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From: Johannes Thumshirn <jth@kernel.org>
Subject: [PATCH v4 0/2] btrfs: zoned: always set aside a zone for
 relocation
Date: Thu, 23 May 2024 17:21:57 +0200
Message-Id: <20240523-zoned-gc-v4-0-23ed9f61afa0@kernel.org>
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To: Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>, 
 David Sterba <dsterba@suse.com>
Cc: Hans Holmberg <Hans.Holmberg@wdc.com>, linux-btrfs@vger.kernel.org, 
 linux-kernel@vger.kernel.org, Naohiro Aota <naohiro.aota@wdc.com>, 
 Filipe Manana <fdmanana@suse.com>, 
 Johannes Thumshirn <johannes.thumshirn@wdc.com>

For zoned filesytsems we heavily rely on relocation for garbage collecting
as we cannot do any in-place updates of disk blocks.

But there can be situations where we're running out of space for doing the
relocation.

To solve this, always have a zone reserved for relocation.

This is a subset of another approach to this problem I've submitted in
https://lore.kernel.org/r/20240328-hans-v1-0-4cd558959407@kernel.org

---
Changes in v4:
- Skip data_reloc_bg in delete_unused_bgs() and reclaim_bgs_work()
- Link to v3: https://lore.kernel.org/r/20240521-zoned-gc-v3-0-7db9742454c7@kernel.org

Changes in v3:
- Rename btrfs_reserve_relocation_zone -> btrfs_reserve_relocation_bg
- Bail out if we already have a relocation bg set
- Link to v2: https://lore.kernel.org/r/20240515-zoned-gc-v2-0-20c7cb9763cd@kernel.org

Changes in v2:
- Incorporate Naohiro's review
- Link to v1: https://lore.kernel.org/r/20240514-zoned-gc-v1-0-109f1a6c7447@kernel.org

---
Johannes Thumshirn (2):
      btrfs: zoned: reserve relocation block-group on mount
      btrfs: reserve new relocation block-group after successful relocation

 fs/btrfs/block-group.c | 17 +++++++++++++
 fs/btrfs/disk-io.c     |  2 ++
 fs/btrfs/relocation.c  |  7 ++++++
 fs/btrfs/zoned.c       | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/zoned.h       |  3 +++
 5 files changed, 96 insertions(+)
---
base-commit: 2aabf192868a0f6d9ee3e35f9b0a8d97c77a46da
change-id: 20240514-zoned-gc-2ce793459eb7

Best regards,
-- 
Johannes Thumshirn <jth@kernel.org>