Re: FAILED: patch "[PATCH] Btrfs: fix early ENOSPC due to delalloc" failed to apply to 4.12-stable tree

[Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>]

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Hey.

Could someone of the devs put some attention on this...?

Thanks,
Chris :-)


On Mon, 2017-07-31 at 18:06 -0700, gregkh@linuxfoundation.org wrote:
> The patch below does not apply to the 4.12-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git
> commit
> id to <stable@vger.kernel.org>.
> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
> From 17024ad0a0fdfcfe53043afb969b813d3e020c21 Mon Sep 17 00:00:00
> 2001
> From: Omar Sandoval <osandov@fb.com>
> Date: Thu, 20 Jul 2017 15:10:35 -0700
> Subject: [PATCH] Btrfs: fix early ENOSPC due to delalloc
> 
> If a lot of metadata is reserved for outstanding delayed allocations,
> we
> rely on shrink_delalloc() to reclaim metadata space in order to
> fulfill
> reservation tickets. However, shrink_delalloc() has a shortcut where
> if
> it determines that space can be overcommitted, it will stop early.
> This
> made sense before the ticketed enospc system, but now it means that
> shrink_delalloc() will often not reclaim enough space to fulfill any
> tickets, leading to an early ENOSPC. (Reservation tickets don't care
> about being able to overcommit, they need every byte accounted for.)
> 
> Fix it by getting rid of the shortcut so that shrink_delalloc()
> reclaims
> all of the metadata it is supposed to. This fixes early ENOSPCs we
> were
> seeing when doing a btrfs receive to populate a new filesystem, as
> well
> as early ENOSPCs Christoph saw when doing a big cp -r onto Btrfs.
> 
> Fixes: 957780eb2788 ("Btrfs: introduce ticketed enospc
> infrastructure")
> Tested-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.na
> me>
> Cc: stable@vger.kernel.org
> Reviewed-by: Josef Bacik <jbacik@fb.com>
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> Signed-off-by: David Sterba <dsterba@suse.com>
> 
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index a6635f07b8f1..e3b0b4196d3d 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -4825,10 +4825,6 @@ static void shrink_delalloc(struct
> btrfs_fs_info *fs_info, u64 to_reclaim,
>  		else
>  			flush = BTRFS_RESERVE_NO_FLUSH;
>  		spin_lock(&space_info->lock);
> -		if (can_overcommit(fs_info, space_info, orig, flush,
> false)) {
> -			spin_unlock(&space_info->lock);
> -			break;
> -		}
>  		if (list_empty(&space_info->tickets) &&
>  		    list_empty(&space_info->priority_tickets)) {
>  			spin_unlock(&space_info->lock);
> 

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