![Dmitry Torokhov](/assets/img/avatar_default.png)
This change allows creating kernfs files and directories with arbitrary uid/gid instead of always using GLOBAL_ROOT_UID/GID by extending kernfs_create_dir_ns() and kernfs_create_file_ns() with uid/gid arguments. The "simple" kernfs_create_file() and kernfs_create_dir() are left alone and always create objects belonging to the global root. When creating symlinks ownership (uid/gid) is taken from the target kernfs object. Co-Developed-by: Tyler Hicks <tyhicks@canonical.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Tyler Hicks <tyhicks@canonical.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1703 lines
42 KiB
C
1703 lines
42 KiB
C
/*
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* fs/kernfs/dir.c - kernfs directory implementation
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*
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* Copyright (c) 2001-3 Patrick Mochel
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
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*
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* This file is released under the GPLv2.
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*/
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/idr.h>
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#include <linux/slab.h>
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#include <linux/security.h>
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#include <linux/hash.h>
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#include "kernfs-internal.h"
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DEFINE_MUTEX(kernfs_mutex);
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static DEFINE_SPINLOCK(kernfs_rename_lock); /* kn->parent and ->name */
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static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by rename_lock */
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static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */
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#define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb)
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static bool kernfs_active(struct kernfs_node *kn)
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{
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lockdep_assert_held(&kernfs_mutex);
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return atomic_read(&kn->active) >= 0;
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}
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static bool kernfs_lockdep(struct kernfs_node *kn)
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{
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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return kn->flags & KERNFS_LOCKDEP;
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#else
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return false;
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#endif
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}
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static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen)
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{
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if (!kn)
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return strlcpy(buf, "(null)", buflen);
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return strlcpy(buf, kn->parent ? kn->name : "/", buflen);
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}
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/* kernfs_node_depth - compute depth from @from to @to */
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static size_t kernfs_depth(struct kernfs_node *from, struct kernfs_node *to)
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{
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size_t depth = 0;
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while (to->parent && to != from) {
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depth++;
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to = to->parent;
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}
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return depth;
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}
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static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a,
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struct kernfs_node *b)
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{
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size_t da, db;
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struct kernfs_root *ra = kernfs_root(a), *rb = kernfs_root(b);
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if (ra != rb)
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return NULL;
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da = kernfs_depth(ra->kn, a);
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db = kernfs_depth(rb->kn, b);
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while (da > db) {
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a = a->parent;
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da--;
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}
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while (db > da) {
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b = b->parent;
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db--;
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}
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/* worst case b and a will be the same at root */
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while (b != a) {
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b = b->parent;
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a = a->parent;
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}
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return a;
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}
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/**
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* kernfs_path_from_node_locked - find a pseudo-absolute path to @kn_to,
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* where kn_from is treated as root of the path.
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* @kn_from: kernfs node which should be treated as root for the path
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* @kn_to: kernfs node to which path is needed
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* @buf: buffer to copy the path into
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* @buflen: size of @buf
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*
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* We need to handle couple of scenarios here:
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* [1] when @kn_from is an ancestor of @kn_to at some level
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* kn_from: /n1/n2/n3
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* kn_to: /n1/n2/n3/n4/n5
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* result: /n4/n5
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*
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* [2] when @kn_from is on a different hierarchy and we need to find common
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* ancestor between @kn_from and @kn_to.
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* kn_from: /n1/n2/n3/n4
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* kn_to: /n1/n2/n5
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* result: /../../n5
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* OR
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* kn_from: /n1/n2/n3/n4/n5 [depth=5]
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* kn_to: /n1/n2/n3 [depth=3]
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* result: /../..
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*
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* [3] when @kn_to is NULL result will be "(null)"
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*
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* Returns the length of the full path. If the full length is equal to or
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* greater than @buflen, @buf contains the truncated path with the trailing
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* '\0'. On error, -errno is returned.
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*/
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static int kernfs_path_from_node_locked(struct kernfs_node *kn_to,
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struct kernfs_node *kn_from,
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char *buf, size_t buflen)
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{
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struct kernfs_node *kn, *common;
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const char parent_str[] = "/..";
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size_t depth_from, depth_to, len = 0;
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int i, j;
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if (!kn_to)
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return strlcpy(buf, "(null)", buflen);
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if (!kn_from)
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kn_from = kernfs_root(kn_to)->kn;
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if (kn_from == kn_to)
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return strlcpy(buf, "/", buflen);
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common = kernfs_common_ancestor(kn_from, kn_to);
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if (WARN_ON(!common))
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return -EINVAL;
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depth_to = kernfs_depth(common, kn_to);
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depth_from = kernfs_depth(common, kn_from);
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if (buf)
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buf[0] = '\0';
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for (i = 0; i < depth_from; i++)
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len += strlcpy(buf + len, parent_str,
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len < buflen ? buflen - len : 0);
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/* Calculate how many bytes we need for the rest */
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for (i = depth_to - 1; i >= 0; i--) {
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for (kn = kn_to, j = 0; j < i; j++)
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kn = kn->parent;
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len += strlcpy(buf + len, "/",
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len < buflen ? buflen - len : 0);
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len += strlcpy(buf + len, kn->name,
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len < buflen ? buflen - len : 0);
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}
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return len;
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}
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/**
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* kernfs_name - obtain the name of a given node
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* @kn: kernfs_node of interest
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* @buf: buffer to copy @kn's name into
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* @buflen: size of @buf
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*
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* Copies the name of @kn into @buf of @buflen bytes. The behavior is
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* similar to strlcpy(). It returns the length of @kn's name and if @buf
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* isn't long enough, it's filled upto @buflen-1 and nul terminated.
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*
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* Fills buffer with "(null)" if @kn is NULL.
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*
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* This function can be called from any context.
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*/
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int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
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{
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unsigned long flags;
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int ret;
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spin_lock_irqsave(&kernfs_rename_lock, flags);
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ret = kernfs_name_locked(kn, buf, buflen);
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spin_unlock_irqrestore(&kernfs_rename_lock, flags);
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return ret;
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}
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/**
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* kernfs_path_from_node - build path of node @to relative to @from.
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* @from: parent kernfs_node relative to which we need to build the path
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* @to: kernfs_node of interest
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* @buf: buffer to copy @to's path into
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* @buflen: size of @buf
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*
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* Builds @to's path relative to @from in @buf. @from and @to must
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* be on the same kernfs-root. If @from is not parent of @to, then a relative
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* path (which includes '..'s) as needed to reach from @from to @to is
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* returned.
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*
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* Returns the length of the full path. If the full length is equal to or
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* greater than @buflen, @buf contains the truncated path with the trailing
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* '\0'. On error, -errno is returned.
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*/
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int kernfs_path_from_node(struct kernfs_node *to, struct kernfs_node *from,
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char *buf, size_t buflen)
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{
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unsigned long flags;
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int ret;
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spin_lock_irqsave(&kernfs_rename_lock, flags);
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ret = kernfs_path_from_node_locked(to, from, buf, buflen);
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spin_unlock_irqrestore(&kernfs_rename_lock, flags);
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return ret;
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}
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EXPORT_SYMBOL_GPL(kernfs_path_from_node);
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/**
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* pr_cont_kernfs_name - pr_cont name of a kernfs_node
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* @kn: kernfs_node of interest
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*
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* This function can be called from any context.
