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Copy pathlinux-2.6-590-dcookies-mm.patch
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linux-2.6-590-dcookies-mm.patch
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From d8e2bd85a3188b65ae8a3a82cc6dade218f69aa0 Mon Sep 17 00:00:00 2001
From: S.Çağlar Onur <[email protected]>
Date: Tue, 7 Dec 2010 11:09:20 -0500
Subject: [PATCH] linux-2.6-590-dcookies-mm.patch
---
fs/dcookies.c | 97 +++++++++++++++++++++++++++++++++++++--------
include/linux/dcookies.h | 21 ++++++++++
2 files changed, 100 insertions(+), 18 deletions(-)
diff --git a/fs/dcookies.c b/fs/dcookies.c
index a21cabd..1e95c94 100644
--- a/fs/dcookies.c
+++ b/fs/dcookies.c
@@ -25,6 +25,7 @@
#include <linux/dcookies.h>
#include <linux/mutex.h>
#include <linux/path.h>
+#include <linux/spinlock.h>
#include <asm/uaccess.h>
/* The dcookies are allocated from a kmem_cache and
@@ -38,15 +39,21 @@ struct dcookie_struct {
static LIST_HEAD(dcookie_users);
static DEFINE_MUTEX(dcookie_mutex);
+spinlock_t dcookie_hash_write_lock = SPIN_LOCK_UNLOCKED;
static struct kmem_cache *dcookie_cache __read_mostly;
-static struct list_head *dcookie_hashtable __read_mostly;
+static struct list_head *dcookie_hashtable[3] __read_mostly;
static size_t hash_size __read_mostly;
+unsigned int current_hash = 1, old_hash = 0;
static inline int is_live(void)
{
return !(list_empty(&dcookie_users));
}
+static inline int is_shared(void)
+{
+ return !(list_empty(&dcookie_users)) && !(list_empty(dcookie_users.next));
+}
/* The dentry is locked, its address will do for the cookie */
static inline unsigned long dcookie_value(struct dcookie_struct * dcs)
@@ -68,7 +75,7 @@ static struct dcookie_struct * find_dcookie(unsigned long dcookie)
struct list_head * pos;
struct list_head * list;
- list = dcookie_hashtable + dcookie_hash(dcookie);
+ list = dcookie_hashtable[current_hash] + dcookie_hash(dcookie);
list_for_each(pos, list) {
dcs = list_entry(pos, struct dcookie_struct, hash_list);
@@ -78,21 +85,33 @@ static struct dcookie_struct * find_dcookie(unsigned long dcookie)
}
}
+ if (!found) {
+ list = dcookie_hashtable[old_hash] + dcookie_hash(dcookie);
+
+ list_for_each(pos, list) {
+ dcs = list_entry(pos, struct dcookie_struct, hash_list);
+ if (dcookie_value(dcs) == dcookie) {
+ found = dcs;
+ break;
+ }
+ }
+ }
+
return found;
}
static void hash_dcookie(struct dcookie_struct * dcs)
{
- struct list_head * list = dcookie_hashtable + dcookie_hash(dcookie_value(dcs));
+ struct list_head * list = dcookie_hashtable[current_hash] + dcookie_hash(dcookie_value(dcs));
list_add(&dcs->hash_list, list);
}
static struct dcookie_struct *alloc_dcookie(struct path *path)
{
- struct dcookie_struct *dcs = kmem_cache_alloc(dcookie_cache,
- GFP_KERNEL);
+ struct dcookie_struct *dcs = kmem_cache_alloc(dcookie_cache, GFP_ATOMIC);
+
struct dentry *d;
if (!dcs)
return NULL;
@@ -117,7 +136,7 @@ int get_dcookie(struct path *path, unsigned long *cookie)
int err = 0;
struct dcookie_struct * dcs;
- mutex_lock(&dcookie_mutex);
+ spin_lock(&dcookie_hash_write_lock);
if (!is_live()) {
err = -EINVAL;
@@ -137,7 +156,7 @@ int get_dcookie(struct path *path, unsigned long *cookie)
*cookie = dcookie_value(dcs);
out:
- mutex_unlock(&dcookie_mutex);
+ spin_unlock(&dcookie_hash_write_lock);
return err;
}
@@ -209,7 +228,7 @@ SYSCALL_ALIAS(sys_lookup_dcookie, SyS_lookup_dcookie);
