Re: [PATCH] btrfs: increment extent count once when logging extents during fast fsync

[Qu Wenruo <wqu@suse.com>]

在 2026/9/11 02:05, fdmanana@kernel.org 写道:
> From: Filipe Manana <fdmanana@suse.com>
> 
> In btrfs_log_changed_extents() we increment the extent count twice, and
> we then fallback to a transaction commit if the count reaches a threshold
> of 32K. However we increment the count twice, which is confusing and
> pointless. So increment the count only once and reduce the threshold to
> half (16K).
> 
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu

> ---
>   fs/btrfs/tree-log.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
> index a00094604e54..6c6b362d7f4c 100644
> --- a/fs/btrfs/tree-log.c
> +++ b/fs/btrfs/tree-log.c
> @@ -5350,7 +5350,7 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
>   		 * have a bunch of extents we just want to commit since it will
>   		 * be faster.
>   		 */
> -		if (++num > 32768) {
> +		if (++num > SZ_16K) {
>   			list_del_init(&tree->modified_extents);
>   			ret = -EFBIG;
>   			goto process;
> @@ -5368,7 +5368,6 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
>   		refcount_inc(&em->refs);
>   		em->flags |= EXTENT_FLAG_LOGGING;
>   		list_add_tail(&em->list, &extents);
> -		num++;
>   	}
>   
>   	list_sort(NULL, &extents, extent_cmp);