Commit 3a637294 authored by Omar Sandoval's avatar Omar Sandoval Committed by Greg Kroah-Hartman

Btrfs: fix early ENOSPC due to delalloc

commit 17024ad0 upstream.

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: 957780eb ("Btrfs: introduce ticketed enospc infrastructure")
Tested-by: default avatarChristoph Anton Mitterer <mail@christoph.anton.mitterer.name>
Reviewed-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0f442c5b
......@@ -4759,10 +4759,6 @@ static void shrink_delalloc(struct btrfs_root *root, u64 to_reclaim, u64 orig,
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);
......
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