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Message-Id: <1229660385-17153-4-git-send-email-crquan@gmail.com>
Date: Fri, 19 Dec 2008 12:19:45 +0800
From: crquan@...il.com
To: dm-devel@...hat.com
Cc: Alasdair G Kergon <agk@...hat.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] dm-target: embed internally used list_head into target_type
From: Cheng Renquan <crquan@...il.com>
The tt_internal is really just a list_head to manage registered target_type
in a double linked list,
Here embed the list_head into target_type directly,
1. to avoid kmalloc/kfree;
2. then tt_internal is really unneeded;
Signed-off-by: Cheng Renquan <crquan@...il.com>
---
drivers/md/dm-target.c | 95 +++++++++++++++--------------------------
include/linux/device-mapper.h | 3 +
2 files changed, 37 insertions(+), 61 deletions(-)
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index a713c7f..ee120a9 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -14,40 +14,34 @@
#define DM_MSG_PREFIX "target"
-struct tt_internal {
- struct target_type *tt;
-
- struct list_head list;
-};
-
static LIST_HEAD(_targets);
static DECLARE_RWSEM(_lock);
#define DM_MOD_NAME_SIZE 32
-static inline struct tt_internal *__find_target_type(const char *name)
+static inline struct target_type *__find_target_type(const char *name)
{
- struct tt_internal *ti;
+ struct target_type *tt;
- list_for_each_entry (ti, &_targets, list)
- if (!strcmp(name, ti->tt->name))
- return ti;
+ list_for_each_entry (tt, &_targets, list)
+ if (!strcmp(name, tt->name))
+ return tt;
return NULL;
}
-static struct tt_internal *get_target_type(const char *name)
+static struct target_type *get_target_type(const char *name)
{
- struct tt_internal *ti;
+ struct target_type *tt;
down_read(&_lock);
- ti = __find_target_type(name);
- if (ti && !try_module_get(ti->tt->module))
- ti = NULL;
+ tt = __find_target_type(name);
+ if (tt && !try_module_get(tt->module))
+ tt = NULL;
up_read(&_lock);
- return ti;
+ return tt;
}
static void load_module(const char *name)
@@ -57,91 +51,70 @@ static void load_module(const char *name)
struct target_type *dm_get_target_type(const char *name)
{
- struct tt_internal *ti = get_target_type(name);
+ struct target_type *tt = get_target_type(name);
- if (!ti) {
+ if (!tt) {
load_module(name);
- ti = get_target_type(name);
+ tt = get_target_type(name);
}
- return ti ? ti->tt : NULL;
+ return tt;
}
-void dm_put_target_type(struct target_type *t)
+void dm_put_target_type(struct target_type *tt)
{
- struct tt_internal *ti = (struct tt_internal *) t;
-
down_read(&_lock);
- module_put(ti->tt->module);
+ module_put(tt->module);
up_read(&_lock);
-
- return;
}
-static struct tt_internal *alloc_target(struct target_type *t)
-{
- struct tt_internal *ti = kzalloc(sizeof(*ti), GFP_KERNEL);
-
- if (ti)
- ti->tt = t;
-
- return ti;
-}
-
-
int dm_target_iterate(void (*iter_func)(struct target_type *tt,
void *param), void *param)
{
- struct tt_internal *ti;
+ struct target_type *tt;
down_read(&_lock);
- list_for_each_entry (ti, &_targets, list)
- iter_func(ti->tt, param);
+ list_for_each_entry (tt, &_targets, list)
+ iter_func(tt, param);
up_read(&_lock);
return 0;
}
-int dm_register_target(struct target_type *t)
+int dm_register_target(struct target_type *tt)
{
int rv = 0;
- struct tt_internal *ti = alloc_target(t);
-
- if (!ti)
- return -ENOMEM;
down_write(&_lock);
- if (__find_target_type(t->name))
+ if (__find_target_type(tt->name))
rv = -EEXIST;
else
- list_add(&ti->list, &_targets);
+ list_add(&tt->list, &_targets);
up_write(&_lock);
- if (rv)
- kfree(ti);
return rv;
}
-int dm_unregister_target(struct target_type *t)
+int dm_unregister_target(struct target_type *tt)
{
- struct tt_internal *ti;
+ int rv = 0;
down_write(&_lock);
- if (!(ti = __find_target_type(t->name))) {
- up_write(&_lock);
- return -EINVAL;
+ if (!__find_target_type(tt->name)) {
+ rv = -EINVAL;
+ goto out;
}
- if (ti->tt->module && module_refcount(ti->tt->module)) {
- up_write(&_lock);
- return -ETXTBSY;
+ if (tt->module && module_refcount(tt->module)) {
+ rv = -ETXTBSY;
+ goto out;
}
- list_del(&ti->list);
- kfree(ti);
+ list_del(&tt->list);
+ out:
up_write(&_lock);
- return 0;
+ return rv;
}
/*
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index c17fd33..8bcc7f5 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -117,6 +117,9 @@ struct target_type {
dm_message_fn message;
dm_ioctl_fn ioctl;
dm_merge_fn merge;
+
+ /* for internal use only */
+ struct list_head list;
};
struct io_restrictions {
--
1.6.0.2.GIT
--
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