On 9.10.19 г. 19:43 ч., fdman...@kernel.org wrote:
> From: Filipe Manana <fdman...@suse.com>
> 
> In the fixup worker, if we fail to mark the range as delalloc in the io
> tree, we must release the previously reserved metadata, as well as update
> the outstanding extents counter for the inode, otherwise we leak metadata
> space.
> 
> In pratice we can't return an error from btrfs_set_extent_delalloc(),
> which is just a wrapper around __set_extent_bit(), as for most errors
> __set_extent_bit() does a BUG_ON() (or panics which hits a BUG_ON() as
> well) and returning an -EEXIST error doesn't happen in this case since
> the exclusive bits parameter always has a value of 0 through this code
> path. Nevertheless, just fix the error handling in the fixup worker,
> in case one day __set_extent_bit() can return an error to this code
> path.
> 
> Fixes: f3038ee3a3f101 ("btrfs: Handle btrfs_set_extent_delalloc failure in 
> fixup worker")
> Signed-off-by: Filipe Manana <fdman...@suse.com>

Reviewed-by: Nikolay Borisov <nbori...@suse.com>

> ---
>  fs/btrfs/inode.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 0f2754eaa05b..f23b14ec743a 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -2201,12 +2201,16 @@ static void btrfs_writepage_fixup_worker(struct 
> btrfs_work *work)
>               mapping_set_error(page->mapping, ret);
>               end_extent_writepage(page, ret, page_start, page_end);
>               ClearPageChecked(page);
> -             goto out;
> +             goto out_reserved;
>       }
>  
>       ClearPageChecked(page);
>       set_page_dirty(page);
> -     btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE, false);
> +out_reserved:
> +     btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE, ret != 0);
> +     if (ret)
> +             btrfs_delalloc_release_space(inode, data_reserved, page_start,
> +                                          PAGE_SIZE, true);
>  out:
>       unlock_extent_cached(&BTRFS_I(inode)->io_tree, page_start, page_end,
>                            &cached_state);
> 

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