mirror of
https://github.com/edk2-porting/linux-next.git
synced 2025-01-17 01:54:01 +08:00
dm ioctl: replace device hash with red-black tree
For high numbers of DM devices the 64-entry hash table has non-trivial overhead. Fix this by replacing the hash table with a red-black tree. Reported-by: Zdenek Kabelac <zkabelac@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka
Mike Snitzer
parent
219a9b5e73
commit
b82096afc8
@ -14,6 +14,7 @@
|
||||
#include <linux/init.h>
|
||||
#include <linux/wait.h>
|
||||
#include <linux/slab.h>
|
||||
#include <linux/rbtree.h>
|
||||
#include <linux/dm-ioctl.h>
|
||||
#include <linux/hdreg.h>
|
||||
#include <linux/compat.h>
|
||||
@ -36,8 +37,10 @@ struct dm_file {
|
||||
* name or uuid.
|
||||
*---------------------------------------------------------------*/
|
||||
struct hash_cell {
|
||||
struct list_head name_list;
|
||||
struct list_head uuid_list;
|
||||
struct rb_node name_node;
|
||||
struct rb_node uuid_node;
|
||||
bool name_set;
|
||||
bool uuid_set;
|
||||
|
||||
char *name;
|
||||
char *uuid;
|
||||
@ -53,10 +56,8 @@ struct vers_iter {
|
||||
};
|
||||
|
||||
|
||||
#define NUM_BUCKETS 64
|
||||
#define MASK_BUCKETS (NUM_BUCKETS - 1)
|
||||
static struct list_head _name_buckets[NUM_BUCKETS];
|
||||
static struct list_head _uuid_buckets[NUM_BUCKETS];
|
||||
static struct rb_root name_rb_tree = RB_ROOT;
|
||||
static struct rb_root uuid_rb_tree = RB_ROOT;
|
||||
|
||||
static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred);
|
||||
|
||||
@ -70,73 +71,110 @@ static DECLARE_RWSEM(_hash_lock);
|
||||
*/
|
||||
static DEFINE_MUTEX(dm_hash_cells_mutex);
|
||||
|
||||
static void init_buckets(struct list_head *buckets)
|
||||
{
|
||||
unsigned int i;
|
||||
|
||||
for (i = 0; i < NUM_BUCKETS; i++)
|
||||
INIT_LIST_HEAD(buckets + i);
|
||||
}
|
||||
|
||||
static int dm_hash_init(void)
|
||||
{
|
||||
init_buckets(_name_buckets);
|
||||
init_buckets(_uuid_buckets);
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void dm_hash_exit(void)
|
||||
{
|
||||
dm_hash_remove_all(false, false, false);
|
||||
}
|
||||
|
||||
/*-----------------------------------------------------------------
|
||||
* Hash function:
|
||||
* We're not really concerned with the str hash function being
|
||||
* fast since it's only used by the ioctl interface.
|
||||
*---------------------------------------------------------------*/
|
||||
static unsigned int hash_str(const char *str)
|
||||
{
|
||||
const unsigned int hash_mult = 2654435387U;
|
||||
unsigned int h = 0;
|
||||
|
||||
while (*str)
|
||||
h = (h + (unsigned int) *str++) * hash_mult;
|
||||
|
||||
return h & MASK_BUCKETS;
|
||||
}
|
||||
|
||||
/*-----------------------------------------------------------------
|
||||
* Code for looking up a device by name
|
||||
*---------------------------------------------------------------*/
|
||||
static struct hash_cell *__get_name_cell(const char *str)
|
||||
{
|
||||
struct hash_cell *hc;
|
||||
unsigned int h = hash_str(str);
|
||||
struct rb_node *n = name_rb_tree.rb_node;
|
||||
|
||||
list_for_each_entry (hc, _name_buckets + h, name_list)
|
||||
if (!strcmp(hc->name, str)) {
|
||||
while (n) {
|
||||
struct hash_cell *hc = container_of(n, struct hash_cell, name_node);
