new;
 			rreq->buffer_tail = new;
@@ -359,11 +357,9 @@ static int netfs_prime_buffer(struct netfs_io_request *rreq)
 	struct folio_batch put_batch;
 	size_t added;
 
-	folioq = kmalloc(sizeof(*folioq), GFP_KERNEL);
+	folioq = netfs_folioq_alloc(GFP_KERNEL);
 	if (!folioq)
 		return -ENOMEM;
-	netfs_stat(&netfs_n_folioq);
-	folioq_init(folioq);
 	rreq->buffer = folioq;
 	rreq->buffer_tail = folioq;
 	rreq->submitted = rreq->start;
@@ -436,12 +432,10 @@ static int netfs_create_singular_buffer(struct netfs_io_request *rreq, struct fo
 {
 	struct folio_queue *folioq;
 
-	folioq = kmalloc(sizeof(*folioq), GFP_KERNEL);
+	folioq = netfs_folioq_alloc(GFP_KERNEL);
 	if (!folioq)
 		return -ENOMEM;
 
-	netfs_stat(&netfs_n_folioq);
-	folioq_init(folioq);
 	folioq_append(folioq, folio);
 	BUG_ON(folioq_folio(folioq, 0) != folio);
 	BUG_ON(folioq_folio_order(folioq, 0) != folio_order(folio));
diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c
index 78fe5796b2b2..6cd7e1ee7a14 100644
--- a/fs/netfs/misc.c
+++ b/fs/netfs/misc.c
@@ -8,6 +8,38 @@
 #include <linux/swap.h>
 #include "internal.h"
 
+/**
+ * netfs_folioq_alloc - Allocate a folio_queue struct
+ * @gfp: Allocation constraints
+ *
+ * Allocate, initialise and account the folio_queue struct.
+ */
+struct folio_queue *netfs_folioq_alloc(gfp_t gfp)
+{
+	struct folio_queue *fq;
+
+	fq = kmalloc(sizeof(*fq), gfp);
+	if (fq) {
+		netfs_stat(&netfs_n_folioq);
+		folioq_init(fq);
+	}
+	return fq;
+}
+EXPORT_SYMBOL(netfs_folioq_alloc);
+
+/**
+ * netfs_folioq_free - Free a folio_queue struct
+ * @folioq: The object to free
+ *
+ * Free and unaccount the folio_queue struct.
+ */
+void netfs_folioq_free(struct folio_queue *folioq)
+{
+	netfs_stat_d(&netfs_n_folioq);
+	kfree(folioq);
+}
+EXPORT_SYMBOL(netfs_folioq_free);
+
 /*
  * Make sure there's space in the rolling queue.
  */
@@ -87,8 +119,7 @@ struct folio_queue *netfs_delete_buffer_head(struct netfs_io_request *wreq)
 
 	if (next)
 		next->prev = NULL;
-	netfs_stat_d(&netfs_n_folioq);
-	kfree(head);
+	netfs_folioq_free(head);
 	wreq->buffer = next;
 	return next;
 }
@@ -111,8 +142,7 @@ void netfs_clear_buffer(struct netfs_io_request *rreq)
 				folio_put(folio);
 			}
 		}
-		netfs_stat_d(&netfs_n_folioq);
-		kfree(p);
+		netfs_folioq_free(p);
 	}
 }
 
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 5eaceef41e6c..b2fa569e875d 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -21,6 +21,7 @@
 
 enum netfs_sreq_ref_trace;
 typedef struct mempool_s mempool_t;
+struct folio_queue;
 
 /**
  * folio_start_private_2 - Start an fscache write on a folio.  [DEPRECATED]
@@ -454,6 +455,10 @@ void netfs_end_io_write(struct inode *inode);
 int netfs_start_io_direct(struct inode *inode);
 void netfs_end_io_direct(struct inode *inode);
 
+/* Miscellaneous APIs. */
+struct folio_queue *netfs_folioq_alloc(gfp_t gfp);
+void netfs_folioq_free(struct folio_queue *folioq);
+
 /**
  * netfs_inode - Get the netfs inode context from the inode
  * @inode: The inode to query