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1964 lines
50 KiB
1964 lines
50 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* dir.c - Operations for configfs directories. |
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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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|
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#undef DEBUG |
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|
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#include <linux/fs.h> |
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#include <linux/fsnotify.h> |
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#include <linux/mount.h> |
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#include <linux/module.h> |
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#include <linux/slab.h> |
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#include <linux/err.h> |
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#include <linux/configfs.h> |
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#include "configfs_internal.h" |
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/* |
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* Protects mutations of configfs_dirent linkage together with proper i_mutex |
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* Also protects mutations of symlinks linkage to target configfs_dirent |
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* Mutators of configfs_dirent linkage must *both* have the proper inode locked |
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* and configfs_dirent_lock locked, in that order. |
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* This allows one to safely traverse configfs_dirent trees and symlinks without |
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* having to lock inodes. |
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* |
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* Protects setting of CONFIGFS_USET_DROPPING: checking the flag |
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* unlocked is not reliable unless in detach_groups() called from |
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* rmdir()/unregister() and from configfs_attach_group() |
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*/ |
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DEFINE_SPINLOCK(configfs_dirent_lock); |
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static void configfs_d_iput(struct dentry * dentry, |
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struct inode * inode) |
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{ |
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struct configfs_dirent *sd = dentry->d_fsdata; |
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|
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if (sd) { |
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/* Coordinate with configfs_readdir */ |
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spin_lock(&configfs_dirent_lock); |
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/* |
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* Set sd->s_dentry to null only when this dentry is the one |
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* that is going to be killed. Otherwise configfs_d_iput may |
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* run just after configfs_attach_attr and set sd->s_dentry to |
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* NULL even it's still in use. |
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*/ |
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if (sd->s_dentry == dentry) |
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sd->s_dentry = NULL; |
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|
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spin_unlock(&configfs_dirent_lock); |
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configfs_put(sd); |
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} |
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iput(inode); |
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} |
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const struct dentry_operations configfs_dentry_ops = { |
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.d_iput = configfs_d_iput, |
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.d_delete = always_delete_dentry, |
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}; |
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|
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#ifdef CONFIG_LOCKDEP |
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|
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/* |
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* Helpers to make lockdep happy with our recursive locking of default groups' |
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* inodes (see configfs_attach_group() and configfs_detach_group()). |
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* We put default groups i_mutexes in separate classes according to their depth |
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* from the youngest non-default group ancestor. |
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* |
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* For a non-default group A having default groups A/B, A/C, and A/C/D, default |
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* groups A/B and A/C will have their inode's mutex in class |
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* default_group_class[0], and default group A/C/D will be in |
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* default_group_class[1]. |
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* |
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* The lock classes are declared and assigned in inode.c, according to the |
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* s_depth value. |
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* The s_depth value is initialized to -1, adjusted to >= 0 when attaching |
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* default groups, and reset to -1 when all default groups are attached. During |
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* attachment, if configfs_create() sees s_depth > 0, the lock class of the new |
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* inode's mutex is set to default_group_class[s_depth - 1]. |
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*/ |
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static void configfs_init_dirent_depth(struct configfs_dirent *sd) |
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{ |
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sd->s_depth = -1; |
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} |
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static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd, |
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struct configfs_dirent *sd) |
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{ |
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int parent_depth = parent_sd->s_depth; |
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|
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if (parent_depth >= 0) |
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sd->s_depth = parent_depth + 1; |
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} |
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static void |
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configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd) |
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{ |
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/* |
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* item's i_mutex class is already setup, so s_depth is now only |
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* used to set new sub-directories s_depth, which is always done |
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* with item's i_mutex locked. |
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*/ |
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/* |
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* sd->s_depth == -1 iff we are a non default group. |
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* else (we are a default group) sd->s_depth > 0 (see |
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* create_dir()). |
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*/ |
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if (sd->s_depth == -1) |
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/* |
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* We are a non default group and we are going to create |
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* default groups. |
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*/ |
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sd->s_depth = 0; |
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} |
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static void |
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configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd) |
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{ |
