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1706 lines
42 KiB
1706 lines
42 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
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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 <[email protected]> |
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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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|
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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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|
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#define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) |
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|
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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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|
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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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|
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return strlcpy(buf, kn->parent ? kn->name : "/", buflen); |
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} |
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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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|
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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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|
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return a; |
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} |
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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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|
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if (!kn_from) |
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kn_from = kernfs_root(kn_to)->kn; |
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|
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if (kn_from == kn_to) |
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return strlcpy(buf, "/", buflen); |
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|
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if (!buf) |
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return -EINVAL; |
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|
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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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|
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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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|
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buf[0] = '\0'; |
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|
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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 |
|
* 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; |
|
} |
|
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 |
|
* @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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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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/** |
|
* pr_cont_kernfs_path - pr_cont path of a kernfs_node |
|
* @kn: kernfs_node of interest |
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* |
|
* This function can be called from any context. |
|
*/ |
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void pr_cont_kernfs_path(struct kernfs_node *kn) |
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{ |
|
unsigned long flags; |
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int sz; |
|
|
|
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) { |
|
pr_cont("(error)"); |
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goto out; |
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} |
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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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pr_cont("%s", kernfs_pr_cont_buf); |
|
|
|
out: |
|
spin_unlock_irqrestore(&kernfs_rename_lock, flags); |
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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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* |
|
* Determines @kn's parent, pins and returns it. This function can be |
|
* called from any context. |
|
*/ |
