ASR_BASE
Change-Id: Icf3719cc0afe3eeb3edc7fa80a2eb5199ca9dda1
diff --git a/marvell/linux/fs/configfs/symlink.c b/marvell/linux/fs/configfs/symlink.c
new file mode 100644
index 0000000..cb61467
--- /dev/null
+++ b/marvell/linux/fs/configfs/symlink.c
@@ -0,0 +1,270 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * symlink.c - operations for configfs symlinks.
+ *
+ * Based on sysfs:
+ * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle. All rights reserved.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/namei.h>
+#include <linux/slab.h>
+
+#include <linux/configfs.h>
+#include "configfs_internal.h"
+
+/* Protects attachments of new symlinks */
+DEFINE_MUTEX(configfs_symlink_mutex);
+
+static int item_depth(struct config_item * item)
+{
+ struct config_item * p = item;
+ int depth = 0;
+ do { depth++; } while ((p = p->ci_parent) && !configfs_is_root(p));
+ return depth;
+}
+
+static int item_path_length(struct config_item * item)
+{
+ struct config_item * p = item;
+ int length = 1;
+ do {
+ length += strlen(config_item_name(p)) + 1;
+ p = p->ci_parent;
+ } while (p && !configfs_is_root(p));
+ return length;
+}
+
+static void fill_item_path(struct config_item * item, char * buffer, int length)
+{
+ struct config_item * p;
+
+ --length;
+ for (p = item; p && !configfs_is_root(p); p = p->ci_parent) {
+ int cur = strlen(config_item_name(p));
+
+ /* back up enough to print this bus id with '/' */
+ length -= cur;
+ memcpy(buffer + length, config_item_name(p), cur);
+ *(buffer + --length) = '/';
+ }
+}
+
+static int configfs_get_target_path(struct config_item *item,
+ struct config_item *target, char *path)
+{
+ int depth, size;
+ char *s;
+
+ depth = item_depth(item);
+ size = item_path_length(target) + depth * 3 - 1;
+ if (size > PATH_MAX)
+ return -ENAMETOOLONG;
+
+ pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size);
+
+ for (s = path; depth--; s += 3)
+ strcpy(s,"../");
+
+ fill_item_path(target, path, size);
+ pr_debug("%s: path = '%s'\n", __func__, path);
+ return 0;
+}
+
+static int create_link(struct config_item *parent_item,
+ struct config_item *item,
+ struct dentry *dentry)
+{
+ struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata;
+ char *body;
+ int ret;
+
+ if (!configfs_dirent_is_ready(target_sd))
+ return -ENOENT;
+
+ body = kzalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!body)
+ return -ENOMEM;
+
+ configfs_get(target_sd);
+ spin_lock(&configfs_dirent_lock);
+ if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
+ spin_unlock(&configfs_dirent_lock);
+ configfs_put(target_sd);
+ kfree(body);
+ return -ENOENT;
+ }
+ target_sd->s_links++;
+ spin_unlock(&configfs_dirent_lock);
+ ret = configfs_get_target_path(parent_item, item, body);
+ if (!ret)
+ ret = configfs_create_link(target_sd, parent_item->ci_dentry,
+ dentry, body);
+ if (ret) {
+ spin_lock(&configfs_dirent_lock);
+ target_sd->s_links--;
+ spin_unlock(&configfs_dirent_lock);
+ configfs_put(target_sd);
+ kfree(body);
+ }
+ return ret;
+}
+
+
+static int get_target(const char *symname, struct path *path,
+ struct config_item **target, struct super_block *sb)
+{
+ int ret;
+
+ ret = kern_path(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, path);
+ if (!ret) {
+ if (path->dentry->d_sb == sb) {
+ *target = configfs_get_config_item(path->dentry);
+ if (!*target) {
+ ret = -ENOENT;
+ path_put(path);
+ }
+ } else {
+ ret = -EPERM;
+ path_put(path);
+ }
+ }
+
+ return ret;
+}
+
+
+int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+{
+ int ret;
+ struct path path;
+ struct configfs_dirent *sd;
+ struct config_item *parent_item;
+ struct config_item *target_item = NULL;
+ const struct config_item_type *type;
+
+ sd = dentry->d_parent->d_fsdata;
+ /*
+ * Fake invisibility if dir belongs to a group/default groups hierarchy
+ * being attached
+ */
+ if (!configfs_dirent_is_ready(sd))
+ return -ENOENT;
+
+ parent_item = configfs_get_config_item(dentry->d_parent);
+ type = parent_item->ci_type;
+
+ ret = -EPERM;
+ if (!type || !type->ct_item_ops ||
+ !type->ct_item_ops->allow_link)
+ goto out_put;
+
+ /*
+ * This is really sick. What they wanted was a hybrid of
+ * link(2) and symlink(2) - they wanted the target resolved
+ * at syscall time (as link(2) would've done), be a directory
+ * (which link(2) would've refused to do) *AND* be a deep
+ * fucking magic, making the target busy from rmdir POV.
