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FROMGIT: erofs: refine z_erofs_transform_plain() for sub-page block support

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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 fdffc091e6 ("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.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231206091057.87027-5-hsiangkao@linux.alibaba.com

Bug: 318378021
Change-Id: I3d50132664f8754f56d62744420060108ed0da4f
(cherry picked from commit 192351616a9dde686492bcb9d1e4895a1411a527
https: //git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git dev)
Signed-off-by: Sandeep Dhavale <dhavale@google.com>
This commit is contained in:
Gao Xiang 2023-12-06 17:10:56 +08:00 committed by Treehugger Robot
parent a18efa4e4a
commit f466d52164
1 changed files with 49 additions and 33 deletions
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82
fs/erofs/decompressor.c
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@ -321,43 +321,59 @@ 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;
const unsigned int bs = rq->sb->s_blocksize;
unsigned int cur = 0, ni = 0, no, pi, po, insz, cnt;
u8 *kin;
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;
}
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]);
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;
}
kunmap_local(src);
for (; rq->outputsize; rq->pageofs_in = 0, cur += PAGE_SIZE, ni++) {
insz = min_t(unsigned int, PAGE_SIZE - rq->pageofs_in,
rq->outputsize);
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_t(unsigned int, insz - pi, PAGE_SIZE - po);
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);
}
DBG_BUGON(ni > nrpages_in);
return 0;
}