|
||||
int c = strcmp(hc->name, str);
|
||||
if (!c) {
|
||||
dm_get(hc->md);
|
||||
return hc;
|
||||
}
|
||||
n = c >= 0 ? n->rb_left : n->rb_right;
|
||||
}
|
||||
|
||||
return NULL;
|
||||
}
|
||||
|
||||
static struct hash_cell *__get_uuid_cell(const char *str)
|
||||
{
|
||||
struct hash_cell *hc;
|
||||
unsigned int h = hash_str(str);
|
||||
struct rb_node *n = uuid_rb_tree.rb_node;
|
||||
|
||||
list_for_each_entry (hc, _uuid_buckets + h, uuid_list)
|
||||
if (!strcmp(hc->uuid, str)) {
|
||||
while (n) {
|
||||
struct hash_cell *hc = container_of(n, struct hash_cell, uuid_node);
|
||||
int c = strcmp(hc->uuid, str);
|
||||
if (!c) {
|
||||
dm_get(hc->md);
|
||||
return hc;
|
||||
}
|
||||
n = c >= 0 ? n->rb_left : n->rb_right;
|
||||
}
|
||||
|
||||
return NULL;
|
||||
}
|
||||
|
||||
static void __unlink_name(struct hash_cell *hc)
|
||||
{
|
||||
if (hc->name_set) {
|
||||
hc->name_set = false;
|
||||
rb_erase(&hc->name_node, &name_rb_tree);
|
||||
}
|
||||
}
|
||||
|
||||
static void __unlink_uuid(struct hash_cell *hc)
|
||||
{
|
||||
if (hc->uuid_set) {
|
||||
hc->uuid_set = false;
|
||||
rb_erase(&hc->uuid_node, &uuid_rb_tree);
|
||||
}
|
||||
}
|
||||
|
||||
static void __link_name(struct hash_cell *new_hc)
|
||||
{
|
||||
struct rb_node **n, *parent;
|
||||
|
||||
__unlink_name(new_hc);
|
||||
|
||||
new_hc->name_set = true;
|
||||
|
||||
n = &name_rb_tree.rb_node;
|
||||
parent = NULL;
|
||||
|
||||
while (*n) {
|
||||
struct hash_cell *hc = container_of(*n, struct hash_cell, name_node);
|
||||
int c = strcmp(hc->name, new_hc->name);
|
||||
BUG_ON(!c);
|
||||
parent = *n;
|
||||
n = c >= 0 ? &hc->name_node.rb_left : &hc->name_node.rb_right;
|
||||
}
|
||||
|
||||
rb_link_node(&new_hc->name_node, parent, n);
|
||||
rb_insert_color(&new_hc->name_node, &name_rb_tree);
|
||||
}
|
||||
|
||||
static void __link_uuid(struct hash_cell *new_hc)
|
||||
{
|
||||
struct rb_node **n, *parent;
|
||||
|
||||
__unlink_uuid(new_hc);
|
||||
|
||||
new_hc->uuid_set = true;
|
||||
|
||||
n = &uuid_rb_tree.rb_node;
|
||||
parent = NULL;
|
||||
|
||||
while (*n) {
|
||||
struct hash_cell *hc = container_of(*n, struct hash_cell, uuid_node);
|
||||
int c = strcmp(hc->uuid, new_hc->uuid);
|
||||
BUG_ON(!c);
|
||||
parent = *n;
|
||||
n = c > 0 ? &hc->uuid_node.rb_left : &hc->uuid_node.rb_right;
|
||||
}
|
||||
|
||||
rb_link_node(&new_hc->uuid_node, parent, n);
|
||||
rb_insert_color(&new_hc->uuid_node, &uuid_rb_tree);
|
||||
}
|
||||
|
||||
static struct hash_cell *__get_dev_cell(uint64_t dev)
|
||||
{
|
||||
struct mapped_device *md;
|
||||
@ -185,8 +223,7 @@ static struct hash_cell *alloc_cell(const char *name, const char *uuid,
|
||||
}
|
||||
}
|
||||
|
||||
INIT_LIST_HEAD(&hc->name_list);
|
||||
INIT_LIST_HEAD(&hc->uuid_list);
|
||||
hc->name_set = hc->uuid_set = false;
|
||||
hc->md = md;
|
||||
hc->new_map = NULL;
|
||||
return hc;
|
||||
@ -226,16 +263,16 @@ static int dm_hash_insert(const char *name, const char *uuid, struct mapped_devi
|
||||
goto bad;
|
||||
}
|
||||
|
||||
list_add(&cell->name_list, _name_buckets + hash_str(name));
|
||||
__link_name(cell);
|
||||
|
||||
if (uuid) {
|
||||
hc = __get_uuid_cell(uuid);
|
||||
if (hc) {
|
||||
list_del(&cell->name_list);
|
||||
__unlink_name(cell);
|
