From 65303de829dd6d291a4947c1a31de31896f8a060 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Mon, 20 Apr 2020 19:42:57 -0300 Subject: [PATCH] cifs: do not share tcons with DFS This disables tcon re-use for DFS shares. tcon->dfs_path stores the path that the tcon should connect to when doing failing over. If that tcon is used multiple times e.g. 2 mounts using it with different prefixpath, each will need a different dfs_path but there is only one tcon. The other solution would be to split the tcon in 2 tcons during failover but that is much harder. tcons could not be shared with DFS in cifs.ko because in a DFS namespace like: //domain/dfsroot -> /serverA/dfsroot, /serverB/dfsroot //serverA/dfsroot/link -> /serverA/target1/aa/bb //serverA/dfsroot/link2 -> /serverA/target1/cc/dd you can see that link and link2 are two DFS links that both resolve to the same target share (/serverA/target1), so cifs.ko will only contain a single tcon for both link and link2. The problem with that is, if we (auto)mount "link" and "link2", cifs.ko will only contain a single tcon for both DFS links so we couldn't perform failover or refresh the DFS cache for both links because tcon->dfs_path was set to either "link" or "link2", but not both -- which is wrong. Signed-off-by: Paulo Alcantara (SUSE) Reviewed-by: Aurelien Aptel Reviewed-by: Ronnie Sahlberg Signed-off-by: Steve French --- fs/cifs/connect.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 63830f228b4a..28268ed461b8 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -3375,6 +3375,10 @@ cifs_find_tcon(struct cifs_ses *ses, struct smb_vol *volume_info) spin_lock(&cifs_tcp_ses_lock); list_for_each(tmp, &ses->tcon_list) { tcon = list_entry(tmp, struct cifs_tcon, tcon_list); +#ifdef CONFIG_CIFS_DFS_UPCALL + if (tcon->dfs_path) + continue; +#endif if (!match_tcon(tcon, volume_info)) continue; ++tcon->tc_count; -- 2.34.1