cifs: Make use of DFS cache to get new DFS referrals

This patch will make use of DFS cache routines where appropriate and
do not always request a new referral from server.
Signed-off-by: Paulo Alcantara <palcantara@suse.de>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifs_dfs_ref.c

@@ -25,6 +25,7 @@
 #include "dns_resolve.h"
 #include "cifs_debug.h"
 #include "cifs_unicode.h"
+#include "dfs_cache.h"
 
 static LIST_HEAD(cifs_dfs_automount_list);
 
@@ -285,16 +286,16 @@ static void dump_referral(const struct dfs_info3_param *ref)
  */
 static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
 {
-	struct dfs_info3_param *referrals = NULL;
-	unsigned int num_referrals = 0;
+	struct dfs_info3_param referral = {0};
 	struct cifs_sb_info *cifs_sb;
 	struct cifs_ses *ses;
-	char *full_path;
+	struct cifs_tcon *tcon;
+	char *full_path, *root_path;
 	unsigned int xid;
-	int i;
+	int len;
 	int rc;
 	struct vfsmount *mnt;
-	struct tcon_link *tlink;
+	char sep;
 
 	cifs_dbg(FYI, "in %s\n", __func__);
 	BUG_ON(IS_ROOT(mntpt));
@@ -313,53 +314,76 @@ static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
 		goto cdda_exit;
 	}
 
+	sep = CIFS_DIR_SEP(cifs_sb);
+
 	/* always use tree name prefix */
 	full_path = build_path_from_dentry_optional_prefix(mntpt, true);
 	if (full_path == NULL)
 		goto cdda_exit;
 
-	tlink = cifs_sb_tlink(cifs_sb);
-	if (IS_ERR(tlink)) {
-		mnt = ERR_CAST(tlink);
+	cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path);
+
+	if (!cifs_sb_master_tlink(cifs_sb)) {
+		cifs_dbg(FYI, "%s: master tlink is NULL\n", __func__);
 		goto free_full_path;
 	}
-	ses = tlink_tcon(tlink)->ses;
 
+	tcon = cifs_sb_master_tcon(cifs_sb);
+	if (!tcon) {
+		cifs_dbg(FYI, "%s: master tcon is NULL\n", __func__);
+		goto free_full_path;
+	}
+
+	root_path = kstrdup(tcon->treeName, GFP_KERNEL);
+	if (!root_path) {
+		mnt = ERR_PTR(-ENOMEM);
+		goto free_full_path;
+	}
+	cifs_dbg(FYI, "%s: root path: %s\n", __func__, root_path);
+
+	ses = tcon->ses;
 	xid = get_xid();
-	rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
-		&num_referrals, &referrals,
-		cifs_remap(cifs_sb));
+
+	/*
+	 * If DFS root has been expired, then unconditionally fetch it again to
+	 * refresh DFS referral cache.
+	 */
+	rc = dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
+			    root_path + 1, NULL, NULL);
+	if (!rc) {
+		rc = dfs_cache_find(xid, ses, cifs_sb->local_nls,
+				    cifs_remap(cifs_sb), full_path + 1,
+				    &referral, NULL);
+	}
+
 	free_xid(xid);
 
-	cifs_put_tlink(tlink);
+	if (rc) {
+		mnt = ERR_PTR(rc);
+		goto free_root_path;
+	}
+
+	dump_referral(&referral);
 
-	mnt = ERR_PTR(-ENOENT);
-	for (i = 0; i < num_referrals; i++) {
-		int len;
-		dump_referral(referrals + i);
-		/* connect to a node */
-		len = strlen(referrals[i].node_name);
+	len = strlen(referral.node_name);
 	if (len < 2) {
 		cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
-				 __func__, referrals[i].node_name);
+			 __func__, referral.node_name);
 		mnt = ERR_PTR(-EINVAL);
-			break;
+		goto free_dfs_ref;
 	}
-		mnt = cifs_dfs_do_refmount(mntpt, cifs_sb,
-				full_path, referrals + i);
-		cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n",
-			 __func__, referrals[i].node_name, mnt);
-		if (!IS_ERR(mnt))
-			goto success;
-	}
-
-	/* no valid submounts were found; return error from get_dfs_path() by
-	 * preference */
-	if (rc != 0)
-		mnt = ERR_PTR(rc);
-
-success:
-	free_dfs_info_array(referrals, num_referrals);
+	/*
+	 * cifs_mount() will retry every available node server in case
+	 * of failures.
+	 */
+	mnt = cifs_dfs_do_refmount(mntpt, cifs_sb, full_path, &referral);
+	cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n", __func__,
+		 referral.node_name, mnt);
+
+free_dfs_ref:
+	free_dfs_info_param(&referral);
+free_root_path:
+	kfree(root_path);
 free_full_path:
 	kfree(full_path);
 cdda_exit:

