On 2018年06月08日 20:47, Nikolay Borisov wrote:
> Currently some instances of btrfs_free_extent are called with the
> last parameter ("offset") being set to 1. This makes no sense, since
> offset is used for data extents. I suspect this is a left-over from
> 95d3f20b51e9 ("Mixed back reference (FORWARD ROLLING FORMAT CHANGE)")
> since this commit changed the signature of the function from :
>
> -int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
> - *root, u64 bytenr, u64 num_bytes, u64 parent,
> - u64 root_objectid, u64 ref_generation,
> - u64 owner_objectid, int pin);
>
> to
>
> +int btrfs_free_extent(struct btrfs_trans_handle *trans,
> + struct btrfs_root *root,
> + u64 bytenr, u64 num_bytes, u64 parent,
> + u64 root_objectid, u64 owner, u64 offset);
>
> I.e the last parameter was "pin" and not offset. So these are just
> leftovers with no semantic meaning. Fix this by passing 0.
And indeed, for tree blocks the @offset parameter is not used at all.
The call sites involving the offset is:
btrfs_free_extent()
|- __free_extent()
|- lookup_extent_backref()
|- lookup_inline_extent_backref() <<<
|- lookup_extent_data_ref() <<<
And in lookup_inline_extent_backref() we won't use @offset for tree
blocks anyway.
The the 1 passed as @offset should be a left-over.
>
> Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>
Thanks,
Qu
> ---
> ctree.c | 4 ++--
> extent-tree.c | 6 +++---
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/ctree.c b/ctree.c
> index 8f3338b4693a..d8a6883aa85f 100644
> --- a/ctree.c
> +++ b/ctree.c
> @@ -334,7 +334,7 @@ int __btrfs_cow_block(struct btrfs_trans_handle *trans,
> WARN_ON(btrfs_header_generation(parent) != trans->transid);
>
> btrfs_free_extent(trans, root, buf->start, buf->len,
> - 0, root->root_key.objectid, level, 1);
> + 0, root->root_key.objectid, level, 0);
> }
> if (!list_empty(&buf->recow)) {
> list_del_init(&buf->recow);
> @@ -738,7 +738,7 @@ static int balance_level(struct btrfs_trans_handle *trans,
>
> ret = btrfs_free_extent(trans, root, mid->start, mid->len,
> 0, root->root_key.objectid,
> - level, 1);
> + level, 0);
> /* once for the root ptr */
> free_extent_buffer(mid);
> return ret;
> diff --git a/extent-tree.c b/extent-tree.c
> index 079204ed290f..ab57c20d9dee 100644
> --- a/extent-tree.c
> +++ b/extent-tree.c
> @@ -2961,7 +2961,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
> path->slots[*level]++;
> ret = btrfs_free_extent(trans, root, bytenr, blocksize,
> parent->start, root_owner,
> - root_gen, *level - 1, 1);
> + root_gen, *level - 1, 0);
> BUG_ON(ret);
> continue;
> }
> @@ -3003,7 +3003,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
> root_gen = btrfs_header_generation(parent);
> ret = btrfs_free_extent(trans, root, path->nodes[*level]->start,
> path->nodes[*level]->len, parent->start,
> - root_owner, root_gen, *level, 1);
> + root_owner, root_gen, *level, 0);
> free_extent_buffer(path->nodes[*level]);
> path->nodes[*level] = NULL;
> *level += 1;
> @@ -3054,7 +3054,7 @@ static int noinline walk_up_tree(struct btrfs_trans_handle *trans,
> path->nodes[*level]->start,
> path->nodes[*level]->len,
> parent->start, root_owner,
> - root_gen, *level, 1);
> + root_gen, *level, 0);
> BUG_ON(ret);
> free_extent_buffer(path->nodes[*level]);
> path->nodes[*level] = NULL;
>
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