||||
dm_put(hc->md);
|
||||
goto bad;
|
||||
}
|
||||
list_add(&cell->uuid_list, _uuid_buckets + hash_str(uuid));
|
||||
__link_uuid(cell);
|
||||
}
|
||||
dm_get(md);
|
||||
mutex_lock(&dm_hash_cells_mutex);
|
||||
@ -256,9 +293,9 @@ static struct dm_table *__hash_remove(struct hash_cell *hc)
|
||||
struct dm_table *table;
|
||||
int srcu_idx;
|
||||
|
||||
/* remove from the dev hash */
|
||||
list_del(&hc->uuid_list);
|
||||
list_del(&hc->name_list);
|
||||
/* remove from the dev trees */
|
||||
__unlink_name(hc);
|
||||
__unlink_uuid(hc);
|
||||
mutex_lock(&dm_hash_cells_mutex);
|
||||
dm_set_mdptr(hc->md, NULL);
|
||||
mutex_unlock(&dm_hash_cells_mutex);
|
||||
@ -279,7 +316,8 @@ static struct dm_table *__hash_remove(struct hash_cell *hc)
|
||||
|
||||
static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred)
|
||||
{
|
||||
int i, dev_skipped;
|
||||
int dev_skipped;
|
||||
struct rb_node *n;
|
||||
struct hash_cell *hc;
|
||||
struct mapped_device *md;
|
||||
struct dm_table *t;
|
||||
@ -289,40 +327,39 @@ retry:
|
||||
|
||||
down_write(&_hash_lock);
|
||||
|
||||
for (i = 0; i < NUM_BUCKETS; i++) {
|
||||
list_for_each_entry(hc, _name_buckets + i, name_list) {
|
||||
md = hc->md;
|
||||
dm_get(md);
|
||||
for (n = rb_first(&name_rb_tree); n; n = rb_next(n)) {
|
||||
hc = container_of(n, struct hash_cell, name_node);
|
||||
md = hc->md;
|
||||
dm_get(md);
|
||||
|
||||
if (keep_open_devices &&
|
||||
dm_lock_for_deletion(md, mark_deferred, only_deferred)) {
|
||||
dm_put(md);
|
||||
dev_skipped++;
|
||||
continue;
|
||||
}
|
||||
|
||||
t = __hash_remove(hc);
|
||||
|
||||
up_write(&_hash_lock);
|
||||
|
||||
if (t) {
|
||||
dm_sync_table(md);
|
||||
dm_table_destroy(t);
|
||||
}
|
||||
if (keep_open_devices &&
|
||||
dm_lock_for_deletion(md, mark_deferred, only_deferred)) {
|
||||
dm_put(md);
|
||||
if (likely(keep_open_devices))
|
||||
dm_destroy(md);
|
||||
else
|
||||
dm_destroy_immediate(md);
|
||||
|
||||
/*
|
||||
* Some mapped devices may be using other mapped
|
||||
* devices, so repeat until we make no further
|
||||
* progress. If a new mapped device is created
|
||||
* here it will also get removed.
|
||||
*/
|
||||
goto retry;
|
||||
dev_skipped++;
|
||||
continue;
|
||||
}
|
||||
|
||||
t = __hash_remove(hc);
|
||||
|
||||
up_write(&_hash_lock);
|
||||
|
||||
if (t) {
|
||||
dm_sync_table(md);
|
||||
dm_table_destroy(t);
|
||||
}
|
||||
dm_put(md);
|
||||
if (likely(keep_open_devices))
|
||||
dm_destroy(md);
|
||||
else
|
||||
dm_destroy_immediate(md);
|
||||
|
||||
/*
|
||||
* Some mapped devices may be using other mapped
|
||||
* devices, so repeat until we make no further
|
||||
* progress. If a new mapped device is created
|
||||
* here it will also get removed.
|
||||
*/
|
||||
goto retry;
|
||||
}
|
||||
|
||||
up_write(&_hash_lock);
|
||||
@ -340,7 +377,7 @@ static void __set_cell_uuid(struct hash_cell *hc, char *new_uuid)
|
||||
hc->uuid = new_uuid;
|
||||
mutex_unlock(&dm_hash_cells_mutex);
|
||||
|
||||
list_add(&hc->uuid_list, _uuid_buckets + hash_str(new_uuid));
|
||||
__link_uuid(hc);
|
||||
}
|
||||
|
||||
/*
|
||||
@ -354,14 +391,14 @@ static char *__change_cell_name(struct hash_cell *hc, char *new_name)
|
||||
/*
|
||||
* Rename and move the name cell.
