The data structure is for storing namesapce string. It allows namespace
string to be shared by cephfs inodes with same layout.
Signed-off-by: Yan, Zheng <zyan@xxxxxxxxxx>
---
include/linux/ceph/libceph.h | 1 +
include/linux/ceph/string_table.h | 58 ++++++++++++++++++
net/ceph/Makefile | 2 +-
net/ceph/ceph_common.c | 1 +
net/ceph/string_table.c | 121 ++++++++++++++++++++++++++++++++++++++
5 files changed, 182 insertions(+), 1 deletion(-)
create mode 100644 include/linux/ceph/string_table.h
create mode 100644 net/ceph/string_table.c
diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
index e7975e4..8e9868d 100644
--- a/include/linux/ceph/libceph.h
+++ b/include/linux/ceph/libceph.h
@@ -21,6 +21,7 @@
#include <linux/ceph/mon_client.h>
#include <linux/ceph/osd_client.h>
#include <linux/ceph/ceph_fs.h>
+#include <linux/ceph/string_table.h>
/*
* mount options
diff --git a/include/linux/ceph/string_table.h b/include/linux/ceph/string_table.h
new file mode 100644
index 0000000..427b6f9
--- /dev/null
+++ b/include/linux/ceph/string_table.h
@@ -0,0 +1,58 @@
+#ifndef _FS_CEPH_STRING_TABLE_H
+#define _FS_CEPH_STRING_TABLE_H
+
+#include <linux/types.h>
+#include <linux/kref.h>
+#include <linux/rbtree.h>
+#include <linux/rcupdate.h>
+
+struct ceph_string {
+ struct kref kref;
+ union {
+ struct rb_node node;
+ struct rcu_head rcu;
+ };
+ size_t len;
+ char str[];
+};
+
+extern void ceph_release_string(struct kref *ref);
+extern struct ceph_string *ceph_find_or_create_string(const char *str,
+ size_t len);
+extern void ceph_string_cleanup(void);
+
+static inline void ceph_get_string(struct ceph_string *str)
+{
+ kref_get(&str->kref);
+}
+
+static inline void ceph_put_string(struct ceph_string *str)
+{
+ if (!str)
+ return;
+ kref_put(&str->kref, ceph_release_string);
+}
+
+static inline int ceph_compare_string(struct ceph_string *cs,
+ const char* str, size_t len)
+{
+ size_t cs_len = cs ? cs->len : 0;
+ if (cs_len != len)
+ return cs_len - len;
+ if (len == 0)
+ return 0;
+ return strncmp(cs->str, str, len);
+}
+
+#define ceph_try_get_string(x) \
+({ \
+ struct ceph_string *___str; \
+ rcu_read_lock(); \
+ ___str = rcu_dereference(x); \
+ if (___str && !kref_get_unless_zero(&___str->kref)) \
+ ___str = NULL; \
+ rcu_read_unlock(); \
+ (___str); \
+})
+
+#endif
diff --git a/net/ceph/Makefile b/net/ceph/Makefile
index 958d9856..84cbed6 100644
--- a/net/ceph/Makefile
+++ b/net/ceph/Makefile
@@ -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
diff --git a/net/ceph/ceph_common.c b/net/ceph/ceph_common.c
index dcc18c6..baca649 100644
--- a/net/ceph/ceph_common.c
+++ b/net/ceph/ceph_common.c
@@ -751,6 +751,7 @@ static void __exit exit_ceph_lib(void)
ceph_msgr_exit();
ceph_crypto_shutdown();
ceph_debugfs_cleanup();
+ ceph_string_cleanup();
}
module_init(init_ceph_lib);
diff --git a/net/ceph/string_table.c b/net/ceph/string_table.c
new file mode 100644
index 0000000..bb49bd7
--- /dev/null
+++ b/net/ceph/string_table.c
@@ -0,0 +1,121 @@
+#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);
+
+void ceph_string_cleanup(void)
+{
+ struct rb_node *p;
+ struct ceph_string *cs;
+ if (RB_EMPTY_ROOT(&string_tree))
+ return;
+
+ pr_err("libceph: detect string leaks\n");
+ while ((p = rb_first(&string_tree))) {
+ cs = rb_entry(p, struct ceph_string, node);
+ rb_erase(p, &string_tree);
+ kfree(cs);
+ }
+}
--
2.5.0
--
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