#include <linux/mount.h>
#include <linux/module.h>
#include <linux/slab.h>
+#include <linux/err.h>
#include <linux/configfs.h>
#include "configfs_internal.h"
DECLARE_RWSEM(configfs_rename_sem);
+/*
+ * Protects mutations of configfs_dirent linkage together with proper i_mutex
+ * Also protects mutations of symlinks linkage to target configfs_dirent
+ * Mutators of configfs_dirent linkage must *both* have the proper inode locked
+ * and configfs_dirent_lock locked, in that order.
+ * This allows one to safely traverse configfs_dirent trees and symlinks without
+ * having to lock inodes.
+ *
+ * Protects setting of CONFIGFS_USET_DROPPING: checking the flag
+ * unlocked is not reliable unless in detach_groups() called from
+ * rmdir()/unregister() and from configfs_attach_group()
+ */
+DEFINE_SPINLOCK(configfs_dirent_lock);
static void configfs_d_iput(struct dentry * dentry,
struct inode * inode)
return 1;
}
-static struct dentry_operations configfs_dentry_ops = {
+static const struct dentry_operations configfs_dentry_ops = {
.d_iput = configfs_d_iput,
/* simple_delete_dentry() isn't exported */
.d_delete = configfs_d_delete,
};
+#ifdef CONFIG_LOCKDEP
+
+/*
+ * Helpers to make lockdep happy with our recursive locking of default groups'
+ * inodes (see configfs_attach_group() and configfs_detach_group()).
+ * We put default groups i_mutexes in separate classes according to their depth
+ * from the youngest non-default group ancestor.
+ *
+ * For a non-default group A having default groups A/B, A/C, and A/C/D, default
+ * groups A/B and A/C will have their inode's mutex in class
+ * default_group_class[0], and default group A/C/D will be in
+ * default_group_class[1].
+ *
+ * The lock classes are declared and assigned in inode.c, according to the
+ * s_depth value.
+ * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
+ * default groups, and reset to -1 when all default groups are attached. During
+ * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
+ * inode's mutex is set to default_group_class[s_depth - 1].
+ */
+
+static void configfs_init_dirent_depth(struct configfs_dirent *sd)
+{
+ sd->s_depth = -1;
+}
+
+static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
+ struct configfs_dirent *sd)
+{
+ int parent_depth = parent_sd->s_depth;
+
+ if (parent_depth >= 0)
+ sd->s_depth = parent_depth + 1;
+}
+
+static void
+configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
+{
+ /*
+ * item's i_mutex class is already setup, so s_depth is now only
+ * used to set new sub-directories s_depth, which is always done
+ * with item's i_mutex locked.
+ */
+ /*
+ * sd->s_depth == -1 iff we are a non default group.
+ * else (we are a default group) sd->s_depth > 0 (see
+ * create_dir()).
+ */
+ if (sd->s_depth == -1)
+ /*
+ * We are a non default group and we are going to create
+ * default groups.
+ */
+ sd->s_depth = 0;
+}
+
+static void
+configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
+{
+ /* We will not create default groups anymore. */
+ sd->s_depth = -1;
+}
+
+#else /* CONFIG_LOCKDEP */
+
+static void configfs_init_dirent_depth(struct configfs_dirent *sd)
+{
+}
+
+static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
+ struct configfs_dirent *sd)
+{
+}
+
+static void
+configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
+{
+}
+
+static void
+configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
+{
+}
+
+#endif /* CONFIG_LOCKDEP */
+
/*
* Allocates a new configfs_dirent and links it to the parent configfs_dirent
*/
-static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent * parent_sd,
- void * element)
+static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
+ void *element, int type)
{
struct configfs_dirent * sd;
- sd = kmalloc(sizeof(*sd), GFP_KERNEL);
+ sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
if (!sd)
- return NULL;
+ return ERR_PTR(-ENOMEM);
- memset(sd, 0, sizeof(*sd));
atomic_set(&sd->s_count, 1);
INIT_LIST_HEAD(&sd->s_links);
INIT_LIST_HEAD(&sd->s_children);
- list_add(&sd->s_sibling, &parent_sd->s_children);
sd->s_element = element;
+ sd->s_type = type;
+ configfs_init_dirent_depth(sd);
+ spin_lock(&configfs_dirent_lock);
+ if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
+ spin_unlock(&configfs_dirent_lock);
+ kmem_cache_free(configfs_dir_cachep, sd);
+ return ERR_PTR(-ENOENT);
+ }
+ list_add(&sd->s_sibling, &parent_sd->s_children);
+ spin_unlock(&configfs_dirent_lock);
return sd;
}
+/*
+ *
+ * Return -EEXIST if there is already a configfs element with the same
+ * name for the same parent.
