From 4c7a6f74ceeafd738b55d1c57349327f7ea8e895 Mon Sep 17 00:00:00 2001 From: Wang Shilong Date: Wed, 29 Jan 2014 00:25:34 +0800 Subject: Btrfs: rework ulist with list+rb_tree 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 Cc: Josef Bacik Cc: Zach Brown Signed-off-by: Wang Shilong Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/ulist.c | 105 +++++++++++++++++++++++-------------------------------- fs/btrfs/ulist.h | 38 ++++++-------------- 2 files changed, 55 insertions(+), 88 deletions(-) (limited to 'fs') diff --git a/fs/btrfs/ulist.c b/fs/btrfs/ulist.c index 35f5de9..8dd0e8d 100644 --- a/fs/btrfs/ulist.c +++ b/fs/btrfs/ulist.c @@ -7,6 +7,7 @@ #include #include #include "ulist.h" +#include "ctree.h" /* * ulist is a generic data structure to hold a collection of unique u64 @@ -14,10 +15,6 @@ * enumerating it. * It is possible to store an auxiliary value along with the key. * - * The implementation is preliminary and can probably be sped up - * significantly. A first step would be to store the values in an rbtree - * as soon as ULIST_SIZE is exceeded. - * * A sample usage for ulists is the enumeration of directed graphs without * visiting a node twice. The pseudo-code could look like this: * @@ -50,10 +47,9 @@ */ 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; + ulist->nnodes = 0; } EXPORT_SYMBOL(ulist_init); @@ -66,14 +62,14 @@ 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; + struct ulist_node *next; + + list_for_each_entry_safe(node, next, &ulist->nodes, list) { + kfree(node); + } ulist->root = RB_ROOT; + INIT_LIST_HEAD(&ulist->nodes); } EXPORT_SYMBOL(ulist_fini); @@ -192,57 +188,29 @@ int ulist_add(struct ulist *ulist, u64 val, u64 aux, gfp_t gfp_mask) int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux, u64 *old_aux, gfp_t gfp_mask) { - int ret = 0; - struct ulist_node *node = NULL; + int ret; + struct ulist_node *node; + node = ulist_rbtree_search(ulist, val); if (node) { if (old_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; + node->val = val; + node->aux = aux; +#ifdef CONFIG_BTRFS_DEBUG + node->seqnum = ulist->nnodes; +#endif - 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; - - /* - * 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); - ++ulist->nnodes; + ret = ulist_rbtree_insert(ulist, node); + ASSERT(!ret); + list_add_tail(&node->list, &ulist->nodes); + ulist->nnodes++; return 1; } @@ -266,11 +234,26 @@ EXPORT_SYMBOL(ulist_add); */ struct ulist_node *ulist_next(struct ulist *ulist, struct ulist_iterator *uiter) { - if (ulist->nnodes == 0) + struct ulist_node *node; + + if (list_empty(&ulist->nodes)) return NULL; - if (uiter->i < 0 || uiter->i >= ulist->nnodes) + if (uiter->cur_list && uiter->cur_list->next == &ulist->nodes) return NULL; - - return &ulist->nodes[uiter->i++]; + if (uiter->cur_list) { + uiter->cur_list = uiter->cur_list->next; + } else { + uiter->cur_list = ulist->nodes.next; +#ifdef CONFIG_BTRFS_DEBUG + uiter->i = 0; +#endif + } + node = list_entry(uiter->cur_list, struct ulist_node, list); +#ifdef CONFIG_BTRFS_DEBUG + ASSERT(node->seqnum == uiter->i); + ASSERT(uiter->i >= 0 && uiter->i < ulist->nnodes); + uiter->i++; +#endif + return node; } EXPORT_SYMBOL(ulist_next); diff --git a/fs/btrfs/ulist.h b/fs/btrfs/ulist.h index fb36731..2be7102 100644 --- a/fs/btrfs/ulist.h +++ b/fs/btrfs/ulist.h @@ -17,18 +17,12 @@ * enumerating it. * It is possible to store an auxiliary value along with the key. * - * The implementation is preliminary and can probably be sped up - * significantly. A first step would be to store the values in an rbtree - * as soon as ULIST_SIZE is exceeded. */ - -/* - * number of elements statically allocated inside struct ulist - */ -#define ULIST_SIZE 16 - struct ulist_iterator { +#ifdef CONFIG_BTRFS_DEBUG int i; +#endif + struct list_head *cur_list; /* hint to start search */ }; /* @@ -37,6 +31,12 @@ struct ulist_iterator { struct ulist_node { u64 val; /* value to store */ u64 aux; /* auxiliary value saved along with the val */ + +#ifdef CONFIG_BTRFS_DEBUG + int seqnum; /* sequence number this node is added */ +#endif + + struct list_head list; /* used to link node */ struct rb_node rb_node; /* used to speed up search */ }; @@ -46,24 +46,8 @@ 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); @@ -77,6 +61,6 @@ int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux, struct ulist_node *ulist_next(struct ulist *ulist, struct ulist_iterator *uiter); -#define ULIST_ITER_INIT(uiter) ((uiter)->i = 0) +#define ULIST_ITER_INIT(uiter) ((uiter)->cur_list = NULL) #endif -- cgit v1.1