[PATCH 3/4] smb: client: handle DFS tcons in cifs_construct_tcon()

[Paulo Alcantara <pc@xxxxxxxxxxxxx>]

The tcons created by cifs_construct_tcon() on multiuser mounts must
also be able to failover and refresh DFS referrals, so set the
appropriate fields in order to get a full DFS tcon.  They could be
shared among different superblocks later, too.

Signed-off-by: Paulo Alcantara (Red Hat) <pc@xxxxxxxxxxxxx>
---
 fs/smb/client/connect.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index 22d152cd24d1..cc0568c3f085 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -3995,6 +3995,7 @@ cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
 	struct cifs_ses *ses;
 	struct cifs_tcon *tcon = NULL;
 	struct smb3_fs_context *ctx;
+	char *origin_fullpath = NULL;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (ctx == NULL)
@@ -4018,6 +4019,7 @@ cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
 	ctx->sign = master_tcon->ses->sign;
 	ctx->seal = master_tcon->seal;
 	ctx->witness = master_tcon->use_witness;
+	ctx->dfs_root_ses = master_tcon->ses->dfs_root_ses;
 
 	rc = cifs_set_vol_auth(ctx, master_tcon->ses);
 	if (rc) {
@@ -4037,12 +4039,35 @@ cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
 		goto out;
 	}
 
+	spin_lock(&master_tcon->tc_lock);
+	if (master_tcon->origin_fullpath) {
+		spin_unlock(&master_tcon->tc_lock);
+		origin_fullpath = dfs_get_path(cifs_sb, cifs_sb->ctx->source);
+		if (IS_ERR(origin_fullpath)) {
+			tcon = ERR_CAST(origin_fullpath);
+			origin_fullpath = NULL;
+			cifs_put_smb_ses(ses);
+			goto out;
+		}
+	} else {
+		spin_unlock(&master_tcon->tc_lock);
+	}
+
 	tcon = cifs_get_tcon(ses, ctx);
 	if (IS_ERR(tcon)) {
 		cifs_put_smb_ses(ses);
 		goto out;
 	}
 
+	if (origin_fullpath) {
+		spin_lock(&tcon->tc_lock);
+		tcon->origin_fullpath = origin_fullpath;
+		spin_unlock(&tcon->tc_lock);
+		origin_fullpath = NULL;
+		queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work,
+				   dfs_cache_get_ttl() * HZ);
+	}
+
 #ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
 	if (cap_unix(ses))
 		reset_cifs_unix_caps(0, tcon, NULL, ctx);
@@ -4051,6 +4076,7 @@ cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
 out:
 	kfree(ctx->username);
 	kfree_sensitive(ctx->password);
+	kfree(origin_fullpath);
 	kfree(ctx);
 
 	return tcon;
-- 
2.44.0