+ *
+ * called with parent inode's i_mutex held
+ */
+static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
+ const unsigned char *new)
+{
+ struct configfs_dirent * sd;
+
+ list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+ if (sd->s_element) {
+ const unsigned char *existing = configfs_get_name(sd);
+ if (strcmp(existing, new))
+ continue;
+ else
+ return -EEXIST;
+ }
+ }
+
+ return 0;
+}
+
+
int configfs_make_dirent(struct configfs_dirent * parent_sd,
struct dentry * dentry, void * element,
umode_t mode, int type)
{
struct configfs_dirent * sd;
- sd = configfs_new_dirent(parent_sd, element);
- if (!sd)
- return -ENOMEM;
+ sd = configfs_new_dirent(parent_sd, element, type);
+ if (IS_ERR(sd))
+ return PTR_ERR(sd);
sd->s_mode = mode;
- sd->s_type = type;
sd->s_dentry = dentry;
if (dentry) {
dentry->d_fsdata = configfs_get(sd);
inode->i_fop = &configfs_dir_operations;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
- inode->i_nlink++;
+ inc_nlink(inode);
return 0;
}
-static int init_file(struct inode * inode)
+static int configfs_init_file(struct inode * inode)
{
inode->i_size = PAGE_SIZE;
inode->i_fop = &configfs_file_operations;
int error;
umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
- error = configfs_create(d, mode, init_dir);
- if (!error) {
+ error = configfs_dirent_exists(p->d_fsdata, d->d_name.name);
+ if (!error)
error = configfs_make_dirent(p->d_fsdata, d, k, mode,
- CONFIGFS_DIR);
+ CONFIGFS_DIR | CONFIGFS_USET_CREATING);
+ if (!error) {
+ configfs_set_dir_dirent_depth(p->d_fsdata, d->d_fsdata);
+ error = configfs_create(d, mode, init_dir);
if (!error) {
- p->d_inode->i_nlink++;
+ inc_nlink(p->d_inode);
(d)->d_op = &configfs_dentry_ops;
+ } else {
+ struct configfs_dirent *sd = d->d_fsdata;
+ if (sd) {
+ spin_lock(&configfs_dirent_lock);
+ list_del_init(&sd->s_sibling);
+ spin_unlock(&configfs_dirent_lock);
+ configfs_put(sd);
+ }
}
}
return error;
* configfs_create_dir - create a directory for an config_item.
* @item: config_itemwe're creating directory for.
* @dentry: config_item's dentry.
+ *
+ * Note: user-created entries won't be allowed under this new directory
+ * until it is validated by configfs_dir_set_ready()
*/
static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
return error;
}
+/*
+ * Allow userspace to create new entries under a new directory created with
+ * configfs_create_dir(), and under all of its chidlren directories recursively.
+ * @sd configfs_dirent of the new directory to validate
+ *
+ * Caller must hold configfs_dirent_lock.
+ */
+static void configfs_dir_set_ready(struct configfs_dirent *sd)
+{
+ struct configfs_dirent *child_sd;
+
+ sd->s_type &= ~CONFIGFS_USET_CREATING;
+ list_for_each_entry(child_sd, &sd->s_children, s_sibling)
+ if (child_sd->s_type & CONFIGFS_USET_CREATING)
+ configfs_dir_set_ready(child_sd);
+}
+
+/*
+ * Check that a directory does not belong to a directory hierarchy being
+ * attached and not validated yet.
+ * @sd configfs_dirent of the directory to check
+ *
+ * @return non-zero iff the directory was validated
+ *
+ * Note: takes configfs_dirent_lock, so the result may change from false to true
+ * in two consecutive calls, but never from true to false.
+ */
+int configfs_dirent_is_ready(struct configfs_dirent *sd)
+{
+ int ret;
+
+ spin_lock(&configfs_dirent_lock);
+ ret = !(sd->s_type & CONFIGFS_USET_CREATING);
+ spin_unlock(&configfs_dirent_lock);
+
+ return ret;
+}
+
int configfs_create_link(struct configfs_symlink *sl,
struct dentry *parent,
struct dentry *dentry)
int err = 0;
umode_t mode = S_IFLNK | S_IRWXUGO;
- err = configfs_create(dentry, mode, init_symlink);
+ err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
+ CONFIGFS_ITEM_LINK);
if (!err) {
- err = configfs_make_dirent(parent->d_fsdata, dentry, sl,
- mode, CONFIGFS_ITEM_LINK);
+ err = configfs_create(dentry, mode, init_symlink);
if (!err)
dentry->d_op = &configfs_dentry_ops;
+ else {
+ struct configfs_dirent *sd = dentry->d_fsdata;
+ if (sd) {
+ spin_lock(&configfs_dirent_lock);
+ list_del_init(&sd->s_sibling);
+ spin_unlock(&configfs_dirent_lock);
+ configfs_put(sd);
+ }
+ }
}
return err;
}
struct configfs_dirent * sd;
sd = d->d_fsdata;
- list_del_init(&sd->s_sibling);
+ spin_lock(&configfs_dirent_lock);
+ list_del_init(&sd->s_sibling);
+ spin_unlock(&configfs_dirent_lock);
configfs_put(sd);
if (d->d_inode)
simple_rmdir(parent->d_inode,d);
* The only thing special about this is that we remove any files in
* the directory before we remove the directory, and we've inlined
* what used to be configfs_rmdir() below, instead of calling separately.
+ *
+ * Caller holds the mutex of the item's inode
*/
static void configfs_remove_dir(struct config_item * item)
struct configfs_attribute * attr = sd->s_element;
int error;
- error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG, init_file);
- if (error)
+ dentry->d_fsdata = configfs_get(sd);
+ sd->s_dentry = dentry;
+ error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
+ configfs_init_file);
+ if (error) {
+ configfs_put(sd);
return error;
+ }
dentry->d_op = &configfs_dentry_ops;
- dentry->d_fsdata = configfs_get(sd);
- sd->s_dentry = dentry;
d_rehash(dentry);
return 0;
struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
struct configfs_dirent * sd;
int found = 0;
- int err = 0;
+ int err;
+
+ /*
+ * Fake invisibility if dir belongs to a group/default groups hierarchy
+ * being attached
+ *
+ * This forbids userspace to read/write attributes of items which may
+ * not complete their initialization, since the dentries of the
+ * attributes won't be instantiated.