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*/
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void pr_cont_kernfs_name(struct kernfs_node *kn)
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{
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unsigned long flags;
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spin_lock_irqsave(&kernfs_rename_lock, flags);
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kernfs_name_locked(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf));
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pr_cont("%s", kernfs_pr_cont_buf);
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spin_unlock_irqrestore(&kernfs_rename_lock, flags);
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}
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/**
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* pr_cont_kernfs_path - pr_cont path of a kernfs_node
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* @kn: kernfs_node of interest
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*
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* This function can be called from any context.
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*/
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void pr_cont_kernfs_path(struct kernfs_node *kn)
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{
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unsigned long flags;
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int sz;
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spin_lock_irqsave(&kernfs_rename_lock, flags);
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sz = kernfs_path_from_node_locked(kn, NULL, kernfs_pr_cont_buf,
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sizeof(kernfs_pr_cont_buf));
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if (sz < 0) {
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pr_cont("(error)");
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goto out;
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}
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if (sz >= sizeof(kernfs_pr_cont_buf)) {
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pr_cont("(name too long)");
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goto out;
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}
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pr_cont("%s", kernfs_pr_cont_buf);
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out:
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spin_unlock_irqrestore(&kernfs_rename_lock, flags);
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}
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/**
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* kernfs_get_parent - determine the parent node and pin it
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* @kn: kernfs_node of interest
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*
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* Determines @kn's parent, pins and returns it. This function can be
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* called from any context.
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*/
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struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
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{
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struct kernfs_node *parent;
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unsigned long flags;
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spin_lock_irqsave(&kernfs_rename_lock, flags);
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parent = kn->parent;
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kernfs_get(parent);
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spin_unlock_irqrestore(&kernfs_rename_lock, flags);
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return parent;
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}
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/**
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* kernfs_name_hash
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* @name: Null terminated string to hash
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* @ns: Namespace tag to hash
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*
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* Returns 31 bit hash of ns + name (so it fits in an off_t )
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*/
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static unsigned int kernfs_name_hash(const char *name, const void *ns)
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{
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unsigned long hash = init_name_hash(ns);
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unsigned int len = strlen(name);
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while (len--)
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hash = partial_name_hash(*name++, hash);
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hash = end_name_hash(hash);
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hash &= 0x7fffffffU;
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/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
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if (hash < 2)
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hash += 2;
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if (hash >= INT_MAX)
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hash = INT_MAX - 1;
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return hash;
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}
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static int kernfs_name_compare(unsigned int hash, const char *name,
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const void *ns, const struct kernfs_node *kn)
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{
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if (hash < kn->hash)
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return -1;
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if (hash > kn->hash)
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return 1;
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if (ns < kn->ns)
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return -1;
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if (ns > kn->ns)
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return 1;
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return strcmp(name, kn->name);
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}
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static int kernfs_sd_compare(const struct kernfs_node *left,
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const struct kernfs_node *right)
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{
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return kernfs_name_compare(left->hash, left->name, left->ns, right);
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}
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/**
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* kernfs_link_sibling - link kernfs_node into sibling rbtree
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* @kn: kernfs_node of interest
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*
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* Link @kn into its sibling rbtree which starts from
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* @kn->parent->dir.children.
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*
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* Locking:
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* mutex_lock(kernfs_mutex)
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*
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* RETURNS:
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* 0 on susccess -EEXIST on failure.
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*/
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static int kernfs_link_sibling(struct kernfs_node *kn)
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{
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struct rb_node **node = &kn->parent->dir.children.rb_node;
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struct rb_node *parent = NULL;
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while (*node) {
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struct kernfs_node *pos;
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int result;
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pos = rb_to_kn(*node);
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parent = *node;
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result = kernfs_sd_compare(kn, pos);
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if (result < 0)
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node = &pos->rb.rb_left;
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else if (result > 0)
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node = &pos->rb.rb_right;
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else
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return -EEXIST;
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}
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/* add new node and rebalance the tree */
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rb_link_node(&kn->rb, parent, node);
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rb_insert_color(&kn->rb, &kn->parent->dir.children);
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/* successfully added, account subdir number */
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if (kernfs_type(kn) == KERNFS_DIR)
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kn->parent->dir.subdirs++;
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return 0;
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}
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/**
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* kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree
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* @kn: kernfs_node of interest
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*
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* Try to unlink @kn from its sibling rbtree which starts from
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* kn->parent->dir.children. Returns %true if @kn was actually
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* removed, %false if @kn wasn't on the rbtree.
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*
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* Locking:
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* mutex_lock(kernfs_mutex)
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*/
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static bool kernfs_unlink_sibling(struct kernfs_node *kn)
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{
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if (RB_EMPTY_NODE(&kn->rb))
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return false;
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if (kernfs_type(kn) == KERNFS_DIR)
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kn->parent->dir.subdirs--;
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rb_erase(&kn->rb, &kn->parent->dir.children);
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RB_CLEAR_NODE(&kn->rb);
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return true;
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}
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/**
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* kernfs_get_active - get an active reference to kernfs_node
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* @kn: kernfs_node to get an active reference to
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*
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* Get an active reference of @kn. This function is noop if @kn
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* is NULL.
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*
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* RETURNS:
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* Pointer to @kn on success, NULL on failure.
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*/
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struct kernfs_node *kernfs_get_active(struct kernfs_node *kn)
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{
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if (unlikely(!kn))
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return NULL;
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if (!atomic_inc_unless_negative(&kn->active))
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return NULL;
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if (kernfs_lockdep(kn))
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rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);
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return kn;
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}
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/**
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* kernfs_put_active - put an active reference to kernfs_node
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* @kn: kernfs_node to put an active reference to
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*
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* Put an active reference to @kn. This function is noop if @kn
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* is NULL.
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*/
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void kernfs_put_active(struct kernfs_node *kn)
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{
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struct kernfs_root *root = kernfs_root(kn);
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int v;
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if (unlikely(!kn))
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return;
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if (kernfs_lockdep(kn))
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rwsem_release(&kn->dep_map, 1, _RET_IP_);
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v = atomic_dec_return(&kn->active);
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if (likely(v != KN_DEACTIVATED_BIAS))
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return;
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wake_up_all(&root->deactivate_waitq);
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}
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/**
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* kernfs_drain - drain kernfs_node
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* @kn: kernfs_node to drain
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*
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* Drain existing usages and nuke all existing mmaps of @kn. Mutiple
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* removers may invoke this function concurrently on @kn and all will
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* return after draining is complete.
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*/
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static void kernfs_drain(struct kernfs_node *kn)
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__releases(&kernfs_mutex) __acquires(&kernfs_mutex)
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{
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struct kernfs_root *root = kernfs_root(kn);
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|
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lockdep_assert_held(&kernfs_mutex);
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WARN_ON_ONCE(kernfs_active(kn));
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mutex_unlock(&kernfs_mutex);
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if (kernfs_lockdep(kn)) {
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rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
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if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
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lock_contended(&kn->dep_map, _RET_IP_);
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}
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/* but everyone should wait for draining */
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wait_event(root->deactivate_waitq,
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atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);
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if (kernfs_lockdep(kn)) {
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lock_acquired(&kn->dep_map, _RET_IP_);
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rwsem_release(&kn->dep_map, 1, _RET_IP_);
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}
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kernfs_drain_open_files(kn);
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mutex_lock(&kernfs_mutex);
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}
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|
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/**
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* kernfs_get - get a reference count on a kernfs_node
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* @kn: the target kernfs_node
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*/
|
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void kernfs_get(struct kernfs_node *kn)
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{
|
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if (kn) {
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WARN_ON(!atomic_read(&kn->count));
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atomic_inc(&kn->count);
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}
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}
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EXPORT_SYMBOL_GPL(kernfs_get);
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|
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/**
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* kernfs_put - put a reference count on a kernfs_node
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* @kn: the target kernfs_node
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*
|
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* Put a reference count of @kn and destroy it if it reached zero.