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/* We will not create default groups anymore. */ |
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sd->s_depth = -1; |
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} |
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#else /* CONFIG_LOCKDEP */ |
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static void configfs_init_dirent_depth(struct configfs_dirent *sd) |
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{ |
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} |
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static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd, |
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struct configfs_dirent *sd) |
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{ |
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} |
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static void |
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configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd) |
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{ |
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} |
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static void |
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configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd) |
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{ |
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} |
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#endif /* CONFIG_LOCKDEP */ |
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static struct configfs_fragment *new_fragment(void) |
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{ |
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struct configfs_fragment *p; |
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p = kmalloc(sizeof(struct configfs_fragment), GFP_KERNEL); |
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if (p) { |
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atomic_set(&p->frag_count, 1); |
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init_rwsem(&p->frag_sem); |
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p->frag_dead = false; |
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} |
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return p; |
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} |
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void put_fragment(struct configfs_fragment *frag) |
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{ |
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if (frag && atomic_dec_and_test(&frag->frag_count)) |
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kfree(frag); |
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} |
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struct configfs_fragment *get_fragment(struct configfs_fragment *frag) |
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{ |
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if (likely(frag)) |
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atomic_inc(&frag->frag_count); |
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return frag; |
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} |
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/* |
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* Allocates a new configfs_dirent and links it to the parent configfs_dirent |
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*/ |
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static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd, |
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void *element, int type, |
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struct configfs_fragment *frag) |
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{ |
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struct configfs_dirent * sd; |
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sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL); |
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if (!sd) |
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return ERR_PTR(-ENOMEM); |
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atomic_set(&sd->s_count, 1); |
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INIT_LIST_HEAD(&sd->s_children); |
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sd->s_element = element; |
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sd->s_type = type; |
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configfs_init_dirent_depth(sd); |
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spin_lock(&configfs_dirent_lock); |
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if (parent_sd->s_type & CONFIGFS_USET_DROPPING) { |
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spin_unlock(&configfs_dirent_lock); |
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kmem_cache_free(configfs_dir_cachep, sd); |
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return ERR_PTR(-ENOENT); |
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} |
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sd->s_frag = get_fragment(frag); |
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list_add(&sd->s_sibling, &parent_sd->s_children); |
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spin_unlock(&configfs_dirent_lock); |
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return sd; |
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} |
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/* |
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* |
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* Return -EEXIST if there is already a configfs element with the same |
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* name for the same parent. |
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* |
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* called with parent inode's i_mutex held |
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*/ |
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static int configfs_dirent_exists(struct configfs_dirent *parent_sd, |
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const unsigned char *new) |
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{ |
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struct configfs_dirent * sd; |
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list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { |
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if (sd->s_element) { |
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const unsigned char *existing = configfs_get_name(sd); |
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if (strcmp(existing, new)) |
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continue; |
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else |
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return -EEXIST; |
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} |
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} |
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return 0; |
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} |
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int configfs_make_dirent(struct configfs_dirent * parent_sd, |
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struct dentry * dentry, void * element, |
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umode_t mode, int type, struct configfs_fragment *frag) |
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{ |
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struct configfs_dirent * sd; |
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sd = configfs_new_dirent(parent_sd, element, type, frag); |
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if (IS_ERR(sd)) |
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return PTR_ERR(sd); |
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sd->s_mode = mode; |
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sd->s_dentry = dentry; |
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if (dentry) |
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dentry->d_fsdata = configfs_get(sd); |
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return 0; |
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} |
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static void configfs_remove_dirent(struct dentry *dentry) |
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{ |
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struct configfs_dirent *sd = dentry->d_fsdata; |
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if (!sd) |
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return; |
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spin_lock(&configfs_dirent_lock); |
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list_del_init(&sd->s_sibling); |
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spin_unlock(&configfs_dirent_lock); |
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configfs_put(sd); |
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} |
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/** |
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* configfs_create_dir - create a directory for an config_item. |
