X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=fs%2Fconfigfs%2Fdir.c;h=1814ba446809ac79ea6ab911a60ac42d1e36d33d;hb=refs%2Fheads%2Fvserver;hp=ca60e3abef451d64ce9df9374b2b49dfe8a5d97c;hpb=76828883507a47dae78837ab5dec5a5b4513c667;p=linux-2.6.git

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index ca60e3abe..1814ba446 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -86,6 +86,32 @@ static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent * pare
 	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)
@@ -113,7 +139,7 @@ static int init_dir(struct inode * inode)
 	inode->i_fop = &configfs_dir_operations;
 
 	/* directory inodes start off with i_nlink == 2 (for "." entry) */
-	inode->i_nlink++;
+	inc_nlink(inode);
 	return 0;
 }
 
@@ -136,12 +162,14 @@ static int create_dir(struct config_item * k, struct dentry * p,
 	int error;
 	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 
-	error = configfs_make_dirent(p->d_fsdata, d, k, mode,
-				     CONFIGFS_DIR);
+	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);
 	if (!error) {
 		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;
@@ -211,7 +239,7 @@ static void remove_dir(struct dentry * d)
 	struct configfs_dirent * sd;
 
 	sd = d->d_fsdata;
- 	list_del_init(&sd->s_sibling);
+	list_del_init(&sd->s_sibling);
 	configfs_put(sd);
 	if (d->d_inode)
 		simple_rmdir(parent->d_inode,d);
@@ -330,7 +358,7 @@ static int configfs_detach_prep(struct dentry *dentry)
 
 			ret = configfs_detach_prep(sd->s_dentry);
 			if (!ret)
-			       	continue;
+				continue;
 		} else
 			ret = -ENOTEMPTY;
 
@@ -504,14 +532,16 @@ static int populate_groups(struct config_group *group)
 	int ret = 0;
 	int i;
 
-	if (group && group->default_groups) {
-		/* FYI, we're faking mkdir here
+	if (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_mutex, so afaik lookup cannot continue through our
 		 * parent to find us, let alone mess with our tree.
 		 * That said, taking our i_mutex is closer to mkdir
-		 * emulation, and shouldn't hurt. */
+		 * emulation, and shouldn't hurt.
+		 */
 		mutex_lock(&dentry->d_inode->i_mutex);
 
 		for (i = 0; group->default_groups[i]; i++) {
@@ -546,20 +576,34 @@ 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);
 }
 
@@ -684,6 +728,10 @@ static void client_drop_item(struct config_item *parent_item,
 	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);
@@ -694,23 +742,28 @@ static void client_drop_item(struct config_item *parent_item,
 
 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 {
-	int ret;
+	int ret, module_got = 0;
 	struct config_group *group;
 	struct config_item *item;
 	struct config_item *parent_item;
 	struct configfs_subsystem *subsys;
 	struct configfs_dirent *sd;
 	struct config_item_type *type;
-	struct module *owner;
+	struct module *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;
+	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;
@@ -719,15 +772,16 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 	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;
 	}
 
 	name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
 	if (!name) {
-		config_item_put(parent_item);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto out_put;
 	}
+
 	snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
 
 	down(&subsys->su_sem);
@@ -748,40 +802,67 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 
 	kfree(name);
 	if (!item) {
-		config_item_put(parent_item);
-		return -ENOMEM;
+		/*
+		 * If item == NULL, then link_obj() was never called.
+		 * There are no extra references to clean up.
+		 */
+		ret = -ENOMEM;
+		goto out_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);
+	owner = type->ct_owner;
+	if (!try_module_get(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;
+
+	if (group)
+		ret = configfs_attach_group(parent_item, item, dentry);
+	else
+		ret = configfs_attach_item(parent_item, item, dentry);
+
+out_unlink:
+	if (ret) {
+		/* Tear down everything we built up */
+		down(&subsys->su_sem);
+		if (group)
+			unlink_group(group);
+		else
+			unlink_obj(item);
+		client_drop_item(parent_item, item);
+		up(&subsys->su_sem);
+
+		if (module_got)
+			module_put(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;
 }
 
@@ -801,6 +882,7 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
 	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);
@@ -817,6 +899,7 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
 		return ret;
 	}
 
+	/* Get a working ref for the duration of this function */
 	item = configfs_get_config_item(dentry);
 
 	/* Drop reference from above, item already holds one. */
@@ -876,7 +959,7 @@ int configfs_rename_dir(struct config_item * item, const char *new_name)
 
 	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);
@@ -897,7 +980,7 @@ int configfs_rename_dir(struct config_item * item, const char *new_name)
 
 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;
 
 	mutex_lock(&dentry->d_inode->i_mutex);
@@ -910,7 +993,7 @@ static int configfs_dir_open(struct inode *inode, struct file *file)
 
 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;
 
 	mutex_lock(&dentry->d_inode->i_mutex);
@@ -930,7 +1013,7 @@ static inline unsigned char dt_type(struct configfs_dirent *sd)
 
 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;
@@ -954,8 +1037,7 @@ static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir
 			/* fallthrough */
 		default:
 			if (filp->f_pos == 2) {
-				list_del(q);
-				list_add(q, &parent_sd->s_children);
+				list_move(q, &parent_sd->s_children);
 			}
 			for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
 				struct configfs_dirent *next;
@@ -978,8 +1060,7 @@ static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir
 						 dt_type(next)) < 0)
 					return 0;
 
-				list_del(q);
-				list_add(q, p);
+				list_move(q, p);
 				p = q;
 				filp->f_pos++;
 			}
@@ -989,7 +1070,7 @@ static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir
 
 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;
 
 	mutex_lock(&dentry->d_inode->i_mutex);
 	switch (origin) {
@@ -999,7 +1080,7 @@ static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
 			if (offset >= 0)
 				break;
 		default:
-			mutex_unlock(&file->f_dentry->d_inode->i_mutex);
+			mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
 			return -EINVAL;
 	}
 	if (offset != file->f_pos) {
@@ -1027,7 +1108,7 @@ static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
 	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,
@@ -1095,8 +1176,9 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
 		return;
 	}
 
-	mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
-	mutex_lock(&dentry->d_inode->i_mutex);
+	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);
 	if (configfs_detach_prep(dentry)) {
 		printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
 	}