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*/
|
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void kernfs_put(struct kernfs_node *kn)
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{
|
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struct kernfs_node *parent;
|
|
struct kernfs_root *root;
|
|
|
|
/*
|
|
* kernfs_node is freed with ->count 0, kernfs_find_and_get_node_by_ino
|
|
* depends on this to filter reused stale node
|
|
*/
|
|
if (!kn || !atomic_dec_and_test(&kn->count))
|
|
return;
|
|
root = kernfs_root(kn);
|
|
repeat:
|
|
/*
|
|
* Moving/renaming is always done while holding reference.
|
|
* kn->parent won't change beneath us.
|
|
*/
|
|
parent = kn->parent;
|
|
|
|
WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS,
|
|
"kernfs_put: %s/%s: released with incorrect active_ref %d\n",
|
|
parent ? parent->name : "", kn->name, atomic_read(&kn->active));
|
|
|
|
if (kernfs_type(kn) == KERNFS_LINK)
|
|
kernfs_put(kn->symlink.target_kn);
|
|
|
|
kfree_const(kn->name);
|
|
|
|
if (kn->iattr) {
|
|
if (kn->iattr->ia_secdata)
|
|
security_release_secctx(kn->iattr->ia_secdata,
|
|
kn->iattr->ia_secdata_len);
|
|
simple_xattrs_free(&kn->iattr->xattrs);
|
|
}
|
|
kfree(kn->iattr);
|
|
spin_lock(&kernfs_idr_lock);
|
|
idr_remove(&root->ino_idr, kn->id.ino);
|
|
spin_unlock(&kernfs_idr_lock);
|
|
kmem_cache_free(kernfs_node_cache, kn);
|
|
|
|
kn = parent;
|
|
if (kn) {
|
|
if (atomic_dec_and_test(&kn->count))
|
|
goto repeat;
|
|
} else {
|
|
/* just released the root kn, free @root too */
|
|
idr_destroy(&root->ino_idr);
|
|
kfree(root);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(kernfs_put);
|
|
|
|
static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
|
|
{
|
|
struct kernfs_node *kn;
|
|
|
|
if (flags & LOOKUP_RCU)
|
|
return -ECHILD;
|
|
|
|
/* Always perform fresh lookup for negatives */
|
|
if (d_really_is_negative(dentry))
|
|
goto out_bad_unlocked;
|
|
|
|
kn = kernfs_dentry_node(dentry);
|
|
mutex_lock(&kernfs_mutex);
|
|
|
|
/* The kernfs node has been deactivated */
|
|
if (!kernfs_active(kn))
|
|
goto out_bad;
|
|
|
|
/* The kernfs node has been moved? */
|
|
if (kernfs_dentry_node(dentry->d_parent) != kn->parent)
|
|
goto out_bad;
|
|
|
|
/* The kernfs node has been renamed */
|
|
if (strcmp(dentry->d_name.name, kn->name) != 0)
|
|
goto out_bad;
|
|
|
|
/* The kernfs node has been moved to a different namespace */
|
|
if (kn->parent && kernfs_ns_enabled(kn->parent) &&
|
|
kernfs_info(dentry->d_sb)->ns != kn->ns)
|
|
goto out_bad;
|
|
|
|
mutex_unlock(&kernfs_mutex);
|
|
return 1;
|
|
out_bad:
|
|
mutex_unlock(&kernfs_mutex);
|
|
out_bad_unlocked:
|
|
return 0;
|
|
}
|
|
|
|
const struct dentry_operations kernfs_dops = {
|
|
.d_revalidate = kernfs_dop_revalidate,
|
|
};
|
|
|
|
/**
|
|
* kernfs_node_from_dentry - determine kernfs_node associated with a dentry
|
|
* @dentry: the dentry in question
|
|
*
|
|
* Return the kernfs_node associated with @dentry. If @dentry is not a
|
|
* kernfs one, %NULL is returned.
|
|
*
|
|
* While the returned kernfs_node will stay accessible as long as @dentry
|
|
* is accessible, the returned node can be in any state and the caller is
|
|
* fully responsible for determining what's accessible.
|
|
*/
|
|
struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
|
|
{
|
|
if (dentry->d_sb->s_op == &kernfs_sops &&
|
|
!d_really_is_negative(dentry))
|
|
return kernfs_dentry_node(dentry);
|
|
return NULL;
|
|
}
|
|
|
|
static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
|
|
const char *name, umode_t mode,
|
|
kuid_t uid, kgid_t gid,
|
|
unsigned flags)
|
|
{
|
|
struct kernfs_node *kn;
|
|
u32 gen;
|
|
int cursor;
|
|
int ret;
|
|
|
|
name = kstrdup_const(name, GFP_KERNEL);
|
|
if (!name)
|
|
return NULL;
|
|
|
|
kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL);
|
|
if (!kn)
|
|
goto err_out1;
|
|
|
|
idr_preload(GFP_KERNEL);
|
|
spin_lock(&kernfs_idr_lock);
|
|
cursor = idr_get_cursor(&root->ino_idr);
|
|
ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC);
|
|
if (ret >= 0 && ret < cursor)
|
|
root->next_generation++;
|
|
gen = root->next_generation;
|
|
spin_unlock(&kernfs_idr_lock);
|
|
idr_preload_end();
|
|
if (ret < 0)
|
|
goto err_out2;
|
|
kn->id.ino = ret;
|
|
kn->id.generation = gen;
|
|
|
|
/*
|
|
* set ino first. This barrier is paired with atomic_inc_not_zero in
|
|
* kernfs_find_and_get_node_by_ino
|
|
*/
|
|
smp_mb__before_atomic();
|
|
atomic_set(&kn->count, 1);
|
|
atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
|
|
RB_CLEAR_NODE(&kn->rb);
|
|
|
|
kn->name = name;
|
|
kn->mode = mode;
|
|
kn->flags = flags;
|
|
|
|
if (!uid_eq(uid, GLOBAL_ROOT_UID) || !gid_eq(gid, GLOBAL_ROOT_GID)) {
|
|
struct iattr iattr = {
|
|
.ia_valid = ATTR_UID | ATTR_GID,
|
|
.ia_uid = uid,
|
|
.ia_gid = gid,
|
|
};
|
|
|
|
ret = __kernfs_setattr(kn, &iattr);
|
|
if (ret < 0)
|
|
goto err_out3;
|
|
}
|
|
|
|
return kn;
|
|
|
|
err_out3:
|
|
idr_remove(&root->ino_idr, kn->id.ino);
|
|
err_out2:
|
|
kmem_cache_free(kernfs_node_cache, kn);
|
|
err_out1:
|
|
kfree_const(name);
|
|
return NULL;
|
|
}
|
|
|
|
struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
|
|
const char *name, umode_t mode,
|
|
kuid_t uid, kgid_t gid,
|
|
unsigned flags)
|
|
{
|
|
struct kernfs_node *kn;
|
|
|
|
kn = __kernfs_new_node(kernfs_root(parent),
|
|
name, mode, uid, gid, flags);
|
|
if (kn) {
|
|
kernfs_get(parent);
|
|
kn->parent = parent;
|
|
}
|
|
return kn;
|
|
}
|
|
|
|
/*
|
|
* kernfs_find_and_get_node_by_ino - get kernfs_node from inode number
|
|
* @root: the kernfs root
|
|
* @ino: inode number
|
|
*
|
|
* RETURNS:
|
|
* NULL on failure. Return a kernfs node with reference counter incremented
|
|
*/
|
|
struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root,
|
|
unsigned int ino)
|
|
{
|
|
struct kernfs_node *kn;
|
|
|
|
rcu_read_lock();
|
|
kn = idr_find(&root->ino_idr, ino);
|
|
if (!kn)
|
|
goto out;
|
|
|
|
/*
|
|
* Since kernfs_node is freed in RCU, it's possible an old node for ino
|
|
* is freed, but reused before RCU grace period. But a freed node (see
|
|
* kernfs_put) or an incompletedly initialized node (see
|
|
* __kernfs_new_node) should have 'count' 0. We can use this fact to
|
|
* filter out such node.