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* @item: config_itemwe're creating directory for. |
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* @dentry: config_item's dentry. |
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* @frag: config_item's fragment. |
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* |
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* Note: user-created entries won't be allowed under this new directory |
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* until it is validated by configfs_dir_set_ready() |
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*/ |
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static int configfs_create_dir(struct config_item *item, struct dentry *dentry, |
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struct configfs_fragment *frag) |
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{ |
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int error; |
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umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO; |
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struct dentry *p = dentry->d_parent; |
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struct inode *inode; |
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BUG_ON(!item); |
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error = configfs_dirent_exists(p->d_fsdata, dentry->d_name.name); |
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if (unlikely(error)) |
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return error; |
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error = configfs_make_dirent(p->d_fsdata, dentry, item, mode, |
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CONFIGFS_DIR | CONFIGFS_USET_CREATING, |
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frag); |
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if (unlikely(error)) |
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return error; |
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configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata); |
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inode = configfs_create(dentry, mode); |
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if (IS_ERR(inode)) |
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goto out_remove; |
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inode->i_op = &configfs_dir_inode_operations; |
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inode->i_fop = &configfs_dir_operations; |
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/* directory inodes start off with i_nlink == 2 (for "." entry) */ |
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inc_nlink(inode); |
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d_instantiate(dentry, inode); |
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/* already hashed */ |
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dget(dentry); /* pin directory dentries in core */ |
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inc_nlink(d_inode(p)); |
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item->ci_dentry = dentry; |
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return 0; |
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out_remove: |
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configfs_remove_dirent(dentry); |
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return PTR_ERR(inode); |
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} |
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/* |
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* Allow userspace to create new entries under a new directory created with |
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* configfs_create_dir(), and under all of its chidlren directories recursively. |
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* @sd configfs_dirent of the new directory to validate |
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* |
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* Caller must hold configfs_dirent_lock. |
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*/ |
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static void configfs_dir_set_ready(struct configfs_dirent *sd) |
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{ |
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struct configfs_dirent *child_sd; |
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sd->s_type &= ~CONFIGFS_USET_CREATING; |
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list_for_each_entry(child_sd, &sd->s_children, s_sibling) |
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if (child_sd->s_type & CONFIGFS_USET_CREATING) |
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configfs_dir_set_ready(child_sd); |
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} |
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/* |
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* Check that a directory does not belong to a directory hierarchy being |
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* attached and not validated yet. |
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* @sd configfs_dirent of the directory to check |
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* |
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* @return non-zero iff the directory was validated |
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* |
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* Note: takes configfs_dirent_lock, so the result may change from false to true |
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* in two consecutive calls, but never from true to false. |
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*/ |
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int configfs_dirent_is_ready(struct configfs_dirent *sd) |
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{ |
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int ret; |
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spin_lock(&configfs_dirent_lock); |
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ret = !(sd->s_type & CONFIGFS_USET_CREATING); |
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spin_unlock(&configfs_dirent_lock); |
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return ret; |
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} |
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int configfs_create_link(struct configfs_dirent *target, struct dentry *parent, |
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struct dentry *dentry, char *body) |
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{ |
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int err = 0; |
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umode_t mode = S_IFLNK | S_IRWXUGO; |
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struct configfs_dirent *p = parent->d_fsdata; |
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struct inode *inode; |
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err = configfs_make_dirent(p, dentry, target, mode, CONFIGFS_ITEM_LINK, |
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p->s_frag); |
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if (err) |
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return err; |
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inode = configfs_create(dentry, mode); |
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if (IS_ERR(inode)) |
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goto out_remove; |
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inode->i_link = body; |
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inode->i_op = &configfs_symlink_inode_operations; |
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d_instantiate(dentry, inode); |
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dget(dentry); /* pin link dentries in core */ |
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return 0; |
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out_remove: |
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configfs_remove_dirent(dentry); |
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return PTR_ERR(inode); |
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} |
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static void remove_dir(struct dentry * d) |
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{ |
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struct dentry * parent = dget(d->d_parent); |
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configfs_remove_dirent(d); |
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if (d_really_is_positive(d)) |
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simple_rmdir(d_inode(parent),d); |
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pr_debug(" o %pd removing done (%d)\n", d, d_count(d)); |
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dput(parent); |
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} |
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|
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/** |
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* configfs_remove_dir - remove an config_item's directory. |
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* @item: config_item we're removing. |
