From 51e9273796a57c08801f45580d3db3c51987a0cb Mon Sep 17 00:00:00 2001 From: "Yan, Zheng" Date: Fri, 5 Feb 2016 15:36:22 +0800 Subject: [PATCH] libceph: introduce reference counted string 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 --- include/linux/ceph/libceph.h | 1 + include/linux/ceph/string_table.h | 62 +++++++++++++++++++++ net/ceph/Makefile | 2 +- net/ceph/ceph_common.c | 2 + net/ceph/string_table.c | 111 ++++++++++++++++++++++++++++++++++++++ 5 files changed, 177 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 690985d..6afc5d9 100644 --- a/include/linux/ceph/libceph.h +++ b/include/linux/ceph/libceph.h @@ -21,6 +21,7 @@ #include #include #include +#include /* * mount options diff --git a/include/linux/ceph/string_table.h b/include/linux/ceph/string_table.h new file mode 100644 index 0000000..1b02c96 --- /dev/null +++ b/include/linux/ceph/string_table.h @@ -0,0 +1,62 @@ +#ifndef _FS_CEPH_STRING_TABLE_H +#define _FS_CEPH_STRING_TABLE_H + +#include +#include +#include +#include + +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 bool ceph_strings_empty(void); + +static inline struct ceph_string *ceph_get_string(struct ceph_string *str) +{ + kref_get(&str->kref); + return str; +} + +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(); \ + for (;;) { \ + ___str = rcu_dereference(x); \ + if (!___str || \ + kref_get_unless_zero(&___str->kref)) \ + break; \ + } \ + 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 55d2bfe..bddfcf6 100644 --- a/net/ceph/ceph_common.c +++ b/net/ceph/ceph_common.c @@ -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(); diff --git a/net/ceph/string_table.c b/net/ceph/string_table.c new file mode 100644 index 0000000..ca53c83 --- /dev/null +++ b/net/ceph/string_table.c @@ -0,0 +1,111 @@ +#include +#include +#include +#include +#include + +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); +} -- 2.7.4