smb: client: use list_sort for iface_list

Adapt iface_cmp to return (-1, 0, 1).
Sort iface_list after parsing+adding all received.

Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>

1 files changed, 41 insertions, 39 deletions

diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 6e09205b53bb..f6df9c2d1117 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -15,6 +15,7 @@
 #include <linux/fiemap.h>
 #include <linux/folio_queue.h>
 #include <uapi/linux/magic.h>
+#include <linux/list_sort.h>
 #include "cifsfs.h"
 #include "cifsglob.h"
 #include "smb2pdu.h"
@@ -581,40 +582,45 @@ smb3_negotiate_rsize(struct cifs_tcon *tcon, struct smb3_fs_context *ctx)
 }
 
 /*
- * compare two interfaces a and b
- * return 0 if everything matches.
- * return 1 if a is rdma capable, or rss capable, or has higher link speed
- * return -1 otherwise.
+ * Compare two interfaces @a and @b.
+ *
+ * Return:
+ *  -1: @a is preferred
+ *   0: exact match
+ *   1: @b is preferred
+ *
+ * "preferred": rdma capable, or rss capable, or has higher link speed
  */
-static int
-iface_cmp(struct cifs_server_iface *a, struct cifs_server_iface *b)
+static int __iface_cmp(struct cifs_server_iface *a, struct cifs_server_iface *b)
 {
-	int cmp_ret = 0;
-
-	WARN_ON(!a || !b);
+	if (unlikely(!a))
+		return 1;
+	if (unlikely(!b))
+		return -1;
 	if (a->rdma_capable == b->rdma_capable) {
 		if (a->rss_capable == b->rss_capable) {
-			if (a->speed == b->speed) {
-				cmp_ret = cifs_ipaddr_cmp((struct sockaddr *) &a->sockaddr,
-							  (struct sockaddr *) &b->sockaddr);
-				if (!cmp_ret)
-					return 0;
-				else if (cmp_ret > 0)
-					return 1;
-				else
-					return -1;
-			} else if (a->speed > b->speed)
-				return 1;
-			else
+			if (a->speed == b->speed)
+				return cifs_ipaddr_cmp((struct sockaddr *)&a->sockaddr,
+						       (struct sockaddr *)&b->sockaddr);
+			if (a->speed > b->speed)
 				return -1;
-		} else if (a->rss_capable > b->rss_capable)
 			return 1;
-		else
+		}
+		if (a->rss_capable > b->rss_capable)
 			return -1;
-	} else if (a->rdma_capable > b->rdma_capable)
 		return 1;
-	else
+	}
+	if (a->rdma_capable > b->rdma_capable)
 		return -1;
+	return 1;
+}
+
+static int iface_cmp(void *unused, const struct list_head *a, const struct list_head *b)
+{
+	struct cifs_server_iface *ifa = container_of(a, struct cifs_server_iface, iface_head);
+	struct cifs_server_iface *ifb = container_of(b, struct cifs_server_iface, iface_head);
+
+	return __iface_cmp(ifa, ifb);
 }
 
 static int
@@ -629,7 +635,7 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
 	struct cifs_server_iface *info = NULL, *iface = NULL, *niface = NULL;
 	struct cifs_server_iface tmp_iface;
 	ssize_t bytes_left;
-	size_t next = 0;
+	size_t next = 0, old_count;
 	int nb_iface = 0;
 	int rc = 0, ret = 0;
 
@@ -652,6 +658,7 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
 				 iface_head)
 		iface->is_active = 0;
 
+	old_count = ses->iface_count;
 	spin_unlock(&ses->iface_lock);
 
 	/*
@@ -719,15 +726,11 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
 		spin_lock(&ses->iface_lock);
 		list_for_each_entry_safe(iface, niface, &ses->iface_list,
 					 iface_head) {
-			ret = iface_cmp(iface, &tmp_iface);
+			ret = __iface_cmp(iface, &tmp_iface);
 			if (!ret) {
 				iface->is_active = 1;
 				spin_unlock(&ses->iface_lock);
 				goto next_iface;
-			} else if (ret < 0) {
-				/* all remaining ifaces are slower */
-				kref_get(&iface->refcount);
-				break;
 			}
 		}
 		spin_unlock(&ses->iface_lock);
@@ -745,18 +748,14 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
 		kref_init(&info->refcount);
 		info->is_active = 1;
 
-		cifs_dbg(FYI, "%s: adding iface %zu\n", __func__, ses->iface_count);
+		cifs_dbg(FYI, "%s: adding iface[%zu]: %pIS\n", __func__, ses->iface_count,
+			 &info->sockaddr);
 		cifs_dbg(FYI, "%s: speed %zu bps\n", __func__, info->speed);
 		cifs_dbg(FYI, "%s: capabilities 0x%08x\n", __func__,
 			 le32_to_cpu(p->Capability));
 
 		spin_lock(&ses->iface_lock);
-		if (!list_entry_is_head(iface, &ses->iface_list, iface_head)) {
-			list_add_tail(&info->iface_head, &iface->iface_head);
-			kref_put(&iface->refcount, release_iface);
-		} else
-			list_add_tail(&info->iface_head, &ses->iface_list);
-
+		list_add_tail(&info->iface_head, &ses->iface_list);
 		ses->iface_count++;
 		spin_unlock(&ses->iface_lock);
 next_iface:
@@ -784,7 +783,7 @@ next_iface:
 
 out:
 	/*
-	 * Go through the list again and put the inactive entries
+	 * Put inactive entries, then sort the list (only if new ifaces added, to save some cycles).
 	 */
 	spin_lock(&ses->iface_lock);
 	list_for_each_entry_safe(iface, niface, &ses->iface_list,
@@ -795,6 +794,9 @@ out:
 			ses->iface_count--;
 		}
 	}
+
+	if (old_count != ses->iface_count)
+		list_sort(NULL, &ses->iface_list, iface_cmp);
 	spin_unlock(&ses->iface_lock);
 
 	return rc;