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* |
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* The only thing special about this is that we remove any files in |
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* the directory before we remove the directory, and we've inlined |
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* what used to be configfs_rmdir() below, instead of calling separately. |
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* |
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* Caller holds the mutex of the item's inode |
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*/ |
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static void configfs_remove_dir(struct config_item * item) |
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{ |
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struct dentry * dentry = dget(item->ci_dentry); |
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if (!dentry) |
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return; |
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remove_dir(dentry); |
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/** |
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* Drop reference from dget() on entrance. |
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*/ |
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dput(dentry); |
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} |
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/* attaches attribute's configfs_dirent to the dentry corresponding to the |
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* attribute file |
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*/ |
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static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry) |
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{ |
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struct configfs_attribute * attr = sd->s_element; |
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struct inode *inode; |
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spin_lock(&configfs_dirent_lock); |
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dentry->d_fsdata = configfs_get(sd); |
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sd->s_dentry = dentry; |
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spin_unlock(&configfs_dirent_lock); |
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inode = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG); |
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if (IS_ERR(inode)) { |
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configfs_put(sd); |
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return PTR_ERR(inode); |
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} |
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if (sd->s_type & CONFIGFS_ITEM_BIN_ATTR) { |
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inode->i_size = 0; |
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inode->i_fop = &configfs_bin_file_operations; |
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} else { |
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inode->i_size = PAGE_SIZE; |
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inode->i_fop = &configfs_file_operations; |
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} |
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d_add(dentry, inode); |
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return 0; |
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} |
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static struct dentry * configfs_lookup(struct inode *dir, |
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struct dentry *dentry, |
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unsigned int flags) |
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{ |
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struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata; |
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struct configfs_dirent * sd; |
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int found = 0; |
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int err; |
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/* |
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* Fake invisibility if dir belongs to a group/default groups hierarchy |
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* being attached |
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* |
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* This forbids userspace to read/write attributes of items which may |
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* not complete their initialization, since the dentries of the |
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* attributes won't be instantiated. |
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*/ |
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err = -ENOENT; |
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if (!configfs_dirent_is_ready(parent_sd)) |
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goto out; |
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list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { |
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if (sd->s_type & CONFIGFS_NOT_PINNED) { |
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const unsigned char * name = configfs_get_name(sd); |
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|
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if (strcmp(name, dentry->d_name.name)) |
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continue; |
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found = 1; |
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err = configfs_attach_attr(sd, dentry); |
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break; |
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} |
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} |
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|
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if (!found) { |
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/* |
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* If it doesn't exist and it isn't a NOT_PINNED item, |
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* it must be negative. |
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*/ |
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if (dentry->d_name.len > NAME_MAX) |
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return ERR_PTR(-ENAMETOOLONG); |
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d_add(dentry, NULL); |
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return NULL; |
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} |
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out: |
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return ERR_PTR(err); |
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} |
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/* |
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* Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are |
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* attributes and are removed by rmdir(). We recurse, setting |
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* CONFIGFS_USET_DROPPING on all children that are candidates for |
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* default detach. |
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* If there is an error, the caller will reset the flags via |
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* configfs_detach_rollback(). |
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*/ |
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static int configfs_detach_prep(struct dentry *dentry, struct dentry **wait) |
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{ |
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struct configfs_dirent *parent_sd = dentry->d_fsdata; |
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struct configfs_dirent *sd; |
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int ret; |
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|
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/* Mark that we're trying to drop the group */ |
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parent_sd->s_type |= CONFIGFS_USET_DROPPING; |
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|
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ret = -EBUSY; |
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if (parent_sd->s_links) |
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goto out; |
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|
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ret = 0; |
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list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { |
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if (!sd->s_element || |
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(sd->s_type & CONFIGFS_NOT_PINNED)) |
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continue; |
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if (sd->s_type & CONFIGFS_USET_DEFAULT) { |
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/* Abort if racing with mkdir() */ |
