smb: client: get rid of dfs code dep in namespace.c

Make namespace.c being built without requiring
CONFIG_CIFS_DFS_UPCALL=y by moving set_dest_addr() to dfs.c and call
it at the beginning of dfs_mount_share() so it can chase the DFS link
starting from the correct server in @ctx->dstaddr.

Signed-off-by: Paulo Alcantara (SUSE) <[email protected]>
Signed-off-by: Steve French <[email protected]>

Author: Paulo Alcantara

fs/smb/client/Makefile

@@ -11,7 +11,8 @@ cifs-y := trace.o cifsfs.o cifs_debug.o connect.o dir.o file.o \
 	  readdir.o ioctl.o sess.o export.o unc.o winucase.o \
 	  smb2ops.o smb2maperror.o smb2transport.o \
 	  smb2misc.o smb2pdu.o smb2inode.o smb2file.o cifsacl.o fs_context.o \
-	  dns_resolve.o cifs_spnego_negtokeninit.asn1.o asn1.o
+	  dns_resolve.o cifs_spnego_negtokeninit.asn1.o asn1.o \
+	  namespace.o
 
 $(obj)/asn1.o: $(obj)/cifs_spnego_negtokeninit.asn1.h
 
@@ -21,7 +22,7 @@ cifs-$(CONFIG_CIFS_XATTR) += xattr.o
 
 cifs-$(CONFIG_CIFS_UPCALL) += cifs_spnego.o
 
-cifs-$(CONFIG_CIFS_DFS_UPCALL) += namespace.o dfs_cache.o dfs.o
+cifs-$(CONFIG_CIFS_DFS_UPCALL) += dfs_cache.o dfs.o
 
 cifs-$(CONFIG_CIFS_SWN_UPCALL) += netlink.o cifs_swn.o
 

fs/smb/client/cifsfs.h

@@ -118,14 +118,7 @@ extern void cifs_pages_write_redirty(struct inode *inode, loff_t start, unsigned
 extern const struct dentry_operations cifs_dentry_ops;
 extern const struct dentry_operations cifs_ci_dentry_ops;
 
-#ifdef CONFIG_CIFS_DFS_UPCALL
 extern struct vfsmount *cifs_d_automount(struct path *path);
-#else
-static inline struct vfsmount *cifs_d_automount(struct path *path)
-{
-	return ERR_PTR(-EREMOTE);
-}
-#endif
 
 /* Functions related to symlinks */
 extern const char *cifs_get_link(struct dentry *, struct inode *,

fs/smb/client/cifsproto.h

@@ -295,11 +295,7 @@ extern void cifs_put_tcp_session(struct TCP_Server_Info *server,
 				 int from_reconnect);
 extern void cifs_put_tcon(struct cifs_tcon *tcon);
 
-#if IS_ENABLED(CONFIG_CIFS_DFS_UPCALL)
 extern void cifs_release_automount_timer(void);
-#else /* ! IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) */
-#define cifs_release_automount_timer()	do { } while (0)
-#endif /* ! IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) */
 
 void cifs_proc_init(void);
 void cifs_proc_clean(void);

fs/smb/client/dfs.c

@@ -263,12 +263,28 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
 	return rc;
 }
 
+/* Resolve UNC hostname in @ctx->source and set ip addr in @ctx->dstaddr */
+static int update_fs_context_dstaddr(struct smb3_fs_context *ctx)
+{
+	struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr;
+	int rc;
+
+	rc = dns_resolve_server_name_to_ip(ctx->source, addr, NULL);
+	if (!rc)
+		cifs_set_port(addr, ctx->port);
+	return rc;
+}
+
 int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
 {
 	struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
 	bool nodfs = ctx->nodfs;
 	int rc;
 
+	rc = update_fs_context_dstaddr(ctx);
+	if (rc)
+		return rc;
+
 	*isdfs = false;
 	rc = get_session(mnt_ctx, NULL);
 	if (rc)

fs/smb/client/dfs.h

@@ -138,43 +138,6 @@ static inline int dfs_get_referral(struct cifs_mount_ctx *mnt_ctx, const char *p
 			      cifs_remap(cifs_sb), path, ref, tl);
 }
 