+ */
+ err = -ENOENT;
+ if (!configfs_dirent_is_ready(parent_sd))
+ goto out;
list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
if (sd->s_type & CONFIGFS_NOT_PINNED) {
return simple_lookup(dir, dentry, nd);
}
+out:
return ERR_PTR(err);
}
/*
* Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
- * attributes and are removed by rmdir(). We recurse, taking i_sem
- * on all children that are candidates for default detach. If the
- * result is clean, then configfs_detach_group() will handle dropping
- * i_sem. If there is an error, the caller will clean up the i_sem
- * holders via configfs_detach_rollback().
+ * attributes and are removed by rmdir(). We recurse, setting
+ * CONFIGFS_USET_DROPPING on all children that are candidates for
+ * default detach.
+ * If there is an error, the caller will reset the flags via
+ * configfs_detach_rollback().
*/
-static int configfs_detach_prep(struct dentry *dentry)
+static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex)
{
struct configfs_dirent *parent_sd = dentry->d_fsdata;
struct configfs_dirent *sd;
int ret;
+ /* Mark that we're trying to drop the group */
+ parent_sd->s_type |= CONFIGFS_USET_DROPPING;
+
ret = -EBUSY;
if (!list_empty(&parent_sd->s_links))
goto out;
ret = 0;
list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
- if (sd->s_type & CONFIGFS_NOT_PINNED)
+ if (!sd->s_element ||
+ (sd->s_type & CONFIGFS_NOT_PINNED))
continue;
if (sd->s_type & CONFIGFS_USET_DEFAULT) {
- down(&sd->s_dentry->d_inode->i_sem);
- /* Mark that we've taken i_sem */
- sd->s_type |= CONFIGFS_USET_DROPPING;
+ /* Abort if racing with mkdir() */
+ if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
+ if (wait_mutex)
+ *wait_mutex = &sd->s_dentry->d_inode->i_mutex;
+ return -EAGAIN;
+ }
- ret = configfs_detach_prep(sd->s_dentry);
+ /*
+ * Yup, recursive. If there's a problem, blame
+ * deep nesting of default_groups
+ */
+ ret = configfs_detach_prep(sd->s_dentry, wait_mutex);
if (!ret)
- continue;
+ continue;
} else
ret = -ENOTEMPTY;
}
/*
- * Walk the tree, dropping i_sem wherever CONFIGFS_USET_DROPPING is
+ * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
* set.
*/
static void configfs_detach_rollback(struct dentry *dentry)
struct configfs_dirent *parent_sd = dentry->d_fsdata;
struct configfs_dirent *sd;
- list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
- if (sd->s_type & CONFIGFS_USET_DEFAULT) {
- configfs_detach_rollback(sd->s_dentry);
+ parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
- if (sd->s_type & CONFIGFS_USET_DROPPING) {
- sd->s_type &= ~CONFIGFS_USET_DROPPING;
- up(&sd->s_dentry->d_inode->i_sem);
- }
- }
- }
+ list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
+ if (sd->s_type & CONFIGFS_USET_DEFAULT)
+ configfs_detach_rollback(sd->s_dentry);
}
static void detach_attrs(struct config_item * item)
list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
continue;
+ spin_lock(&configfs_dirent_lock);
list_del_init(&sd->s_sibling);
+ spin_unlock(&configfs_dirent_lock);
configfs_drop_dentry(sd, dentry);
configfs_put(sd);
}
child = sd->s_dentry;
+ mutex_lock(&child->d_inode->i_mutex);
+
configfs_detach_group(sd->s_element);
child->d_inode->i_flags |= S_DEAD;
- /*
- * From rmdir/unregister, a configfs_detach_prep() pass
- * has taken our i_sem for us. Drop it.
- * From mkdir/register cleanup, there is no sem held.
- */
- if (sd->s_type & CONFIGFS_USET_DROPPING)
- up(&child->d_inode->i_sem);
+ mutex_unlock(&child->d_inode->i_mutex);
d_delete(child);
dput(child);
static int populate_groups(struct config_group *group)
{
struct config_group *new_group;
- struct dentry *dentry = group->cg_item.ci_dentry;
int ret = 0;
int i;
- if (group && group->default_groups) {
- /* FYI, we're faking mkdir here
- * I'm not sure we need this semaphore, as we're called
- * from our parent's mkdir. That holds our parent's
- * i_sem, so afaik lookup cannot continue through our
- * parent to find us, let alone mess with our tree.
- * That said, taking our i_sem is closer to mkdir
- * emulation, and shouldn't hurt. */
- down(&dentry->d_inode->i_sem);
-
+ if (group->default_groups) {
for (i = 0; group->default_groups[i]; i++) {
new_group = group->default_groups[i];
ret = create_default_group(group, new_group);
- if (ret)
+ if (ret) {
+ detach_groups(group);
break;
+ }
}
-
- up(&dentry->d_inode->i_sem);
}
- if (ret)
- detach_groups(group);
-
return ret;
}
/*
* All of link_obj/unlink_obj/link_group/unlink_group require that
- * subsys->su_sem is held.
+ * subsys->su_mutex is held.
