[PATCH] configfs: User-driven configuration filesystem

Configfs, a file system for userspace-driven kernel object configuration.
The OCFS2 stack makes extensive use of this for propagation of cluster
configuration information into kernel.

Signed-off-by: Joel Becker <joel.becker@oracle.com>

1 files changed, 142 insertions, 0 deletions

diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h
new file mode 100644
index 000000000000..8899d9c5f6bf
--- /dev/null
+++ b/fs/configfs/configfs_internal.h
@@ -0,0 +1,142 @@
+/* -*- mode: c; c-basic-offset:8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * configfs_internal.h - Internal stuff for configfs
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Based on sysfs:
+ *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle.  All rights reserved.
+ */
+
+#include <linux/slab.h>
+#include <linux/list.h>
+
+struct configfs_dirent {
+        atomic_t                s_count;
+        struct list_head        s_sibling;
+        struct list_head        s_children;
+        struct list_head        s_links;
+        void                    * s_element;
+        int                     s_type;
+        umode_t                 s_mode;
+        struct dentry           * s_dentry;
+};
+
+#define CONFIGFS_ROOT           0x0001
+#define CONFIGFS_DIR            0x0002
+#define CONFIGFS_ITEM_ATTR      0x0004
+#define CONFIGFS_ITEM_LINK      0x0020
+#define CONFIGFS_USET_DIR       0x0040
+#define CONFIGFS_USET_DEFAULT   0x0080
+#define CONFIGFS_USET_DROPPING  0x0100
+#define CONFIGFS_NOT_PINNED     (CONFIGFS_ITEM_ATTR)
+
+extern struct vfsmount * configfs_mount;
+
+extern int configfs_is_root(struct config_item *item);
+
+extern struct inode * configfs_new_inode(mode_t mode);
+extern int configfs_create(struct dentry *, int mode, int (*init)(struct inode *));
+
+extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);
+extern int configfs_make_dirent(struct configfs_dirent *,
+                                struct dentry *, void *, umode_t, int);
+
+extern int configfs_add_file(struct dentry *, const struct configfs_attribute *, int);
+extern void configfs_hash_and_remove(struct dentry * dir, const char * name);
+
+extern const unsigned char * configfs_get_name(struct configfs_dirent *sd);
+extern void configfs_drop_dentry(struct configfs_dirent *sd, struct dentry *parent);
+
+extern int configfs_pin_fs(void);
+extern void configfs_release_fs(void);
+
+extern struct rw_semaphore configfs_rename_sem;
+extern struct super_block * configfs_sb;
+extern struct file_operations configfs_dir_operations;
+extern struct file_operations configfs_file_operations;
+extern struct file_operations bin_fops;
+extern struct inode_operations configfs_dir_inode_operations;
+extern struct inode_operations configfs_symlink_inode_operations;
+
+extern int configfs_symlink(struct inode *dir, struct dentry *dentry,
+                            const char *symname);
+extern int configfs_unlink(struct inode *dir, struct dentry *dentry);
+
+struct configfs_symlink {
+        struct list_head sl_list;
+        struct config_item *sl_target;
+};
+
+extern int configfs_create_link(struct configfs_symlink *sl,
+                                struct dentry *parent,
+                                struct dentry *dentry);
+
+static inline struct config_item * to_item(struct dentry * dentry)
+{
+        struct configfs_dirent * sd = dentry->d_fsdata;
+        return ((struct config_item *) sd->s_element);
+}
+
+static inline struct configfs_attribute * to_attr(struct dentry * dentry)
+{
+        struct configfs_dirent * sd = dentry->d_fsdata;
+        return ((struct configfs_attribute *) sd->s_element);
+}
+
+static inline struct config_item *configfs_get_config_item(struct dentry *dentry)
+{
+        struct config_item * item = NULL;
+
+        spin_lock(&dcache_lock);
+        if (!d_unhashed(dentry)) {
+                struct configfs_dirent * sd = dentry->d_fsdata;
+                if (sd->s_type & CONFIGFS_ITEM_LINK) {
+                        struct configfs_symlink * sl = sd->s_element;
+                        item = config_item_get(sl->sl_target);
+                } else
+                        item = config_item_get(sd->s_element);
+        }
+        spin_unlock(&dcache_lock);
+
+        return item;
+}
+
+static inline void release_configfs_dirent(struct configfs_dirent * sd)
+{
+        if (!(sd->s_type & CONFIGFS_ROOT))
+                kfree(sd);
+}
+
+static inline struct configfs_dirent * configfs_get(struct configfs_dirent * sd)
+{
+        if (sd) {
+                WARN_ON(!atomic_read(&sd->s_count));
+                atomic_inc(&sd->s_count);
+        }
+        return sd;
+}
+
+static inline void configfs_put(struct configfs_dirent * sd)
+{
+        WARN_ON(!atomic_read(&sd->s_count));
+        if (atomic_dec_and_test(&sd->s_count))
+                release_configfs_dirent(sd);
+}
+