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if (sd->s_type & CONFIGFS_USET_IN_MKDIR) { |
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if (wait) |
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*wait= dget(sd->s_dentry); |
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return -EAGAIN; |
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} |
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|
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/* |
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* Yup, recursive. If there's a problem, blame |
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* deep nesting of default_groups |
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*/ |
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ret = configfs_detach_prep(sd->s_dentry, wait); |
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if (!ret) |
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continue; |
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} else |
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ret = -ENOTEMPTY; |
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|
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break; |
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} |
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|
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out: |
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return ret; |
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} |
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|
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/* |
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* Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was |
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* set. |
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*/ |
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static void configfs_detach_rollback(struct dentry *dentry) |
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{ |
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struct configfs_dirent *parent_sd = dentry->d_fsdata; |
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struct configfs_dirent *sd; |
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|
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parent_sd->s_type &= ~CONFIGFS_USET_DROPPING; |
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|
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list_for_each_entry(sd, &parent_sd->s_children, s_sibling) |
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if (sd->s_type & CONFIGFS_USET_DEFAULT) |
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configfs_detach_rollback(sd->s_dentry); |
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} |
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|
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static void detach_attrs(struct config_item * item) |
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{ |
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struct dentry * dentry = dget(item->ci_dentry); |
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struct configfs_dirent * parent_sd; |
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struct configfs_dirent * sd, * tmp; |
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|
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if (!dentry) |
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return; |
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|
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pr_debug("configfs %s: dropping attrs for dir\n", |
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dentry->d_name.name); |
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|
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parent_sd = dentry->d_fsdata; |
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list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) { |
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if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED)) |
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continue; |
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spin_lock(&configfs_dirent_lock); |
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list_del_init(&sd->s_sibling); |
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spin_unlock(&configfs_dirent_lock); |
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configfs_drop_dentry(sd, dentry); |
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configfs_put(sd); |
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} |
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|
|
/** |
|
* Drop reference from dget() on entrance. |
|
*/ |
|
dput(dentry); |
|
} |
|
|
|
static int populate_attrs(struct config_item *item) |
|
{ |
|
const struct config_item_type *t = item->ci_type; |
|
struct configfs_attribute *attr; |
|
struct configfs_bin_attribute *bin_attr; |
|
int error = 0; |
|
int i; |
|
|
|
if (!t) |
|
return -EINVAL; |
|
if (t->ct_attrs) { |
|
for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) { |
|
if ((error = configfs_create_file(item, attr))) |
|
break; |
|
} |
|
} |
|
if (t->ct_bin_attrs) { |
|
for (i = 0; (bin_attr = t->ct_bin_attrs[i]) != NULL; i++) { |
|
error = configfs_create_bin_file(item, bin_attr); |
|
if (error) |
|
break; |
|
} |
|
} |
|
|
|
if (error) |
|
detach_attrs(item); |
|
|
|
return error; |
|
} |
|
|
|
static int configfs_attach_group(struct config_item *parent_item, |
|
struct config_item *item, |
|
struct dentry *dentry, |
|
struct configfs_fragment *frag); |
|
static void configfs_detach_group(struct config_item *item); |
|
|
|
static void detach_groups(struct config_group *group) |
|
{ |
|
struct dentry * dentry = dget(group->cg_item.ci_dentry); |
|
struct dentry *child; |
|
struct configfs_dirent *parent_sd; |
|
struct configfs_dirent *sd, *tmp; |
|
|
|
if (!dentry) |
|
return; |
|
|
|
parent_sd = dentry->d_fsdata; |
|
list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) { |
|
if (!sd->s_element || |
|
!(sd->s_type & CONFIGFS_USET_DEFAULT)) |
|
continue; |
|
|
|
child = sd->s_dentry; |
|
|
|
inode_lock(d_inode(child)); |
|
|
|
configfs_detach_group(sd->s_element); |
|
d_inode(child)->i_flags |= S_DEAD; |
|
dont_mount(child); |
|
|
|
inode_unlock(d_inode(child)); |
|
|
|
d_delete(child); |
|
dput(child); |
|
} |
|
|
|
/** |
|
* Drop reference from dget() on entrance. |
|
*/ |
|
dput(dentry); |
|
} |
|
|
|
/* |
|
* This fakes mkdir(2) on a default_groups[] entry. It |
|
* creates a dentry, attachs it, and then does fixup |
|
* on the sd->s_type. |
|
* |
|
* We could, perhaps, tweak our parent's ->mkdir for a minute and |
|
* try using vfs_mkdir. Just a thought. |
|
*/ |
|
static int create_default_group(struct config_group *parent_group, |
|
struct config_group *group, |
|
struct configfs_fragment *frag) |
|
{ |
|
int ret; |
|
struct configfs_dirent *sd; |
|
/* We trust the caller holds a reference to parent */ |
|
struct dentry *child, *parent = parent_group->cg_item.ci_dentry; |
|
|
|
if (!group->cg_item.ci_name) |
|
group->cg_item.ci_name = group->cg_item.ci_namebuf; |
|
|
|
ret = -ENOMEM; |
|
child = d_alloc_name(parent, group->cg_item.ci_name); |
|
if (child) { |
|
d_add(child, NULL); |
|
|
|
ret = configfs_attach_group(&parent_group->cg_item, |
|
&group->cg_item, child, frag); |
|
if (!ret) { |
|
sd = child->d_fsdata; |
|
sd->s_type |= CONFIGFS_USET_DEFAULT; |
|
} else { |
|
BUG_ON(d_inode(child)); |
|
d_drop(child); |
|
dput(child); |
|
} |
|
} |
|
|
|
return ret; |
|
} |
|
|
|
static int populate_groups(struct config_group *group, |
|
struct configfs_fragment *frag) |
|
{ |
|
struct config_group *new_group; |
|
int ret = 0; |
|
|
|
list_for_each_entry(new_group, &group->default_groups, group_entry) { |
|
ret = create_default_group(group, new_group, frag); |
|
if (ret) { |
|
detach_groups(group); |
|
break; |
|
} |
|
} |
|
|
|
return ret; |
|
} |
|
|
|
void configfs_remove_default_groups(struct config_group *group) |
|
{ |
|
struct config_group *g, *n; |
|
|
|
list_for_each_entry_safe(g, n, &group->default_groups, group_entry) { |
|
list_del(&g->group_entry); |
|
config_item_put(&g->cg_item); |
|
} |
|
} |
|
EXPORT_SYMBOL(configfs_remove_default_groups); |
|
|
|
/* |
|
* All of link_obj/unlink_obj/link_group/unlink_group require that |
|
* subsys->su_mutex is held. |
|
*/ |
|
|
|
static void unlink_obj(struct config_item *item) |
|
{ |
|
struct config_group *group; |
|
|
|
group = item->ci_group; |
|
if (group) { |
|
list_del_init(&item->ci_entry); |
|
|
|
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. |
|
*/ |
|
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); |
|
} |
|
|
|
static void unlink_group(struct config_group *group) |
|
{ |
|
struct config_group *new_group; |
|
|
|
list_for_each_entry(new_group, &group->default_groups, group_entry) |
|
unlink_group(new_group); |
|
|
|
group->cg_subsys = NULL; |
|
unlink_obj(&group->cg_item); |
|
} |
|
|
|
static void link_group(struct config_group *parent_group, struct config_group *group) |
|
{ |
|
struct config_group *new_group; |
|
struct configfs_subsystem *subsys = NULL; /* gcc is a turd */ |
|
|
|
link_obj(&parent_group->cg_item, &group->cg_item); |
|
|
|
if (parent_group->cg_subsys) |
|
subsys = parent_group->cg_subsys; |
|