*/
static void unlink_obj(struct config_item *item)
item->ci_group = NULL;
item->ci_parent = NULL;
+
+ /* Drop the reference for ci_entry */
config_item_put(item);
+ /* Drop the reference for ci_parent */
config_group_put(group);
}
}
static void link_obj(struct config_item *parent_item, struct config_item *item)
{
- /* Parent seems redundant with group, but it makes certain
- * traversals much nicer. */
+ /*
+ * Parent seems redundant with group, but it makes certain
+ * traversals much nicer.
+ */
item->ci_parent = parent_item;
+
+ /*
+ * We hold a reference on the parent for the child's ci_parent
+ * link.
+ */
item->ci_group = config_group_get(to_config_group(parent_item));
list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
+ /*
+ * We hold a reference on the child for ci_entry on the parent's
+ * cg_children
+ */
config_item_get(item);
}
if (!ret) {
ret = populate_attrs(item);
if (ret) {
+ /*
+ * We are going to remove an inode and its dentry but
+ * the VFS may already have hit and used them. Thus,
+ * we must lock them as rmdir() would.
+ */
+ mutex_lock(&dentry->d_inode->i_mutex);
configfs_remove_dir(item);
+ dentry->d_inode->i_flags |= S_DEAD;
+ mutex_unlock(&dentry->d_inode->i_mutex);
d_delete(dentry);
}
}
return ret;
}
+/* Caller holds the mutex of the item's inode */
static void configfs_detach_item(struct config_item *item)
{
detach_attrs(item);
sd = dentry->d_fsdata;
sd->s_type |= CONFIGFS_USET_DIR;
+ /*
+ * FYI, we're faking mkdir in populate_groups()
+ * We must lock the group's inode to avoid races with the VFS
+ * which can already hit the inode and try to add/remove entries
+ * under it.
+ *
+ * We must also lock the inode to remove it safely in case of
+ * error, as rmdir() would.
+ */
+ mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
+ configfs_adjust_dir_dirent_depth_before_populate(sd);
ret = populate_groups(to_config_group(item));
if (ret) {
configfs_detach_item(item);
- d_delete(dentry);
+ dentry->d_inode->i_flags |= S_DEAD;
}
+ configfs_adjust_dir_dirent_depth_after_populate(sd);
+ mutex_unlock(&dentry->d_inode->i_mutex);
+ if (ret)
+ d_delete(dentry);
}
return ret;
}
+/* Caller holds the mutex of the group's inode */
static void configfs_detach_group(struct config_item *item)
{
detach_groups(to_config_group(item));
}
/*
+ * After the item has been detached from the filesystem view, we are
+ * ready to tear it out of the hierarchy. Notify the client before
+ * we do that so they can perform any cleanup that requires
+ * navigating the hierarchy. A client does not need to provide this
+ * callback. The subsystem semaphore MUST be held by the caller, and
+ * references must be valid for both items. It also assumes the
+ * caller has validated ci_type.
+ */
+static void client_disconnect_notify(struct config_item *parent_item,
+ struct config_item *item)
+{
+ struct config_item_type *type;
+
+ type = parent_item->ci_type;
+ BUG_ON(!type);
+
+ if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
+ type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
+ item);
+}
+
+/*
* Drop the initial reference from make_item()/make_group()
* This function assumes that reference is held on item
* and that item holds a valid reference to the parent. Also, it
type = parent_item->ci_type;
BUG_ON(!type);
+ /*
+ * If ->drop_item() exists, it is responsible for the
+ * config_item_put().
+ */
if (type->ct_group_ops && type->ct_group_ops->drop_item)
type->ct_group_ops->drop_item(to_config_group(parent_item),
- item);
+ item);
else
config_item_put(item);
}
+#ifdef DEBUG
+static void configfs_dump_one(struct configfs_dirent *sd, int level)
+{
+ printk(KERN_INFO "%*s\"%s\":\n", level, " ", configfs_get_name(sd));
+
+#define type_print(_type) if (sd->s_type & _type) printk(KERN_INFO "%*s %s\n", level, " ", #_type);
+ type_print(CONFIGFS_ROOT);
+ type_print(CONFIGFS_DIR);
+ type_print(CONFIGFS_ITEM_ATTR);
+ type_print(CONFIGFS_ITEM_LINK);
+ type_print(CONFIGFS_USET_DIR);
+ type_print(CONFIGFS_USET_DEFAULT);
+ type_print(CONFIGFS_USET_DROPPING);
+#undef type_print
+}
-static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+static int configfs_dump(struct configfs_dirent *sd, int level)
+{
+ struct configfs_dirent *child_sd;
+ int ret = 0;
+
+ configfs_dump_one(sd, level);
+
+ if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
+ return 0;
+
+ list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
+ ret = configfs_dump(child_sd, level + 2);
+ if (ret)
+ break;
+ }
+
+ return ret;
+}
+#endif
+
+
+/*
+ * configfs_depend_item() and configfs_undepend_item()
+ *
+ * WARNING: Do not call these from a configfs callback!
+ *
+ * This describes these functions and their helpers.
+ *
+ * Allow another kernel system to depend on a config_item. If this
+ * happens, the item cannot go away until the dependant can live without
+ * it. The idea is to give client modules as simple an interface as
+ * possible. When a system asks them to depend on an item, they just
+ * call configfs_depend_item(). If the item is live and the client
+ * driver is in good shape, we'll happily do the work for them.
