[Linux-cachefs] [PATCH] cifs: add server conn_id to fscache client cookie

[Shyam Prasad N]

The fscache client cookie uses the server address
(and port) as the cookie key. This is a problem when
nosharesock is used. Two different connections will
use duplicate cookies. Avoid this by adding
server->conn_id to the key, so that it's guaranteed
that cookie will not be duplicated.

Also, for secondary channels of a session, copy the
fscache pointer from the primary channel. The primary
channel is guaranteed not to go away as long as secondary
channels are in use.

Signed-off-by: Shyam Prasad N <sprasad at microsoft.com>
---
 fs/cifs/connect.c |  2 ++
 fs/cifs/fscache.c | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index eee994b0925f..d8822e835cc4 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1562,6 +1562,8 @@ cifs_get_tcp_session(struct smb3_fs_context *ctx,
  /* fscache server cookies are based on primary channel only */
  if (!CIFS_SERVER_IS_CHAN(tcp_ses))
  cifs_fscache_get_client_cookie(tcp_ses);
+ else
+ tcp_ses->fscache = tcp_ses->primary_server->fscache;

  /* queue echo request delayed work */
  queue_delayed_work(cifsiod_wq, &tcp_ses->echo, tcp_ses->echo_interval);
diff --git a/fs/cifs/fscache.c b/fs/cifs/fscache.c
index f4da693760c1..1db3437f3b7d 100644
--- a/fs/cifs/fscache.c
+++ b/fs/cifs/fscache.c
@@ -24,6 +24,7 @@ struct cifs_server_key {
  struct in_addr ipv4_addr;
  struct in6_addr ipv6_addr;
  };
+ __u64 conn_id;
 } __packed;

 /*
@@ -37,6 +38,14 @@ void cifs_fscache_get_client_cookie(struct
TCP_Server_Info *server)
  struct cifs_server_key key;
  uint16_t key_len = sizeof(key.hdr);

+ /*
+ * Check if cookie was already initialized so don't reinitialize it.
+ * In the future, as we integrate with newer fscache features,
+ * we may want to instead add a check if cookie has changed
+ */
+ if (server->fscache)
+ return;
+
  memset(&key, 0, sizeof(key));

  /*
@@ -62,6 +71,7 @@ void cifs_fscache_get_client_cookie(struct
TCP_Server_Info *server)
  server->fscache = NULL;
  return;
  }
+ key.conn_id = server->conn_id;

  server->fscache =
  fscache_acquire_cookie(cifs_fscache_netfs.primary_index,