|
|
*/
|
|
if (!atomic_inc_not_zero(&kn->count)) {
|
|
kn = NULL;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* The node could be a new node or a reused node. If it's a new node,
|
|
* we are ok. If it's reused because of RCU (because of
|
|
* SLAB_TYPESAFE_BY_RCU), the __kernfs_new_node always sets its 'ino'
|
|
* before 'count'. So if 'count' is uptodate, 'ino' should be uptodate,
|
|
* hence we can use 'ino' to filter stale node.
|
|
*/
|
|
if (kn->id.ino != ino)
|
|
goto out;
|
|
rcu_read_unlock();
|
|
|
|
return kn;
|
|
out:
|
|
rcu_read_unlock();
|
|
kernfs_put(kn);
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* kernfs_add_one - add kernfs_node to parent without warning
|
|
* @kn: kernfs_node to be added
|
|
*
|
|
* The caller must already have initialized @kn->parent. This
|
|
* function increments nlink of the parent's inode if @kn is a
|
|
* directory and link into the children list of the parent.
|
|
*
|
|
* RETURNS:
|
|
* 0 on success, -EEXIST if entry with the given name already
|
|
* exists.
|
|
*/
|
|
int kernfs_add_one(struct kernfs_node *kn)
|
|
{
|
|
struct kernfs_node *parent = kn->parent;
|
|
struct kernfs_iattrs *ps_iattr;
|
|
bool has_ns;
|
|
int ret;
|
|
|
|
mutex_lock(&kernfs_mutex);
|
|
|
|
ret = -EINVAL;
|
|
has_ns = kernfs_ns_enabled(parent);
|
|
if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
|
|
has_ns ? "required" : "invalid", parent->name, kn->name))
|
|
goto out_unlock;
|
|
|
|
if (kernfs_type(parent) != KERNFS_DIR)
|
|
goto out_unlock;
|
|
|
|
ret = -ENOENT;
|
|
if (parent->flags & KERNFS_EMPTY_DIR)
|
|
goto out_unlock;
|
|
|
|
if ((parent->flags & KERNFS_ACTIVATED) && !kernfs_active(parent))
|
|
goto out_unlock;
|
|
|
|
kn->hash = kernfs_name_hash(kn->name, kn->ns);
|
|
|
|
ret = kernfs_link_sibling(kn);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
/* Update timestamps on the parent */
|
|
ps_iattr = parent->iattr;
|
|
if (ps_iattr) {
|
|
struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
|
|
ktime_get_real_ts64(&ps_iattrs->ia_ctime);
|
|
ps_iattrs->ia_mtime = ps_iattrs->ia_ctime;
|
|
}
|
|
|
|
mutex_unlock(&kernfs_mutex);
|
|
|
|
/*
|
|
* Activate the new node unless CREATE_DEACTIVATED is requested.
|
|
* If not activated here, the kernfs user is responsible for
|
|
* activating the node with kernfs_activate(). A node which hasn't
|
|
* been activated is not visible to userland and its removal won't
|
|
* trigger deactivation.
|
|
*/
|
|
if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED))
|
|
kernfs_activate(kn);
|
|
return 0;
|
|
|
|
out_unlock:
|
|
mutex_unlock(&kernfs_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* kernfs_find_ns - find kernfs_node with the given name
|
|
* @parent: kernfs_node to search under
|
|
* @name: name to look for
|
|
* @ns: the namespace tag to use
|
|
*
|
|
* Look for kernfs_node with name @name under @parent. Returns pointer to
|
|
* the found kernfs_node on success, %NULL on failure.
|
|
*/
|
|
static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent,
|
|
const unsigned char *name,
|
|
const void *ns)
|
|
{
|
|
struct rb_node *node = parent->dir.children.rb_node;
|
|
bool has_ns = kernfs_ns_enabled(parent);
|
|
unsigned int hash;
|
|
|
|
lockdep_assert_held(&kernfs_mutex);
|
|
|
|
if (has_ns != (bool)ns) {
|
|
WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
|
|
has_ns ? "required" : "invalid", parent->name, name);
|
|
return NULL;
|
|
}
|
|
|
|
hash = kernfs_name_hash(name, ns);
|
|
while (node) {
|
|
struct kernfs_node *kn;
|
|
int result;
|
|
|
|
kn = rb_to_kn(node);
|
|
result = kernfs_name_compare(hash, name, ns, kn);
|
|
if (result < 0)
|
|
node = node->rb_left;
|
|
else if (result > 0)
|
|
node = node->rb_right;
|
|
else
|
|
return kn;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent,
|
|
const unsigned char *path,
|
|
const void *ns)
|
|
{
|
|
size_t len;
|
|
char *p, *name;
|
|
|
|
lockdep_assert_held(&kernfs_mutex);
|
|
|
|
/* grab kernfs_rename_lock to piggy back on kernfs_pr_cont_buf */
|
|
spin_lock_irq(&kernfs_rename_lock);
|
|
|
|
len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf));
|
|
|
|
if (len >= sizeof(kernfs_pr_cont_buf)) {
|
|
spin_unlock_irq(&kernfs_rename_lock);
|
|
return NULL;
|
|
}
|
|
|
|
p = kernfs_pr_cont_buf;
|
|
|
|
while ((name = strsep(&p, "/")) && parent) {
|
|
if (*name == '\0')
|
|
continue;
|
|
parent = kernfs_find_ns(parent, name, ns);
|
|
}
|
|
|
|
spin_unlock_irq(&kernfs_rename_lock);
|
|
|
|
return parent;
|
|
}
|
|
|
|
/**
|
|
* kernfs_find_and_get_ns - find and get kernfs_node with the given name
|
|
* @parent: kernfs_node to search under
|
|
* @name: name to look for
|
|
* @ns: the namespace tag to use
|
|
*
|
|
* Look for kernfs_node with name @name under @parent and get a reference
|
|
* if found. This function may sleep and returns pointer to the found
|
|
* kernfs_node on success, %NULL on failure.
