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From: Nikolay Borisov <nborisov@suse.com>
To: Josef Bacik <josef@toxicpanda.com>,
	linux-btrfs@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 3/8] btrfs: don't use global rsv for chunk allocation
Date: Mon, 26 Nov 2018 13:25:04 +0200
Message-ID: <d321d237-012b-f000-3771-f7946b38b2b7@suse.com> (raw)
In-Reply-To: <20181121190313.24575-4-josef@toxicpanda.com>



On 21.11.18 г. 21:03 ч., Josef Bacik wrote:
> We've done this forever because of the voodoo around knowing how much
> space we have.  However we have better ways of doing this now, and on
> normal file systems we'll easily have a global reserve of 512MiB, and
> since metadata chunks are usually 1GiB that means we'll allocate
> metadata chunks more readily.  Instead use the actual used amount when
> determining if we need to allocate a chunk or not.

This explanation could use more concrete wording currently it's way too
"hand wavy"/vague.

> 
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> ---
>  fs/btrfs/extent-tree.c | 9 ---------
>  1 file changed, 9 deletions(-)
> 
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index 7a30fbc05e5e..a91b3183dcae 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -4388,21 +4388,12 @@ static inline u64 calc_global_rsv_need_space(struct btrfs_block_rsv *global)
>  static int should_alloc_chunk(struct btrfs_fs_info *fs_info,
>  			      struct btrfs_space_info *sinfo, int force)
>  {
> -	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
>  	u64 bytes_used = btrfs_space_info_used(sinfo, false);
>  	u64 thresh;
>  
>  	if (force == CHUNK_ALLOC_FORCE)
>  		return 1;
>  
> -	/*
> -	 * We need to take into account the global rsv because for all intents
> -	 * and purposes it's used space.  Don't worry about locking the
> -	 * global_rsv, it doesn't change except when the transaction commits.
> -	 */
> -	if (sinfo->flags & BTRFS_BLOCK_GROUP_METADATA)
> -		bytes_used += calc_global_rsv_need_space(global_rsv);
> -
>  	/*
>  	 * in limited mode, we want to have some free space up to
>  	 * about 1% of the FS size.
> 

  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-21 19:03 [PATCH 0/8] Enospc cleanups and fixes Josef Bacik
2018-11-21 19:03 ` [PATCH 1/8] btrfs: check if free bgs for commit Josef Bacik
2018-11-26 10:45   ` Nikolay Borisov
2018-11-21 19:03 ` [PATCH 2/8] btrfs: dump block_rsv whe dumping space info Josef Bacik
2018-11-21 19:03 ` [PATCH 3/8] btrfs: don't use global rsv for chunk allocation Josef Bacik
2018-11-26 11:25   ` Nikolay Borisov [this message]
2018-11-21 19:03 ` [PATCH 4/8] btrfs: add ALLOC_CHUNK_FORCE to the flushing code Josef Bacik
2018-11-26 11:28   ` Nikolay Borisov
2018-11-21 19:03 ` [PATCH 5/8] btrfs: don't enospc all tickets on flush failure Josef Bacik
2018-11-26 12:25   ` Nikolay Borisov
2018-11-27 19:46     ` Josef Bacik
2018-11-28  8:11       ` Nikolay Borisov
2018-11-21 19:03 ` [PATCH 6/8] btrfs: loop in inode_rsv_refill Josef Bacik
2018-11-21 19:03 ` [PATCH 7/8] btrfs: be more explicit about allowed flush states Josef Bacik
2018-11-26 12:41   ` Nikolay Borisov
2018-11-26 12:45     ` Nikolay Borisov
2018-11-21 19:03 ` [PATCH 8/8] btrfs: reserve extra space during evict() Josef Bacik
2018-12-03 15:24 [PATCH 0/8][V2] Enospc cleanups and fixeS Josef Bacik
2018-12-03 15:24 ` [PATCH 3/8] btrfs: don't use global rsv for chunk allocation Josef Bacik
2018-12-11  9:59   ` Nikolay Borisov

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