Make sure that DFS referrals are sent to newly resolved root targets as in a multi tier DFS setup.

Signed-off-by: Paulo Alcantara (SUSE) pc@cjr.nz Link: https://lkml.kernel.org/r/05aa2995-e85e-0ff4-d003-5bb08bd17a22@canonical.com Cc: stable@vger.kernel.org Tested-by: Matthew Ruffell matthew.ruffell@canonical.com --- fs/cifs/connect.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 668d477cc9c7..86d98d73749d 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -4776,6 +4776,17 @@ static int is_path_remote(struct cifs_sb_info *cifs_sb, struct smb_vol *vol, }

#ifdef CONFIG_CIFS_DFS_UPCALL +static inline void set_root_tcon(struct cifs_sb_info *cifs_sb, + struct cifs_tcon *tcon, + struct cifs_tcon **root) +{ + spin_lock(&cifs_tcp_ses_lock); + tcon->tc_count++; + tcon->remap = cifs_remap(cifs_sb); + spin_unlock(&cifs_tcp_ses_lock); + *root = tcon; +} + int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol) { int rc = 0; @@ -4877,18 +4888,10 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol) /* Cache out resolved root server */ (void)dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb), root_path + 1, NULL, NULL); - /* - * Save root tcon for additional DFS requests to update or create a new - * DFS cache entry, or even perform DFS failover. - */ - spin_lock(&cifs_tcp_ses_lock); - tcon->tc_count++; - tcon->dfs_path = root_path; + kfree(root_path); root_path = NULL; - tcon->remap = cifs_remap(cifs_sb); - spin_unlock(&cifs_tcp_ses_lock);

- root_tcon = tcon; + set_root_tcon(cifs_sb, tcon, &root_tcon);

for (count = 1; ;) { if (!rc && tcon) { @@ -4925,6 +4928,15 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol) mount_put_conns(cifs_sb, xid, server, ses, tcon); rc = mount_get_conns(vol, cifs_sb, &xid, &server, &ses, &tcon); + /* + * Ensure that DFS referrals go through new root server. + */ + if (!rc && tcon && + (tcon->share_flags & (SHI1005_FLAGS_DFS | + SHI1005_FLAGS_DFS_ROOT))) { + cifs_put_tcon(root_tcon); + set_root_tcon(cifs_sb, tcon, &root_tcon); + } } if (rc) { if (rc == -EACCES || rc == -EOPNOTSUPP)