forked from Minki/linux
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 <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Aneesh Kumar K.V
Theodore Ts'o
parent
c2774d84fd
commit
c894058d66
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@ -2300,6 +2300,7 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
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}
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INIT_LIST_HEAD(&meta_group_info[i]->bb_prealloc_list);
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meta_group_info[i]->bb_free_root.rb_node = NULL;;
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#ifdef DOUBLE_CHECK
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{
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@ -2647,13 +2648,11 @@ int ext4_mb_release(struct super_block *sb)
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static noinline_for_stack void
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ext4_mb_free_committed_blocks(struct super_block *sb)
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{
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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int err;
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int i;
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int count = 0;
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int count2 = 0;
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struct ext4_free_metadata *md;
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struct ext4_buddy e4b;
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struct ext4_group_info *db;
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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int err, count = 0, count2 = 0;
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struct ext4_free_data *entry;
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if (list_empty(&sbi->s_committed_transaction))
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return;
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@ -2661,44 +2660,46 @@ ext4_mb_free_committed_blocks(struct super_block *sb)
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/* there is committed blocks to be freed yet */
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do {
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/* get next array of blocks */
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md = NULL;
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entry = NULL;
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spin_lock(&sbi->s_md_lock);
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if (!list_empty(&sbi->s_committed_transaction)) {
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md = list_entry(sbi->s_committed_transaction.next,
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struct ext4_free_metadata, list);
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list_del(&md->list);
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entry = list_entry(sbi->s_committed_transaction.next,
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struct ext4_free_data, list);
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list_del(&entry->list);
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}
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spin_unlock(&sbi->s_md_lock);
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if (md == NULL)
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if (entry == NULL)
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break;
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mb_debug("gonna free %u blocks in group %lu (0x%p):",
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md->num, md->group, md);
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entry->count, entry->group, entry);
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err = ext4_mb_load_buddy(sb, md->group, &e4b);
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err = ext4_mb_load_buddy(sb, entry->group, &e4b);
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/* we expect to find existing buddy because it's pinned */
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BUG_ON(err != 0);
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db = e4b.bd_info;
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/* there are blocks to put in buddy to make them really free */
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count += md->num;
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count += entry->count;
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count2++;
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ext4_lock_group(sb, md->group);
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for (i = 0; i < md->num; i++) {
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mb_debug(" %u", md->blocks[i]);
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mb_free_blocks(NULL, &e4b, md->blocks[i], 1);
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ext4_lock_group(sb, entry->group);
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/* Take it out of per group rb tree */
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rb_erase(&entry->node, &(db->bb_free_root));
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mb_free_blocks(NULL, &e4b, entry->start_blk, entry->count);
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if (!db->bb_free_root.rb_node) {
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/* No more items in the per group rb tree
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* balance refcounts from ext4_mb_free_metadata()
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*/
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page_cache_release(e4b.bd_buddy_page);
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page_cache_release(e4b.bd_bitmap_page);
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}
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mb_debug("\n");
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ext4_unlock_group(sb, md->group);
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ext4_unlock_group(sb, entry->group);
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/* balance refcounts from ext4_mb_free_metadata() */
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page_cache_release(e4b.bd_buddy_page);
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page_cache_release(e4b.bd_bitmap_page);
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kfree(md);
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kmem_cache_free(ext4_free_ext_cachep, entry);
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ext4_mb_release_desc(&e4b);
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} while (md);
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} while (1);
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mb_debug("freed %u blocks in %u structures\n", count, count2);
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}
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@ -2771,6 +2772,16 @@ int __init init_ext4_mballoc(void)
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kmem_cache_destroy(ext4_pspace_cachep);
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return -ENOMEM;
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}
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ext4_free_ext_cachep =
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kmem_cache_create("ext4_free_block_extents",
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sizeof(struct ext4_free_data),
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0, SLAB_RECLAIM_ACCOUNT, NULL);
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if (ext4_free_ext_cachep == NULL) {
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kmem_cache_destroy(ext4_pspace_cachep);
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kmem_cache_destroy(ext4_ac_cachep);
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return -ENOMEM;
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}
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return 0;
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}
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@ -2779,6 +2790,7 @@ void exit_ext4_mballoc(void)
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/* XXX: synchronize_rcu(); */
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kmem_cache_destroy(ext4_pspace_cachep);
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kmem_cache_destroy(ext4_ac_cachep);
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kmem_cache_destroy(ext4_free_ext_cachep);
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}
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@ -4415,6 +4427,21 @@ static void ext4_mb_poll_new_transaction(struct super_block *sb,
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ext4_mb_free_committed_blocks(sb);
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}
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/*
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* We can merge two free data extents only if the physical blocks
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* are contiguous, AND the extents were freed by the same transaction,
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* AND the blocks are associated with the same group.