|
||||
*/
|
||||
list_del(&hc->name_list);
|
||||
__unlink_name(hc);
|
||||
old_name = hc->name;
|
||||
|
||||
mutex_lock(&dm_hash_cells_mutex);
|
||||
hc->name = new_name;
|
||||
mutex_unlock(&dm_hash_cells_mutex);
|
||||
|
||||
list_add(&hc->name_list, _name_buckets + hash_str(new_name));
|
||||
__link_name(hc);
|
||||
|
||||
return old_name;
|
||||
}
|
||||
@ -505,7 +542,7 @@ static void *get_result_buffer(struct dm_ioctl *param, size_t param_size,
|
||||
|
||||
static int list_devices(struct file *filp, struct dm_ioctl *param, size_t param_size)
|
||||
{
|
||||
unsigned int i;
|
||||
struct rb_node *n;
|
||||
struct hash_cell *hc;
|
||||
size_t len, needed = 0;
|
||||
struct gendisk *disk;
|
||||
@ -518,11 +555,10 @@ static int list_devices(struct file *filp, struct dm_ioctl *param, size_t param_
|
||||
* Loop through all the devices working out how much
|
||||
* space we need.
|
||||
*/
|
||||
for (i = 0; i < NUM_BUCKETS; i++) {
|
||||
list_for_each_entry (hc, _name_buckets + i, name_list) {
|
||||
needed += align_val(offsetof(struct dm_name_list, name) + strlen(hc->name) + 1);
|
||||
needed += align_val(sizeof(uint32_t));
|
||||
}
|
||||
for (n = rb_first(&name_rb_tree); n; n = rb_next(n)) {
|
||||
hc = container_of(n, struct hash_cell, name_node);
|
||||
needed += align_val(offsetof(struct dm_name_list, name) + strlen(hc->name) + 1);
|
||||
needed += align_val(sizeof(uint32_t));
|
||||
}
|
||||
|
||||
/*
|
||||
@ -540,21 +576,20 @@ static int list_devices(struct file *filp, struct dm_ioctl *param, size_t param_
|
||||
/*
|
||||
* Now loop through filling out the names.
|
||||
*/
|
||||
for (i = 0; i < NUM_BUCKETS; i++) {
|
||||
list_for_each_entry (hc, _name_buckets + i, name_list) {
|
||||
if (old_nl)
|
||||
old_nl->next = (uint32_t) ((void *) nl -
|
||||
(void *) old_nl);
|
||||
disk = dm_disk(hc->md);
|
||||
nl->dev = huge_encode_dev(disk_devt(disk));
|
||||
nl->next = 0;
|
||||
strcpy(nl->name, hc->name);
|
||||
for (n = rb_first(&name_rb_tree); n; n = rb_next(n)) {
|
||||
hc = container_of(n, struct hash_cell, name_node);
|
||||
if (old_nl)
|
||||
old_nl->next = (uint32_t) ((void *) nl -
|
||||
(void *) old_nl);
|
||||
disk = dm_disk(hc->md);
|
||||
nl->dev = huge_encode_dev(disk_devt(disk));
|
||||
nl->next = 0;
|
||||
strcpy(nl->name, hc->name);
|
||||
|
||||
old_nl = nl;
|
||||
event_nr = align_ptr(nl->name + strlen(hc->name) + 1);
|
||||
*event_nr = dm_get_event_nr(hc->md);
|
||||
nl = align_ptr(event_nr + 1);
|
||||
}
|
||||
old_nl = nl;
|
||||
event_nr = align_ptr(nl->name + strlen(hc->name) + 1);
|
||||
*event_nr = dm_get_event_nr(hc->md);
|
||||
nl = align_ptr(event_nr + 1);
|
||||
}
|
||||
/*
|
||||
* If mismatch happens, security may be compromised due to buffer
|
||||
@ -1991,14 +2026,9 @@ int __init dm_interface_init(void)
|
||||
{
|
||||
int r;
|
||||
|
||||
r = dm_hash_init();
|
||||
if (r)
|
||||
return r;
|
||||
|
||||
r = misc_register(&_dm_misc);
|
||||
if (r) {
|
||||
DMERR("misc_register failed for control device");
|
||||
dm_hash_exit();
|
||||
return r;
|
||||
}
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user