fs/cifs/cifsfs.c

@@ -52,6 +52,9 @@
 #include "cifs_spnego.h"
 #include "fscache.h"
 #include "smb2pdu.h"
+#ifdef CONFIG_CIFS_DFS_UPCALL
+#include "dfs_cache.h"
+#endif
 
 int cifsFYI = 0;
 bool traceSMB;
@@ -1494,10 +1497,15 @@ init_cifs(void)
 	if (rc)
 		goto out_destroy_mids;
 
+#ifdef CONFIG_CIFS_DFS_UPCALL
+	rc = dfs_cache_init();
+	if (rc)
+		goto out_destroy_request_bufs;
+#endif /* CONFIG_CIFS_DFS_UPCALL */
 #ifdef CONFIG_CIFS_UPCALL
 	rc = init_cifs_spnego();
 	if (rc)
-		goto out_destroy_request_bufs;
+		goto out_destroy_dfs_cache;
 #endif /* CONFIG_CIFS_UPCALL */
 
 #ifdef CONFIG_CIFS_ACL
@@ -1525,6 +1533,10 @@ init_cifs(void)
 #endif
 #ifdef CONFIG_CIFS_UPCALL
 	exit_cifs_spnego();
+out_destroy_dfs_cache:
+#endif
+#ifdef CONFIG_CIFS_DFS_UPCALL
+	dfs_cache_destroy();
 out_destroy_request_bufs:
 #endif
 	cifs_destroy_request_bufs();
@@ -1555,6 +1567,9 @@ exit_cifs(void)
 #endif
 #ifdef CONFIG_CIFS_UPCALL
 	exit_cifs_spnego();
+#endif
+#ifdef CONFIG_CIFS_DFS_UPCALL
+	dfs_cache_destroy();
 #endif
 	cifs_destroy_request_bufs();
 	cifs_destroy_mids();

fs/cifs/cifsglob.h

@@ -1551,7 +1551,6 @@ static inline void free_dfs_info_param(struct dfs_info3_param *param)
 	if (param) {
 		kfree(param->path_name);
 		kfree(param->node_name);
-		kfree(param);
 	}
 }
 

fs/cifs/cifsproto.h

@@ -22,6 +22,9 @@
 #define _CIFSPROTO_H
 #include <linux/nls.h>
 #include "trace.h"
+#ifdef CONFIG_CIFS_DFS_UPCALL
+#include "dfs_cache.h"
+#endif
 
 struct statfs;
 struct smb_vol;
@@ -294,11 +297,6 @@ extern int CIFSGetDFSRefer(const unsigned int xid, struct cifs_ses *ses,
 			   unsigned int *num_of_nodes,
 			   const struct nls_table *nls_codepage, int remap);
 
-extern int get_dfs_path(const unsigned int xid, struct cifs_ses *ses,
-			const char *old_path,
-			const struct nls_table *nls_codepage,
-			unsigned int *num_referrals,
-			struct dfs_info3_param **referrals, int remap);
 extern int parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 			       unsigned int *num_of_nodes,
 			       struct dfs_info3_param **target_nodes,
@@ -567,4 +565,15 @@ void cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc);
 extern void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
 				unsigned int *len, unsigned int *offset);
 
+#ifdef CONFIG_CIFS_DFS_UPCALL
+static inline int get_dfs_path(const unsigned int xid, struct cifs_ses *ses,
+			       const char *old_path,
+			       const struct nls_table *nls_codepage,
+			       struct dfs_info3_param *referral, int remap)
+{
+	return dfs_cache_find(xid, ses, nls_codepage, remap, old_path,
+			      referral, NULL);
+}
+#endif
+
 #endif			/* _CIFSPROTO_H */

fs/cifs/connect.c

@@ -56,6 +56,10 @@
 #include "fscache.h"
 #include "smb2proto.h"
 #include "smbdirect.h"
+#include "dns_resolve.h"
+#ifdef CONFIG_CIFS_DFS_UPCALL
+#include "dfs_cache.h"
+#endif
 
 extern mempool_t *cifs_req_poolp;
 extern bool disable_legacy_dialects;
@@ -3262,25 +3266,6 @@ cifs_match_super(struct super_block *sb, void *data)
 	return rc;
 }
 