|
|
*/
|
|
struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
|
|
const char *name, const void *ns)
|
|
{
|
|
struct kernfs_node *kn;
|
|
|
|
mutex_lock(&kernfs_mutex);
|
|
kn = kernfs_find_ns(parent, name, ns);
|
|
kernfs_get(kn);
|
|
mutex_unlock(&kernfs_mutex);
|
|
|
|
return kn;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
|
|
|
|
/**
|
|
* kernfs_walk_and_get_ns - find and get kernfs_node with the given path
|
|
* @parent: kernfs_node to search under
|
|
* @path: path to look for
|
|
* @ns: the namespace tag to use
|
|
*
|
|
* Look for kernfs_node with path @path under @parent and get a reference
|
|
* if found. This function may sleep and returns pointer to the found
|
|
* kernfs_node on success, %NULL on failure.
|
|
*/
|
|
struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent,
|
|
const char *path, const void *ns)
|
|
{
|
|
struct kernfs_node *kn;
|
|
|
|
mutex_lock(&kernfs_mutex);
|
|
kn = kernfs_walk_ns(parent, path, ns);
|
|
kernfs_get(kn);
|
|
mutex_unlock(&kernfs_mutex);
|
|
|
|
return kn;
|
|
}
|
|
|
|
/**
|
|
* kernfs_create_root - create a new kernfs hierarchy
|
|
* @scops: optional syscall operations for the hierarchy
|
|
* @flags: KERNFS_ROOT_* flags
|
|
* @priv: opaque data associated with the new directory
|
|
*
|
|
* Returns the root of the new hierarchy on success, ERR_PTR() value on
|
|
* failure.
|
|
*/
|
|
struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
|
|
unsigned int flags, void *priv)
|
|
{
|
|
struct kernfs_root *root;
|
|
struct kernfs_node *kn;
|
|
|
|
root = kzalloc(sizeof(*root), GFP_KERNEL);
|
|
if (!root)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
idr_init(&root->ino_idr);
|
|
INIT_LIST_HEAD(&root->supers);
|
|
root->next_generation = 1;
|
|
|
|
kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO,
|
|
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
|
|
KERNFS_DIR);
|
|
if (!kn) {
|
|
idr_destroy(&root->ino_idr);
|
|
kfree(root);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
kn->priv = priv;
|
|
kn->dir.root = root;
|
|
|
|
root->syscall_ops = scops;
|
|
root->flags = flags;
|
|
root->kn = kn;
|
|
init_waitqueue_head(&root->deactivate_waitq);
|
|
|
|
if (!(root->flags & KERNFS_ROOT_CREATE_DEACTIVATED))
|
|
kernfs_activate(kn);
|
|
|
|
return root;
|
|
}
|
|
|
|
/**
|
|
* kernfs_destroy_root - destroy a kernfs hierarchy
|
|
* @root: root of the hierarchy to destroy
|
|
*
|
|
* Destroy the hierarchy anchored at @root by removing all existing
|
|
* directories and destroying @root.
|
|
*/
|
|
void kernfs_destroy_root(struct kernfs_root *root)
|
|
{
|
|
kernfs_remove(root->kn); /* will also free @root */
|
|
}
|
|
|
|
/**
|
|
* kernfs_create_dir_ns - create a directory
|
|
* @parent: parent in which to create a new directory
|
|
* @name: name of the new directory
|
|
* @mode: mode of the new directory
|
|
* @uid: uid of the new directory
|
|
* @gid: gid of the new directory
|
|
* @priv: opaque data associated with the new directory
|
|
* @ns: optional namespace tag of the directory
|
|
*
|
|
* Returns the created node on success, ERR_PTR() value on failure.
|
|
*/
|
|
struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
|
|
const char *name, umode_t mode,
|
|
kuid_t uid, kgid_t gid,
|
|
void *priv, const void *ns)
|
|
{
|
|
struct kernfs_node *kn;
|
|
int rc;
|
|
|
|
/* allocate */
|
|
kn = kernfs_new_node(parent, name, mode | S_IFDIR,
|
|
uid, gid, KERNFS_DIR);
|
|
if (!kn)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
kn->dir.root = parent->dir.root;
|
|
kn->ns = ns;
|
|
kn->priv = priv;
|
|
|
|
/* link in */
|
|
rc = kernfs_add_one(kn);
|
|
if (!rc)
|
|
return kn;
|
|
|
|
kernfs_put(kn);
|
|
return ERR_PTR(rc);
|
|
}
|
|
|
|
/**
|
|
* kernfs_create_empty_dir - create an always empty directory
|
|
* @parent: parent in which to create a new directory
|
|
* @name: name of the new directory
|
|
*
|
|
* Returns the created node on success, ERR_PTR() value on failure.
|
|
*/
|
|
struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
|
|
const char *name)
|
|
{
|
|
struct kernfs_node *kn;
|
|
int rc;
|
|
|
|
/* allocate */
|
|
kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR,
|
|
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, KERNFS_DIR);
|
|
if (!kn)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
kn->flags |= KERNFS_EMPTY_DIR;
|
|
kn->dir.root = parent->dir.root;
|
|
kn->ns = NULL;
|
|
kn->priv = NULL;
|
|
|
|
/* link in */
|
|
rc = kernfs_add_one(kn);
|
|
if (!rc)
|
|
return kn;
|
|
|
|
kernfs_put(kn);
|
|
return ERR_PTR(rc);
|
|
}
|
|
|
|
static struct dentry *kernfs_iop_lookup(struct inode *dir,
|
|
struct dentry *dentry,
|
|
unsigned int flags)
|
|
{
|
|
struct dentry *ret;
|
|
struct kernfs_node *parent = dir->i_private;
|
|
struct kernfs_node *kn;
|
|
struct inode *inode;
|
|
const void *ns = NULL;
|
|
|
|
mutex_lock(&kernfs_mutex);
|
|
|
|
if (kernfs_ns_enabled(parent))
|
|
ns = kernfs_info(dir->i_sb)->ns;
|
|
|
|
kn = kernfs_find_ns(parent, dentry->d_name.name, ns);
|
|
|
|
/* no such entry */
|
|
if (!kn || !kernfs_active(kn)) {
|
|
ret = NULL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* attach dentry and inode */
|
|
inode = kernfs_get_inode(dir->i_sb, kn);
|
|
if (!inode) {
|
|
ret = ERR_PTR(-ENOMEM);
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* instantiate and hash dentry */
|
|
ret = d_splice_alias(inode, dentry);
|
|
out_unlock:
|
|
mutex_unlock(&kernfs_mutex);
|
|
return ret;
|
|
}
|
|
|
|
static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry,
|
|
umode_t mode)
|
|
{
|
|
struct kernfs_node *parent = dir->i_private;
|
|
struct kernfs_syscall_ops *scops = kernfs_root(parent)->syscall_ops;
|
|
int ret;
|
|
|
|
if (!scops || !scops->mkdir)
|
|
return -EPERM;