+ * symlink(2) is nothing of that sort, and the locking it
+ * gets matches the normal symlink(2) semantics. Without
+ * attempts to resolve the target (which might very well
+ * not even exist yet) done prior to locking the parent
+ * directory. This perversion, OTOH, needs to resolve
+ * the target, which would lead to obvious deadlocks if
+ * attempted with any directories locked.
+ *
+ * Unfortunately, that garbage is userland ABI and we should've
+ * said "no" back in 2005. Too late now, so we get to
+ * play very ugly games with locking.
+ *
+ * Try *ANYTHING* of that sort in new code, and you will
+ * really regret it. Just ask yourself - what could a BOFH
+ * do to me and do I want to find it out first-hand?
+ *
+ * AV, a thoroughly annoyed bastard.
+ */
+ inode_unlock(dir);
+ ret = get_target(symname, &path, &target_item, dentry->d_sb);
+ inode_lock(dir);
+ if (ret)
+ goto out_put;
+
+ if (dentry->d_inode || d_unhashed(dentry))
+ ret = -EEXIST;
+ else
+ ret = inode_permission(dir, MAY_WRITE | MAY_EXEC);
+ if (!ret)
+ ret = type->ct_item_ops->allow_link(parent_item, target_item);
+ if (!ret) {
+ mutex_lock(&configfs_symlink_mutex);
+ ret = create_link(parent_item, target_item, dentry);
+ mutex_unlock(&configfs_symlink_mutex);
+ if (ret && type->ct_item_ops->drop_link)
+ type->ct_item_ops->drop_link(parent_item,
+ target_item);
+ }
+
+ config_item_put(target_item);
+ path_put(&path);
+
+out_put:
+ config_item_put(parent_item);
+ return ret;
+}
+
+int configfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+ struct configfs_dirent *sd = dentry->d_fsdata, *target_sd;
+ struct config_item *parent_item;
+ const struct config_item_type *type;
+ int ret;
+
+ ret = -EPERM; /* What lack-of-symlink returns */
+ if (!(sd->s_type & CONFIGFS_ITEM_LINK))
+ goto out;
+
+ target_sd = sd->s_element;
+
+ parent_item = configfs_get_config_item(dentry->d_parent);
+ type = parent_item->ci_type;
+
+ spin_lock(&configfs_dirent_lock);
+ list_del_init(&sd->s_sibling);
+ spin_unlock(&configfs_dirent_lock);
+ configfs_drop_dentry(sd, dentry->d_parent);
+ dput(dentry);
+ configfs_put(sd);
+
+ /*
+ * drop_link() must be called before
+ * decrementing target's ->s_links, so that the order of
+ * drop_link(this, target) and drop_item(target) is preserved.
+ */
+ if (type && type->ct_item_ops &&
+ type->ct_item_ops->drop_link)
+ type->ct_item_ops->drop_link(parent_item,
+ target_sd->s_element);
+
+ spin_lock(&configfs_dirent_lock);
+ target_sd->s_links--;
+ spin_unlock(&configfs_dirent_lock);
+ configfs_put(target_sd);
+
+ config_item_put(parent_item);
+
+ ret = 0;
+
+out:
+ return ret;
+}
+
+const struct inode_operations configfs_symlink_inode_operations = {
+ .get_link = simple_get_link,
+ .setattr = configfs_setattr,
+};
+