Commit ab749bad authored by Gao Xiang's avatar Gao Xiang
Browse files

erofs: support unaligned data decompression 

Previously, compressed data was assumed as block-aligned. This
should be changed due to in-block tail-packing inline data.

Link: https://lore.kernel.org/r/20211228054604.114518-4-hsiangkao@linux.alibaba.com


Reviewed-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarYue Hu <huyue2@yulong.com>
Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
parent 10e5f6e4

fs/erofs/decompressor.c

+9 −8
Original line number Diff line number Diff line
@@ -121,7 +121,7 @@ static int z_erofs_lz4_prepare_dstpages(struct z_erofs_lz4_decompress_ctx *ctx, 


static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,

			void *inpage, unsigned int *inputmargin, int *maptype,

			bool support_0padding)

			bool may_inplace)

{

	struct z_erofs_decompress_req *rq = ctx->rq;

	unsigned int omargin, total, i, j;
@@ -130,7 +130,7 @@ static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx, 


	if (rq->inplace_io) {

		omargin = PAGE_ALIGN(ctx->oend) - ctx->oend;

		if (rq->partial_decoding || !support_0padding ||

		if (rq->partial_decoding || !may_inplace ||

		    omargin < LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize))

			goto docopy;
@@ -206,15 +206,13 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx, 
				      u8 *out)

{

	struct z_erofs_decompress_req *rq = ctx->rq;

	bool support_0padding = false, may_inplace = false;

	unsigned int inputmargin;

	u8 *headpage, *src;

	bool support_0padding;

	int ret, maptype;



	DBG_BUGON(*rq->in == NULL);

	headpage = kmap_atomic(*rq->in);

	inputmargin = 0;

	support_0padding = false;



	/* LZ4 decompression inplace is only safe if zero_padding is enabled */

	if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
@@ -226,11 +224,13 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx, 
			kunmap_atomic(headpage);

			return ret;

		}

		may_inplace = !((rq->pageofs_in + rq->inputsize) &

				(EROFS_BLKSIZ - 1));

	}



	inputmargin = rq->pageofs_in;

	src = z_erofs_lz4_handle_overlap(ctx, headpage, &inputmargin,

					 &maptype, support_0padding);

					 &maptype, may_inplace);

	if (IS_ERR(src))

		return PTR_ERR(src);
@@ -320,7 +320,8 @@ static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq, 
{

	const unsigned int nrpages_out =

		PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;

	const unsigned int righthalf = PAGE_SIZE - rq->pageofs_out;

	const unsigned int righthalf = min_t(unsigned int, rq->outputsize,

					     PAGE_SIZE - rq->pageofs_out);

	unsigned char *src, *dst;



	if (nrpages_out > 2) {
@@ -333,7 +334,7 @@ static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq, 
		return 0;

	}



	src = kmap_atomic(*rq->in);

	src = kmap_atomic(*rq->in) + rq->pageofs_in;

	if (rq->out[0]) {

		dst = kmap_atomic(rq->out[0]);

		memcpy(dst + rq->pageofs_out, src, righthalf);