Hi,
I am using the CIFS module from Linux kernel 3.2.9.
We have the following setup:
In DNS, domain.net resolves to our secondary AD server ad2.domain.net
Our primary domain controller is ad1.domain.net and has a DFS redirection set
up from \\ad1\share\Users to \\files\share\Users.
When mounting \\domain.net\share\Users I get an error.
I traced this down to the cifs_mount function in fs/cifs/connect.c. In there,
rc is set to 0 at the beginning but never reset.
In short, adding an rc=0; line after the label try_mount_again: fixes the issue.
Detailed information:
- Connecting to \\domain.net\share\Users connects to ad2 with a
SMB_COM_NEGOTIATE, SMB_COM_SESSION_SETUP_ANDX, and SMB_COM_TREE_CONNECT_ANDX.
- SMB_COM_TREE_CONNECT_ANDX fails with STATUS_BAD_NETWORK_NAME causing rc to be
non-zero and jumping to remote_path_check:
- It connects to ad2's IPC$ share and retrieves the DFS_REFERRAL which leads to
\\ad1\share and jumps to try_mount_again:
- It closes the samba session to ad2.
- Now, it connects to ad1 with SMB_COM_NEGOTIATE, SMB_COM_SESSION_SETUP_ANDX,
and SMB_COM_TREE_CONNECT_ANDX.
- This time, it succeeds and continues with SMB_COM_TRANSACTION2/
TRANS2_QUERY_FS_INFORMATION/SMB_QUERY_FS_DEVICE_INFO and
SMB_QUERY_FS_ATTRIBUTE_INFO.
- It comes to:
/* check if a whole path is not remote */
if (!rc && tcon) {
/* build_path_to_root works only when we have a valid tcon */
where rc is still non-zero and, thus, does NOT check again for
a DFS_REFERRAL.
- I closes the samba session to ad1 and exists with the -6 mount error from the
initial tree connect.
The correct behavior would be to reset rc to 0 when connecting to a different
samba session.
Patch info:
rc = bdi_setup_and_register(&cifs_sb->bdi, "cifs", BDI_CAP_MAP_COPY);
if (rc)
return rc;
#ifdef CONFIG_CIFS_DFS_UPCALL
try_mount_again:
/* cleanup activities if we're chasing a referral */
if (referral_walks_count) {
if (tcon)
cifs_put_tcon(tcon);
else if (pSesInfo)
cifs_put_smb_ses(pSesInfo);
FreeXid(xid);
}
#endif
tcon = NULL;
pSesInfo = NULL;
srvTcp = NULL;
full_path = NULL;
tlink = NULL;
+ rc=0;
xid = GetXid();
/* get a reference to a tcp session */
srvTcp = cifs_get_tcp_session(volume_info);
if (IS_ERR(srvTcp)) {
rc = PTR_ERR(srvTcp);
bdi_destroy(&cifs_sb->bdi);
goto out;
}
Thanks
Thomas
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