erofs: tidy up stream decompressors

Just use a generic helper to prepare buffers for all supported
stream decompressors, eliminating similar logic.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240709094106.3018109-3-hsiangkao@linux.alibaba.com

1 files changed, 15 insertions, 0 deletions

diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h
index 601f533c9649..526edc0a7d2d 100644
--- a/fs/erofs/compress.h
+++ b/fs/erofs/compress.h
@@ -88,6 +88,21 @@ extern const struct z_erofs_decompressor z_erofs_deflate_decomp;
 extern const struct z_erofs_decompressor z_erofs_zstd_decomp;
 extern const struct z_erofs_decompressor *z_erofs_decomp[];
 
+struct z_erofs_stream_dctx {
+	struct z_erofs_decompress_req *rq;
+	unsigned int inpages, outpages;	/* # of {en,de}coded pages */
+	int no, ni;			/* the current {en,de}coded page # */
+
+	unsigned int avail_out;		/* remaining bytes in the decoded buffer */
+	unsigned int inbuf_pos, inbuf_sz;
+					/* current status of the encoded buffer */
+	u8 *kin, *kout;			/* buffer mapped pointers */
+	void *bounce;			/* bounce buffer for inplace I/Os */
+	bool bounced;			/* is the bounce buffer used now? */
+};
+
+int z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, void **dst,
+			       void **src, struct page **pgpl);
 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
 			 unsigned int padbufsize);
 int __init z_erofs_init_decompressor(void);