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struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn) |
|
{ |
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struct kernfs_node *parent; |
|
unsigned long flags; |
|
|
|
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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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); |
|
hash = end_name_hash(hash); |
|
hash &= 0x7fffffffU; |
|
/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */ |
|
if (hash < 2) |
|
hash += 2; |
|
if (hash >= INT_MAX) |
|
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; |
|
if (ns > kn->ns) |
|
return 1; |
|
return strcmp(name, kn->name); |
|
} |
|
|
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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 |
|
* @kn: kernfs_node of interest |
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* |
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* Link @kn into its sibling rbtree which starts from |
|
* @kn->parent->dir.children. |
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* |
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* Locking: |
|
* mutex_lock(kernfs_mutex) |
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* |
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* RETURNS: |
|
* 0 on susccess -EEXIST on failure. |
|
*/ |
|
static int kernfs_link_sibling(struct kernfs_node *kn) |
|
{ |
|
struct rb_node **node = &kn->parent->dir.children.rb_node; |
|
struct rb_node *parent = NULL; |
|
|
|
while (*node) { |
|
struct kernfs_node *pos; |
|
int result; |
|
|
|
pos = rb_to_kn(*node); |
|
parent = *node; |
|
result = kernfs_sd_compare(kn, pos); |
|
if (result < 0) |
|
node = &pos->rb.rb_left; |
|
else if (result > 0) |
|
node = &pos->rb.rb_right; |
|
else |
|
return -EEXIST; |
|
} |
|
|
|
/* add new node and rebalance the tree */ |
|
rb_link_node(&kn->rb, parent, node); |
|
rb_insert_color(&kn->rb, &kn->parent->dir.children); |
|
|
|
/* successfully added, account subdir number */ |
|
if (kernfs_type(kn) == KERNFS_DIR) |
|
kn->parent->dir.subdirs++; |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree |
|
* @kn: kernfs_node of interest |
|
* |
|
* Try to unlink @kn from its sibling rbtree which starts from |
|
* kn->parent->dir.children. Returns %true if @kn was actually |
|
* removed, %false if @kn wasn't on the rbtree. |
|
* |
|
* Locking: |
|
* mutex_lock(kernfs_mutex) |
|
*/ |
|
static bool kernfs_unlink_sibling(struct kernfs_node *kn) |
|
{ |
|
if (RB_EMPTY_NODE(&kn->rb)) |
|
return false; |
|
|
|
if (kernfs_type(kn) == KERNFS_DIR) |
|
kn->parent->dir.subdirs--; |
|
|
|
rb_erase(&kn->rb, &kn->parent->dir.children); |
|
RB_CLEAR_NODE(&kn->rb); |
|
return true; |
|
} |
|
|
|
/** |
|
* kernfs_get_active - get an active reference to kernfs_node |
|
* @kn: kernfs_node to get an active reference to |
|
* |
|
* Get an active reference of @kn. This function is noop if @kn |
|
* is NULL. |
|
* |
|
* RETURNS: |
|
* Pointer to @kn on success, NULL on failure. |
|
*/ |
|
struct kernfs_node *kernfs_get_active(struct kernfs_node *kn) |
|
{ |
|
if (unlikely(!kn)) |
|
return NULL; |
|
|
|
if (!atomic_inc_unless_negative(&kn->active)) |
|
return NULL; |
|
|
|
if (kernfs_lockdep(kn)) |
|
rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_); |
|
return kn; |
|
} |
|
|
|
/** |
|
* kernfs_put_active - put an active reference to kernfs_node |
|
* @kn: kernfs_node to put an active reference to |
|
* |
|
* Put an active reference to @kn. This function is noop if @kn |
|
* is NULL. |
|
*/ |
|
void kernfs_put_active(struct kernfs_node *kn) |
|
{ |
|
int v; |
|
|
|
if (unlikely(!kn)) |
|
return; |
|
|
|
if (kernfs_lockdep(kn)) |
|
rwsem_release(&kn->dep_map, _RET_IP_); |
|
v = atomic_dec_return(&kn->active); |
|
if (likely(v != KN_DEACTIVATED_BIAS)) |
|
return; |
|
|
|
wake_up_all(&kernfs_root(kn)->deactivate_waitq); |
|
} |
|
|
|
/** |
|
* kernfs_drain - drain kernfs_node |
|
* @kn: kernfs_node to drain |
|
* |
|
* Drain existing usages and nuke all existing mmaps of @kn. Mutiple |
|
* removers may invoke this function concurrently on @kn and all will |
|
* return after draining is complete. |
|
*/ |
|
static void kernfs_drain(struct kernfs_node *kn) |
|
__releases(&kernfs_mutex) __acquires(&kernfs_mutex) |
|
{ |
|
struct kernfs_root *root = kernfs_root(kn); |
|
|
|
lockdep_assert_held(&kernfs_mutex); |
|
WARN_ON_ONCE(kernfs_active(kn)); |
|
|
|
mutex_unlock(&kernfs_mutex); |
|
|
|
if (kernfs_lockdep(kn)) { |
|
rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); |
|