-int
-get_dfs_path(const unsigned int xid, struct cifs_ses *ses, const char *old_path,
-	     const struct nls_table *nls_codepage, unsigned int *num_referrals,
-	     struct dfs_info3_param **referrals, int remap)
-{
-	int rc = 0;
-
-	if (!ses->server->ops->get_dfs_refer)
-		return -ENOSYS;
-
-	*num_referrals = 0;
-	*referrals = NULL;
-
-	rc = ses->server->ops->get_dfs_refer(xid, ses, old_path,
-					     referrals, num_referrals,
-					     nls_codepage, remap);
-	return rc;
-}
-
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 static struct lock_class_key cifs_key[2];
 static struct lock_class_key cifs_slock_key[2];
@@ -3931,8 +3916,9 @@ build_unc_path_to_root(const struct smb_vol *vol,
 	return full_path;
 }
 
-/*
- * Perform a dfs referral query for a share and (optionally) prefix
+/**
+ * expand_dfs_referral - Perform a dfs referral query and update the cifs_sb
+ *
  *
  * If a referral is found, cifs_sb->mountdata will be (re-)allocated
  * to a string containing updated options for the submount.  Otherwise it
@@ -3947,8 +3933,7 @@ expand_dfs_referral(const unsigned int xid, struct cifs_ses *ses,
 		    int check_prefix)
 {
 	int rc;
-	unsigned int num_referrals = 0;
-	struct dfs_info3_param *referrals = NULL;
+	struct dfs_info3_param referral = {0};
 	char *full_path = NULL, *ref_path = NULL, *mdata = NULL;
 
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS)
@@ -3961,17 +3946,15 @@ expand_dfs_referral(const unsigned int xid, struct cifs_ses *ses,
 	/* For DFS paths, skip the first '\' of the UNC */
 	ref_path = check_prefix ? full_path + 1 : volume_info->UNC + 1;
 
-	rc = get_dfs_path(xid, ses, ref_path, cifs_sb->local_nls,
-			  &num_referrals, &referrals, cifs_remap(cifs_sb));
-
-	if (!rc && num_referrals > 0) {
+	rc = dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
+			    ref_path, &referral, NULL);
+	if (!rc) {
 		char *fake_devname = NULL;
 
 		mdata = cifs_compose_mount_options(cifs_sb->mountdata,
-						   full_path + 1, referrals,
+						   full_path + 1, &referral,
 						   &fake_devname);
-
-		free_dfs_info_array(referrals, num_referrals);
+		free_dfs_info_param(&referral);
 
 		if (IS_ERR(mdata)) {
 			rc = PTR_ERR(mdata);

fs/cifs/smb1ops.c

@@ -929,19 +929,18 @@ cifs_unix_dfs_readlink(const unsigned int xid, struct cifs_tcon *tcon,
 {
 #ifdef CONFIG_CIFS_DFS_UPCALL
 	int rc;
-	unsigned int num_referrals = 0;
-	struct dfs_info3_param *referrals = NULL;
+	struct dfs_info3_param referral = {0};
 
-	rc = get_dfs_path(xid, tcon->ses, searchName, nls_codepage,
-			  &num_referrals, &referrals, 0);
+	rc = get_dfs_path(xid, tcon->ses, searchName, nls_codepage, &referral,
+			  0);
 
-	if (!rc && num_referrals > 0) {
-		*symlinkinfo = kstrndup(referrals->node_name,
-					strlen(referrals->node_name),
+	if (!rc) {
+		*symlinkinfo = kstrndup(referral.node_name,
+					strlen(referral.node_name),
 					GFP_KERNEL);
+		free_dfs_info_param(&referral);
 		if (!*symlinkinfo)
 			rc = -ENOMEM;
-		free_dfs_info_array(referrals, num_referrals);
 	}
 	return rc;
 #else /* No DFS support */