+ *
+ * Why is the locking complex? Because configfs uses the VFS to handle
+ * all locking, but this function is called outside the normal
+ * VFS->configfs path. So it must take VFS locks to prevent the
+ * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc). This is
+ * why you can't call these functions underneath configfs callbacks.
+ *
+ * Note, btw, that this can be called at *any* time, even when a configfs
+ * subsystem isn't registered, or when configfs is loading or unloading.
+ * Just like configfs_register_subsystem(). So we take the same
+ * precautions. We pin the filesystem. We lock configfs_dirent_lock.
+ * If we can find the target item in the
+ * configfs tree, it must be part of the subsystem tree as well, so we
+ * do not need the subsystem semaphore. Holding configfs_dirent_lock helps
+ * locking out mkdir() and rmdir(), who might be racing us.
+ */
+
+/*
+ * configfs_depend_prep()
+ *
+ * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
+ * attributes. This is similar but not the same to configfs_detach_prep().
+ * Note that configfs_detach_prep() expects the parent to be locked when it
+ * is called, but we lock the parent *inside* configfs_depend_prep(). We
+ * do that so we can unlock it if we find nothing.
+ *
+ * Here we do a depth-first search of the dentry hierarchy looking for
+ * our object.
+ * We deliberately ignore items tagged as dropping since they are virtually
+ * dead, as well as items in the middle of attachment since they virtually
+ * do not exist yet. This completes the locking out of racing mkdir() and
+ * rmdir().
+ * Note: subdirectories in the middle of attachment start with s_type =
+ * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir(). When
+ * CONFIGFS_USET_CREATING is set, we ignore the item. The actual set of
+ * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
+ *
+ * If the target is not found, -ENOENT is bubbled up.
+ *
+ * This adds a requirement that all config_items be unique!
+ *
+ * This is recursive. There isn't
+ * much on the stack, though, so folks that need this function - be careful
+ * about your stack! Patches will be accepted to make it iterative.
+ */
+static int configfs_depend_prep(struct dentry *origin,
+ struct config_item *target)
+{
+ struct configfs_dirent *child_sd, *sd = origin->d_fsdata;
+ int ret = 0;
+
+ BUG_ON(!origin || !sd);
+
+ if (sd->s_element == target) /* Boo-yah */
+ goto out;
+
+ list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
+ if ((child_sd->s_type & CONFIGFS_DIR) &&
+ !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
+ !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
+ ret = configfs_depend_prep(child_sd->s_dentry,
+ target);
+ if (!ret)
+ goto out; /* Child path boo-yah */
+ }
+ }
+
+ /* We looped all our children and didn't find target */
+ ret = -ENOENT;
+
+out:
+ return ret;
+}
+
+int configfs_depend_item(struct configfs_subsystem *subsys,
+ struct config_item *target)
{
int ret;
- struct config_group *group;
- struct config_item *item;
+ struct configfs_dirent *p, *root_sd, *subsys_sd = NULL;
+ struct config_item *s_item = &subsys->su_group.cg_item;
+
+ /*
+ * Pin the configfs filesystem. This means we can safely access
+ * the root of the configfs filesystem.
+ */
+ ret = configfs_pin_fs();
+ if (ret)
+ return ret;
+
+ /*
+ * Next, lock the root directory. We're going to check that the
+ * subsystem is really registered, and so we need to lock out
+ * configfs_[un]register_subsystem().
+ */
+ mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
+
+ root_sd = configfs_sb->s_root->d_fsdata;
+
+ list_for_each_entry(p, &root_sd->s_children, s_sibling) {
+ if (p->s_type & CONFIGFS_DIR) {
+ if (p->s_element == s_item) {
+ subsys_sd = p;
+ break;
+ }
+ }
+ }
+
+ if (!subsys_sd) {
+ ret = -ENOENT;
+ goto out_unlock_fs;
+ }
+
+ /* Ok, now we can trust subsys/s_item */
+
+ spin_lock(&configfs_dirent_lock);
+ /* Scan the tree, return 0 if found */
+ ret = configfs_depend_prep(subsys_sd->s_dentry, target);
+ if (ret)
+ goto out_unlock_dirent_lock;
+
+ /*
+ * We are sure that the item is not about to be removed by rmdir(), and
+ * not in the middle of attachment by mkdir().
+ */
+ p = target->ci_dentry->d_fsdata;
+ p->s_dependent_count += 1;
+
+out_unlock_dirent_lock:
+ spin_unlock(&configfs_dirent_lock);
+out_unlock_fs:
+ mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
+
+ /*
+ * If we succeeded, the fs is pinned via other methods. If not,
+ * we're done with it anyway. So release_fs() is always right.
+ */
+ configfs_release_fs();
+
+ return ret;
+}
+EXPORT_SYMBOL(configfs_depend_item);
+
+/*
+ * Release the dependent linkage. This is much simpler than
+ * configfs_depend_item() because we know that that the client driver is
+ * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
+ */
+void configfs_undepend_item(struct configfs_subsystem *subsys,
+ struct config_item *target)
+{
+ struct configfs_dirent *sd;
+
+ /*
+ * Since we can trust everything is pinned, we just need
+ * configfs_dirent_lock.
+ */
+ spin_lock(&configfs_dirent_lock);
+
+ sd = target->ci_dentry->d_fsdata;
+ BUG_ON(sd->s_dependent_count < 1);
+
+ sd->s_dependent_count -= 1;
+
+ /*
+ * After this unlock, we cannot trust the item to stay alive!
