From c894058d66637c7720569fbe12957f4de64d9991 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Thu, 16 Oct 2008 10:14:27 -0400 Subject: ext4: Use an rbtree for tracking blocks freed during transaction. With this patch we track the block freed during a transaction using red-black tree. We also make sure contiguous blocks freed are collected in one node in the tree. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Theodore Ts'o diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 154f8de..bd9b011 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2300,6 +2300,7 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group, } INIT_LIST_HEAD(&meta_group_info[i]->bb_prealloc_list); + meta_group_info[i]->bb_free_root.rb_node = NULL;; #ifdef DOUBLE_CHECK { @@ -2647,13 +2648,11 @@ int ext4_mb_release(struct super_block *sb) static noinline_for_stack void ext4_mb_free_committed_blocks(struct super_block *sb) { - struct ext4_sb_info *sbi = EXT4_SB(sb); - int err; - int i; - int count = 0; - int count2 = 0; - struct ext4_free_metadata *md; struct ext4_buddy e4b; + struct ext4_group_info *db; + struct ext4_sb_info *sbi = EXT4_SB(sb); + int err, count = 0, count2 = 0; + struct ext4_free_data *entry; if (list_empty(&sbi->s_committed_transaction)) return; @@ -2661,44 +2660,46 @@ ext4_mb_free_committed_blocks(struct super_block *sb) /* there is committed blocks to be freed yet */ do { /* get next array of blocks */ - md = NULL; + entry = NULL; spin_lock(&sbi->s_md_lock); if (!list_empty(&sbi->s_committed_transaction)) { - md = list_entry(sbi->s_committed_transaction.next, - struct ext4_free_metadata, list); - list_del(&md->list); + entry = list_entry(sbi->s_committed_transaction.next, + struct ext4_free_data, list); + list_del(&entry->list); } spin_unlock(&sbi->s_md_lock); - if (md == NULL) + if (entry == NULL) break; mb_debug("gonna free %u blocks in group %lu (0x%p):", - md->num, md->group, md); + entry->count, entry->group, entry); - err = ext4_mb_load_buddy(sb, md->group, &e4b); + err = ext4_mb_load_buddy(sb, entry->group, &e4b); /* we expect to find existing buddy because it's pinned */ BUG_ON(err != 0); + db = e4b.bd_info; /* there are blocks to put in buddy to make them really free */ - count += md->num; + count += entry->count; count2++; - ext4_lock_group(sb, md->group); - for (i = 0; i < md->num; i++) { - mb_debug(" %u", md->blocks[i]); - mb_free_blocks(NULL, &e4b, md->blocks[i], 1); + ext4_lock_group(sb, entry->group); + /* Take it out of per group rb tree */ + rb_erase(&entry->node, &(db->bb_free_root)); + mb_free_blocks(NULL, &e4b, entry->start_blk, entry->count); + + if (!db->bb_free_root.rb_node) { + /* No more items in the per group rb tree + * balance refcounts from ext4_mb_free_metadata() + */ + page_cache_release(e4b.bd_buddy_page); + page_cache_release(e4b.bd_bitmap_page); } - mb_debug("\n"); - ext4_unlock_group(sb, md->group); - - /* balance refcounts from ext4_mb_free_metadata() */ - page_cache_release(e4b.bd_buddy_page); - page_cache_release(e4b.bd_bitmap_page); + ext4_unlock_group(sb, entry->group); - kfree(md); + kmem_cache_free(ext4_free_ext_cachep, entry); ext4_mb_release_desc(&e4b); - - } while (md); + } while (1); mb_debug("freed %u blocks in %u structures\n", count, count2); } @@ -2771,6 +2772,16 @@ int __init init_ext4_mballoc(void) kmem_cache_destroy(ext4_pspace_cachep); return -ENOMEM; } + + ext4_free_ext_cachep = + kmem_cache_create("ext4_free_block_extents", + sizeof(struct ext4_free_data), + 0, SLAB_RECLAIM_ACCOUNT, NULL); + if (ext4_free_ext_cachep == NULL) { + kmem_cache_destroy(ext4_pspace_cachep); + kmem_cache_destroy(ext4_ac_cachep); + return -ENOMEM; + } return 0; } @@ -2779,6 +2790,7 @@ void exit_ext4_mballoc(void) /* XXX: synchronize_rcu(); */ kmem_cache_destroy(ext4_pspace_cachep); kmem_cache_destroy(ext4_ac_cachep); + kmem_cache_destroy(ext4_free_ext_cachep); } @@ -4415,6 +4427,21 @@ static void ext4_mb_poll_new_transaction(struct super_block *sb, ext4_mb_free_committed_blocks(sb); } +/* + * We can merge two free data extents only if the physical blocks + * are contiguous, AND the extents were freed by the same transaction, + * AND the blocks are associated with the same group. + */ +static int can_merge(struct ext4_free_data *entry1, + struct ext4_free_data *entry2) +{ + if ((entry1->t_tid == entry2->t_tid) && + (entry1->group == entry2->group) && + ((entry1->start_blk + entry1->count) == entry2->start_blk)) + return 1; + return 0; +} + static noinline_for_stack int ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b, ext4_group_t group, ext4_grpblk_t block, int count) @@ -4422,57 +4449,80 