else if (configfs_is_root(&parent_group->cg_item)) |
|
subsys = to_configfs_subsystem(group); |
|
else |
|
BUG(); |
|
group->cg_subsys = subsys; |
|
|
|
list_for_each_entry(new_group, &group->default_groups, group_entry) |
|
link_group(group, new_group); |
|
} |
|
|
|
/* |
|
* The goal is that configfs_attach_item() (and |
|
* configfs_attach_group()) can be called from either the VFS or this |
|
* module. That is, they assume that the items have been created, |
|
* the dentry allocated, and the dcache is all ready to go. |
|
* |
|
* If they fail, they must clean up after themselves as if they |
|
* had never been called. The caller (VFS or local function) will |
|
* handle cleaning up the dcache bits. |
|
* |
|
* configfs_detach_group() and configfs_detach_item() behave similarly on |
|
* the way out. They assume that the proper semaphores are held, they |
|
* clean up the configfs items, and they expect their callers will |
|
* handle the dcache bits. |
|
*/ |
|
static int configfs_attach_item(struct config_item *parent_item, |
|
struct config_item *item, |
|
struct dentry *dentry, |
|
struct configfs_fragment *frag) |
|
{ |
|
int ret; |
|
|
|
ret = configfs_create_dir(item, dentry, frag); |
|
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. |
|
*/ |
|
inode_lock(d_inode(dentry)); |
|
configfs_remove_dir(item); |
|
d_inode(dentry)->i_flags |= S_DEAD; |
|
dont_mount(dentry); |
|
inode_unlock(d_inode(dentry)); |
|
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); |
|
configfs_remove_dir(item); |
|
} |
|
|
|
static int configfs_attach_group(struct config_item *parent_item, |
|
struct config_item *item, |
|
struct dentry *dentry, |
|
struct configfs_fragment *frag) |
|
{ |
|
int ret; |
|
struct configfs_dirent *sd; |
|
|
|
ret = configfs_attach_item(parent_item, item, dentry, frag); |
|
if (!ret) { |
|
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. |
|
*/ |
|
inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD); |
|
configfs_adjust_dir_dirent_depth_before_populate(sd); |
|
ret = populate_groups(to_config_group(item), frag); |
|
if (ret) { |
|
configfs_detach_item(item); |
|
d_inode(dentry)->i_flags |= S_DEAD; |
|
dont_mount(dentry); |
|
} |
|
configfs_adjust_dir_dirent_depth_after_populate(sd); |
|
inode_unlock(d_inode(dentry)); |
|
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)); |
|
configfs_detach_item(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) |
|
{ |
|
const 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 |
|
* assumes the caller has validated ci_type. |
|
*/ |
|
static void client_drop_item(struct config_item *parent_item, |
|
struct config_item *item) |
|
{ |
|
const struct config_item_type *type; |
|
|
|
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); |
|
else |
|
config_item_put(item); |
|
} |
|
|
|
#ifdef DEBUG |
|
static void configfs_dump_one(struct configfs_dirent *sd, int level) |
|
{ |
|
pr_info("%*s\"%s\":\n", level, " ", configfs_get_name(sd)); |
|
|
|
#define type_print(_type) if (sd->s_type & _type) pr_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_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 dependent 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; |
|
int ret = 0; |
|
|
|
BUG_ON(!origin || !origin->d_fsdata); |
|
sd = origin->d_fsdata; |
|
|
|
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; |
|
} |
|
|
|
static int configfs_do_depend_item(struct dentry *subsys_dentry, |
|
struct config_item *target) |
|
{ |
|
struct configfs_dirent *p; |
|
int ret; |
|
|
|
spin_lock(&configfs_dirent_lock); |
|
/* Scan the tree, return 0 if found */ |
|
ret = configfs_depend_prep(subsys_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); |
|
|
|
return ret; |
|
} |
|
|
|
static inline struct configfs_dirent * |
|
configfs_find_subsys_dentry(struct configfs_dirent *root_sd, |
|
struct config_item *subsys_item) |
|
{ |
|
struct configfs_dirent *p; |
|
struct configfs_dirent *ret = NULL; |
|
|
|
list_for_each_entry(p, &root_sd->s_children, s_sibling) { |
|
if (p->s_type & CONFIGFS_DIR && |
|
p->s_element == subsys_item) { |
|
ret = p; |
|
break; |
|
} |
|
} |
|
|
|
return ret; |
|
} |
|
|
|
|
|
int configfs_depend_item(struct configfs_subsystem *subsys, |
|
struct config_item *target) |
|
{ |
|
int ret; |
|
struct configfs_dirent *subsys_sd; |
|
struct config_item *s_item = &subsys->su_group.cg_item; |
|
struct dentry *root; |
|
|
|
/* |
|
* Pin the configfs filesystem. This means we can safely access |
|
* the root of the configfs filesystem. |
|
*/ |
|
root = configfs_pin_fs(); |
|
if (IS_ERR(root)) |
|
return PTR_ERR(root); |
|
|
|
/* |
|
* 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(). |
|
*/ |
|
inode_lock(d_inode(root)); |
|
|
|
subsys_sd = configfs_find_subsys_dentry(root->d_fsdata, s_item); |
|
if (!subsys_sd) { |
|
ret = -ENOENT; |
|
goto out_unlock_fs; |
|
} |
|
|
|
/* Ok, now we can trust subsys/s_item */ |
|
ret = configfs_do_depend_item(subsys_sd->s_dentry, target); |
|
|
|
out_unlock_fs: |
|
inode_unlock(d_inode(root)); |
|
|
|
/* |
|
* 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 the client driver is |
|
* pinned, thus the subsystem is pinned, and therefore configfs is pinned. |
|
*/ |
|
void configfs_undepend_item(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); |
|
|
|
/* |
|
* caller_subsys is a caller's subsystem not target's. This is used to |
|
* determine if we should lock root and check subsys or not. When we are |
|
* in the same subsystem as our target there is no need to do locking as |
|
* we know that subsys is valid and is not unregistered during this function |
|
* as we are called from callback of one of his children and VFS holds a lock |
|
* on some inode. Otherwise we have to lock our root to ensure that target's |
|
* subsystem it is not unregistered during this function. |
|
*/ |
|
int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys, |
|
struct config_item *target) |
|
{ |
|
struct configfs_subsystem *target_subsys; |
|
struct config_group *root, *parent; |
|
struct configfs_dirent *subsys_sd; |
|
int ret = -ENOENT; |
|
|
|
/* Disallow this function for configfs root */ |
|
if (configfs_is_root(target)) |
|
return -EINVAL; |
|
|
|
parent = target->ci_group; |
|
/* |
|
* This may happen when someone is trying to depend root |
|
* directory of some subsystem |
|
*/ |
|
if (configfs_is_root(&parent->cg_item)) { |
|
target_subsys = to_configfs_subsystem(to_config_group(target)); |
|
root = parent; |
|
} else { |
|
target_subsys = parent->cg_subsys; |
|
/* Find a cofnigfs root as we may need it for locking */ |
|
for (root = parent; !configfs_is_root(&root->cg_item); |
|
root = root->cg_item.ci_group) |
|
; |
|
} |
|
|
|
if (target_subsys != caller_subsys) { |
|
/* |
|
* We are in other configfs subsystem, so we have to do |
|
* additional locking to prevent other subsystem from being |
|
* unregistered |
|
*/ |
|
inode_lock(d_inode(root->cg_item.ci_dentry)); |
|
|
|
/* |
|
* As we are trying to depend item from other subsystem |
|
* we have to check if this subsystem is still registered |
|
*/ |
|
subsys_sd = configfs_find_subsys_dentry( |
|
root->cg_item.ci_dentry->d_fsdata, |
|
&target_subsys->su_group.cg_item); |
|
if (!subsys_sd) |
|
goto out_root_unlock; |
|
} else { |
|
subsys_sd = target_subsys->su_group.cg_item.ci_dentry->d_fsdata; |
|
} |
|
|
|
/* Now we can execute core of depend item */ |
|
ret = configfs_do_depend_item(subsys_sd->s_dentry, target); |
|
|
|
if (target_subsys != caller_subsys) |
|
out_root_unlock: |
|
/* |
|
* We were called from subsystem other than our target so we |
|
* took some locks so now it's time to release them |
|
*/ |
|
inode_unlock(d_inode(root->cg_item.ci_dentry)); |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL(configfs_depend_item_unlocked); |
|
|
|
static int configfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir, |
|
struct dentry *dentry, umode_t 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; |
|
const struct config_item_type *type; |
|
struct module *subsys_owner = NULL, *new_item_owner = NULL; |
|
struct configfs_fragment *frag; |
|
char *name; |
|
|
|
sd = dentry->d_parent->d_fsdata; |
|
|
|
/* |
|
* 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; |
|
} |
|
|
|
frag = new_fragment(); |
|
if (!frag) { |
|
ret = -ENOMEM; |
|
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; |
|
BUG_ON(!subsys); |
|
|
|
if (!type || !type->ct_group_ops || |
|
(!type->ct_group_ops->make_group && |
|
!type->ct_group_ops->make_item)) { |
|
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) { |
|
ret = -ENOMEM; |
|
goto out_subsys_put; |
|
} |
|
|
|
snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name); |
|
|
|
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) |
|
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) |
|
item = ERR_PTR(-ENOMEM); |
|
if (!IS_ERR(item)) |
|
link_obj(parent_item, item); |
|
else |
|
ret = PTR_ERR(item); |
|
} |
|
mutex_unlock(&subsys->su_mutex); |
|
|
|
kfree(name); |
|
if (ret) { |
|
/* |
|
* If ret != 0, then link_obj() was never called. |
|
* There are no extra references to clean up. |
|
*/ |
|
goto out_subsys_put; |
|
} |
|
|
|
/* |
|
* 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) { |
|
ret = -EINVAL; |
|
goto out_unlink; |
|
} |
|
|
|
new_item_owner = type->ct_owner; |
|
if (!try_module_get(new_item_owner)) { |
|
ret = -EINVAL; |
|
goto out_unlink; |
|
