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631d1febab
Sometimes other drivers depend on particular configfs items. For example, ocfs2 mounts depend on a heartbeat region item. If that region item is removed with rmdir(2), the ocfs2 mount must BUG or go readonly. Not happy. This provides two additional API calls: configfs_depend_item() and configfs_undepend_item(). A client driver can call configfs_depend_item() on an existing item to tell configfs that it is depended on. configfs will then return -EBUSY from rmdir(2) for that item. When the item is no longer depended on, the client driver calls configfs_undepend_item() on it. These API cannot be called underneath any configfs callbacks, as they will conflict. They can block and allocate. A client driver probably shouldn't calling them of its own gumption. Rather it should be providing an API that external subsystems call. How does this work? Imagine the ocfs2 mount process. When it mounts, it asks for a heart region item. This is done via a call into the heartbeat code. Inside the heartbeat code, the region item is looked up. Here, the heartbeat code calls configfs_depend_item(). If it succeeds, then heartbeat knows the region is safe to give to ocfs2. If it fails, it was being torn down anyway, and heartbeat can gracefully pass up an error. [ Fixed some bad whitespace in configfs.txt. --Mark ] Signed-off-by: Joel Becker <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
149 lines
4.6 KiB
C
149 lines
4.6 KiB
C
/* -*- mode: c; c-basic-offset:8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* configfs_internal.h - Internal stuff for configfs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*
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* Based on sysfs:
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* sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
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*
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* configfs Copyright (C) 2005 Oracle. All rights reserved.
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*/
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#include <linux/slab.h>
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#include <linux/list.h>
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struct configfs_dirent {
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atomic_t s_count;
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int s_dependent_count;
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struct list_head s_sibling;
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struct list_head s_children;
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struct list_head s_links;
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void * s_element;
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int s_type;
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umode_t s_mode;
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struct dentry * s_dentry;
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struct iattr * s_iattr;
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};
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#define CONFIGFS_ROOT 0x0001
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#define CONFIGFS_DIR 0x0002
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#define CONFIGFS_ITEM_ATTR 0x0004
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#define CONFIGFS_ITEM_LINK 0x0020
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#define CONFIGFS_USET_DIR 0x0040
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#define CONFIGFS_USET_DEFAULT 0x0080
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#define CONFIGFS_USET_DROPPING 0x0100
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#define CONFIGFS_NOT_PINNED (CONFIGFS_ITEM_ATTR)
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extern struct vfsmount * configfs_mount;
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extern struct kmem_cache *configfs_dir_cachep;
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extern int configfs_is_root(struct config_item *item);
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extern struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent *);
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extern int configfs_create(struct dentry *, int mode, int (*init)(struct inode *));
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extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);
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extern int configfs_make_dirent(struct configfs_dirent *,
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struct dentry *, void *, umode_t, int);
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extern int configfs_add_file(struct dentry *, const struct configfs_attribute *, int);
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extern void configfs_hash_and_remove(struct dentry * dir, const char * name);
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extern const unsigned char * configfs_get_name(struct configfs_dirent *sd);
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extern void configfs_drop_dentry(struct configfs_dirent *sd, struct dentry *parent);
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extern int configfs_setattr(struct dentry *dentry, struct iattr *iattr);
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extern int configfs_pin_fs(void);
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extern void configfs_release_fs(void);
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extern struct rw_semaphore configfs_rename_sem;
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extern struct super_block * configfs_sb;
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extern const struct file_operations configfs_dir_operations;
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extern const struct file_operations configfs_file_operations;
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extern const struct file_operations bin_fops;
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extern const struct inode_operations configfs_dir_inode_operations;
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extern const struct inode_operations configfs_symlink_inode_operations;
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extern int configfs_symlink(struct inode *dir, struct dentry *dentry,
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const char *symname);
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extern int configfs_unlink(struct inode *dir, struct dentry *dentry);
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struct configfs_symlink {
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struct list_head sl_list;
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struct config_item *sl_target;
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};
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extern int configfs_create_link(struct configfs_symlink *sl,
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struct dentry *parent,
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struct dentry *dentry);
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static inline struct config_item * to_item(struct dentry * dentry)
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{
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struct configfs_dirent * sd = dentry->d_fsdata;
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return ((struct config_item *) sd->s_element);
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}
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static inline struct configfs_attribute * to_attr(struct dentry * dentry)
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{
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struct configfs_dirent * sd = dentry->d_fsdata;
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return ((struct configfs_attribute *) sd->s_element);
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}
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static inline struct config_item *configfs_get_config_item(struct dentry *dentry)
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{
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struct config_item * item = NULL;
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spin_lock(&dcache_lock);
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if (!d_unhashed(dentry)) {
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struct configfs_dirent * sd = dentry->d_fsdata;
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if (sd->s_type & CONFIGFS_ITEM_LINK) {
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struct configfs_symlink * sl = sd->s_element;
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item = config_item_get(sl->sl_target);
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} else
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item = config_item_get(sd->s_element);
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}
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spin_unlock(&dcache_lock);
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return item;
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}
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static inline void release_configfs_dirent(struct configfs_dirent * sd)
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{
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if (!(sd->s_type & CONFIGFS_ROOT)) {
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kfree(sd->s_iattr);
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kmem_cache_free(configfs_dir_cachep, sd);
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}
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}
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static inline struct configfs_dirent * configfs_get(struct configfs_dirent * sd)
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{
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if (sd) {
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WARN_ON(!atomic_read(&sd->s_count));
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atomic_inc(&sd->s_count);
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}
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return sd;
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}
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static inline void configfs_put(struct configfs_dirent * sd)
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{
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WARN_ON(!atomic_read(&sd->s_count));
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if (atomic_dec_and_test(&sd->s_count))
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release_configfs_dirent(sd);
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}
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