On Wed, 6 Dec 2023 17:10:56 +0800
Gao Xiang <hsiang...@linux.alibaba.com> wrote:
> Sub-page block support is still unusable even with previous commits if
> interlaced PLAIN pclusters exist. Such pclusters can be found if the
> fragment feature is enabled.
>
> This commit tries to handle "the head part" of interlaced PLAIN
> pclusters first: it was once explained in commit fdffc091e6f9 ("erofs:
> support interlaced uncompressed data for compressed files").
>
> It uses a unique way for both shifted and interlaced PLAIN pclusters.
> As an added bonus, PLAIN pclusters larger than the block size is also
> supported now for the upcoming large lclusters.
>
> Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com>
> ---
> fs/erofs/decompressor.c | 81 ++++++++++++++++++++++++-----------------
> 1 file changed, 48 insertions(+), 33 deletions(-)
>
> diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
> index 021be5feb1bc..5ec11f5024b7 100644
> --- a/fs/erofs/decompressor.c
> +++ b/fs/erofs/decompressor.c
> @@ -319,43 +319,58 @@ static int z_erofs_lz4_decompress(struct
> z_erofs_decompress_req *rq,
> static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
> struct page **pagepool)
> {
> - const unsigned int inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
> - const unsigned int outpages =
> + const unsigned int nrpages_in =
> + PAGE_ALIGN(rq->pageofs_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;
> - const unsigned int interlaced_offset =
> - rq->alg == Z_EROFS_COMPRESSION_SHIFTED ? 0 : rq->pageofs_out;
> - u8 *src;
> -
> - if (outpages > 2 && rq->alg == Z_EROFS_COMPRESSION_SHIFTED) {
> - DBG_BUGON(1);
> - return -EFSCORRUPTED;
> - }
> -
> - if (rq->out[0] == *rq->in) {
> - DBG_BUGON(rq->pageofs_out);
> - return 0;
> + const unsigned int bs = rq->sb->s_blocksize;
> + unsigned int cur = 0, ni = 0, no, pi, po, insz, cnt;
> + u8 *kin;
> +
> + DBG_BUGON(rq->outputsize > rq->inputsize);
> + if (rq->alg == Z_EROFS_COMPRESSION_INTERLACED) {
> + cur = bs - (rq->pageofs_out & (bs - 1));
> + pi = (rq->pageofs_in + rq->inputsize - cur) & ~PAGE_MASK;
> + cur = min(cur, rq->outputsize);
> + if (cur && rq->out[0]) {
> + kin = kmap_local_page(rq->in[nrpages_in - 1]);
> + if (rq->out[0] == rq->in[nrpages_in - 1]) {
> + memmove(kin + rq->pageofs_out, kin + pi, cur);
> + flush_dcache_page(rq->out[0]);
> + } else {
> + memcpy_to_page(rq->out[0], rq->pageofs_out,
> + kin + pi, cur);
> + }
> + kunmap_local(kin);
> + }
> + rq->outputsize -= cur;
> }
>
> - src = kmap_local_page(rq->in[inpages - 1]) + rq->pageofs_in;
> - if (rq->out[0])
> - memcpy_to_page(rq->out[0], rq->pageofs_out,
> - src + interlaced_offset, righthalf);
> -
> - if (outpages > inpages) {
> - DBG_BUGON(!rq->out[outpages - 1]);
> - if (rq->out[outpages - 1] != rq->in[inpages - 1]) {
> - memcpy_to_page(rq->out[outpages - 1], 0, src +
> - (interlaced_offset ? 0 : righthalf),
> - lefthalf);
> - } else if (!interlaced_offset) {
> - memmove(src, src + righthalf, lefthalf);
> - flush_dcache_page(rq->in[inpages - 1]);
> - }
> + for (; rq->outputsize; rq->pageofs_in = 0, cur += PAGE_SIZE, ni++) {
> + insz = min(PAGE_SIZE - rq->pageofs_in, rq->outputsize);
min_t(unsigned int, ,)?
../include/linux/minmax.h:21:28: error: comparison of distinct pointer types
lacks a cast [-Werror]
(!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
> + rq->outputsize -= insz;
> + if (!rq->in[ni])
> + continue;
> + kin = kmap_local_page(rq->in[ni]);
> + pi = 0;
> + do {
> + no = (rq->pageofs_out + cur + pi) >> PAGE_SHIFT;
> + po = (rq->pageofs_out + cur + pi) & ~PAGE_MASK;
> + DBG_BUGON(no >= nrpages_out);
> + cnt = min(insz - pi, PAGE_SIZE - po);
ditto
> + if (rq->out[no] == rq->in[ni]) {
> + memmove(kin + po,
> + kin + rq->pageofs_in + pi, cnt);
> + flush_dcache_page(rq->out[no]);
> + } else if (rq->out[no]) {
> + memcpy_to_page(rq->out[no], po,
> + kin + rq->pageofs_in + pi, cnt);
> + }
> + pi += cnt;
> + } while (pi < insz);
> + kunmap_local(kin);
> }
> - kunmap_local(src);
> + DBG_BUGON(ni > nrpages_in);
> return 0;
> }
>
