cifs: add refcounted and timestamped container for holding tcons

Eventually, we'll need to track the use of tcons on a per-sb basis, so that
we know when it's ok to tear them down. Begin this conversion by adding a
new "tcon_link" struct and accessors that get it. For now, the core data
structures are untouched -- cifs_sb still just points to a single tcon and
the pointers are just cast to deal with the accessor functions. A later
patch will flesh this out.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 12 insertions, 9 deletions

diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index f1e13ea45a1..f4aab6f0117 100644
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -306,6 +306,7 @@ cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
 	int xid, i;
 	int rc = 0;
 	struct vfsmount *mnt = ERR_PTR(-ENOENT);
+	struct tcon_link *tlink;
 
 	cFYI(1, "in %s", __func__);
 	BUG_ON(IS_ROOT(dentry));
@@ -315,14 +316,6 @@ cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
 	dput(nd->path.dentry);
 	nd->path.dentry = dget(dentry);
 
-	cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
-	ses = cifs_sb_tcon(cifs_sb)->ses;
-
-	if (!ses) {
-		rc = -EINVAL;
-		goto out_err;
-	}
-
 	/*
 	 * The MSDFS spec states that paths in DFS referral requests and
 	 * responses must be prefixed by a single '\' character instead of
@@ -335,10 +328,20 @@ cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
 		goto out_err;
 	}
 
-	rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls,
+	cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
+	tlink = cifs_sb_tlink(cifs_sb);
+	if (IS_ERR(tlink)) {
+		rc = PTR_ERR(tlink);
+		goto out_err;
+	}
+	ses = tlink_tcon(tlink)->ses;
+
+	rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
 		&num_referrals, &referrals,
 		cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
 
+	cifs_put_tlink(tlink);
+
 	for (i = 0; i < num_referrals; i++) {
 		int len;
 		dump_referral(referrals+i);