From 47feff2c8eefe85099f87c43d3096855f0085ca0 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 25 Jul 2008 19:45:29 -0700 Subject: radix-tree: add gang_lookup_slot, gang_lookup_slot_tag Introduce gang_lookup_slot() and gang_lookup_slot_tag() functions, which are used by lockless pagecache. Signed-off-by: Nick Piggin Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Hugh Dickins Cc: "Paul E. McKenney" Reviewed-by: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/radix-tree.c | 178 ++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 155 insertions(+), 23 deletions(-) (limited to 'lib/radix-tree.c') diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 56ec21a7f73..9c4f1ffa286 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -359,18 +359,17 @@ EXPORT_SYMBOL(radix_tree_insert); * Returns: the slot corresponding to the position @index in the * radix tree @root. This is useful for update-if-exists operations. * - * This function cannot be called under rcu_read_lock, it must be - * excluded from writers, as must the returned slot for subsequent - * use by radix_tree_deref_slot() and radix_tree_replace slot. - * Caller must hold tree write locked across slot lookup and - * replace. + * This function can be called under rcu_read_lock iff the slot is not + * modified by radix_tree_replace_slot, otherwise it must be called + * exclusive from other writers. Any dereference of the slot must be done + * using radix_tree_deref_slot. */ void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) { unsigned int height, shift; struct radix_tree_node *node, **slot; - node = root->rnode; + node = rcu_dereference(root->rnode); if (node == NULL) return NULL; @@ -390,7 +389,7 @@ void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) do { slot = (struct radix_tree_node **) (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); - node = *slot; + node = rcu_dereference(*slot); if (node == NULL) return NULL; @@ -667,7 +666,7 @@ unsigned long radix_tree_next_hole(struct radix_tree_root *root, EXPORT_SYMBOL(radix_tree_next_hole); static unsigned int -__lookup(struct radix_tree_node *slot, void **results, unsigned long index, +__lookup(struct radix_tree_node *slot, void ***results, unsigned long index, unsigned int max_items, unsigned long *next_index) { unsigned int nr_found = 0; @@ -701,11 +700,9 @@ __lookup(struct radix_tree_node *slot, void **results, unsigned long index, /* Bottom level: grab some items */ for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) { - struct radix_tree_node *node; index++; - node = slot->slots[i]; - if (node) { - results[nr_found++] = rcu_dereference(node); + if (slot->slots[i]) { + results[nr_found++] = &(slot->slots[i]); if (nr_found == max_items) goto out; } @@ -759,13 +756,22 @@ radix_tree_gang_lookup(struct radix_tree_root *root, void **results, ret = 0; while (ret < max_items) { - unsigned int nr_found; + unsigned int nr_found, slots_found, i; unsigned long next_index; /* Index of next search */ if (cur_index > max_index) break; - nr_found = __lookup(node, results + ret, cur_index, + slots_found = __lookup(node, (void ***)results + ret, cur_index, max_items - ret, &next_index); + nr_found = 0; + for (i = 0; i < slots_found; i++) { + struct radix_tree_node *slot; + slot = *(((void ***)results)[ret + i]); + if (!slot) + continue; + results[ret + nr_found] = rcu_dereference(slot); + nr_found++; + } ret += nr_found; if (next_index == 0) break; @@ -776,12 +782,71 @@ radix_tree_gang_lookup(struct radix_tree_root *root, void **results, } EXPORT_SYMBOL(radix_tree_gang_lookup); +/** + * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree + * @root: radix tree root + * @results: where the results of the lookup are placed + * @first_index: start the lookup from this key + * @max_items: place up to this many items at *results + * + * Performs an index-ascending scan of the tree for present items. Places + * their slots at *@results and returns the number of items which were + * placed at *@results. + * + * The implementation is naive. + * + * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must + * be dereferenced with radix_tree_deref_slot, and if using only RCU + * protection, radix_tree_deref_slot may fail requiring a retry. + */ +unsigned int +radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results, + unsigned long first_index, unsigned int max_items) +{ + unsigned long max_index; + struct radix_tree_node *node; + unsigned long cur_index = first_index; + unsigned int ret; + + node = rcu_dereference(root->rnode); + if (!node) + return 0; + + if (!radix_tree_is_indirect_ptr(node)) { + if (first_index > 0) + return 0; + results[0] = (void **)&root->rnode; + return 1; + } + node = radix_tree_indirect_to_ptr(node); + + max_index = radix_tree_maxindex(node->height); + + ret = 0; + while (ret < max_items) { + unsigned int slots_found; + unsigned long next_index; /* Index of next search */ + + if (cur_index > max_index) + break; + slots_found = __lookup(node, results + ret, cur_index, + max_items - ret, &next_index); + ret += slots_found; + if (next_index == 0) + break; + cur_index = next_index; + } + + return ret; +} +EXPORT_SYMBOL(radix_tree_gang_lookup_slot); + /* * FIXME: the two tag_get()s here should use find_next_bit() instead of * open-coding the search. */ static unsigned int -__lookup_tag(struct radix_tree_node *slot, void **results, unsigned long index, +__lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index, unsigned int max_items, unsigned long *next_index, unsigned int tag) { unsigned int nr_found = 0; @@ -811,11 +876,9 @@ __lookup_tag(struct radix_tree_node *slot, void **results, unsigned long index, unsigned long j = index & RADIX_TREE_MAP_MASK; for ( ; j < RADIX_TREE_MAP_SIZE; j++) { - struct radix_tree_node *node; index++; if (!tag_get(slot, tag, j)) continue; - node = slot->slots[j]; /* * Even though the tag was found set, we need to * recheck that we have a non-NULL node, because @@ -826,9 +889,8 @@ __lookup_tag(struct radix_tree_node *slot, void **results, unsigned long index, * lookup ->slots[x] without a lock (ie. can't * rely on its value remaining the same). */ - if (node) { - node = rcu_dereference(node); - results[nr_found++] = node; + if (slot->slots[j]) { + results[nr_found++] = &(slot->slots[j]); if (nr_found == max_items) goto out; } @@ -887,13 +949,22 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, ret = 0; while (ret < max_items) { - unsigned int nr_found; + unsigned int nr_found, slots_found, i; unsigned long next_index; /* Index of next search */ if (cur_index > max_index) break; - nr_found = __lookup_tag(node, results + ret, cur_index, - max_items - ret, &next_index, tag); + slots_found = __lookup_tag(node, (void ***)results + ret, + cur_index, max_items - ret, &next_index, tag); + nr_found = 0; + for (i = 0; i < slots_found; i++) { + struct radix_tree_node *slot; + slot = *(((void ***)results)[ret + i]); + if (!slot) + continue; + results[ret + nr_found] = rcu_dereference(slot); + nr_found++; + } ret += nr_found; if (next_index == 0) break; @@ -904,6 +975,67 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, } EXPORT_SYMBOL(radix_tree_gang_lookup_tag); +/** + * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a + * radix tree based on a tag + * @root: radix tree root + * @results: where the results of the lookup are placed + * @first_index: start the lookup from this key + * @max_items: place up to this many items at *results + * @tag: the tag index (< RADIX_TREE_MAX_TAGS) + * + * Performs an index-ascending scan of the tree for present items which + * have the tag indexed by @tag set. Places the slots at *@results and + * returns the number of slots which were placed at *@results. + */ +unsigned int +radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, + unsigned long first_index, unsigned int max_items, + unsigned int tag) +{ + struct radix_tree_node *node; + unsigned long max_index; + unsigned long cur_index = first_index; + unsigned int ret; + + /* check the root's tag bit */ + if (!root_tag_get(root, tag)) + return 0; + + node = rcu_dereference(root->rnode); + if (!node) + return 0; + + if (!radix_tree_is_indirect_ptr(node)) { + if (first_index > 0) + return 0; + results[0] = (void **)&root->rnode; + return 1; + } + node = radix_tree_indirect_to_ptr(node); + + max_index = radix_tree_maxindex(node->height); + + ret = 0; + while (ret < max_items) { + unsigned int slots_found; + unsigned long next_index; /* Index of next search */ + + if (cur_index > max_index) + break; + slots_found = __lookup_tag(node, results + ret, + cur_index, max_items - ret, &next_index, tag); + ret += slots_found; + if (next_index == 0) + break; + cur_index = next_index; + } + + return ret; +} +EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); + + /** * radix_tree_shrink - shrink height of a radix tree to minimal * @root radix tree root -- cgit v1.2.3 From 51cc50685a4275c6a02653670af9f108a64e01cf Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Fri, 25 Jul 2008 19:45:34 -0700 Subject: SL*B: drop kmem cache argument from constructor Kmem cache passed to constructor is only needed for constructors that are themselves multiplexeres. Nobody uses this "feature", nor does anybody uses passed kmem cache in non-trivial way, so pass only pointer to object. Non-trivial places are: arch/powerpc/mm/init_64.c arch/powerpc/mm/hugetlbpage.c This is flag day, yes. Signed-off-by: Alexey Dobriyan Acked-by: Pekka Enberg Acked-by: Christoph Lameter Cc: Jon Tollefson Cc: Nick Piggin Cc: Matt Mackall [akpm@linux-foundation.org: fix arch/powerpc/mm/hugetlbpage.c] [akpm@linux-foundation.org: fix mm/slab.c] [akpm@linux-foundation.org: fix ubifs] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/radix-tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'lib/radix-tree.c') diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 9c4f1ffa286..be86b32bc87 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -1183,7 +1183,7 @@ int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) EXPORT_SYMBOL(radix_tree_tagged); static void -radix_tree_node_ctor(struct kmem_cache *cachep, void *node) +radix_tree_node_ctor(void *node) { memset(node, 0, sizeof(struct radix_tree_node)); } -- cgit v1.2.3