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https://github.com/torvalds/linux
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51e9273796
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 <zyan@redhat.com>
112 lines
2.3 KiB
C
112 lines
2.3 KiB
C
#include <linux/slab.h>
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#include <linux/gfp.h>
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#include <linux/string.h>
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#include <linux/spinlock.h>
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#include <linux/ceph/string_table.h>
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static DEFINE_SPINLOCK(string_tree_lock);
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static struct rb_root string_tree = RB_ROOT;
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struct ceph_string *ceph_find_or_create_string(const char* str, size_t len)
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{
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struct ceph_string *cs, *exist;
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struct rb_node **p, *parent;
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int ret;
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exist = NULL;
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spin_lock(&string_tree_lock);
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p = &string_tree.rb_node;
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while (*p) {
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exist = rb_entry(*p, struct ceph_string, node);
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ret = ceph_compare_string(exist, str, len);
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if (ret > 0)
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p = &(*p)->rb_left;
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else if (ret < 0)
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p = &(*p)->rb_right;
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else
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break;
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exist = NULL;
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}
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if (exist && !kref_get_unless_zero(&exist->kref)) {
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rb_erase(&exist->node, &string_tree);
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RB_CLEAR_NODE(&exist->node);
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exist = NULL;
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}
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spin_unlock(&string_tree_lock);
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if (exist)
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return exist;
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cs = kmalloc(sizeof(*cs) + len + 1, GFP_NOFS);
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if (!cs)
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return NULL;
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kref_init(&cs->kref);
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cs->len = len;
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memcpy(cs->str, str, len);
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cs->str[len] = 0;
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retry:
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exist = NULL;
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parent = NULL;
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p = &string_tree.rb_node;
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spin_lock(&string_tree_lock);
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while (*p) {
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parent = *p;
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exist = rb_entry(*p, struct ceph_string, node);
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ret = ceph_compare_string(exist, str, len);
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if (ret > 0)
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p = &(*p)->rb_left;
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else if (ret < 0)
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p = &(*p)->rb_right;
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else
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break;
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exist = NULL;
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}
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ret = 0;
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if (!exist) {
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rb_link_node(&cs->node, parent, p);
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rb_insert_color(&cs->node, &string_tree);
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} else if (!kref_get_unless_zero(&exist->kref)) {
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rb_erase(&exist->node, &string_tree);
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RB_CLEAR_NODE(&exist->node);
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ret = -EAGAIN;
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}
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spin_unlock(&string_tree_lock);
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if (ret == -EAGAIN)
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goto retry;
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if (exist) {
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kfree(cs);
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cs = exist;
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}
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return cs;
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}
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EXPORT_SYMBOL(ceph_find_or_create_string);
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static void ceph_free_string(struct rcu_head *head)
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{
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struct ceph_string *cs = container_of(head, struct ceph_string, rcu);
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kfree(cs);
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}
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void ceph_release_string(struct kref *ref)
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{
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struct ceph_string *cs = container_of(ref, struct ceph_string, kref);
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spin_lock(&string_tree_lock);
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if (!RB_EMPTY_NODE(&cs->node)) {
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rb_erase(&cs->node, &string_tree);
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RB_CLEAR_NODE(&cs->node);
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}
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spin_unlock(&string_tree_lock);
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call_rcu(&cs->rcu, ceph_free_string);
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}
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EXPORT_SYMBOL(ceph_release_string);
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bool ceph_strings_empty(void)
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{
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return RB_EMPTY_ROOT(&string_tree);
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}
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