+ * DO NOT REFERENCE item after this unlock.
+ */
+ spin_unlock(&configfs_dirent_lock);
+}
+EXPORT_SYMBOL(configfs_undepend_item);
+
+static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+ int ret = 0;
+ int module_got = 0;
+ struct config_group *group = NULL;
+ struct config_item *item = NULL;
struct config_item *parent_item;
struct configfs_subsystem *subsys;
struct configfs_dirent *sd;
struct config_item_type *type;
- struct module *owner;
+ struct module *subsys_owner = NULL, *new_item_owner = NULL;
char *name;
- if (dentry->d_parent == configfs_sb->s_root)
- return -EPERM;
+ if (dentry->d_parent == configfs_sb->s_root) {
+ ret = -EPERM;
+ goto out;
+ }
sd = dentry->d_parent->d_fsdata;
- if (!(sd->s_type & CONFIGFS_USET_DIR))
- return -EPERM;
+ /*
+ * Fake invisibility if dir belongs to a group/default groups hierarchy
+ * being attached
+ */
+ if (!configfs_dirent_is_ready(sd)) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ if (!(sd->s_type & CONFIGFS_USET_DIR)) {
+ ret = -EPERM;
+ goto out;
+ }
+
+ /* Get a working ref for the duration of this function */
parent_item = configfs_get_config_item(dentry->d_parent);
type = parent_item->ci_type;
subsys = to_config_group(parent_item)->cg_subsys;
if (!type || !type->ct_group_ops ||
(!type->ct_group_ops->make_group &&
!type->ct_group_ops->make_item)) {
- config_item_put(parent_item);
- return -EPERM; /* What lack-of-mkdir returns */
+ ret = -EPERM; /* Lack-of-mkdir returns -EPERM */
+ goto out_put;
+ }
+
+ /*
+ * The subsystem may belong to a different module than the item
+ * being created. We don't want to safely pin the new item but
+ * fail to pin the subsystem it sits under.
+ */
+ if (!subsys->su_group.cg_item.ci_type) {
+ ret = -EINVAL;
+ goto out_put;
+ }
+ subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
+ if (!try_module_get(subsys_owner)) {
+ ret = -EINVAL;
+ goto out_put;
}
name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
if (!name) {
- config_item_put(parent_item);
- return -ENOMEM;
+ ret = -ENOMEM;
+ goto out_subsys_put;
}
+
snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
- down(&subsys->su_sem);
- group = NULL;
- item = NULL;
+ mutex_lock(&subsys->su_mutex);
if (type->ct_group_ops->make_group) {
group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
- if (group) {
+ if (!group)
+ group = ERR_PTR(-ENOMEM);
+ if (!IS_ERR(group)) {
link_group(to_config_group(parent_item), group);
item = &group->cg_item;
- }
+ } else
+ ret = PTR_ERR(group);
} else {
item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
- if (item)
+ if (!item)
+ item = ERR_PTR(-ENOMEM);
+ if (!IS_ERR(item))
link_obj(parent_item, item);
+ else
+ ret = PTR_ERR(item);
}
- up(&subsys->su_sem);
+ mutex_unlock(&subsys->su_mutex);
kfree(name);
- if (!item) {
- config_item_put(parent_item);
- return -ENOMEM;
+ if (ret) {
+ /*
+ * If ret != 0, then link_obj() was never called.
+ * There are no extra references to clean up.
+ */
+ goto out_subsys_put;
}
- ret = -EINVAL;
+ /*
+ * link_obj() has been called (via link_group() for groups).
+ * From here on out, errors must clean that up.
+ */
+
type = item->ci_type;
- if (type) {
- owner = type->ct_owner;
- if (try_module_get(owner)) {
- if (group) {
- ret = configfs_attach_group(parent_item,
- item,
- dentry);
- } else {
- ret = configfs_attach_item(parent_item,
- item,
- dentry);
- }
+ if (!type) {
+ ret = -EINVAL;
+ goto out_unlink;
+ }
- if (ret) {
- down(&subsys->su_sem);
- if (group)
- unlink_group(group);
- else
- unlink_obj(item);
- client_drop_item(parent_item, item);
- up(&subsys->su_sem);
+ new_item_owner = type->ct_owner;
+ if (!try_module_get(new_item_owner)) {
+ ret = -EINVAL;
+ goto out_unlink;
+ }
- config_item_put(parent_item);
- module_put(owner);
- }
- }
+ /*
+ * I hate doing it this way, but if there is
+ * an error, module_put() probably should
+ * happen after any cleanup.
+ */
+ module_got = 1;
+
+ /*
+ * Make racing rmdir() fail if it did not tag parent with
+ * CONFIGFS_USET_DROPPING
+ * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
+ * fail and let rmdir() terminate correctly
+ */
+ spin_lock(&configfs_dirent_lock);
+ /* This will make configfs_detach_prep() fail */
+ sd->s_type |= CONFIGFS_USET_IN_MKDIR;
+ spin_unlock(&configfs_dirent_lock);
+
+ if (group)
+ ret = configfs_attach_group(parent_item, item, dentry);
+ else
+ ret = configfs_attach_item(parent_item, item, dentry);
+
+ spin_lock(&configfs_dirent_lock);
+ sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
+ if (!ret)
+ configfs_dir_set_ready(dentry->d_fsdata);
+ spin_unlock(&configfs_dirent_lock);
+
+out_unlink:
+ if (ret) {
+ /* Tear down everything we built up */
+ mutex_lock(&subsys->su_mutex);
+
+ client_disconnect_notify(parent_item, item);
+ if (group)
+ unlink_group(group);
+ else
+ unlink_obj(item);
+ client_drop_item(parent_item, item);
+
+ mutex_unlock(&subsys->su_mutex);
+
+ if (module_got)
+ module_put(new_item_owner);
}
+out_subsys_put:
+ if (ret)
+ module_put(subsys_owner);
+
+out_put:
+ /*
+ * link_obj()/link_group() took a reference from child->parent,
+ * so the parent is safely pinned. We can drop our working
+ * reference.
