Re: [PATCH v2 3/4] btrfs: Add zstd support

From: Adam Borowski
Date: Thu Jun 29 2017 - 23:24:56 EST


On Thu, Jun 29, 2017 at 12:41:07PM -0700, Nick Terrell wrote:
> Add zstd compression and decompression support to BtrFS. zstd at its
> fastest level compresses almost as well as zlib, while offering much
> faster compression and decompression, approaching lzo speeds.

> +static int zstd_decompress_bio(struct list_head *ws, struct page **pages_in,
> + u64 disk_start,
> + struct bio *orig_bio,
> + size_t srclen)

Note that this fails to build if e1ddce71 is applied, and it'll be in
mainline in just a few days from now. Fixing that is obvious, but
to avoid duplicating the effort:


diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 838741b3732c..e9403e569d8e 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -25,6 +25,7 @@
#include <linux/pagemap.h>
#include <linux/bio.h>
#include <linux/zstd.h>
+#include <linux/refcount.h>
#include "compression.h"

#define ZSTD_BTRFS_MAX_WINDOWLOG 17
@@ -262,17 +263,18 @@ static int zstd_compress_pages(struct list_head *ws,
return ret;
}

-static int zstd_decompress_bio(struct list_head *ws, struct page **pages_in,
- u64 disk_start,
- struct bio *orig_bio,
- size_t srclen)
+static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
ZSTD_DStream *stream;
int ret = 0;
unsigned long page_in_index = 0;
+ size_t srclen = cb->compressed_len;
unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
unsigned long buf_start;
+ struct page **pages_in = cb->compressed_pages;
+ u64 disk_start = cb->start;
+ struct bio *orig_bio = cb->orig_bio;
unsigned long total_out = 0;
ZSTD_inBuffer in_buf = { NULL, 0, 0 };
ZSTD_outBuffer out_buf = { NULL, 0, 0 };


--
âââââââ
âââââââ A dumb species has no way to open a tuna can.
âââââââ A smart species invents a can opener.
âââââââ A master species delegates.