[PATCH 2/2] f2fs: compress: add .{init,destroy}_decompress_ctx callback

[Chao Yu]

Add below two callback interfaces in struct f2fs_compress_ops:

	int (*init_decompress_ctx)(struct decompress_io_ctx *dic);
	void (*destroy_decompress_ctx)(struct decompress_io_ctx *dic);

Which will be used by zstd compress algorithm later.

In addition, this patch adds callback function pointer check, so that
specified algorithm can avoid defining unneeded functions.

Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
---
 fs/f2fs/compress.c | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index b373102ed4af..6688fe091281 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -20,6 +20,8 @@ struct f2fs_compress_ops {
 	int (*init_compress_ctx)(struct compress_ctx *cc);
 	void (*destroy_compress_ctx)(struct compress_ctx *cc);
 	int (*compress_pages)(struct compress_ctx *cc);
+	int (*init_decompress_ctx)(struct decompress_io_ctx *dic);
+	void (*destroy_decompress_ctx)(struct decompress_io_ctx *dic);
 	int (*decompress_pages)(struct decompress_io_ctx *dic);
 };
 
@@ -334,9 +336,11 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
 	trace_f2fs_compress_pages_start(cc->inode, cc->cluster_idx,
 				cc->cluster_size, fi->i_compress_algorithm);
 
-	ret = cops->init_compress_ctx(cc);
-	if (ret)
-		goto out;
+	if (cops->init_compress_ctx) {
+		ret = cops->init_compress_ctx(cc);
+		if (ret)
+			goto out;
+	}
 
 	max_len = COMPRESS_HEADER_SIZE + cc->clen;
 	cc->nr_cpages = DIV_ROUND_UP(max_len, PAGE_SIZE);
@@ -398,7 +402,8 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
 		cc->cpages[i] = NULL;
 	}
 
-	cops->destroy_compress_ctx(cc);
+	if (cops->destroy_compress_ctx)
+		cops->destroy_compress_ctx(cc);
 
 	cc->nr_cpages = nr_cpages;
 
@@ -418,7 +423,8 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
 	kfree(cc->cpages);
 	cc->cpages = NULL;
 destroy_compress_ctx:
-	cops->destroy_compress_ctx(cc);
+	if (cops->destroy_compress_ctx)
+		cops->destroy_compress_ctx(cc);
 out:
 	trace_f2fs_compress_pages_end(cc->inode, cc->cluster_idx,
 							cc->clen, ret);
@@ -452,10 +458,16 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
 		goto out_free_dic;
 	}
 
+	if (cops->init_decompress_ctx) {
+		ret = cops->init_decompress_ctx(dic);
+		if (ret)
+			goto out_free_dic;
+	}
+
 	dic->rbuf = vmap(dic->tpages, dic->cluster_size, VM_MAP, PAGE_KERNEL);
 	if (!dic->rbuf) {
 		ret = -ENOMEM;
-		goto out_free_dic;
+		goto destroy_decompress_ctx;
 	}
 
 	dic->cbuf = vmap(dic->cpages, dic->nr_cpages, VM_MAP, PAGE_KERNEL_RO);
@@ -478,6 +490,9 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
 	vunmap(dic->cbuf);
 out_vunmap_rbuf:
 	vunmap(dic->rbuf);
+destroy_decompress_ctx:
+	if (cops->destroy_decompress_ctx)
+		cops->destroy_decompress_ctx(dic);
 out_free_dic:
 	if (!verity)
 		f2fs_decompress_end_io(dic->rpages, dic->cluster_size,
-- 
2.18.0.rc1