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: Chao Yu <chao@kernel.org>
Signed-off-by: Yue Hu <huyue2@yulong.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 92814913fe00381eaf230becf31ddbcfc19ddbf4..3efa686c764417eb0b4cf8b46f600555b641cbf9 100644 (file)
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -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);