if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS) |
|
lock_contended(&kn->dep_map, _RET_IP_); |
|
} |
|
|
|
/* but everyone should wait for draining */ |
|
wait_event(root->deactivate_waitq, |
|
atomic_read(&kn->active) == KN_DEACTIVATED_BIAS); |
|
|
|
if (kernfs_lockdep(kn)) { |
|
lock_acquired(&kn->dep_map, _RET_IP_); |
|
rwsem_release(&kn->dep_map, _RET_IP_); |
|
} |
|
|
|
kernfs_drain_open_files(kn); |
|
|
|
mutex_lock(&kernfs_mutex); |
|
} |
|
|
|
/** |
|
* kernfs_get - get a reference count on a kernfs_node |
|
* @kn: the target kernfs_node |
|
*/ |
|
void kernfs_get(struct kernfs_node *kn) |
|
{ |
|
if (kn) { |
|
WARN_ON(!atomic_read(&kn->count)); |
|
atomic_inc(&kn->count); |
|
} |
|
} |
|
EXPORT_SYMBOL_GPL(kernfs_get); |
|
|
|
/** |
|
* kernfs_put - put a reference count on a kernfs_node |
|
* @kn: the target kernfs_node |
|
* |
|
* Put a reference count of @kn and destroy it if it reached zero. |
|
*/ |
|
void kernfs_put(struct kernfs_node *kn) |
|
{ |
|
struct kernfs_node *parent; |
|
struct kernfs_root *root; |
|
|
|
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) { |
|
simple_xattrs_free(&kn->iattr->xattrs); |
|
kmem_cache_free(kernfs_iattrs_cache, kn->iattr); |
|
} |
|
spin_lock(&kernfs_idr_lock); |
|
idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); |
|
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, |
|
struct kernfs_node *parent, |
|
const char *name, umode_t mode, |
|
kuid_t uid, kgid_t gid, |
|
unsigned flags) |
|
{ |
|
struct kernfs_node *kn; |
|
u32 id_highbits; |
|
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); |
|
ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC); |
|
if (ret >= 0 && ret < root->last_id_lowbits) |
|
root->id_highbits++; |
|
id_highbits = root->id_highbits; |
|
root->last_id_lowbits = ret; |
|
spin_unlock(&kernfs_idr_lock); |
|
idr_preload_end(); |
|
if (ret < 0) |
|
goto err_out2; |
|
|
|
kn->id = (u64)id_highbits << 32 | ret; |
|
|
|
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; |
|
} |
|
|
|
if (parent) { |
|
ret = security_kernfs_init_security(parent, kn); |
|
if (ret) |
|
goto err_out3; |
|
} |
|
|
|
return kn; |
|
|
|
err_out3: |
|
idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); |
|
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), parent, |
|
name, mode, uid, gid, flags); |
|
if (kn) { |
|
kernfs_get(parent); |
|
kn->parent = parent; |
|
} |
|
return kn; |
|
} |
|
|
|
/* |
|
* kernfs_find_and_get_node_by_id - get kernfs_node from node id |
|
* @root: the kernfs root |
|
* @id: the target node id |
|
* |
|
* @id's lower 32bits encode ino and upper gen. If the gen portion is |
|
* zero, all generations are matched. |
|
* |
|
* RETURNS: |
|
* NULL on failure. Return a kernfs node with reference counter incremented |
|
*/ |
|
struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root, |
|
u64 id) |
|
{ |
|
struct kernfs_node *kn; |
|
ino_t ino = kernfs_id_ino(id); |
|
u32 gen = kernfs_id_gen(id); |
|
|
|
spin_lock(&kernfs_idr_lock); |
|
|
|
kn = idr_find(&root->ino_idr, (u32)ino); |
|
if (!kn) |
|
goto err_unlock; |
|
|
|
if (sizeof(ino_t) >= sizeof(u64)) { |
|
/* we looked up with the low 32bits, compare the whole */ |
|
if (kernfs_ino(kn) != ino) |
|
goto err_unlock; |
|
} else { |
|
/* 0 matches all generations */ |
|
if (unlikely(gen && kernfs_gen(kn) != gen)) |
|
goto err_unlock; |
|
} |
|
|
|
/* |
|
* ACTIVATED is protected with kernfs_mutex but it was clear when |
|
* @kn was added to idr and we just wanna see it set. No need to |
|
* grab kernfs_mutex. |
|
*/ |
|
if (unlikely(!(kn->flags & KERNFS_ACTIVATED) || |
|
!atomic_inc_not_zero(&kn->count))) |
|
goto err_unlock; |
|
|
|
spin_unlock(&kernfs_idr_lock); |
|
return kn; |
|
err_unlock: |
|
spin_unlock(&kernfs_idr_lock); |
|
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) { |
|
ktime_get_real_ts64(&ps_iattr->ia_ctime); |
|
ps_iattr->ia_mtime = ps_iattr->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); |
|
|
|
/* |
|
* On 64bit ino setups, id is ino. On 32bit, low 32bits are ino. |
|
* High bits generation. The starting value for both ino and |
|
* genenration is 1. Initialize upper 32bit allocation |
|
* accordingly. |
|
*/ |
|
if (sizeof(ino_t) >= sizeof(u64)) |
|
root->id_highbits = 0; |
|
else |
|
root->id_highbits = 1; |
|
|
|
kn = __kernfs_new_node(root, NULL, "", 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->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_ctime); |
|
ps_iattr->ia_mtime = ps_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 = kernfs_ino(pos); |
|
|
|
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, |
|
};
|
|
|