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*/
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static int can_merge(struct ext4_free_data *entry1,
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struct ext4_free_data *entry2)
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{
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if ((entry1->t_tid == entry2->t_tid) &&
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(entry1->group == entry2->group) &&
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((entry1->start_blk + entry1->count) == entry2->start_blk))
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return 1;
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return 0;
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}
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static noinline_for_stack int
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ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
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ext4_group_t group, ext4_grpblk_t block, int count)
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@ -4422,57 +4449,80 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
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struct ext4_group_info *db = e4b->bd_info;
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struct super_block *sb = e4b->bd_sb;
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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struct ext4_free_metadata *md;
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int i;
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struct ext4_free_data *entry, *new_entry;
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struct rb_node **n = &db->bb_free_root.rb_node, *node;
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struct rb_node *parent = NULL, *new_node;
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BUG_ON(e4b->bd_bitmap_page == NULL);
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BUG_ON(e4b->bd_buddy_page == NULL);
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new_entry = kmem_cache_alloc(ext4_free_ext_cachep, GFP_NOFS);
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new_entry->start_blk = block;
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new_entry->group = group;
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new_entry->count = count;
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new_entry->t_tid = handle->h_transaction->t_tid;
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new_node = &new_entry->node;
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ext4_lock_group(sb, group);
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for (i = 0; i < count; i++) {
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md = db->bb_md_cur;
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if (md && db->bb_tid != handle->h_transaction->t_tid) {
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db->bb_md_cur = NULL;
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md = NULL;
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}
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if (md == NULL) {
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ext4_unlock_group(sb, group);
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md = kmalloc(sizeof(*md), GFP_NOFS);
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if (md == NULL)
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return -ENOMEM;
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md->num = 0;
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md->group = group;
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ext4_lock_group(sb, group);
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if (db->bb_md_cur == NULL) {
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spin_lock(&sbi->s_md_lock);
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list_add(&md->list, &sbi->s_active_transaction);
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spin_unlock(&sbi->s_md_lock);
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/* protect buddy cache from being freed,
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* otherwise we'll refresh it from
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* on-disk bitmap and lose not-yet-available
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* blocks */
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page_cache_get(e4b->bd_buddy_page);
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page_cache_get(e4b->bd_bitmap_page);
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db->bb_md_cur = md;
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db->bb_tid = handle->h_transaction->t_tid;
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mb_debug("new md 0x%p for group %lu\n",
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md, md->group);
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} else {
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kfree(md);
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md = db->bb_md_cur;
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}
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}
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BUG_ON(md->num >= EXT4_BB_MAX_BLOCKS);
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md->blocks[md->num] = block + i;
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md->num++;
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if (md->num == EXT4_BB_MAX_BLOCKS) {
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/* no more space, put full container on a sb's list */
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db->bb_md_cur = NULL;
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if (!*n) {
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/* first free block exent. We need to
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protect buddy cache from being freed,
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* otherwise we'll refresh it from
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* on-disk bitmap and lose not-yet-available
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* blocks */
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page_cache_get(e4b->bd_buddy_page);
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page_cache_get(e4b->bd_bitmap_page);
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}
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while (*n) {
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parent = *n;
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entry = rb_entry(parent, struct ext4_free_data, node);
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if (block < entry->start_blk)
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n = &(*n)->rb_left;
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else if (block >= (entry->start_blk + entry->count))
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n = &(*n)->rb_right;
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else {
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ext4_error(sb, __func__,
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"Double free of blocks %d (%d %d)\n",
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block, entry->start_blk, entry->count);
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return 0;
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}
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}
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rb_link_node(new_node, parent, n);
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rb_insert_color(new_node, &db->bb_free_root);
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/* Now try to see the extent can be merged to left and right */
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node = rb_prev(new_node);
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if (node) {
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entry = rb_entry(node, struct ext4_free_data, node);
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if (can_merge(entry, new_entry)) {
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new_entry->start_blk = entry->start_blk;
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new_entry->count += entry->count;
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rb_erase(node, &(db->bb_free_root));
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spin_lock(&sbi->s_md_lock);
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list_del(&entry->list);
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spin_unlock(&sbi->s_md_lock);
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kmem_cache_free(ext4_free_ext_cachep, entry);
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}
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}
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node = rb_next(new_node);
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if (node) {
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entry = rb_entry(node, struct ext4_free_data, node);
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if (can_merge(new_entry, entry)) {
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new_entry->count += entry->count;
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rb_erase(node, &(db->bb_free_root));
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spin_lock(&sbi->s_md_lock);
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list_del(&entry->list);
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spin_unlock(&sbi->s_md_lock);
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kmem_cache_free(ext4_free_ext_cachep, entry);
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}
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}
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/* Add the extent to active_transaction list */
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spin_lock(&sbi->s_md_lock);
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list_add(&new_entry->list, &sbi->s_active_transaction);
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spin_unlock(&sbi->s_md_lock);
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ext4_unlock_group(sb, group);
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return 0;
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}
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@ -98,23 +98,29 @@
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static struct kmem_cache *ext4_pspace_cachep;
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static struct kmem_cache *ext4_ac_cachep;
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static struct kmem_cache *ext4_free_ext_cachep;
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#ifdef EXT4_BB_MAX_BLOCKS
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#undef EXT4_BB_MAX_BLOCKS
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#endif
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#define EXT4_BB_MAX_BLOCKS 30
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struct ext4_free_data {
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/* this links the free block information from group_info */
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struct rb_node node;
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struct ext4_free_metadata {
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ext4_group_t group;
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unsigned short num;
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ext4_grpblk_t blocks[EXT4_BB_MAX_BLOCKS];
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/* this links the free block information from ext4_sb_info */
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struct list_head list;
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/* group which free block extent belongs */
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ext4_group_t group;
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/* free block extent */
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ext4_grpblk_t start_blk;
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ext4_grpblk_t count;
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/* transaction which freed this extent */
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tid_t t_tid;
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};
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struct ext4_group_info {
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unsigned long bb_state;
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unsigned long bb_tid;
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struct ext4_free_metadata *bb_md_cur;
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struct rb_root bb_free_root;
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unsigned short bb_first_free;
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unsigned short bb_free;
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unsigned short bb_fragments;
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