smb: client: let destroy_mr_list() remove locked from the list

This should make sure get_mr() can't see the removed entries.

Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: metze-samba

fs/smb/client/smbdirect.c

@@ -2355,9 +2355,16 @@ static void smbd_mr_recovery_work(struct work_struct *work)
 static void destroy_mr_list(struct smbdirect_socket *sc)
 {
 	struct smbdirect_mr_io *mr, *tmp;
+	LIST_HEAD(all_list);
+	unsigned long flags;
 
 	disable_work_sync(&sc->mr_io.recovery_work);
-	list_for_each_entry_safe(mr, tmp, &sc->mr_io.all.list, list) {
+
+	spin_lock_irqsave(&sc->mr_io.all.lock, flags);
+	list_splice_tail_init(&sc->mr_io.all.list, &all_list);
+	spin_unlock_irqrestore(&sc->mr_io.all.lock, flags);
+
+	list_for_each_entry_safe(mr, tmp, &all_list, list) {
 		if (mr->state == SMBDIRECT_MR_INVALIDATED)
 			ib_dma_unmap_sg(sc->ib.dev, mr->sgt.sgl,
 				mr->sgt.nents, mr->dir);