|
|
|
|
if (!kernfs_get_active(parent))
|
|
return -ENODEV;
|
|
|
|
ret = scops->mkdir(parent, dentry->d_name.name, mode);
|
|
|
|
kernfs_put_active(parent);
|
|
return ret;
|
|
}
|
|
|
|
static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry)
|
|
{
|
|
struct kernfs_node *kn = kernfs_dentry_node(dentry);
|
|
struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
|
|
int ret;
|
|
|
|
if (!scops || !scops->rmdir)
|
|
return -EPERM;
|
|
|
|
if (!kernfs_get_active(kn))
|
|
return -ENODEV;
|
|
|
|
ret = scops->rmdir(kn);
|
|
|
|
kernfs_put_active(kn);
|
|
return ret;
|
|
}
|
|
|
|
static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry,
|
|
unsigned int flags)
|
|
{
|
|
struct kernfs_node *kn = kernfs_dentry_node(old_dentry);
|
|
struct kernfs_node *new_parent = new_dir->i_private;
|
|
struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
|
|
int ret;
|
|
|
|
if (flags)
|
|
return -EINVAL;
|
|
|
|
if (!scops || !scops->rename)
|
|
return -EPERM;
|
|
|
|
if (!kernfs_get_active(kn))
|
|
return -ENODEV;
|
|
|
|
if (!kernfs_get_active(new_parent)) {
|
|
kernfs_put_active(kn);
|
|
return -ENODEV;
|
|
}
|
|
|
|
ret = scops->rename(kn, new_parent, new_dentry->d_name.name);
|
|
|
|
kernfs_put_active(new_parent);
|
|
kernfs_put_active(kn);
|
|
return ret;
|
|
}
|
|
|
|
const struct inode_operations kernfs_dir_iops = {
|
|
.lookup = kernfs_iop_lookup,
|
|
.permission = kernfs_iop_permission,
|
|
.setattr = kernfs_iop_setattr,
|
|
.getattr = kernfs_iop_getattr,
|
|
.listxattr = kernfs_iop_listxattr,
|
|
|
|
.mkdir = kernfs_iop_mkdir,
|
|
.rmdir = kernfs_iop_rmdir,
|
|
.rename = kernfs_iop_rename,
|
|
};
|
|
|
|
static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos)
|
|
{
|
|
struct kernfs_node *last;
|
|
|
|
while (true) {
|
|
struct rb_node *rbn;
|
|
|
|
last = pos;
|
|
|
|
if (kernfs_type(pos) != KERNFS_DIR)
|
|
break;
|
|
|
|
rbn = rb_first(&pos->dir.children);
|
|
if (!rbn)
|
|
break;
|
|
|
|
pos = rb_to_kn(rbn);
|
|
}
|
|
|
|
return last;
|
|
}
|
|
|
|
/**
|
|
* kernfs_next_descendant_post - find the next descendant for post-order walk
|
|
* @pos: the current position (%NULL to initiate traversal)
|
|
* @root: kernfs_node whose descendants to walk
|
|
*
|
|
* Find the next descendant to visit for post-order traversal of @root's
|
|
* descendants. @root is included in the iteration and the last node to be
|
|
* visited.
|
|
*/
|
|
static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos,
|
|
struct kernfs_node *root)
|
|
{
|
|
struct rb_node *rbn;
|
|
|
|
lockdep_assert_held(&kernfs_mutex);
|
|
|
|
/* if first iteration, visit leftmost descendant which may be root */
|
|
if (!pos)
|
|
return kernfs_leftmost_descendant(root);
|
|
|
|
/* if we visited @root, we're done */
|
|
if (pos == root)
|
|
return NULL;
|
|
|
|
/* if there's an unvisited sibling, visit its leftmost descendant */
|
|
rbn = rb_next(&pos->rb);
|
|
if (rbn)
|
|
return kernfs_leftmost_descendant(rb_to_kn(rbn));
|
|
|
|
/* no sibling left, visit parent */
|
|
return pos->parent;
|
|
}
|
|
|
|
/**
|
|
* kernfs_activate - activate a node which started deactivated
|
|
* @kn: kernfs_node whose subtree is to be activated
|
|
*
|
|
* If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node
|
|
* needs to be explicitly activated. A node which hasn't been activated
|
|
* isn't visible to userland and deactivation is skipped during its
|
|
* removal. This is useful to construct atomic init sequences where
|
|
* creation of multiple nodes should either succeed or fail atomically.
|
|
*
|
|
* The caller is responsible for ensuring that this function is not called
|
|
* after kernfs_remove*() is invoked on @kn.
|
|
*/
|
|
void kernfs_activate(struct kernfs_node *kn)
|
|
{
|
|
struct kernfs_node *pos;
|
|
|
|
mutex_lock(&kernfs_mutex);
|
|
|
|
pos = NULL;
|
|
while ((pos = kernfs_next_descendant_post(pos, kn))) {
|
|
if (!pos || (pos->flags & KERNFS_ACTIVATED))
|
|
continue;
|
|
|
|
WARN_ON_ONCE(pos->parent && RB_EMPTY_NODE(&pos->rb));
|
|
WARN_ON_ONCE(atomic_read(&pos->active) != KN_DEACTIVATED_BIAS);
|
|
|
|
atomic_sub(KN_DEACTIVATED_BIAS, &pos->active);
|
|
pos->flags |= KERNFS_ACTIVATED;
|
|
}
|
|
|
|
mutex_unlock(&kernfs_mutex);
|
|
}
|
|
|
|
static void __kernfs_remove(struct kernfs_node *kn)
|
|
{
|
|
struct kernfs_node *pos;
|
|
|
|
lockdep_assert_held(&kernfs_mutex);
|
|
|
|
/*
|
|
* Short-circuit if non-root @kn has already finished removal.
|
|
* This is for kernfs_remove_self() which plays with active ref
|
|
* after removal.
|
|
*/
|
|
if (!kn || (kn->parent && RB_EMPTY_NODE(&kn->rb)))
|
|
return;
|
|
|
|
pr_debug("kernfs %s: removing\n", kn->name);
|
|
|
|
/* prevent any new usage under @kn by deactivating all nodes */
|
|
pos = NULL;
|
|
while ((pos = kernfs_next_descendant_post(pos, kn)))
|
|
if (kernfs_active(pos))
|
|
atomic_add(KN_DEACTIVATED_BIAS, &pos->active);
|
|
|
|
/* deactivate and unlink the subtree node-by-node */
|
|
do {
|
|
pos = kernfs_leftmost_descendant(kn);
|
|
|
|
/*
|
|
* kernfs_drain() drops kernfs_mutex temporarily and @pos's
|
|
* base ref could have been put by someone else by the time
|
|
* the function returns. Make sure it doesn't go away
|
|
* underneath us.
|
|
*/
|
|
kernfs_get(pos);
|
|
|
|
/*
|
|
* Drain iff @kn was activated. This avoids draining and
|
|
* its lockdep annotations for nodes which have never been
|
|
* activated and allows embedding kernfs_remove() in create
|
|
* error paths without worrying about draining.
|
|
*/
|
|
if (kn->flags & KERNFS_ACTIVATED)
|
|
kernfs_drain(pos);
|
|
else
|
|
WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS);
|
|
|
|
/*
|
|
* kernfs_unlink_sibling() succeeds once per node. Use it
|
|
* to decide who's responsible for cleanups.
