Re: [PATCH] btrfs: fix the folio leak on S390 hardware acceleration

[Qu Wenruo <wqu@suse.com>]

Adding S390 to the mailing list, I got the incorrect address in the 
initial patch.

Much appreciated if S390 people can give it a test.

Thanks,
Qu


在 2026/1/19 16:24, Qu Wenruo 写道:
> [BUG]
> After commit aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration
> buffer preparation"), we no longer release the folio of the page cache
> of folio returned by btrfs_compress_filemap_get_folio() for S390
> hardware accerlation path.
> 
> [CAUSE]
> Before that commit, we call kumap_local() and folio_put() after handling
> each folio.
> 
> Although the timing is not ideal (it release previous folio at the
> beginning of the loop, and rely on some extra cleanup out of the loop),
> it at least handles the folio release correctly.
> 
> Meanwhile the refactored code is easier to read, it lacks the call to
> release the filemap folio.
> 
> [FIX]
> Add the missing folio_put() for copy_data_into_buffer().
> 
> Cc: linux-s390@vger.kernel.orgaa60fe12b4f49f49fc73e5023f8675e2df1f7805
> Fixes: aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration buffer preparation")
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
>   fs/btrfs/zlib.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
> index 6caba8be7c84..10ed48d4a846 100644
> --- a/fs/btrfs/zlib.c
> +++ b/fs/btrfs/zlib.c
> @@ -139,6 +139,7 @@ static int copy_data_into_buffer(struct address_space *mapping,
>   		data_in = kmap_local_folio(folio, offset);
>   		memcpy(workspace->buf + cur - filepos, data_in, copy_length);
>   		kunmap_local(data_in);
> +		folio_put(folio);
>   		cur += copy_length;
>   	}
>   	return 0;