On Mon, Nov 14, 2016 at 02:06:21PM -0500, Josef Bacik wrote:
> In order to do hole punching we have a block reserve to hold the reservation
> we
> need to drop the extents in our range. Since we could end up dropping a lot
> of
> extents we set rsv->failfast so we can just loop around again and drop the
> remaining of the range. Unfortunately we unconditionally fill the hole
> extents
> in and start from the last extent we encountered, which we may or may not have
> dropped. So this can result in overlapping file extent entries, which can be
> tripped over in a variety of ways, either by hitting BUG_ON(!ret) in
> fill_holes() after the search, or in btrfs_set_item_key_safe() in
> btrfs_drop_extent() at a later time by an unrelated task. Fix this by only
> setting drop_end to the last extent we did actually drop. This way our holes
> are filled in properly for the range that we did drop, and the rest of the
> range
> that remains to be dropped is actually dropped. Thanks,
Can you pleaes share the reproducer?
Thanks,
-liubo
>
> Signed-off-by: Josef Bacik <jba...@fb.com>
> ---
> fs/btrfs/file.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index cbefdc8..1c15a98 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -706,6 +706,7 @@ int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
> u64 num_bytes = 0;
> u64 extent_offset = 0;
> u64 extent_end = 0;
> + u64 last_end = 0;
> int del_nr = 0;
> int del_slot = 0;
> int extent_type;
> @@ -797,8 +798,10 @@ next_slot:
> * extent item in the call to setup_items_for_insert() later
> * in this function.
> */
> - if (extent_end == key.offset && extent_end >= search_start)
> + if (extent_end == key.offset && extent_end >= search_start) {
> + last_end = extent_end;
> goto delete_extent_item;
> + }
>
> if (extent_end <= search_start) {
> path->slots[0]++;
> @@ -861,6 +864,12 @@ next_slot:
> key.offset = start;
> }
> /*
> + * From here on out we will have actually dropped something, so
> + * last_end can be updated.
> + */
> + last_end = extent_end;
> +
> + /*
> * | ---- range to drop ----- |
> * | -------- extent -------- |
> */
> @@ -1010,7 +1019,7 @@ delete_extent_item:
> if (!replace_extent || !(*key_inserted))
> btrfs_release_path(path);
> if (drop_end)
> - *drop_end = found ? min(end, extent_end) : end;
> + *drop_end = found ? min(end, last_end) : end;
> return ret;
> }
>
> --
> 2.7.4
>
> --
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