|
|
*/
|
|
if (!pos->parent || kernfs_unlink_sibling(pos)) {
|
|
struct kernfs_iattrs *ps_iattr =
|
|
pos->parent ? pos->parent->iattr : NULL;
|
|
|
|
/* update timestamps on the parent */
|
|
if (ps_iattr) {
|
|
ktime_get_real_ts64(&ps_iattr->ia_iattr.ia_ctime);
|
|
ps_iattr->ia_iattr.ia_mtime =
|
|
ps_iattr->ia_iattr.ia_ctime;
|
|
}
|
|
|
|
kernfs_put(pos);
|
|
}
|
|
|
|
kernfs_put(pos);
|
|
} while (pos != kn);
|
|
}
|
|
|
|
/**
|
|
* kernfs_remove - remove a kernfs_node recursively
|
|
* @kn: the kernfs_node to remove
|
|
*
|
|
* Remove @kn along with all its subdirectories and files.
|
|
*/
|
|
void kernfs_remove(struct kernfs_node *kn)
|
|
{
|
|
mutex_lock(&kernfs_mutex);
|
|
__kernfs_remove(kn);
|
|
mutex_unlock(&kernfs_mutex);
|
|
}
|
|
|
|
/**
|
|
* kernfs_break_active_protection - break out of active protection
|
|
* @kn: the self kernfs_node
|
|
*
|
|
* The caller must be running off of a kernfs operation which is invoked
|
|
* with an active reference - e.g. one of kernfs_ops. Each invocation of
|
|
* this function must also be matched with an invocation of
|
|
* kernfs_unbreak_active_protection().
|
|
*
|
|
* This function releases the active reference of @kn the caller is
|
|
* holding. Once this function is called, @kn may be removed at any point
|
|
* and the caller is solely responsible for ensuring that the objects it
|
|
* dereferences are accessible.
|
|
*/
|
|
void kernfs_break_active_protection(struct kernfs_node *kn)
|
|
{
|
|
/*
|
|
* Take out ourself out of the active ref dependency chain. If
|
|
* we're called without an active ref, lockdep will complain.
|
|
*/
|
|
kernfs_put_active(kn);
|
|
}
|
|
|
|
/**
|
|
* kernfs_unbreak_active_protection - undo kernfs_break_active_protection()
|
|
* @kn: the self kernfs_node
|
|
*
|
|
* If kernfs_break_active_protection() was called, this function must be
|
|
* invoked before finishing the kernfs operation. Note that while this
|
|
* function restores the active reference, it doesn't and can't actually
|
|
* restore the active protection - @kn may already or be in the process of
|
|
* being removed. Once kernfs_break_active_protection() is invoked, that
|
|
* protection is irreversibly gone for the kernfs operation instance.
|
|
*
|
|
* While this function may be called at any point after
|
|
* kernfs_break_active_protection() is invoked, its most useful location
|
|
* would be right before the enclosing kernfs operation returns.
|
|
*/
|
|
void kernfs_unbreak_active_protection(struct kernfs_node *kn)
|
|
{
|
|
/*
|
|
* @kn->active could be in any state; however, the increment we do
|
|
* here will be undone as soon as the enclosing kernfs operation
|
|
* finishes and this temporary bump can't break anything. If @kn
|
|
* is alive, nothing changes. If @kn is being deactivated, the
|
|
* soon-to-follow put will either finish deactivation or restore
|
|
* deactivated state. If @kn is already removed, the temporary
|
|
* bump is guaranteed to be gone before @kn is released.
|
|
*/
|
|
atomic_inc(&kn->active);
|
|
if (kernfs_lockdep(kn))
|
|
rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_);
|
|
}
|
|
|
|
/**
|
|
* kernfs_remove_self - remove a kernfs_node from its own method
|
|
* @kn: the self kernfs_node to remove
|
|
*
|
|
* The caller must be running off of a kernfs operation which is invoked
|
|
* with an active reference - e.g. one of kernfs_ops. This can be used to
|
|
* implement a file operation which deletes itself.
|
|
*
|
|
* For example, the "delete" file for a sysfs device directory can be
|
|
* implemented by invoking kernfs_remove_self() on the "delete" file
|
|
* itself. This function breaks the circular dependency of trying to
|
|
* deactivate self while holding an active ref itself. It isn't necessary
|
|
* to modify the usual removal path to use kernfs_remove_self(). The
|
|
* "delete" implementation can simply invoke kernfs_remove_self() on self
|
|
* before proceeding with the usual removal path. kernfs will ignore later
|
|
* kernfs_remove() on self.
|
|
*
|
|
* kernfs_remove_self() can be called multiple times concurrently on the
|
|
* same kernfs_node. Only the first one actually performs removal and
|
|
* returns %true. All others will wait until the kernfs operation which
|
|
* won self-removal finishes and return %false. Note that the losers wait
|
|
* for the completion of not only the winning kernfs_remove_self() but also
|
|
* the whole kernfs_ops which won the arbitration. This can be used to
|
|
* guarantee, for example, all concurrent writes to a "delete" file to
|
|
* finish only after the whole operation is complete.
|
|
*/
|
|
bool kernfs_remove_self(struct kernfs_node *kn)
|
|
{
|
|
bool ret;
|
|
|
|
mutex_lock(&kernfs_mutex);
|
|
kernfs_break_active_protection(kn);
|
|
|
|
/*
|
|
* SUICIDAL is used to arbitrate among competing invocations. Only
|
|
* the first one will actually perform removal. When the removal
|
|
* is complete, SUICIDED is set and the active ref is restored
|
|
* while holding kernfs_mutex. The ones which lost arbitration
|
|
* waits for SUICDED && drained which can happen only after the
|
|
* enclosing kernfs operation which executed the winning instance
|
|
* of kernfs_remove_self() finished.
|
|
*/
|
|
if (!(kn->flags & KERNFS_SUICIDAL)) {
|
|
kn->flags |= KERNFS_SUICIDAL;
|
|
__kernfs_remove(kn);
|
|
kn->flags |= KERNFS_SUICIDED;
|
|
ret = true;
|
|
} else {
|
|
wait_queue_head_t *waitq = &kernfs_root(kn)->deactivate_waitq;
|
|
DEFINE_WAIT(wait);
|
|
|
|
while (true) {
|
|
prepare_to_wait(waitq, &wait, TASK_UNINTERRUPTIBLE);
|
|
|
|
if ((kn->flags & KERNFS_SUICIDED) &&
|
|
atomic_read(&kn->active) == KN_DEACTIVATED_BIAS)
|
|
break;
|
|
|
|
mutex_unlock(&kernfs_mutex);
|
|
schedule();
|
|
mutex_lock(&kernfs_mutex);
|
|
}
|
|
finish_wait(waitq, &wait);
|
|
WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb));
|
|
ret = false;
|
|
}
|
|
|
|
/*
|
|
* This must be done while holding kernfs_mutex; otherwise, waiting
|
|
* for SUICIDED && deactivated could finish prematurely.
|
|
*/
|
|
kernfs_unbreak_active_protection(kn);
|
|
|
|
mutex_unlock(&kernfs_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* kernfs_remove_by_name_ns - find a kernfs_node by name and remove it
|
|
* @parent: parent of the target
|
|
* @name: name of the kernfs_node to remove
|
|
* @ns: namespace tag of the kernfs_node to remove
|
|
*
|
|
* Look for the kernfs_node with @name and @ns under @parent and remove it.