static int dcookie_init(void)
{
struct list_head * d;
- unsigned int i, hash_bits;
+ unsigned int i, j, hash_bits;
int err = -ENOMEM;
dcookie_cache = kmem_cache_create("dcookie_cache",
@@ -219,9 +238,11 @@ static int dcookie_init(void)
if (!dcookie_cache)
goto out;
- dcookie_hashtable = kmalloc(PAGE_SIZE, GFP_KERNEL);
- if (!dcookie_hashtable)
+ for (i=0; i<3; i++) {
+ dcookie_hashtable[i] = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!dcookie_hashtable[i])
goto out_kmem;
+ }
err = 0;
@@ -244,13 +265,15 @@ static int dcookie_init(void)
hash_size = 1UL << hash_bits;
/* And initialize the newly allocated array */
- d = dcookie_hashtable;
- i = hash_size;
+ for (i=0; i<3; i++) {
+ d = dcookie_hashtable[i];
+ j = hash_size;
do {
INIT_LIST_HEAD(d);
d++;
- i--;
- } while (i);
+ j--;
+ } while (j);
+ }
out:
return err;
@@ -272,17 +295,31 @@ static void free_dcookie(struct dcookie_struct * dcs)
kmem_cache_free(dcookie_cache, dcs);
}
+int dcookie_swap(void) {
+ if (is_shared())
+ return -EAGAIN;
+
+ old_hash=current_hash;
+ current_hash = (current_hash + 1) % 3;
+ return 0;
+}
-static void dcookie_exit(void)
-{
+/* Switch to the second hash */
+int dcookie_garbage_collect(void) {
struct list_head * list;
struct list_head * pos;
struct list_head * pos2;
struct dcookie_struct * dcs;
size_t i;
+
+ int next_hash=(current_hash + 1) % 3;
+
+ if (is_shared())
+ return -EAGAIN;
+ /* XXX consider the consequence of dcookie allocation concurring with this cleanup */
for (i = 0; i < hash_size; ++i) {
- list = dcookie_hashtable + i;
+ list = dcookie_hashtable[next_hash] + i;
list_for_each_safe(pos, pos2, list) {
dcs = list_entry(pos, struct dcookie_struct, hash_list);
list_del(&dcs->hash_list);
@@ -290,7 +327,29 @@ static void dcookie_exit(void)
}
}
- kfree(dcookie_hashtable);
+ return 0;
+}
+
+static void dcookie_exit(void)
+{
+ struct list_head * list;
+ struct list_head * pos;
+ struct list_head * pos2;
+ struct dcookie_struct * dcs;
+ size_t j;
+ unsigned int i;
+
+ for (i = 0; i < 3; ++i) {
+ for (j = 0; j < hash_size; ++j) {
+ list = dcookie_hashtable[i] + j;
+ list_for_each_safe(pos, pos2, list) {
+ dcs = list_entry(pos, struct dcookie_struct, hash_list);
+ list_del(&dcs->hash_list);
+ free_dcookie(dcs);
+ }
+ }
+ kfree(dcookie_hashtable[i]);
+ }
kmem_cache_destroy(dcookie_cache);
}
@@ -340,3 +399,5 @@ void dcookie_unregister(struct dcookie_user * user)
EXPORT_SYMBOL_GPL(dcookie_register);
EXPORT_SYMBOL_GPL(dcookie_unregister);
EXPORT_SYMBOL_GPL(get_dcookie);
+EXPORT_SYMBOL_GPL(dcookie_garbage_collect);
+EXPORT_SYMBOL_GPL(dcookie_swap);
diff --git a/include/linux/dcookies.h b/include/linux/dcookies.h
index 24c806f..3c1d2b2 100644
--- a/include/linux/dcookies.h
+++ b/include/linux/dcookies.h
@@ -46,6 +46,27 @@ void dcookie_unregister(struct dcookie_user * user);
*/
int get_dcookie(struct path *path, unsigned long *cookie);
+/**
+ * dcookie_swap - switch to the next dcookie epoch
+ *
+ * Deactivate the current dcookie hash table and activate
+ * the next one
+ *
+ * Returns 0 on success
+ */
+
+int dcookie_swap(void);
+
+/**
+ * dcookie_garbage_collect - clear the hash table next in line
+ *
+ * Clear the hash table to be activated in the next epoch.
+ *
+ * Returns 0 on success
+ */
+
+int dcookie_garbage_collect(void);
+
#else
static inline struct dcookie_user * dcookie_register(void)
--
1.5.4.3