+ */
+ config_item_put(parent_item);
+
+out:
return ret;
}
struct config_item *item;
struct configfs_subsystem *subsys;
struct configfs_dirent *sd;
- struct module *owner = NULL;
+ struct module *subsys_owner = NULL, *dead_item_owner = NULL;
int ret;
if (dentry->d_parent == configfs_sb->s_root)
if (sd->s_type & CONFIGFS_USET_DEFAULT)
return -EPERM;
+ /* Get a working ref until we have the child */
parent_item = configfs_get_config_item(dentry->d_parent);
subsys = to_config_group(parent_item)->cg_subsys;
BUG_ON(!subsys);
return -EINVAL;
}
- ret = configfs_detach_prep(dentry);
- if (ret) {
- configfs_detach_rollback(dentry);
- config_item_put(parent_item);
- return ret;
- }
+ /* configfs_mkdir() shouldn't have allowed this */
+ BUG_ON(!subsys->su_group.cg_item.ci_type);
+ subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
+
+ /*
+ * Ensure that no racing symlink() will make detach_prep() fail while
+ * the new link is temporarily attached
+ */
+ do {
+ struct mutex *wait_mutex;
+
+ mutex_lock(&configfs_symlink_mutex);
+ spin_lock(&configfs_dirent_lock);
+ /*
+ * Here's where we check for dependents. We're protected by
+ * configfs_dirent_lock.
+ * If no dependent, atomically tag the item as dropping.
+ */
+ ret = sd->s_dependent_count ? -EBUSY : 0;
+ if (!ret) {
+ ret = configfs_detach_prep(dentry, &wait_mutex);
+ if (ret)
+ configfs_detach_rollback(dentry);
+ }
+ spin_unlock(&configfs_dirent_lock);
+ mutex_unlock(&configfs_symlink_mutex);
+ if (ret) {
+ if (ret != -EAGAIN) {
+ config_item_put(parent_item);
+ return ret;
+ }
+
+ /* Wait until the racing operation terminates */
+ mutex_lock(wait_mutex);
+ mutex_unlock(wait_mutex);
+ }
+ } while (ret == -EAGAIN);
+
+ /* Get a working ref for the duration of this function */
item = configfs_get_config_item(dentry);
/* Drop reference from above, item already holds one. */
config_item_put(parent_item);
if (item->ci_type)
- owner = item->ci_type->ct_owner;
+ dead_item_owner = item->ci_type->ct_owner;
if (sd->s_type & CONFIGFS_USET_DIR) {
configfs_detach_group(item);
- down(&subsys->su_sem);
+ mutex_lock(&subsys->su_mutex);
+ client_disconnect_notify(parent_item, item);
unlink_group(to_config_group(item));
} else {
configfs_detach_item(item);
- down(&subsys->su_sem);
+ mutex_lock(&subsys->su_mutex);
+ client_disconnect_notify(parent_item, item);
unlink_obj(item);
}
client_drop_item(parent_item, item);
- up(&subsys->su_sem);
+ mutex_unlock(&subsys->su_mutex);
/* Drop our reference from above */
config_item_put(item);
- module_put(owner);
+ module_put(dead_item_owner);
+ module_put(subsys_owner);
return 0;
}
-struct inode_operations configfs_dir_inode_operations = {
+const struct inode_operations configfs_dir_inode_operations = {
.mkdir = configfs_mkdir,
.rmdir = configfs_rmdir,
.symlink = configfs_symlink,
.unlink = configfs_unlink,
.lookup = configfs_lookup,
+ .setattr = configfs_setattr,
};
#if 0
down_write(&configfs_rename_sem);
parent = item->parent->dentry;
- down(&parent->d_inode->i_sem);
+ mutex_lock(&parent->d_inode->i_mutex);
new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
if (!IS_ERR(new_dentry)) {
- if (!new_dentry->d_inode) {
+ if (!new_dentry->d_inode) {
error = config_item_set_name(item, "%s", new_name);
if (!error) {
d_add(new_dentry, NULL);
error = -EEXIST;
dput(new_dentry);
}
- up(&parent->d_inode->i_sem);
+ mutex_unlock(&parent->d_inode->i_mutex);
up_write(&configfs_rename_sem);
return error;
static int configfs_dir_open(struct inode *inode, struct file *file)
{
- struct dentry * dentry = file->f_dentry;
+ struct dentry * dentry = file->f_path.dentry;
struct configfs_dirent * parent_sd = dentry->d_fsdata;
+ int err;
- down(&dentry->d_inode->i_sem);
- file->private_data = configfs_new_dirent(parent_sd, NULL);
- up(&dentry->d_inode->i_sem);
-
- return file->private_data ? 0 : -ENOMEM;
+ mutex_lock(&dentry->d_inode->i_mutex);
+ /*
+ * Fake invisibility if dir belongs to a group/default groups hierarchy
+ * being attached
+ */
+ err = -ENOENT;
+ if (configfs_dirent_is_ready(parent_sd)) {
+ file->private_data = configfs_new_dirent(parent_sd, NULL, 0);
+ if (IS_ERR(file->private_data))
+ err = PTR_ERR(file->private_data);
+ else
+ err = 0;
+ }
+ mutex_unlock(&dentry->d_inode->i_mutex);
+ return err;
}
