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![Christian Brauner](/assets/img/avatar_default.png)
Extend some inode methods with an additional user namespace argument. A filesystem that is aware of idmapped mounts will receive the user namespace the mount has been marked with. This can be used for additional permission checking and also to enable filesystems to translate between uids and gids if they need to. We have implemented all relevant helpers in earlier patches. As requested we simply extend the exisiting inode method instead of introducing new ones. This is a little more code churn but it's mostly mechanical and doesnt't leave us with additional inode methods. Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
252 lines
6.2 KiB
C
252 lines
6.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* -*- mode: c; c-basic-offset: 8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* inode.c - basic inode and dentry operations.
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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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* Please see Documentation/filesystems/configfs.rst for more
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* information.
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*/
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#undef DEBUG
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#include <linux/pagemap.h>
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#include <linux/namei.h>
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#include <linux/backing-dev.h>
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#include <linux/capability.h>
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#include <linux/sched.h>
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#include <linux/lockdep.h>
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#include <linux/slab.h>
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#include <linux/configfs.h>
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#include "configfs_internal.h"
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#ifdef CONFIG_LOCKDEP
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static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
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#endif
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static const struct address_space_operations configfs_aops = {
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.readpage = simple_readpage,
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.write_begin = simple_write_begin,
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.write_end = simple_write_end,
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};
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static const struct inode_operations configfs_inode_operations ={
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.setattr = configfs_setattr,
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};
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int configfs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
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struct iattr *iattr)
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{
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struct inode * inode = d_inode(dentry);
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struct configfs_dirent * sd = dentry->d_fsdata;
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struct iattr * sd_iattr;
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unsigned int ia_valid = iattr->ia_valid;
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int error;
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if (!sd)
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return -EINVAL;
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sd_iattr = sd->s_iattr;
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if (!sd_iattr) {
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/* setting attributes for the first time, allocate now */
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sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
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if (!sd_iattr)
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return -ENOMEM;
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/* assign default attributes */
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sd_iattr->ia_mode = sd->s_mode;
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sd_iattr->ia_uid = GLOBAL_ROOT_UID;
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sd_iattr->ia_gid = GLOBAL_ROOT_GID;
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sd_iattr->ia_atime = sd_iattr->ia_mtime =
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sd_iattr->ia_ctime = current_time(inode);
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sd->s_iattr = sd_iattr;
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}
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/* attributes were changed atleast once in past */
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error = simple_setattr(mnt_userns, dentry, iattr);
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if (error)
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return error;
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if (ia_valid & ATTR_UID)
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sd_iattr->ia_uid = iattr->ia_uid;
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if (ia_valid & ATTR_GID)
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sd_iattr->ia_gid = iattr->ia_gid;
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if (ia_valid & ATTR_ATIME)
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sd_iattr->ia_atime = iattr->ia_atime;
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if (ia_valid & ATTR_MTIME)
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sd_iattr->ia_mtime = iattr->ia_mtime;
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if (ia_valid & ATTR_CTIME)
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sd_iattr->ia_ctime = iattr->ia_ctime;
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if (ia_valid & ATTR_MODE) {
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umode_t mode = iattr->ia_mode;
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if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
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mode &= ~S_ISGID;
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sd_iattr->ia_mode = sd->s_mode = mode;
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}
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return error;
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}
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static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
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{
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inode->i_mode = mode;
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inode->i_atime = inode->i_mtime =
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inode->i_ctime = current_time(inode);
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}
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static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
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{
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inode->i_mode = iattr->ia_mode;
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inode->i_uid = iattr->ia_uid;
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inode->i_gid = iattr->ia_gid;
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inode->i_atime = iattr->ia_atime;
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inode->i_mtime = iattr->ia_mtime;
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inode->i_ctime = iattr->ia_ctime;
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}
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struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
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struct super_block *s)
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{
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struct inode * inode = new_inode(s);
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if (inode) {
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inode->i_ino = get_next_ino();
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inode->i_mapping->a_ops = &configfs_aops;
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inode->i_op = &configfs_inode_operations;
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if (sd->s_iattr) {
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/* sysfs_dirent has non-default attributes
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* get them for the new inode from persistent copy
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* in sysfs_dirent
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*/
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set_inode_attr(inode, sd->s_iattr);
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} else
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set_default_inode_attr(inode, mode);
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}
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return inode;
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}
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#ifdef CONFIG_LOCKDEP
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static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
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struct inode *inode)
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{
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int depth = sd->s_depth;
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if (depth > 0) {
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if (depth <= ARRAY_SIZE(default_group_class)) {
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lockdep_set_class(&inode->i_rwsem,
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&default_group_class[depth - 1]);
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} else {
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/*
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* In practice the maximum level of locking depth is
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* already reached. Just inform about possible reasons.
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*/
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pr_info("Too many levels of inodes for the locking correctness validator.\n");
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pr_info("Spurious warnings may appear.\n");
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}
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}
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}
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#else /* CONFIG_LOCKDEP */
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static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
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struct inode *inode)
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{
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}
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#endif /* CONFIG_LOCKDEP */
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struct inode *configfs_create(struct dentry *dentry, umode_t mode)
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{
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struct inode *inode = NULL;
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struct configfs_dirent *sd;
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struct inode *p_inode;
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if (!dentry)
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return ERR_PTR(-ENOENT);
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if (d_really_is_positive(dentry))
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return ERR_PTR(-EEXIST);
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sd = dentry->d_fsdata;
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inode = configfs_new_inode(mode, sd, dentry->d_sb);
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if (!inode)
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return ERR_PTR(-ENOMEM);
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p_inode = d_inode(dentry->d_parent);
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p_inode->i_mtime = p_inode->i_ctime = current_time(p_inode);
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configfs_set_inode_lock_class(sd, inode);
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return inode;
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}
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/*
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* Get the name for corresponding element represented by the given configfs_dirent
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*/
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const unsigned char * configfs_get_name(struct configfs_dirent *sd)
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{
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struct configfs_attribute *attr;
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BUG_ON(!sd || !sd->s_element);
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/* These always have a dentry, so use that */
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if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
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return sd->s_dentry->d_name.name;
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if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
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attr = sd->s_element;
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return attr->ca_name;
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}
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return NULL;
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}
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/*
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* Unhashes the dentry corresponding to given configfs_dirent
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* Called with parent inode's i_mutex held.
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*/
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void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
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{
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struct dentry * dentry = sd->s_dentry;
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if (dentry) {
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spin_lock(&dentry->d_lock);
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if (simple_positive(dentry)) {
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dget_dlock(dentry);
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__d_drop(dentry);
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spin_unlock(&dentry->d_lock);
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simple_unlink(d_inode(parent), dentry);
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} else
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spin_unlock(&dentry->d_lock);
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}
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}
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void configfs_hash_and_remove(struct dentry * dir, const char * name)
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{
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struct configfs_dirent * sd;
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struct configfs_dirent * parent_sd = dir->d_fsdata;
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if (d_really_is_negative(dir))
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/* no inode means this hasn't been made visible yet */
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return;
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inode_lock(d_inode(dir));
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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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continue;
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if (!strcmp(configfs_get_name(sd), name)) {
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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, dir);
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configfs_put(sd);
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break;
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}
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}
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inode_unlock(d_inode(dir));
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}
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