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libceph: introduce reference counted string

Browse source 
The data structure is for storing namesapce string. It allows namespace
string to be shared between cephfs inodes with same layout. This data
structure can also be referenced by OSD request.

Signed-off-by: Yan, Zheng <[email protected]>
This commit is contained in:
Yan, Zheng 2016-02-05 15:36:22 +08:00 • committed by Ilya Dryomov
commit 51e9273796
5 changed files with 177 additions and 1 deletions
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2
net/ceph/Makefile
View file

@ -11,5 +11,5 @@ libceph-y := ceph_common.o messenger.o msgpool.o buffer.o pagelist.o \
crypto.o armor.o \
auth_x.o \
ceph_fs.o ceph_strings.o ceph_hash.o \
pagevec.o snapshot.o
pagevec.o snapshot.o string_table.o

2
net/ceph/ceph_common.c
View file

@ -747,6 +747,8 @@ out:
static void __exit exit_ceph_lib(void)
{
dout("exit_ceph_lib\n");
WARN_ON(!ceph_strings_empty());
ceph_osdc_cleanup();
ceph_msgr_exit();
ceph_crypto_shutdown();

111
net/ceph/string_table.c Normal file
View file

@ -0,0 +1,111 @@
#include <linux/slab.h>
#include <linux/gfp.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/ceph/string_table.h>
static DEFINE_SPINLOCK(string_tree_lock);
static struct rb_root string_tree = RB_ROOT;
struct ceph_string *ceph_find_or_create_string(const char* str, size_t len)
{
struct ceph_string *cs, *exist;
struct rb_node **p, *parent;
int ret;
exist = NULL;
spin_lock(&string_tree_lock);
p = &string_tree.rb_node;
while (*p) {
exist = rb_entry(*p, struct ceph_string, node);
ret = ceph_compare_string(exist, str, len);
if (ret > 0)
p = &(*p)->rb_left;
else if (ret < 0)
p = &(*p)->rb_right;
else
break;
exist = NULL;
}
if (exist && !kref_get_unless_zero(&exist->kref)) {
rb_erase(&exist->node, &string_tree);
RB_CLEAR_NODE(&exist->node);
exist = NULL;
}
spin_unlock(&string_tree_lock);
if (exist)
return exist;
cs = kmalloc(sizeof(*cs) + len + 1, GFP_NOFS);
if (!cs)
return NULL;
kref_init(&cs->kref);
cs->len = len;
memcpy(cs->str, str, len);
cs->str[len] = 0;
retry:
exist = NULL;
parent = NULL;
p = &string_tree.rb_node;
spin_lock(&string_tree_lock);
while (*p) {
parent = *p;
exist = rb_entry(*p, struct ceph_string, node);
ret = ceph_compare_string(exist, str, len);
if (ret > 0)
p = &(*p)->rb_left;
else if (ret < 0)
p = &(*p)->rb_right;
else
break;
exist = NULL;
}
ret = 0;
if (!exist) {
rb_link_node(&cs->node, parent, p);
rb_insert_color(&cs->node, &string_tree);
} else if (!kref_get_unless_zero(&exist->kref)) {
rb_erase(&exist->node, &string_tree);
RB_CLEAR_NODE(&exist->node);
ret = -EAGAIN;
}
spin_unlock(&string_tree_lock);
if (ret == -EAGAIN)
goto retry;
if (exist) {
kfree(cs);
cs = exist;
}
return cs;
}
EXPORT_SYMBOL(ceph_find_or_create_string);
static void ceph_free_string(struct rcu_head *head)
{
struct ceph_string *cs = container_of(head, struct ceph_string, rcu);
kfree(cs);
}
void ceph_release_string(struct kref *ref)
{
struct ceph_string *cs = container_of(ref, struct ceph_string, kref);
spin_lock(&string_tree_lock);
if (!RB_EMPTY_NODE(&cs->node)) {
rb_erase(&cs->node, &string_tree);
RB_CLEAR_NODE(&cs->node);
}
spin_unlock(&string_tree_lock);
call_rcu(&cs->rcu, ceph_free_string);
}
EXPORT_SYMBOL(ceph_release_string);
bool ceph_strings_empty(void)
{
return RB_EMPTY_ROOT(&string_tree);
}