-/* Return DFS full path out of a dentry set for automount */
-static inline char *dfs_get_automount_devname(struct dentry *dentry, void *page)
-{
-	struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb);
-	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
-	size_t len;
-	char *s;
-
-	spin_lock(&tcon->tc_lock);
-	if (unlikely(!tcon->origin_fullpath)) {
-		spin_unlock(&tcon->tc_lock);
-		return ERR_PTR(-EREMOTE);
-	}
-	spin_unlock(&tcon->tc_lock);
-
-	s = dentry_path_raw(dentry, page, PATH_MAX);
-	if (IS_ERR(s))
-		return s;
-	/* for root, we want "" */
-	if (!s[1])
-		s++;
-
-	spin_lock(&tcon->tc_lock);
-	len = strlen(tcon->origin_fullpath);
-	if (s < (char *)page + len) {
-		spin_unlock(&tcon->tc_lock);
-		return ERR_PTR(-ENAMETOOLONG);
-	}
-
-	s -= len;
-	memcpy(s, tcon->origin_fullpath, len);
-	spin_unlock(&tcon->tc_lock);
-	convert_delimiter(s, '/');
-
-	return s;
-}
-
 static inline void dfs_put_root_smb_sessions(struct list_head *head)
 {
 	struct dfs_root_ses *root, *tmp;

fs/smb/client/inode.c

@@ -58,13 +58,9 @@ static void cifs_set_ops(struct inode *inode)
 			inode->i_data.a_ops = &cifs_addr_ops;
 		break;
 	case S_IFDIR:
-#ifdef CONFIG_CIFS_DFS_UPCALL
 		if (IS_AUTOMOUNT(inode)) {
 			inode->i_op = &cifs_namespace_inode_operations;
 		} else {
-#else /* NO DFS support, treat as a directory */
-		{
-#endif
 			inode->i_op = &cifs_dir_inode_ops;
 			inode->i_fop = &cifs_dir_ops;
 		}

fs/smb/client/namespace.c

@@ -6,6 +6,7 @@
  *   Copyright (C) International Business Machines  Corp., 2008
  *   Author(s): Igor Mammedov ([email protected])
  *		Steve French ([email protected])
+ *   Copyright (c) 2023 Paulo Alcantara <[email protected]>
  */
 
 #include <linux/dcache.h>
@@ -18,9 +19,7 @@
 #include "cifsglob.h"
 #include "cifsproto.h"
 #include "cifsfs.h"
-#include "dns_resolve.h"
 #include "cifs_debug.h"
-#include "dfs.h"
 #include "fs_context.h"
 
 static LIST_HEAD(cifs_automount_list);
@@ -118,15 +117,41 @@ cifs_build_devname(char *nodename, const char *prepath)
 	return dev;
 }
 
-static int set_dest_addr(struct smb3_fs_context *ctx)
+/* Return full path out of a dentry set for automount */
+static char *automount_fullpath(struct dentry *dentry, void *page)
 {
-	struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr;
-	int rc;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb);
+	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+	size_t len;
+	char *s;
+
+	spin_lock(&tcon->tc_lock);
+	if (unlikely(!tcon->origin_fullpath)) {
+		spin_unlock(&tcon->tc_lock);
+		return ERR_PTR(-EREMOTE);
+	}
+	spin_unlock(&tcon->tc_lock);
+
+	s = dentry_path_raw(dentry, page, PATH_MAX);
+	if (IS_ERR(s))
+		return s;
+	/* for root, we want "" */
+	if (!s[1])
+		s++;
+
+	spin_lock(&tcon->tc_lock);
+	len = strlen(tcon->origin_fullpath);
+	if (s < (char *)page + len) {
+		spin_unlock(&tcon->tc_lock);
+		return ERR_PTR(-ENAMETOOLONG);
+	}
 
-	rc = dns_resolve_server_name_to_ip(ctx->source, addr, NULL);
-	if (!rc)
-		cifs_set_port(addr, ctx->port);
-	return rc;
+	s -= len;
+	memcpy(s, tcon->origin_fullpath, len);
+	spin_unlock(&tcon->tc_lock);
+	convert_delimiter(s, '/');
+
+	return s;
 }
 
 /*
@@ -166,7 +191,7 @@ static struct vfsmount *cifs_do_automount(struct path *path)
 	ctx = smb3_fc2context(fc);
 
 	page = alloc_dentry_path();
-	full_path = dfs_get_automount_devname(mntpt, page);
+	full_path = automount_fullpath(mntpt, page);
 	if (IS_ERR(full_path)) {
 		mnt = ERR_CAST(full_path);
 		goto out;
@@ -196,15 +221,10 @@ static struct vfsmount *cifs_do_automount(struct path *path)
 		ctx->source = NULL;
 		goto out;
 	}
-	cifs_dbg(FYI, "%s: ctx: source=%s UNC=%s prepath=%s dstaddr=%pISpc\n",
-		 __func__, ctx->source, ctx->UNC, ctx->prepath, &ctx->dstaddr);
-
-	rc = set_dest_addr(ctx);
-	if (!rc)
-		mnt = fc_mount(fc);
-	else
-		mnt = ERR_PTR(rc);
+	cifs_dbg(FYI, "%s: ctx: source=%s UNC=%s prepath=%s\n",
+		 __func__, ctx->source, ctx->UNC, ctx->prepath);
 
+	mnt = fc_mount(fc);
 out:
 	put_fs_context(fc);
 	free_dentry_path(page);