On 08/01/17 03:06, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
>
> The patch below does not apply to the 4.9-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@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From 17024ad0a0fdfcfe53043afb969b813d3e020c21 Mon Sep 17 00:00:00 2001
> From: Omar Sandoval <osandov@xxxxxx>
> 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@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Reviewed-by: Josef Bacik <jbacik@xxxxxx>
> Signed-off-by: Omar Sandoval <osandov@xxxxxx>
> Signed-off-by: David Sterba <dsterba@xxxxxxxx>
>
> 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);
>
This is kind of important to have, so attached is the backport for 4.9.40
that I've been using; I just rediffed it to apply cleanly.
For 4.12.x someone else needs to step up.
-h
Signed-off-by: Holger Hoffstätte <holger@xxxxxxxxxxxxxxxxxxxxxx>
diff -rup linux-4.9.40/fs/btrfs/extent-tree.c linux-4.9.40+/fs/btrfs/extent-tree.c
--- linux-4.9.40/fs/btrfs/extent-tree.c 2017-06-29 13:00:49.000000000 +0200
+++ linux-4.9.40+/fs/btrfs/extent-tree.c 2017-08-04 19:05:27.717936241 +0200
@@ -4759,10 +4759,6 @@ skip_async:
else
flush = BTRFS_RESERVE_NO_FLUSH;
spin_lock(&space_info->lock);
- if (can_overcommit(root, space_info, orig, flush)) {
- spin_unlock(&space_info->lock);
- break;
- }
if (list_empty(&space_info->tickets) &&
list_empty(&space_info->priority_tickets)) {
spin_unlock(&space_info->lock);