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Subject[RFC PATCH v2] erofs: support uncompressed pcluster with more than 1 block
Date
From: Yue Hu <huyue2@coolpad.com>

The length of uncompressed pcluster may exceed one block in some new
scenarios such as non 4K-sized lcluster (which will be supported later).
So, let's support the decompression for this firstly.

Signed-off-by: Yue Hu <huyue2@coolpad.com>
---
v2: fix tail data length.

fs/erofs/decompressor.c | 64 ++++++++++++++++++++++++++---------------
1 file changed, 41 insertions(+), 23 deletions(-)

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 2d55569f96ac..77d2b6cb6eda 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -320,41 +320,59 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq,
struct page **pagepool)
{
+ const unsigned int nrpages_in = rq->inputsize >> PAGE_SHIFT;
const unsigned int nrpages_out =
PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
- const unsigned int righthalf = min_t(unsigned int, rq->outputsize,
- PAGE_SIZE - rq->pageofs_out);
- const unsigned int lefthalf = rq->outputsize - righthalf;
+ unsigned int righthalf, lefthalf, i;
unsigned char *src, *dst;

- if (nrpages_out > 2) {
+ if (nrpages_in == 1 && nrpages_out > 2) {
DBG_BUGON(1);
return -EIO;
}

- if (rq->out[0] == *rq->in) {
- DBG_BUGON(nrpages_out != 1);
- return 0;
- }
+ i = 0;
+ do {
+ unsigned int outputsize = rq->outputsize;
+
+ righthalf = min_t(unsigned int, outputsize,
+ PAGE_SIZE - rq->pageofs_out);
+ lefthalf = min_t(unsigned int, outputsize - righthalf,
+ PAGE_SIZE - righthalf);
+
+ src = kmap_atomic(rq->in[i]) + rq->pageofs_in;
+ if (rq->out[i]) {
+ if (rq->out[i] == rq->in[i]) {
+ DBG_BUGON(nrpages_in == 1 && nrpages_out != 1);
+ } else {
+ dst = kmap_atomic(rq->out[i]);
+ memcpy(dst + rq->pageofs_out, src, righthalf);
+ kunmap_atomic(dst);
+ }
+ }

- 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);
- kunmap_atomic(dst);
- }
+ if (i + 1 == nrpages_out) {
+ kunmap_atomic(src);
+ break;
+ }

- if (nrpages_out == 2) {
- DBG_BUGON(!rq->out[1]);
- if (rq->out[1] == *rq->in) {
- memmove(src, src + righthalf, lefthalf);
+ if (rq->out[i + 1]) {
+ if (rq->out[i + 1] == rq->in[i]) {
+ memmove(src, src + righthalf, lefthalf);
+ } else {
+ dst = kmap_atomic(rq->out[i + 1]);
+ memcpy(dst, src + righthalf, lefthalf);
+ kunmap_atomic(dst);
+ }
} else {
- dst = kmap_atomic(rq->out[1]);
- memcpy(dst, src + righthalf, lefthalf);
- kunmap_atomic(dst);
+ DBG_BUGON(nrpages_in == 1 && nrpages_out == 2);
}
- }
- kunmap_atomic(src);
+ kunmap_atomic(src);
+
+ if (outputsize > PAGE_SIZE)
+ outputsize -= PAGE_SIZE;
+ } while (++i < nrpages_in);
+
return 0;
}

--
2.17.1
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