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b, struct ext4_group_info *db = e4b->bd_info; struct super_block *sb = e4b->bd_sb; struct ext4_sb_info *sbi = EXT4_SB(sb); - struct ext4_free_metadata *md; - int i; + struct ext4_free_data *entry, *new_entry; + struct rb_node **n = &db->bb_free_root.rb_node, *node; + struct rb_node *parent = NULL, *new_node; + BUG_ON(e4b->bd_bitmap_page == NULL); BUG_ON(e4b->bd_buddy_page == NULL); + new_entry = kmem_cache_alloc(ext4_free_ext_cachep, GFP_NOFS); + new_entry->start_blk = block; + new_entry->group = group; + new_entry->count = count; + new_entry->t_tid = handle->h_transaction->t_tid; + new_node = &new_entry->node; + ext4_lock_group(sb, group); - for (i = 0; i < count; i++) { - md = db->bb_md_cur; - if (md && db->bb_tid != handle->h_transaction->t_tid) { - db->bb_md_cur = NULL; - md = NULL; + if (!*n) { + /* first free block exent. We need to + protect buddy cache from being freed, + * otherwise we'll refresh it from + * on-disk bitmap and lose not-yet-available + * blocks */ + page_cache_get(e4b->bd_buddy_page); + page_cache_get(e4b->bd_bitmap_page); + } + while (*n) { + parent = *n; + entry = rb_entry(parent, struct ext4_free_data, node); + if (block < entry->start_blk) + n = &(*n)->rb_left; + else if (block >= (entry->start_blk + entry->count)) + n = &(*n)->rb_right; + else { + ext4_error(sb, __func__, + "Double free of blocks %d (%d %d)\n", + block, entry->start_blk, entry->count); + return 0; } + } - if (md == NULL) { - ext4_unlock_group(sb, group); - md = kmalloc(sizeof(*md), GFP_NOFS); - if (md == NULL) - return -ENOMEM; - md->num = 0; - md->group = group; - - ext4_lock_group(sb, group); - if (db->bb_md_cur == NULL) { - spin_lock(&sbi->s_md_lock); - list_add(&md->list, &sbi->s_active_transaction); - spin_unlock(&sbi->s_md_lock); - /* protect buddy cache from being freed, - * otherwise we'll refresh it from - * on-disk bitmap and lose not-yet-available - * blocks */ - page_cache_get(e4b->bd_buddy_page); - page_cache_get(e4b->bd_bitmap_page); - db->bb_md_cur = md; - db->bb_tid = handle->h_transaction->t_tid; - mb_debug("new md 0x%p for group %lu\n", - md, md->group); - } else { - kfree(md); - md = db->bb_md_cur; - } + rb_link_node(new_node, parent, n); + rb_insert_color(new_node, &db->bb_free_root); + + /* Now try to see the extent can be merged to left and right */ + node = rb_prev(new_node); + if (node) { + entry = rb_entry(node, struct ext4_free_data, node); + if (can_merge(entry, new_entry)) { + new_entry->start_blk = entry->start_blk; + new_entry->count += entry->count; + rb_erase(node, &(db->bb_free_root)); + spin_lock(&sbi->s_md_lock); + list_del(&entry->list); + spin_unlock(&sbi->s_md_lock); + kmem_cache_free(ext4_free_ext_cachep, entry); } + } - BUG_ON(md->num >= EXT4_BB_MAX_BLOCKS); - md->blocks[md->num] = block + i; - md->num++; - if (md->num == EXT4_BB_MAX_BLOCKS) { - /* no more space, put full container on a sb's list */ - db->bb_md_cur = NULL; + node = rb_next(new_node); + if (node) { + entry = rb_entry(node, struct ext4_free_data, node); + if (can_merge(new_entry, entry)) { + new_entry->count += entry->count; + rb_erase(node, &(db->bb_free_root)); + spin_lock(&sbi->s_md_lock); + list_del(&entry->list); + spin_unlock(&sbi->s_md_lock); + kmem_cache_free(ext4_free_ext_cachep, entry); } } + /* Add the extent to active_transaction list */ + spin_lock(&sbi->s_md_lock); + list_add(&new_entry->list, &sbi->s_active_transaction); + spin_unlock(&sbi->s_md_lock); ext4_unlock_group(sb, group); return 0; } diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h index b3b4828..9e815c4 100644 --- a/fs/ext4/mballoc.h +++ b/fs/ext4/mballoc.h @@ -98,23 +98,29 @@ static struct kmem_cache *ext4_pspace_cachep; static struct kmem_cache *ext4_ac_cachep; +static struct kmem_cache *ext4_free_ext_cachep; -#ifdef EXT4_BB_MAX_BLOCKS -#undef EXT4_BB_MAX_BLOCKS -#endif -#define EXT4_BB_MAX_BLOCKS 30 +struct ext4_free_data { + /* this links the free block information from group_info */ + struct rb_node node; -struct ext4_free_metadata { - ext4_group_t group; - unsigned short num; - ext4_grpblk_t blocks[EXT4_BB_MAX_BLOCKS]; + /* this links the free block information from ext4_sb_info */ struct list_head list; + + /* group which free block extent belongs */ + ext4_group_t group; + + /* free block extent */ + ext4_grpblk_t start_blk; + ext4_grpblk_t count; + + /* transaction which freed this extent */ + tid_t t_tid; }; struct ext4_group_info { unsigned long bb_state; - unsigned long bb_tid; - struct ext4_free_metadata *bb_md_cur; + struct rb_root bb_free_root; unsigned short bb_first_free; unsigned short bb_free; unsigned short bb_fragments; -- cgit v0.10.2