} |
|
|
|
/* |
|
* 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, frag); |
|
else |
|
ret = configfs_attach_item(parent_item, item, dentry, frag); |
|
|
|
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); |
|
put_fragment(frag); |
|
|
|
out: |
|
return ret; |
|
} |
|
|
|
static int configfs_rmdir(struct inode *dir, struct dentry *dentry) |
|
{ |
|
struct config_item *parent_item; |
|
struct config_item *item; |
|
struct configfs_subsystem *subsys; |
|
struct configfs_dirent *sd; |
|
struct configfs_fragment *frag; |
|
struct module *subsys_owner = NULL, *dead_item_owner = NULL; |
|
int ret; |
|
|
|
sd = dentry->d_fsdata; |
|
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); |
|
|
|
if (!parent_item->ci_type) { |
|
config_item_put(parent_item); |
|
return -EINVAL; |
|
} |
|
|
|
/* 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 dentry *wait; |
|
|
|
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); |
|
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 */ |
|
inode_lock(d_inode(wait)); |
|
inode_unlock(d_inode(wait)); |
|
dput(wait); |
|
} |
|
} while (ret == -EAGAIN); |
|
|
|
frag = sd->s_frag; |
|
if (down_write_killable(&frag->frag_sem)) { |
|
spin_lock(&configfs_dirent_lock); |
|
configfs_detach_rollback(dentry); |
|
spin_unlock(&configfs_dirent_lock); |
|
config_item_put(parent_item); |
|
return -EINTR; |
|
} |
|
frag->frag_dead = true; |
|
up_write(&frag->frag_sem); |
|
|
|
/* 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) |
|
dead_item_owner = item->ci_type->ct_owner; |
|
|
|
if (sd->s_type & CONFIGFS_USET_DIR) { |
|
configfs_detach_group(item); |
|
|
|
mutex_lock(&subsys->su_mutex); |
|
client_disconnect_notify(parent_item, item); |
|
unlink_group(to_config_group(item)); |
|
} else { |
|
configfs_detach_item(item); |
|
|
|
mutex_lock(&subsys->su_mutex); |
|
client_disconnect_notify(parent_item, item); |
|
unlink_obj(item); |
|
} |
|
|
|
client_drop_item(parent_item, item); |
|
mutex_unlock(&subsys->su_mutex); |
|
|
|
/* Drop our reference from above */ |
|
config_item_put(item); |
|
|
|
module_put(dead_item_owner); |
|
module_put(subsys_owner); |
|
|
|
return 0; |
|
} |
|
|
|
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, |
|
}; |
|
|
|
const struct inode_operations configfs_root_inode_operations = { |
|
.lookup = configfs_lookup, |
|
.setattr = configfs_setattr, |
|
}; |
|
|
|
static int configfs_dir_open(struct inode *inode, struct file *file) |
|
{ |
|
struct dentry * dentry = file->f_path.dentry; |
|
struct configfs_dirent * parent_sd = dentry->d_fsdata; |
|
int err; |
|
|
|
inode_lock(d_inode(dentry)); |
|
/* |
|
* 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, NULL); |
|
if (IS_ERR(file->private_data)) |
|
err = PTR_ERR(file->private_data); |
|
else |
|
err = 0; |
|
} |
|
inode_unlock(d_inode(dentry)); |
|
|
|
return err; |
|
} |
|
|
|
static int configfs_dir_close(struct inode *inode, struct file *file) |
|
{ |
|
struct dentry * dentry = file->f_path.dentry; |
|
struct configfs_dirent * cursor = file->private_data; |
|
|
|
inode_lock(d_inode(dentry)); |
|
spin_lock(&configfs_dirent_lock); |
|
list_del_init(&cursor->s_sibling); |
|
spin_unlock(&configfs_dirent_lock); |
|
inode_unlock(d_inode(dentry)); |
|
|
|
release_configfs_dirent(cursor); |
|
|
|
return 0; |
|
} |
|
|
|
/* Relationship between s_mode and the DT_xxx types */ |
|
static inline unsigned char dt_type(struct configfs_dirent *sd) |
|
{ |
|
return (sd->s_mode >> 12) & 15; |
|
} |
|
|
|
static int configfs_readdir(struct file *file, struct dir_context *ctx) |
|
{ |
|
struct dentry *dentry = file->f_path.dentry; |
|
struct super_block *sb = dentry->d_sb; |
|
struct configfs_dirent * parent_sd = dentry->d_fsdata; |
|
struct configfs_dirent *cursor = file->private_data; |
|
struct list_head *p, *q = &cursor->s_sibling; |
|
ino_t ino = 0; |
|
|
|
if (!dir_emit_dots(file, ctx)) |
|
return 0; |
|
spin_lock(&configfs_dirent_lock); |
|
if (ctx->pos == 2) |
|
list_move(q, &parent_sd->s_children); |
|
for (p = q->next; p != &parent_sd->s_children; p = p->next) { |
|
struct configfs_dirent *next; |
|
const char *name; |
|
int len; |
|
struct inode *inode = NULL; |
|
|
|
next = list_entry(p, struct configfs_dirent, s_sibling); |
|
if (!next->s_element) |
|
continue; |
|
|
|
/* |
|
* We'll have a dentry and an inode for |
|
* PINNED items and for open attribute |
|
* files. We lock here to prevent a race |
|
* with configfs_d_iput() clearing |
|
* s_dentry before calling iput(). |
|
* |
|
* Why do we go to the trouble? If |
|
* someone has an attribute file open, |
|
* the inode number should match until |
|
* they close it. Beyond that, we don't |
|
* care. |
|
*/ |
|
dentry = next->s_dentry; |
|
if (dentry) |
|
inode = d_inode(dentry); |
|
if (inode) |
|
ino = inode->i_ino; |
|
spin_unlock(&configfs_dirent_lock); |
|
if (!inode) |
|
ino = iunique(sb, 2); |
|
|
|
name = configfs_get_name(next); |
|
len = strlen(name); |
|
|
|
if (!dir_emit(ctx, name, len, ino, dt_type(next))) |
|
return 0; |
|
|
|
spin_lock(&configfs_dirent_lock); |
|
list_move(q, p); |
|
p = q; |
|
ctx->pos++; |
|
} |
|
spin_unlock(&configfs_dirent_lock); |
|
return 0; |
|
} |
|
|
|
static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence) |
|
{ |
|
struct dentry * dentry = file->f_path.dentry; |
|
|
|
switch (whence) { |
|
case 1: |
|
offset += file->f_pos; |
|
fallthrough; |
|
case 0: |
|
if (offset >= 0) |
|
break; |
|
fallthrough; |
|
default: |
|
return -EINVAL; |
|
} |
|
if (offset != file->f_pos) { |
|
file->f_pos = offset; |
|
if (file->f_pos >= 2) { |
|
struct configfs_dirent *sd = dentry->d_fsdata; |
|
struct configfs_dirent *cursor = file->private_data; |
|
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) { |
|
struct configfs_dirent *next; |
|
next = list_entry(p, struct configfs_dirent, |
|
s_sibling); |
|
if (next->s_element) |
|
n--; |
|
p = p->next; |
|
} |
|
list_add_tail(&cursor->s_sibling, p); |
|
spin_unlock(&configfs_dirent_lock); |
|
} |
|
} |
|
return offset; |
|
} |
|
|
|
const struct file_operations configfs_dir_operations = { |
|
.open = configfs_dir_open, |
|
.release = configfs_dir_close, |
|
.llseek = configfs_dir_lseek, |
|
.read = generic_read_dir, |
|
.iterate_shared = configfs_readdir, |
|
}; |
|
|
|
/** |
|
* configfs_register_group - creates a parent-child relation between two groups |
|
* @parent_group: parent group |
|
* @group: child group |
|
* |
|
* link groups, creates dentry for the child and attaches it to the |
|
* parent dentry. |
|
* |
|
* Return: 0 on success, negative errno code on error |
|
*/ |
|
int configfs_register_group(struct config_group *parent_group, |
|
struct config_group *group) |
|
{ |
|
struct configfs_subsystem *subsys = parent_group->cg_subsys; |
|
struct dentry *parent; |
|
struct configfs_fragment *frag; |
|
int ret; |
|
|
|
frag = new_fragment(); |
|
if (!frag) |
|
return -ENOMEM; |
|
|
|
mutex_lock(&subsys->su_mutex); |
|
link_group(parent_group, group); |
|
mutex_unlock(&subsys->su_mutex); |
|
|
|
parent = parent_group->cg_item.ci_dentry; |
|
|
|
inode_lock_nested(d_inode(parent), I_MUTEX_PARENT); |
|
ret = create_default_group(parent_group, group, frag); |
|
if (ret) |
|
goto err_out; |
|
|
|
spin_lock(&configfs_dirent_lock); |
|
configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata); |
|
spin_unlock(&configfs_dirent_lock); |
|
inode_unlock(d_inode(parent)); |
|
put_fragment(frag); |
|
return 0; |
|
err_out: |
|
inode_unlock(d_inode(parent)); |
|
mutex_lock(&subsys->su_mutex); |
|
unlink_group(group); |
|
mutex_unlock(&subsys->su_mutex); |
|
put_fragment(frag); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(configfs_register_group); |
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|
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/** |
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* configfs_unregister_group() - unregisters a child group from its parent |
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* @group: parent group to be unregistered |
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* |
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* Undoes configfs_register_group() |
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*/ |
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void configfs_unregister_group(struct config_group *group) |
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{ |
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struct configfs_subsystem *subsys = group->cg_subsys; |
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struct dentry *dentry = group->cg_item.ci_dentry; |
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struct dentry *parent = group->cg_item.ci_parent->ci_dentry; |
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struct configfs_dirent *sd = dentry->d_fsdata; |
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struct configfs_fragment *frag = sd->s_frag; |
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|
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down_write(&frag->frag_sem); |
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frag->frag_dead = true; |
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up_write(&frag->frag_sem); |
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inode_lock_nested(d_inode(parent), I_MUTEX_PARENT); |
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spin_lock(&configfs_dirent_lock); |
