From 9ef17228e1096e7e75bdde752ae1f0e9a5bcc8ab Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Thu, 28 Sep 2023 11:12:50 +0100 Subject: [PATCH] btrfs: stop reserving excessive space for block group item insertions Space for block group item insertions, necessary after allocating a new block group, is reserved in the delayed refs block reserve. Currently we do this by incrementing the transaction handle's delayed_ref_updates counter and then calling btrfs_update_delayed_refs_rsv(), which will increase the size of the delayed refs block reserve by an amount that corresponds to the same amount we use for delayed refs, given by btrfs_calc_delayed_ref_bytes(). That is an excessive amount because it corresponds to the amount of space needed to insert one item in a btree (btrfs_calc_insert_metadata_size()) times 2 when the free space tree feature is enabled. All we need is an amount as given by btrfs_calc_insert_metadata_size(), since we only need to insert a block group item in the extent tree (or block group tree if this feature is enabled). By using btrfs_calc_insert_metadata_size() we will need to reserve 2 times less space when using the free space tree, putting less pressure on space reservation. So use helpers to reserve and release space for block group item insertions that use btrfs_calc_insert_metadata_size() for calculation of the space. Signed-off-by: Filipe Manana Signed-off-by: David Sterba --- fs/btrfs/block-group.c | 5 ++--- fs/btrfs/delayed-ref.c | 35 +++++++++++++++++++++++++++++++++++ fs/btrfs/delayed-ref.h | 2 ++ fs/btrfs/transaction.c | 2 +- 4 files changed, 40 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index 9d17b0580fbf9..6e5dc68ff661f 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -2709,7 +2709,7 @@ void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans) /* Already aborted the transaction if it failed. */ next: - btrfs_delayed_refs_rsv_release(fs_info, 1, 0); + btrfs_dec_delayed_refs_rsv_bg_inserts(fs_info); list_del_init(&block_group->bg_list); clear_bit(BLOCK_GROUP_FLAG_NEW, &block_group->runtime_flags); } @@ -2819,8 +2819,7 @@ struct btrfs_block_group *btrfs_make_block_group(struct btrfs_trans_handle *tran #endif list_add_tail(&cache->bg_list, &trans->new_bgs); - trans->delayed_ref_updates++; - btrfs_update_delayed_refs_rsv(trans); + btrfs_inc_delayed_refs_rsv_bg_inserts(fs_info); set_avail_alloc_bits(fs_info, type); return cache; diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index de84347959134..9223934d95f47 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -125,6 +125,41 @@ void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans) trans->delayed_ref_csum_deletions = 0; } +/* + * Adjust the size of the delayed refs block reserve for 1 block group item + * insertion, used after allocating a block group. + */ +void btrfs_inc_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info) +{ + struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv; + + spin_lock(&delayed_rsv->lock); + /* + * Inserting a block group item does not require changing the free space + * tree, only the extent tree or the block group tree, so this is all we + * need. + */ + delayed_rsv->size += btrfs_calc_insert_metadata_size(fs_info, 1); + delayed_rsv->full = false; + spin_unlock(&delayed_rsv->lock); +} + +/* + * Adjust the size of the delayed refs block reserve to release space for 1 + * block group item insertion. + */ +void btrfs_dec_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info) +{ + struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv; + const u64 num_bytes = btrfs_calc_insert_metadata_size(fs_info, 1); + u64 released; + + released = btrfs_block_rsv_release(fs_info, delayed_rsv, num_bytes, NULL); + if (released > 0) + trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv", + 0, released, 0); +} + /* * Adjust the size of the delayed refs block reserve for 1 block group item * update. diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index 250e8742a1365..62d679d40f4f9 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -436,6 +436,8 @@ int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq); void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr_refs, int nr_csums); void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans); +void btrfs_inc_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info); +void btrfs_dec_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info); void btrfs_inc_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info); void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info); int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info, diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 77f8175d464ba..3aa59cfa4ab01 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -2135,7 +2135,7 @@ static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans) struct btrfs_block_group *block_group, *tmp; list_for_each_entry_safe(block_group, tmp, &trans->new_bgs, bg_list) { - btrfs_delayed_refs_rsv_release(fs_info, 1, 0); + btrfs_dec_delayed_refs_rsv_bg_inserts(fs_info); list_del_init(&block_group->bg_list); } } -- 2.39.2