cifs: Add support for follow_link on dfs shares under posix extensions
When using posix extensions, dfs shares in the dfs root show up as
symlinks resulting in userland tools such as 'ls' calling readlink() on
these shares. Since these are dfs shares, we end up returning -EREMOTE.
$ ls -l /mnt
ls: cannot read symbolic link /mnt/test: Object is remote
total 0
lrwxrwxrwx. 1 root root 19 Nov 6 09:47 test
With added follow_link() support for dfs shares, when using unix
extensions, we call GET_DFS_REFERRAL to obtain the DFS referral and
return the first node returned.
The dfs share in the dfs root is now displayed in the following manner.
$ ls -l /mnt
total 0
lrwxrwxrwx. 1 root root 19 Nov 6 09:47 test -> \vm140-31\test
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c
index 988fddb7..abd2cc9 100644
--- a/fs/cifs/smb1ops.c
+++ b/fs/cifs/smb1ops.c
@@ -908,6 +908,33 @@
}
static int
+cifs_unix_dfs_readlink(const unsigned int xid, struct cifs_tcon *tcon,
+ const unsigned char *searchName, char **symlinkinfo,
+ const struct nls_table *nls_codepage)
+{
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ int rc;
+ unsigned int num_referrals = 0;
+ struct dfs_info3_param *referrals = NULL;
+
+ rc = get_dfs_path(xid, tcon->ses, searchName, nls_codepage,
+ &num_referrals, &referrals, 0);
+
+ if (!rc && num_referrals > 0) {
+ *symlinkinfo = kstrndup(referrals->node_name,
+ strlen(referrals->node_name),
+ GFP_KERNEL);
+ if (!*symlinkinfo)
+ rc = -ENOMEM;
+ free_dfs_info_array(referrals, num_referrals);
+ }
+ return rc;
+#else /* No DFS support */
+ return -EREMOTE;
+#endif
+}
+
+static int
cifs_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
const char *full_path, char **target_path,
struct cifs_sb_info *cifs_sb)
@@ -922,6 +949,11 @@
if (cap_unix(tcon->ses)) {
rc = CIFSSMBUnixQuerySymLink(xid, tcon, full_path, target_path,
cifs_sb->local_nls);
+ if (rc == -EREMOTE)
+ rc = cifs_unix_dfs_readlink(xid, tcon, full_path,
+ target_path,
+ cifs_sb->local_nls);
+
goto out;
}