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configfs_detach_prep(dentry, NULL); |
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spin_unlock(&configfs_dirent_lock); |
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|
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configfs_detach_group(&group->cg_item); |
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d_inode(dentry)->i_flags |= S_DEAD; |
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dont_mount(dentry); |
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fsnotify_rmdir(d_inode(parent), dentry); |
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d_delete(dentry); |
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inode_unlock(d_inode(parent)); |
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|
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dput(dentry); |
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|
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mutex_lock(&subsys->su_mutex); |
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unlink_group(group); |
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mutex_unlock(&subsys->su_mutex); |
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} |
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EXPORT_SYMBOL(configfs_unregister_group); |
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|
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/** |
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* configfs_register_default_group() - allocates and registers a child group |
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* @parent_group: parent group |
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* @name: child group name |
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* @item_type: child item type description |
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* |
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* boilerplate to allocate and register a child group with its parent. We need |
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* kzalloc'ed memory because child's default_group is initially empty. |
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* |
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* Return: allocated config group or ERR_PTR() on error |
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*/ |
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struct config_group * |
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configfs_register_default_group(struct config_group *parent_group, |
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const char *name, |
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const struct config_item_type *item_type) |
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{ |
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int ret; |
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struct config_group *group; |
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|
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group = kzalloc(sizeof(*group), GFP_KERNEL); |
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if (!group) |
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return ERR_PTR(-ENOMEM); |
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config_group_init_type_name(group, name, item_type); |
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|
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ret = configfs_register_group(parent_group, group); |
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if (ret) { |
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kfree(group); |
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return ERR_PTR(ret); |
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} |
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return group; |
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} |
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EXPORT_SYMBOL(configfs_register_default_group); |
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|
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/** |
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* configfs_unregister_default_group() - unregisters and frees a child group |
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* @group: the group to act on |
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*/ |
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void configfs_unregister_default_group(struct config_group *group) |
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{ |
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configfs_unregister_group(group); |
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kfree(group); |
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} |
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EXPORT_SYMBOL(configfs_unregister_default_group); |
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|
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int configfs_register_subsystem(struct configfs_subsystem *subsys) |
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{ |
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int err; |
|
struct config_group *group = &subsys->su_group; |
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struct dentry *dentry; |
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struct dentry *root; |
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struct configfs_dirent *sd; |
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struct configfs_fragment *frag; |
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|
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frag = new_fragment(); |
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if (!frag) |
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return -ENOMEM; |
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|
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root = configfs_pin_fs(); |
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if (IS_ERR(root)) { |
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put_fragment(frag); |
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return PTR_ERR(root); |
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} |
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|
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if (!group->cg_item.ci_name) |
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group->cg_item.ci_name = group->cg_item.ci_namebuf; |
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|
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sd = root->d_fsdata; |
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link_group(to_config_group(sd->s_element), group); |
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|
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inode_lock_nested(d_inode(root), I_MUTEX_PARENT); |
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|
|
err = -ENOMEM; |
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dentry = d_alloc_name(root, group->cg_item.ci_name); |
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if (dentry) { |
|
d_add(dentry, NULL); |
|
|
|
err = configfs_attach_group(sd->s_element, &group->cg_item, |
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dentry, frag); |
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if (err) { |
|
BUG_ON(d_inode(dentry)); |
|
d_drop(dentry); |
|
dput(dentry); |
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} else { |
|
spin_lock(&configfs_dirent_lock); |
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configfs_dir_set_ready(dentry->d_fsdata); |
|
spin_unlock(&configfs_dirent_lock); |
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} |
|
} |
|
|
|
inode_unlock(d_inode(root)); |
|
|
|
if (err) { |
|
unlink_group(group); |
|
configfs_release_fs(); |
|
} |
|
put_fragment(frag); |
|
|
|
return err; |
|
} |
|
|
|
void configfs_unregister_subsystem(struct configfs_subsystem *subsys) |
|
{ |
|
struct config_group *group = &subsys->su_group; |
|
struct dentry *dentry = group->cg_item.ci_dentry; |
|
struct dentry *root = dentry->d_sb->s_root; |
|
struct configfs_dirent *sd = dentry->d_fsdata; |
|
struct configfs_fragment *frag = sd->s_frag; |
|
|
|
if (dentry->d_parent != root) { |
|
pr_err("Tried to unregister non-subsystem!\n"); |
|
return; |
|
} |
|
|
|
down_write(&frag->frag_sem); |
|
frag->frag_dead = true; |
|
up_write(&frag->frag_sem); |
|
|
|
inode_lock_nested(d_inode(root), |
|
I_MUTEX_PARENT); |
|
inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD); |
|
mutex_lock(&configfs_symlink_mutex); |
|
spin_lock(&configfs_dirent_lock); |
|
if (configfs_detach_prep(dentry, NULL)) { |
|
pr_err("Tried to unregister non-empty subsystem!\n"); |
|
} |
|
spin_unlock(&configfs_dirent_lock); |
|
mutex_unlock(&configfs_symlink_mutex); |
|
configfs_detach_group(&group->cg_item); |
|
d_inode(dentry)->i_flags |= S_DEAD; |
|
dont_mount(dentry); |
|
fsnotify_rmdir(d_inode(root), dentry); |
|
inode_unlock(d_inode(dentry)); |
|
|
|
d_delete(dentry); |
|
|
|
inode_unlock(d_inode(root)); |
|
|
|
dput(dentry); |
|
|
|
unlink_group(group); |
|
configfs_release_fs(); |
|
} |
|
|
|
EXPORT_SYMBOL(configfs_register_subsystem); |
|
EXPORT_SYMBOL(configfs_unregister_subsystem);
|
|
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