static int configfs_dir_close(struct inode *inode, struct file *file)
{
- struct dentry * dentry = file->f_dentry;
+ struct dentry * dentry = file->f_path.dentry;
struct configfs_dirent * cursor = file->private_data;
- down(&dentry->d_inode->i_sem);
+ mutex_lock(&dentry->d_inode->i_mutex);
+ spin_lock(&configfs_dirent_lock);
list_del_init(&cursor->s_sibling);
- up(&dentry->d_inode->i_sem);
+ spin_unlock(&configfs_dirent_lock);
+ mutex_unlock(&dentry->d_inode->i_mutex);
release_configfs_dirent(cursor);
static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
- struct dentry *dentry = filp->f_dentry;
+ struct dentry *dentry = filp->f_path.dentry;
struct configfs_dirent * parent_sd = dentry->d_fsdata;
struct configfs_dirent *cursor = filp->private_data;
struct list_head *p, *q = &cursor->s_sibling;
/* fallthrough */
default:
if (filp->f_pos == 2) {
- list_del(q);
- list_add(q, &parent_sd->s_children);
+ spin_lock(&configfs_dirent_lock);
+ list_move(q, &parent_sd->s_children);
+ spin_unlock(&configfs_dirent_lock);
}
for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
struct configfs_dirent *next;
dt_type(next)) < 0)
return 0;
- list_del(q);
- list_add(q, p);
+ spin_lock(&configfs_dirent_lock);
+ list_move(q, p);
+ spin_unlock(&configfs_dirent_lock);
p = q;
filp->f_pos++;
}
static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
{
- struct dentry * dentry = file->f_dentry;
+ struct dentry * dentry = file->f_path.dentry;
- down(&dentry->d_inode->i_sem);
+ mutex_lock(&dentry->d_inode->i_mutex);
switch (origin) {
case 1:
offset += file->f_pos;
if (offset >= 0)
break;
default:
- up(&file->f_dentry->d_inode->i_sem);
+ mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
return -EINVAL;
}
if (offset != file->f_pos) {
struct list_head *p;
loff_t n = file->f_pos - 2;
+ spin_lock(&configfs_dirent_lock);
list_del(&cursor->s_sibling);
p = sd->s_children.next;
while (n && p != &sd->s_children) {
p = p->next;
}
list_add_tail(&cursor->s_sibling, p);
+ spin_unlock(&configfs_dirent_lock);
}
}
- up(&dentry->d_inode->i_sem);
+ mutex_unlock(&dentry->d_inode->i_mutex);
return offset;
}
-struct file_operations configfs_dir_operations = {
+const struct file_operations configfs_dir_operations = {
.open = configfs_dir_open,
.release = configfs_dir_close,
.llseek = configfs_dir_lseek,
sd = configfs_sb->s_root->d_fsdata;
link_group(to_config_group(sd->s_element), group);
- down(&configfs_sb->s_root->d_inode->i_sem);
+ mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
+ I_MUTEX_PARENT);
name.name = group->cg_item.ci_name;
name.len = strlen(name.name);
err = -ENOMEM;
dentry = d_alloc(configfs_sb->s_root, &name);
- if (!dentry)
- goto out_release;
-
- d_add(dentry, NULL);
+ if (dentry) {
+ d_add(dentry, NULL);
- err = configfs_attach_group(sd->s_element, &group->cg_item,
- dentry);
- if (!err)
- dentry = NULL;
- else
- d_delete(dentry);
+ err = configfs_attach_group(sd->s_element, &group->cg_item,
+ dentry);
+ if (err) {
+ d_delete(dentry);
+ dput(dentry);
+ } else {
+ spin_lock(&configfs_dirent_lock);
+ configfs_dir_set_ready(dentry->d_fsdata);
+ spin_unlock(&configfs_dirent_lock);
+ }
+ }
- up(&configfs_sb->s_root->d_inode->i_sem);
+ mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
- if (dentry) {
- dput(dentry);
-out_release:
- unlink_group(group);
- configfs_release_fs();
+ if (err) {
+ unlink_group(group);
+ configfs_release_fs();
}
return err;
return;
}
- down(&configfs_sb->s_root->d_inode->i_sem);
- down(&dentry->d_inode->i_sem);
- if (configfs_detach_prep(dentry)) {
+ mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
+ I_MUTEX_PARENT);
+ mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
+ mutex_lock(&configfs_symlink_mutex);
+ spin_lock(&configfs_dirent_lock);
+ if (configfs_detach_prep(dentry, NULL)) {
printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
}
+ spin_unlock(&configfs_dirent_lock);
+ mutex_unlock(&configfs_symlink_mutex);
configfs_detach_group(&group->cg_item);
dentry->d_inode->i_flags |= S_DEAD;
- up(&dentry->d_inode->i_sem);
+ mutex_unlock(&dentry->d_inode->i_mutex);
d_delete(dentry);
- up(&configfs_sb->s_root->d_inode->i_sem);
+ mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
dput(dentry);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff