Re: [PATCH 2/2] btrfs: replace stripe extents

From: Qu Wenruo
Date: Tue Jul 09 2024 - 03:19:05 EST




在 2024/7/9 16:02, Johannes Thumshirn 写道:
From: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>

Update stripe extents in case a write to an already existing address
incoming.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>

Looks good to me.

Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>

But still as I mentioned in the original thread, I'm wondering why
dev-replace of RST needs to update RST entry.

I'd prefer to do a dev-extent level copy so that no RST/chunk needs to
be updated, just like what we did for non-RST cases.

But so far the change should be good enough for us to continue the testing.

Thanks,
Qu

---
fs/btrfs/raid-stripe-tree.c | 51 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)

diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
index e6f7a234b8f6..fd56535b2289 100644
--- a/fs/btrfs/raid-stripe-tree.c
+++ b/fs/btrfs/raid-stripe-tree.c
@@ -73,6 +73,55 @@ int btrfs_delete_raid_extent(struct btrfs_trans_handle *trans, u64 start, u64 le
return ret;
}

+static int update_raid_extent_item(struct btrfs_trans_handle *trans,
+ struct btrfs_key *key,
+ struct btrfs_io_context *bioc)
+{
+ struct btrfs_path *path;
+ struct extent_buffer *leaf;
+ struct btrfs_stripe_extent *stripe_extent;
+ int num_stripes;
+ int ret;
+ int slot;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ ret = btrfs_search_slot(trans, trans->fs_info->stripe_root, key, path,
+ 0, 1);
+ if (ret)
+ return ret == 1 ? ret : -EINVAL;
+
+ leaf = path->nodes[0];
+ slot = path->slots[0];
+
+ btrfs_item_key_to_cpu(leaf, key, slot);
+ num_stripes = btrfs_num_raid_stripes(btrfs_item_size(leaf, slot));
+ stripe_extent = btrfs_item_ptr(leaf, slot, struct btrfs_stripe_extent);
+
+ ASSERT(key->offset == bioc->size);
+
+ for (int i = 0; i < num_stripes; i++) {
+ u64 devid = bioc->stripes[i].dev->devid;
+ u64 physical = bioc->stripes[i].physical;
+ u64 length = bioc->stripes[i].length;
+ struct btrfs_raid_stride *raid_stride =
+ &stripe_extent->strides[i];
+
+ if (length == 0)
+ length = bioc->size;
+
+ btrfs_set_raid_stride_devid(leaf, raid_stride, devid);
+ btrfs_set_raid_stride_physical(leaf, raid_stride, physical);
+ }
+
+ btrfs_mark_buffer_dirty(trans, leaf);
+ btrfs_free_path(path);
+
+ return ret;
+}
+
static int btrfs_insert_one_raid_extent(struct btrfs_trans_handle *trans,
struct btrfs_io_context *bioc)
{
@@ -112,6 +161,8 @@ static int btrfs_insert_one_raid_extent(struct btrfs_trans_handle *trans,

ret = btrfs_insert_item(trans, stripe_root, &stripe_key, stripe_extent,
item_size);
+ if (ret == -EEXIST)
+ ret = update_raid_extent_item(trans, &stripe_key, bioc);
if (ret)
btrfs_abort_transaction(trans, ret);