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Subject[PATCH v4 3/5] erofs: support unaligned data decompression
Date
Previously, compressed data was assumed as block-aligned. This
should be changed due to in-block tail-packing inline data.

Signed-off-by: Yue Hu <huyue2@yulong.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
fs/erofs/decompressor.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index b8b2a3e34053..789bdc548a1a 100644
--- 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);
--
2.24.4
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