[CIFS] Migrate from prefixpath logic

Now we point superblock to a server share root and set a root dentry
appropriately. This let us share superblock between mounts like
//server/sharename/foo/bar and //server/sharename/foo further.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>

Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifs_fs_sb.h

@@ -56,8 +56,6 @@ struct cifs_sb_info {
 	mode_t	mnt_file_mode;
 	mode_t	mnt_dir_mode;
 	unsigned int mnt_cifs_flags;
-	int	prepathlen;
-	char   *prepath; /* relative path under the share to mount to */
 	char   *mountdata; /* options received at mount time or via DFS refs */
 	struct backing_dev_info bdi;
 	struct delayed_work prune_tlinks;

fs/cifs/cifsfs.c

@@ -415,8 +415,6 @@ cifs_show_options(struct seq_file *s, struct vfsmount *m)
 		seq_printf(s, ",nocase");
 	if (tcon->retry)
 		seq_printf(s, ",hard");
-	if (cifs_sb->prepath)
-		seq_printf(s, ",prepath=%s", cifs_sb->prepath);
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)
 		seq_printf(s, ",posixpaths");
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID)
@@ -530,6 +528,100 @@ static const struct super_operations cifs_super_ops = {
 #endif
 };
 
+/*
+ * Get root dentry from superblock according to prefix path mount option.
+ * Return dentry with refcount + 1 on success and NULL otherwise.
+ */
+static struct dentry *
+cifs_get_root(struct smb_vol *vol, struct super_block *sb)
+{
+	int xid, rc;
+	struct inode *inode;
+	struct qstr name;
+	struct dentry *dparent = NULL, *dchild = NULL, *alias;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+	unsigned int i, full_len, len;
+	char *full_path = NULL, *pstart;
+	char sep;
+
+	full_path = cifs_build_path_to_root(vol, cifs_sb,
+					    cifs_sb_master_tcon(cifs_sb));
+	if (full_path == NULL)
+		return NULL;
+
+	cFYI(1, "Get root dentry for %s", full_path);
+
+	xid = GetXid();
+	sep = CIFS_DIR_SEP(cifs_sb);
+	dparent = dget(sb->s_root);
+	full_len = strlen(full_path);
+	full_path[full_len] = sep;
+	pstart = full_path + 1;
+
+	for (i = 1, len = 0; i <= full_len; i++) {
+		if (full_path[i] != sep || !len) {
+			len++;
+			continue;
+		}
+
+		full_path[i] = 0;
+		cFYI(1, "get dentry for %s", pstart);
+
+		name.name = pstart;
+		name.len = len;
+		name.hash = full_name_hash(pstart, len);
+		dchild = d_lookup(dparent, &name);
+		if (dchild == NULL) {
+			cFYI(1, "not exists");
+			dchild = d_alloc(dparent, &name);
+			if (dchild == NULL) {
+				dput(dparent);
+				dparent = NULL;
+				goto out;
+			}
+		}
+
+		cFYI(1, "get inode");
+		if (dchild->d_inode == NULL) {
+			cFYI(1, "not exists");
+			inode = NULL;
+			if (cifs_sb_master_tcon(CIFS_SB(sb))->unix_ext)
+				rc = cifs_get_inode_info_unix(&inode, full_path,
+							      sb, xid);
+			else
+				rc = cifs_get_inode_info(&inode, full_path,
+							 NULL, sb, xid, NULL);
+			if (rc) {
+				dput(dchild);
+				dput(dparent);
+				dparent = NULL;
+				goto out;
+			}
+			alias = d_materialise_unique(dchild, inode);
+			if (alias != NULL) {
+				dput(dchild);
+				if (IS_ERR(alias)) {
+					dput(dparent);
+					dparent = NULL;
+					goto out;
+				}
+				dchild = alias;
+			}
+		}
+		cFYI(1, "parent %p, child %p", dparent, dchild);
+
+		dput(dparent);
+		dparent = dchild;
+		len = 0;
+		pstart = full_path + i + 1;
+		full_path[i] = sep;
+	}
+out:
+	_FreeXid(xid);
+	kfree(full_path);
+	return dparent;
+}
+
 static struct dentry *
 cifs_do_mount(struct file_system_type *fs_type,
 	      int flags, const char *dev_name, void *data)
@@ -585,7 +677,10 @@ cifs_do_mount(struct file_system_type *fs_type,
 
 	sb->s_flags |= MS_ACTIVE;
 
