We are really suffering from now ulist's implementation, some developers
gave their try, and i just gave some of my ideas for things:
1. use list+rb_tree instead of arrary+rb_tree
2. add cur_list to iterator rather than ulist structure.
3. add seqnum into every node when they are added, this is
used to do selfcheck when iterating node.
I noticed Zach Brown's comments before, long term is to kick off
ulist implementation, however, for now, we need at least avoid
arrary from ulist.
Cc: Liu Bo <bo.li.liu@oracle.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Zach Brown <zab@redhat.com>
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
---
fs/btrfs/ulist.c | 84 +++++++++++++++++++++-----------------------------------
fs/btrfs/ulist.h | 22 ++++-----------
2 files changed, 37 insertions(+), 69 deletions(-)
diff --git a/fs/btrfs/ulist.c b/fs/btrfs/ulist.c
index 35f5de9..674430b 100644
--- a/fs/btrfs/ulist.c
+++ b/fs/btrfs/ulist.c
@@ -7,6 +7,7 @@
#include <linux/slab.h>
#include <linux/export.h>
#include "ulist.h"
+#include "ctree.h"
/*
* ulist is a generic data structure to hold a collection of unique u64
@@ -51,8 +52,7 @@
void ulist_init(struct ulist *ulist)
{
ulist->nnodes = 0;
- ulist->nodes = ulist->int_nodes;
- ulist->nodes_alloced = ULIST_SIZE;
+ INIT_LIST_HEAD(&ulist->nodes);
ulist->root = RB_ROOT;
}
EXPORT_SYMBOL(ulist_init);
@@ -66,13 +66,11 @@ EXPORT_SYMBOL(ulist_init);
*/
void ulist_fini(struct ulist *ulist)
{
- /*
- * The first ULIST_SIZE elements are stored inline in struct ulist.
- * Only if more elements are alocated they need to be freed.
- */
- if (ulist->nodes_alloced > ULIST_SIZE)
- kfree(ulist->nodes);
- ulist->nodes_alloced = 0; /* in case ulist_fini is called twice */
+ struct ulist_node *node;
+
+ list_for_each_entry(node, &ulist->nodes, list) {
+ kfree(node);
+ }
ulist->root = RB_ROOT;
}
EXPORT_SYMBOL(ulist_fini);
@@ -200,48 +198,17 @@ int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux,
*old_aux = node->aux;
return 0;
}
+ node = kmalloc(sizeof(*node), gfp_mask);
+ if (!node)
+ return -ENOMEM;
- if (ulist->nnodes >= ulist->nodes_alloced) {
- u64 new_alloced = ulist->nodes_alloced + 128;
- struct ulist_node *new_nodes;
- void *old = NULL;
- int i;
-
- /*
- * if nodes_alloced == ULIST_SIZE no memory has been allocated
- * yet, so pass NULL to krealloc
- */
- if (ulist->nodes_alloced > ULIST_SIZE)
- old = ulist->nodes;
-
- new_nodes = krealloc(old, sizeof(*new_nodes) * new_alloced,
- gfp_mask);
- if (!new_nodes)
- return -ENOMEM;
-
- if (!old)
- memcpy(new_nodes, ulist->int_nodes,
- sizeof(ulist->int_nodes));
-
- ulist->nodes = new_nodes;
- ulist->nodes_alloced = new_alloced;
+ node->val = val;
+ node->aux = aux;
+ node->seqnum = ulist->nnodes;
- /*
- * krealloc actually uses memcpy, which does not copy rb_node
- * pointers, so we have to do it ourselves. Otherwise we may
- * be bitten by crashes.
- */
- ulist->root = RB_ROOT;
- for (i = 0; i < ulist->nnodes; i++) {
- ret = ulist_rbtree_insert(ulist, &ulist->nodes[i]);
- if (ret < 0)
- return ret;
- }
- }
- ulist->nodes[ulist->nnodes].val = val;
- ulist->nodes[ulist->nnodes].aux = aux;
- ret = ulist_rbtree_insert(ulist, &ulist->nodes[ulist->nnodes]);
- BUG_ON(ret);
+ ret = ulist_rbtree_insert(ulist, node);
+ ASSERT(!ret);
+ list_add_tail(&node->list, &ulist->nodes);
++ulist->nnodes;
return 1;
@@ -266,11 +233,22 @@ EXPORT_SYMBOL(ulist_add);
*/
struct ulist_node *ulist_next(struct ulist *ulist, struct ulist_iterator
*uiter)
{
- if (ulist->nnodes == 0)
- return NULL;
- if (uiter->i < 0 || uiter->i >= ulist->nnodes)
+ struct ulist_node *node;
+
+ if (ulist->nnodes == 0 || uiter->i >= ulist->nnodes)
return NULL;
+ ASSERT(uiter->i >= 0);
+
+ if (uiter->i == 0) {
+ uiter->cur_list = ulist->nodes.next;
+ uiter->i++;
+ return list_entry(uiter->cur_list, struct ulist_node, list);
+ }
+ uiter->cur_list = uiter->cur_list->next;
+ node = list_entry(uiter->cur_list, struct ulist_node, list);
+ ASSERT(node->seqnum == uiter->i);
+ uiter->i++;
- return &ulist->nodes[uiter->i++];
+ return node;
}
EXPORT_SYMBOL(ulist_next);
diff --git a/fs/btrfs/ulist.h b/fs/btrfs/ulist.h
index fb36731..b84d27b 100644
--- a/fs/btrfs/ulist.h
+++ b/fs/btrfs/ulist.h
@@ -29,6 +29,7 @@
struct ulist_iterator {
int i;
+ struct list_head *cur_list; /* hint to start search*/
};
/*
@@ -37,6 +38,10 @@ struct ulist_iterator {
struct ulist_node {
u64 val; /* value to store */
u64 aux; /* auxiliary value saved along with the val */
+
+ int seqnum; /* sequence of number this node is added */
+
+ struct list_head list; /* used to link node */
struct rb_node rb_node; /* used to speed up search */
};
@@ -46,24 +51,9 @@ struct ulist {
*/
unsigned long nnodes;
- /*
- * number of nodes we already have room for
- */
- unsigned long nodes_alloced;
-
- /*
- * pointer to the array storing the elements. The first ULIST_SIZE
- * elements are stored inline. In this case the it points to int_nodes.
- * After exceeding ULIST_SIZE, dynamic memory is allocated.
- */
- struct ulist_node *nodes;
+ struct list_head nodes;
struct rb_root root;
-
- /*
- * inline storage space for the first ULIST_SIZE entries
- */
- struct ulist_node int_nodes[ULIST_SIZE];
};
void ulist_init(struct ulist *ulist);
--
1.8.3.1
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs"
in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html