From: Paulo Alcantara pc@cjr.nz
[ Upstream commit aaa3aef34d3ab9499a5c7633823429f7a24e6dff ]
If we mount a very specific DFS link
\FS0.FOO.COM\dfs\link -> \FS0\share1, \FS1\share2
where its target list contains NB names ("FS0" & "FS1") rather than FQDN ones ("FS0.FOO.COM" & "FS1.FOO.COM"), we end up connecting to \FOO\share1 but server->hostname will have "FOO.COM". The reason is because both "FS0" and "FS0.FOO.COM" resolve to same IP address and they share same TCP server connection, but "FS0.FOO.COM" was the first hostname set -- which is OK.
However, if the echo thread timeouts and we still have a good connection to "FS0", in cifs_reconnect()
rc = generic_ip_connect(server) -> success if (rc) { ... reconn_inval_dfs_target(server, cifs_sb, &tgt_list, &tgt_it); ... } ...
it successfully reconnects to "FS0" server but does not set up next DFS target - which should be the same target server "\FS0\share1" - and server->hostname remains set to "FS0.FOO.COM" rather than "FS0", as reconn_inval_dfs_target() would have it set to "FS0" if called earlier.
Finally, in __smb2_reconnect(), the reconnect of tcons would fail because tcon->ses->server->hostname (FS0.FOO.COM) does not match DFS target's hostname (FS0).
Fix that by calling reconn_inval_dfs_target() before generic_ip_connect() so server->hostname will get updated correctly prior to reconnecting its tcons in __smb2_reconnect().
With "cifs: handle hostnames that resolve to same ip in failover" patch
- The above problem would not occur. - We could save an DNS query to find out that they both resolve to the same ip address.
Signed-off-by: Paulo Alcantara (SUSE) pc@cjr.nz Reviewed-by: Aurelien Aptel aaptel@suse.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/cifs/connect.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 28268ed461b82..47b9fbb70bf5e 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -572,26 +572,26 @@ cifs_reconnect(struct TCP_Server_Info *server) try_to_freeze();
mutex_lock(&server->srv_mutex); +#ifdef CONFIG_CIFS_DFS_UPCALL /* * Set up next DFS target server (if any) for reconnect. If DFS * feature is disabled, then we will retry last server we * connected to before. */ + reconn_inval_dfs_target(server, cifs_sb, &tgt_list, &tgt_it); +#endif + rc = reconn_set_ipaddr(server); + if (rc) { + cifs_dbg(FYI, "%s: failed to resolve hostname: %d\n", + __func__, rc); + } + if (cifs_rdma_enabled(server)) rc = smbd_reconnect(server); else rc = generic_ip_connect(server); if (rc) { cifs_dbg(FYI, "reconnect error %d\n", rc); -#ifdef CONFIG_CIFS_DFS_UPCALL - reconn_inval_dfs_target(server, cifs_sb, &tgt_list, - &tgt_it); -#endif - rc = reconn_set_ipaddr(server); - if (rc) { - cifs_dbg(FYI, "%s: failed to resolve hostname: %d\n", - __func__, rc); - } mutex_unlock(&server->srv_mutex); msleep(3000); } else {