-	root = dget(sb->s_root);
+	root = cifs_get_root(volume_info, sb);
+	if (root == NULL)
+		goto out_super;
+	cFYI(1, "dentry root is: %p", root);
 	goto out;
 
 out_super:

fs/cifs/cifsglob.h

@@ -155,6 +155,61 @@ struct cifs_cred {
  *****************************************************************
  */
 
+struct smb_vol {
+	char *username;
+	char *password;
+	char *domainname;
+	char *UNC;
+	char *UNCip;
+	char *iocharset;  /* local code page for mapping to and from Unicode */
+	char source_rfc1001_name[RFC1001_NAME_LEN_WITH_NULL]; /* clnt nb name */
+	char target_rfc1001_name[RFC1001_NAME_LEN_WITH_NULL]; /* srvr nb name */
+	uid_t cred_uid;
+	uid_t linux_uid;
+	gid_t linux_gid;
+	mode_t file_mode;
+	mode_t dir_mode;
+	unsigned secFlg;
+	bool retry:1;
+	bool intr:1;
+	bool setuids:1;
+	bool override_uid:1;
+	bool override_gid:1;
+	bool dynperm:1;
+	bool noperm:1;
+	bool no_psx_acl:1; /* set if posix acl support should be disabled */
+	bool cifs_acl:1;
+	bool no_xattr:1;   /* set if xattr (EA) support should be disabled*/
+	bool server_ino:1; /* use inode numbers from server ie UniqueId */
+	bool direct_io:1;
+	bool strict_io:1; /* strict cache behavior */
+	bool remap:1;      /* set to remap seven reserved chars in filenames */
+	bool posix_paths:1; /* unset to not ask for posix pathnames. */
+	bool no_linux_ext:1;
+	bool sfu_emul:1;
+	bool nullauth:1;   /* attempt to authenticate with null user */
+	bool nocase:1;     /* request case insensitive filenames */
+	bool nobrl:1;      /* disable sending byte range locks to srv */
+	bool mand_lock:1;  /* send mandatory not posix byte range lock reqs */
+	bool seal:1;       /* request transport encryption on share */
+	bool nodfs:1;      /* Do not request DFS, even if available */
+	bool local_lease:1; /* check leases only on local system, not remote */
+	bool noblocksnd:1;
+	bool noautotune:1;
+	bool nostrictsync:1; /* do not force expensive SMBflush on every sync */
+	bool fsc:1;	/* enable fscache */
+	bool mfsymlinks:1; /* use Minshall+French Symlinks */
+	bool multiuser:1;
+	unsigned int rsize;
+	unsigned int wsize;
+	bool sockopt_tcp_nodelay:1;
+	unsigned short int port;
+	unsigned long actimeo; /* attribute cache timeout (jiffies) */
+	char *prepath;
+	struct sockaddr_storage srcaddr; /* allow binding to a local IP */
+	struct nls_table *local_nls;
+};
+
 struct TCP_Server_Info {
 	struct list_head tcp_ses_list;
 	struct list_head smb_ses_list;
@@ -517,6 +572,26 @@ static inline char CIFS_DIR_SEP(const struct cifs_sb_info *cifs_sb)
 		return '\\';
 }
 
+static inline void
+convert_delimiter(char *path, char delim)
+{
+	int i;
+	char old_delim;
+
+	if (path == NULL)
+		return;
+
+	if (delim == '/')
+		old_delim = '\\';
+	else
+		old_delim = '/';
+
+	for (i = 0; path[i] != '\0'; i++) {
+		if (path[i] == old_delim)
+			path[i] = delim;
+	}
+}
+
 #ifdef CONFIG_CIFS_STATS
 #define cifs_stats_inc atomic_inc
 

fs/cifs/cifsproto.h

@@ -57,8 +57,9 @@ extern int init_cifs_idmap(void);
 extern void exit_cifs_idmap(void);
 extern void cifs_destroy_idmaptrees(void);
 extern char *build_path_from_dentry(struct dentry *);
-extern char *cifs_build_path_to_root(struct cifs_sb_info *cifs_sb,
-					struct cifsTconInfo *tcon);
+extern char *cifs_build_path_to_root(struct smb_vol *vol,
+				     struct cifs_sb_info *cifs_sb,
+				     struct cifsTconInfo *tcon);
 extern char *build_wildcard_path_from_dentry(struct dentry *direntry);
 extern char *cifs_compose_mount_options(const char *sb_mountdata,
 		const char *fullpath, const struct dfs_info3_param *ref,