Hi Mattew,
I am trying to apply your Xarrays suggestion, but I don't
understand how to make them properly work. In particular, the __xa_alloc
function always returns -EINVAL.
I tried to follow the Xarrays kernel doc and the example you provided to
replace the subordinates linked list, but alloc always returns that error.
Below you can find the changes I intended to do.
Can you help me?
Thank you,
Emanuele
------ 8< -----------
>From ad5d20b6ce7995b2d1164104cf958f7bc3e692fa Mon Sep 17 00:00:00 2001
From: Emanuele Giuseppe Esposito <eesposit@xxxxxxxxxx>
Date: Tue, 28 Apr 2020 12:21:00 +0200
Subject: [PATCH] statsfs: switch subordinate sources to xarray
---
fs/statsfs/statsfs.c | 45 +++++++++++++++++++++++++++--------------
include/linux/statsfs.h | 5 ++---
2 files changed, 32 insertions(+), 18 deletions(-)
diff --git a/fs/statsfs/statsfs.c b/fs/statsfs/statsfs.c
index c8cfa590a3b0..0cf135c36776 100644
--- a/fs/statsfs/statsfs.c
+++ b/fs/statsfs/statsfs.c
@@ -107,11 +107,12 @@ const struct file_operations statsfs_ops = {
static void statsfs_source_remove_files_locked(struct statsfs_source *src)
{
struct statsfs_source *child;
+ unsigned long index;
if (src->source_dentry == NULL)
return;
- list_for_each_entry(child, &src->subordinates_head, list_element)
+ xa_for_each (&src->subordinates, index, child)
statsfs_source_remove_files(child);
statsfs_remove_recursive(src->source_dentry);
@@ -180,6 +181,7 @@ static void statsfs_create_files_recursive_locked(struct statsfs_source *source,
struct dentry *parent_dentry)
{
struct statsfs_source *child;
+ unsigned long index;
/* first check values in this folder, since it might be new */
if (!source->source_dentry) {
@@ -189,7 +191,7 @@ static void statsfs_create_files_recursive_locked(struct statsfs_source *source,
statsfs_create_files_locked(source);
- list_for_each_entry(child, &source->subordinates_head, list_element) {
+ xa_for_each (&source->subordinates, index, child) {
if (child->source_dentry == NULL) {
/* assume that if child has a folder,
* also the sub-child have that.
@@ -258,10 +260,23 @@ EXPORT_SYMBOL_GPL(statsfs_source_add_values);
void statsfs_source_add_subordinate(struct statsfs_source *source,
struct statsfs_source *sub)
{
+ int err;
+ uint32_t index;
+
down_write(&source->rwsem);
statsfs_source_get(sub);
- list_add(&sub->list_element, &source->subordinates_head);
+ err = __xa_alloc(&source->subordinates, &index, sub, xa_limit_32b,
+ GFP_KERNEL);
+
+ if (err) {
+ printk(KERN_ERR "Failed to insert subordinate %s\n"
+ "Too many subordinates in source %s\n",
+ sub->name, source->name);
+ up_write(&source->rwsem);
+ return;
+ }
+
if (source->source_dentry)
statsfs_create_files_recursive_locked(sub,
source->source_dentry);
@@ -276,10 +291,11 @@ statsfs_source_remove_subordinate_locked(struct statsfs_source *source,
struct statsfs_source *sub)
{
struct statsfs_source *src_entry;
+ unsigned long index;
- list_for_each_entry(src_entry, &source->subordinates_head, list_element) {
+ xa_for_each (&source->subordinates, index, src_entry) {
if (src_entry == sub) {
- list_del_init(&src_entry->list_element);
+ xa_erase(&source->subordinates, index);
statsfs_source_remove_files(src_entry);
statsfs_source_put(src_entry);
return;
@@ -431,13 +447,13 @@ static void do_recursive_aggregation(struct statsfs_source *root,
struct statsfs_aggregate_value *agg)
{
struct statsfs_source *subordinate;
+ unsigned long index;
/* search all simple values in this folder */
search_all_simple_values(root, ref_src_entry, val, agg);
/* recursively search in all subfolders */
- list_for_each_entry(subordinate, &root->subordinates_head,
- list_element) {
+ xa_for_each (&root->subordinates, index, subordinate) {
down_read(&subordinate->rwsem);
do_recursive_aggregation(subordinate, ref_src_entry, val, agg);
up_read(&subordinate->rwsem);
@@ -571,13 +587,13 @@ static void do_recursive_clean(struct statsfs_source *root,
struct statsfs_value *val)
{
struct statsfs_source *subordinate;
+ unsigned long index;
/* search all simple values in this folder */
set_all_simple_values(root, ref_src_entry, val);
/* recursively search in all subfolders */
- list_for_each_entry(subordinate, &root->subordinates_head,
- list_element) {
+ xa_for_each (&root->subordinates, index, subordinate) {
down_read(&subordinate->rwsem);
do_recursive_clean(subordinate, ref_src_entry, val);
up_read(&subordinate->rwsem);
@@ -703,9 +719,10 @@ EXPORT_SYMBOL_GPL(statsfs_source_revoke);
*/
static void statsfs_source_destroy(struct kref *kref_source)
{
- struct statsfs_value_source *val_src_entry;
struct list_head *it, *safe;
+ struct statsfs_value_source *val_src_entry;
struct statsfs_source *child, *source;
+ unsigned long index;
source = container_of(kref_source, struct statsfs_source, refcount);
@@ -717,15 +734,14 @@ static void statsfs_source_destroy(struct kref *kref_source)
}
/* iterate through the subordinates and delete them */
- list_for_each_safe(it, safe, &source->subordinates_head) {
- child = list_entry(it, struct statsfs_source, list_element);
+ xa_for_each (&source->subordinates, index, child)
statsfs_source_remove_subordinate_locked(source, child);
- }
statsfs_source_remove_files_locked(source);
up_write(&source->rwsem);
kfree(source->name);
+ xa_destroy(&source->subordinates);
kfree(source);
}
@@ -761,8 +777,7 @@ struct statsfs_source *statsfs_source_create(const char *fmt, ...)
init_rwsem(&ret->rwsem);
INIT_LIST_HEAD(&ret->values_head);
- INIT_LIST_HEAD(&ret->subordinates_head);
- INIT_LIST_HEAD(&ret->list_element);
+ xa_init(&ret->subordinates);
return ret;
}
diff --git a/include/linux/statsfs.h b/include/linux/statsfs.h
index f6e8eead1124..20153f50ffc0 100644
--- a/include/linux/statsfs.h
+++ b/include/linux/statsfs.h
@@ -11,6 +11,7 @@
#define _STATSFS_H_
#include <linux/list.h>
+#include <linux/xarray.h>
/* Used to distinguish signed types */
#define STATSFS_SIGN 0x8000
@@ -64,9 +65,7 @@ struct statsfs_source {
struct list_head values_head;
/* list of struct statsfs_source for subordinate sources */
- struct list_head subordinates_head;
-
- struct list_head list_element;
+ struct xarray subordinates;
struct rw_semaphore rwsem;
--
2.25.2
