On 21.11.18 г. 20:59 ч., Josef Bacik wrote:
> We have a bunch of magic to make sure we're throttling delayed refs when
> truncating a file. Now that we have a delayed refs rsv and a mechanism
> for refilling that reserve simply use that instead of all of this magic.
>
> Signed-off-by: Josef Bacik <jo...@toxicpanda.com>
Reviewed-by: Nikolay Borisov <nbori...@suse.com>
> ---
> fs/btrfs/inode.c | 79
> ++++++++++++--------------------------------------------
> 1 file changed, 17 insertions(+), 62 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 8532a2eb56d1..cae30f6c095f 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -4437,31 +4437,6 @@ static int btrfs_rmdir(struct inode *dir, struct
> dentry *dentry)
> return err;
> }
>
> -static int truncate_space_check(struct btrfs_trans_handle *trans,
> - struct btrfs_root *root,
> - u64 bytes_deleted)
> -{
> - struct btrfs_fs_info *fs_info = root->fs_info;
> - int ret;
> -
> - /*
> - * This is only used to apply pressure to the enospc system, we don't
> - * intend to use this reservation at all.
> - */
> - bytes_deleted = btrfs_csum_bytes_to_leaves(fs_info, bytes_deleted);
> - bytes_deleted *= fs_info->nodesize;
> - ret = btrfs_block_rsv_add(root, &fs_info->trans_block_rsv,
> - bytes_deleted, BTRFS_RESERVE_NO_FLUSH);
> - if (!ret) {
> - trace_btrfs_space_reservation(fs_info, "transaction",
> - trans->transid,
> - bytes_deleted, 1);
> - trans->bytes_reserved += bytes_deleted;
> - }
> - return ret;
> -
> -}
> -
> /*
> * Return this if we need to call truncate_block for the last bit of the
> * truncate.
> @@ -4506,7 +4481,6 @@ int btrfs_truncate_inode_items(struct
> btrfs_trans_handle *trans,
> u64 bytes_deleted = 0;
> bool be_nice = false;
> bool should_throttle = false;
> - bool should_end = false;
>
> BUG_ON(new_size > 0 && min_type != BTRFS_EXTENT_DATA_KEY);
>
> @@ -4719,15 +4693,7 @@ int btrfs_truncate_inode_items(struct
> btrfs_trans_handle *trans,
> btrfs_abort_transaction(trans, ret);
> break;
> }
> - if (btrfs_should_throttle_delayed_refs(trans))
> - btrfs_async_run_delayed_refs(fs_info,
> - trans->delayed_ref_updates * 2,
> - trans->transid, 0);
> if (be_nice) {
> - if (truncate_space_check(trans, root,
> - extent_num_bytes)) {
> - should_end = true;
> - }
> if (btrfs_should_throttle_delayed_refs(trans))
> should_throttle = true;
> }
> @@ -4738,7 +4704,7 @@ int btrfs_truncate_inode_items(struct
> btrfs_trans_handle *trans,
>
> if (path->slots[0] == 0 ||
> path->slots[0] != pending_del_slot ||
> - should_throttle || should_end) {
> + should_throttle) {
> if (pending_del_nr) {
> ret = btrfs_del_items(trans, root, path,
> pending_del_slot,
> @@ -4750,23 +4716,24 @@ int btrfs_truncate_inode_items(struct
> btrfs_trans_handle *trans,
> pending_del_nr = 0;
> }
> btrfs_release_path(path);
> - if (should_throttle) {
> - unsigned long updates =
> trans->delayed_ref_updates;
> - if (updates) {
> - trans->delayed_ref_updates = 0;
> - ret = btrfs_run_delayed_refs(trans,
> - updates * 2);
> - if (ret)
> - break;
> - }
> - }
> +
> /*
> - * if we failed to refill our space rsv, bail out
> - * and let the transaction restart
> + * We can generate a lot of delayed refs, so we need to
> + * throttle every once and a while and make sure we're
> + * adding enough space to keep up with the work we are
> + * generating. Since we hold a transaction here we
> + * can't flush, and we don't want to FLUSH_LIMIT because
> + * we could have generated too many delayed refs to
> + * actually allocate, so just bail if we're short and
> + * let the normal reservation dance happen higher up.
> */
> - if (should_end) {
> - ret = -EAGAIN;
> - break;
> + if (should_throttle) {
> + ret = btrfs_throttle_delayed_refs(fs_info,
> + BTRFS_RESERVE_NO_FLUSH);
> + if (ret) {
> + ret = -EAGAIN;
> + break;
> + }
> }
> goto search_again;
> } else {
> @@ -4792,18 +4759,6 @@ int btrfs_truncate_inode_items(struct
> btrfs_trans_handle *trans,
> }
>
> btrfs_free_path(path);
> -
> - if (be_nice && bytes_deleted > SZ_32M && (ret >= 0 || ret == -EAGAIN)) {
> - unsigned long updates = trans->delayed_ref_updates;
> - int err;
> -
> - if (updates) {
> - trans->delayed_ref_updates = 0;
> - err = btrfs_run_delayed_refs(trans, updates * 2);
> - if (err)
> - ret = err;
> - }
> - }
> return ret;
> }
>
>