|
|
* Returns 0 on success, -ENOENT if such entry doesn't exist.
|
|
*/
|
|
int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
|
|
const void *ns)
|
|
{
|
|
struct kernfs_node *kn;
|
|
|
|
if (!parent) {
|
|
WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n",
|
|
name);
|
|
return -ENOENT;
|
|
}
|
|
|
|
mutex_lock(&kernfs_mutex);
|
|
|
|
kn = kernfs_find_ns(parent, name, ns);
|
|
if (kn)
|
|
__kernfs_remove(kn);
|
|
|
|
mutex_unlock(&kernfs_mutex);
|
|
|
|
if (kn)
|
|
return 0;
|
|
else
|
|
return -ENOENT;
|
|
}
|
|
|
|
/**
|
|
* kernfs_rename_ns - move and rename a kernfs_node
|
|
* @kn: target node
|
|
* @new_parent: new parent to put @sd under
|
|
* @new_name: new name
|
|
* @new_ns: new namespace tag
|
|
*/
|
|
int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
|
|
const char *new_name, const void *new_ns)
|
|
{
|
|
struct kernfs_node *old_parent;
|
|
const char *old_name = NULL;
|
|
int error;
|
|
|
|
/* can't move or rename root */
|
|
if (!kn->parent)
|
|
return -EINVAL;
|
|
|
|
mutex_lock(&kernfs_mutex);
|
|
|
|
error = -ENOENT;
|
|
if (!kernfs_active(kn) || !kernfs_active(new_parent) ||
|
|
(new_parent->flags & KERNFS_EMPTY_DIR))
|
|
goto out;
|
|
|
|
error = 0;
|
|
if ((kn->parent == new_parent) && (kn->ns == new_ns) &&
|
|
(strcmp(kn->name, new_name) == 0))
|
|
goto out; /* nothing to rename */
|
|
|
|
error = -EEXIST;
|
|
if (kernfs_find_ns(new_parent, new_name, new_ns))
|
|
goto out;
|
|
|
|
/* rename kernfs_node */
|
|
if (strcmp(kn->name, new_name) != 0) {
|
|
error = -ENOMEM;
|
|
new_name = kstrdup_const(new_name, GFP_KERNEL);
|
|
if (!new_name)
|
|
goto out;
|
|
} else {
|
|
new_name = NULL;
|
|
}
|
|
|
|
/*
|
|
* Move to the appropriate place in the appropriate directories rbtree.
|
|
*/
|
|
kernfs_unlink_sibling(kn);
|
|
kernfs_get(new_parent);
|
|
|
|
/* rename_lock protects ->parent and ->name accessors */
|
|
spin_lock_irq(&kernfs_rename_lock);
|
|
|
|
old_parent = kn->parent;
|
|
kn->parent = new_parent;
|
|
|
|
kn->ns = new_ns;
|
|
if (new_name) {
|
|
old_name = kn->name;
|
|
kn->name = new_name;
|
|
}
|
|
|
|
spin_unlock_irq(&kernfs_rename_lock);
|
|
|
|
kn->hash = kernfs_name_hash(kn->name, kn->ns);
|
|
kernfs_link_sibling(kn);
|
|
|
|
kernfs_put(old_parent);
|
|
kfree_const(old_name);
|
|
|
|
error = 0;
|
|
out:
|
|
mutex_unlock(&kernfs_mutex);
|
|
return error;
|
|
}
|
|
|
|
/* Relationship between s_mode and the DT_xxx types */
|
|
static inline unsigned char dt_type(struct kernfs_node *kn)
|
|
{
|
|
return (kn->mode >> 12) & 15;
|
|
}
|
|
|
|
static int kernfs_dir_fop_release(struct inode *inode, struct file *filp)
|
|
{
|
|
kernfs_put(filp->private_data);
|
|
return 0;
|
|
}
|
|
|
|
static struct kernfs_node *kernfs_dir_pos(const void *ns,
|
|
struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos)
|
|
{
|
|
if (pos) {
|
|
int valid = kernfs_active(pos) &&
|
|
pos->parent == parent && hash == pos->hash;
|
|
kernfs_put(pos);
|
|
if (!valid)
|
|
pos = NULL;
|
|
}
|
|
if (!pos && (hash > 1) && (hash < INT_MAX)) {
|
|
struct rb_node *node = parent->dir.children.rb_node;
|
|
while (node) {
|
|
pos = rb_to_kn(node);
|
|
|
|
if (hash < pos->hash)
|
|
node = node->rb_left;
|
|
else if (hash > pos->hash)
|
|
node = node->rb_right;
|
|
else
|
|
break;
|
|
}
|
|
}
|
|
/* Skip over entries which are dying/dead or in the wrong namespace */
|
|
while (pos && (!kernfs_active(pos) || pos->ns != ns)) {
|
|
struct rb_node *node = rb_next(&pos->rb);
|
|
if (!node)
|
|
pos = NULL;
|
|
else
|
|
pos = rb_to_kn(node);
|
|
}
|
|
return pos;
|
|
}
|
|
|
|
static struct kernfs_node *kernfs_dir_next_pos(const void *ns,
|
|
struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos)
|
|
{
|
|
pos = kernfs_dir_pos(ns, parent, ino, pos);
|
|
if (pos) {
|
|
do {
|
|
struct rb_node *node = rb_next(&pos->rb);
|
|
if (!node)
|
|
pos = NULL;
|
|
else
|
|
pos = rb_to_kn(node);
|
|
} while (pos && (!kernfs_active(pos) || pos->ns != ns));
|
|
}
|
|
return pos;
|
|
}
|
|
|
|
static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
|
|
{
|
|
struct dentry *dentry = file->f_path.dentry;
|
|
struct kernfs_node *parent = kernfs_dentry_node(dentry);
|
|
struct kernfs_node *pos = file->private_data;
|
|
const void *ns = NULL;
|
|
|
|
if (!dir_emit_dots(file, ctx))
|
|
return 0;
|
|
mutex_lock(&kernfs_mutex);
|
|
|
|
if (kernfs_ns_enabled(parent))
|
|
ns = kernfs_info(dentry->d_sb)->ns;
|
|
|
|
for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos);
|
|
pos;
|
|
pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) {
|
|
const char *name = pos->name;
|
|
unsigned int type = dt_type(pos);
|
|
int len = strlen(name);
|
|
ino_t ino = pos->id.ino;
|
|
|
|
ctx->pos = pos->hash;
|
|
file->private_data = pos;
|
|
kernfs_get(pos);
|
|
|
|
mutex_unlock(&kernfs_mutex);
|
|
if (!dir_emit(ctx, name, len, ino, type))
|
|
return 0;
|
|
mutex_lock(&kernfs_mutex);
|
|
}
|
|
mutex_unlock(&kernfs_mutex);
|
|
file->private_data = NULL;
|
|
ctx->pos = INT_MAX;
|
|
return 0;
|
|
}
|
|
|
|
const struct file_operations kernfs_dir_fops = {
|
|
.read = generic_read_dir,
|
|
.iterate_shared = kernfs_fop_readdir,
|
|
.release = kernfs_dir_fop_release,
|
|
.llseek = generic_file_llseek,
|
|
};
|