[PATCH 3/3] btrfs: split RAID stripes on deletion

Johannes Thumshirn
2024-06-10T08:40:36Z

From: JohnnesThumshirn <johannes.thumshirn@wdc.com>

The current RAID stripe code assumes, that we will always remove a
whole stripe entry.

But ff we're only removing a part of a RAID stripe we're hitting the
ASSERT()ion checking for this condition.

Instead of assuming the complete deletion of a RAID stripe, split the
stripe if we need to.

Signed-off-by: Johnnes Thumshirn <johannes.thumshirn@wdc.com>
---
fs/btrfs/raid-stripe-tree.c | 101 +++++++++++++++++++++++++++++++++-----------
1 file changed, 77 insertions(+), 24 deletions(-)

diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
index 3020820dd6e2..41403217c3e6 100644
--- a/fs/btrfs/raid-stripe-tree.c
+++ b/fs/btrfs/raid-stripe-tree.c
@@ -33,42 +33,95 @@ int btrfs_delete_raid_extent(struct btrfs_trans_handle *trans, u64 start, u64 le
if (!path)
return -ENOMEM;

- while (1) {
- key.objectid = start;
- key.type = BTRFS_RAID_STRIPE_KEY;
- key.offset = length;
+again:
+ key.objectid = start;
+ key.type = BTRFS_RAID_STRIPE_KEY;
+ key.offset = length;

- ret = btrfs_search_slot(trans, stripe_root, &key, path, -1, 1);
- if (ret < 0)
- break;
- if (ret > 0) {
- ret = 0;
- if (path->slots[0] == 0)
- break;
- path->slots[0]--;
- }
+ ret = btrfs_search_slot(trans, stripe_root, &key, path, -1, 1);
+ if (ret < 0)
+ goto out;
+ if (ret > 0) {
+ ret = 0;
+ if (path->slots[0] == 0)
+ goto out;
+ path->slots[0]--;
+ }
+
+ leaf = path->nodes[0];
+ slot = path->slots[0];
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+ found_start = key.objectid;
+ found_end = found_start + key.offset;
+
+ /* That stripe ends before we start, we're done. */
+ if (found_end <= start)
+ goto out;
+
+ trace_btrfs_raid_extent_delete(fs_info, start, end,
+ found_start, found_end);
+
+ if (found_start < start) {
+ u64 diff = start - found_start;
+ struct btrfs_key new_key;
+ int num_stripes;
+ struct btrfs_stripe_extent *stripe_extent;
+
+ new_key.objectid = start;
+ new_key.type = BTRFS_RAID_STRIPE_KEY;
+ new_key.offset = length - diff;
+
+ ret = btrfs_duplicate_item(trans, stripe_root, path,
+ &new_key);
+ if (ret)
+ goto out;

leaf = path->nodes[0];
slot = path->slots[0];
- btrfs_item_key_to_cpu(leaf, &key, slot);
- found_start = key.objectid;
- found_end = found_start + key.offset;

- /* That stripe ends before we start, we're done. */
- if (found_end <= start)
- break;
+ num_stripes =
+ btrfs_num_raid_stripes(btrfs_item_size(leaf, slot));
+ stripe_extent =
+ btrfs_item_ptr(leaf, slot, struct btrfs_stripe_extent);

- trace_btrfs_raid_extent_delete(fs_info, start, end,
- found_start, found_end);
+ for (int i = 0; i < num_stripes; i++) {
+ struct btrfs_raid_stride *raid_stride =
+ &stripe_extent->strides[i];
+ u64 physical =
+ btrfs_raid_stride_physical(leaf, raid_stride);

- ASSERT(found_start >= start && found_end <= end);
- ret = btrfs_del_item(trans, stripe_root, path);
+ btrfs_set_stack_raid_stride_physical(raid_stride,
+ physical + diff);
+ }
+
+ btrfs_mark_buffer_dirty(trans, leaf);
+ btrfs_release_path(path);
+ goto again;
+ }
+
+ if (found_end > end) {
+ u64 diff = found_end - end;
+ struct btrfs_key new_key;
+
+ new_key.objectid = found_start;
+ new_key.type = BTRFS_RAID_STRIPE_KEY;
+ new_key.offset = length - diff;
+
+ ret = btrfs_duplicate_item(trans, stripe_root, path,
+ &new_key);
if (ret)
- break;
+ goto out;

+ btrfs_mark_buffer_dirty(trans, leaf);
btrfs_release_path(path);
+ goto again;
+
}

+ if (found_start == start && found_end == end)
+ ret = btrfs_del_item(trans, stripe_root, path);
+
+ out:
btrfs_free_path(path);
return ret;
}

--
2.43.0