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erofs: support interlaced uncompressed data for compressed files 

Currently, uncompressed data is all handled in the shifted way, which
means we have to shift the whole on-disk plain pcluster to get the
logical data.   However, since we are also using in-place I/O for
uncompressed data, data copy will be reduced a lot if pcluster is
recorded in the interlaced way as illustrated below:
 _______________________________________________________________
|               |    |               |_ tail part |_ head part _|
|<-   blk0    ->| .. |<-   blkn-2  ->|<-         blkn-1       ->|

The logical data then becomes:
 ________________________________________________________
|_ head part _|_  blk0  _| .. |_  blkn-2  _|_ tail part _|

In addition, non-4k plain pclusters are also survived by the
interlaced way, which can be used for non-4k lclusters as well.

However, it's almost impossible to de-duplicate uncompressed data
in the interlaced way, therefore shifted uncompressed data is still
useful.

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/8369112678604fdf4ef796626d59b1fdd0745a53.1663898962.git.huyue2@coolpad.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
This commit is contained in:
Yue Hu 2022-09-23 10:11:21 +08:00 committed by Gao Xiang
parent 1ae9470c3e
commit fdffc091e6
4 changed files with 41 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
fs/erofs/decompressor.c
View File

@ -317,52 +317,61 @@ dstmap_out:
return ret;
}
static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq,
struct page **pagepool)
static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
struct page **pagepool)
{
const unsigned int nrpages_out =
const unsigned int inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
const unsigned int outpages =
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;
unsigned char *src, *dst;
if (nrpages_out > 2) {
if (outpages > 2 && rq->alg == Z_EROFS_COMPRESSION_SHIFTED) {
DBG_BUGON(1);
return -EIO;
return -EFSCORRUPTED;
}
if (rq->out[0] == *rq->in) {
DBG_BUGON(nrpages_out != 1);
DBG_BUGON(rq->pageofs_out);
return 0;
}
src = kmap_atomic(*rq->in) + rq->pageofs_in;
src = kmap_local_page(rq->in[inpages - 1]) + rq->pageofs_in;
if (rq->out[0]) {
dst = kmap_atomic(rq->out[0]);
memcpy(dst + rq->pageofs_out, src, righthalf);
kunmap_atomic(dst);
dst = kmap_local_page(rq->out[0]);
memcpy(dst + rq->pageofs_out, src + interlaced_offset,
righthalf);
kunmap_local(dst);
}
if (nrpages_out == 2) {
DBG_BUGON(!rq->out[1]);
if (rq->out[1] == *rq->in) {
if (outpages > inpages) {
DBG_BUGON(!rq->out[outpages - 1]);
if (rq->out[outpages - 1] != rq->in[inpages - 1]) {
dst = kmap_local_page(rq->out[outpages - 1]);
memcpy(dst, interlaced_offset ? src :
(src + righthalf), lefthalf);
kunmap_local(dst);
} else if (!interlaced_offset) {
memmove(src, src + righthalf, lefthalf);
} else {
dst = kmap_atomic(rq->out[1]);
memcpy(dst, src + righthalf, lefthalf);
kunmap_atomic(dst);
}
}
kunmap_atomic(src);
kunmap_local(src);
return 0;
}
static struct z_erofs_decompressor decompressors[] = {
[Z_EROFS_COMPRESSION_SHIFTED] = {
.decompress = z_erofs_shifted_transform,
.decompress = z_erofs_transform_plain,
.name = "shifted"
},
[Z_EROFS_COMPRESSION_INTERLACED] = {
.decompress = z_erofs_transform_plain,
.name = "interlaced"
},
[Z_EROFS_COMPRESSION_LZ4] = {
.decompress = z_erofs_lz4_decompress,
.name = "lz4"

2
fs/erofs/erofs_fs.h
View File

@ -295,11 +295,13 @@ struct z_erofs_lzma_cfgs {
* bit 1 : HEAD1 big pcluster (0 - off; 1 - on)
* bit 2 : HEAD2 big pcluster (0 - off; 1 - on)
* bit 3 : tailpacking inline pcluster (0 - off; 1 - on)
* bit 4 : interlaced plain pcluster (0 - off; 1 - on)
*/
#define Z_EROFS_ADVISE_COMPACTED_2B 0x0001
#define Z_EROFS_ADVISE_BIG_PCLUSTER_1 0x0002
#define Z_EROFS_ADVISE_BIG_PCLUSTER_2 0x0004
#define Z_EROFS_ADVISE_INLINE_PCLUSTER 0x0008
#define Z_EROFS_ADVISE_INTERLACED_PCLUSTER 0x0010
struct z_erofs_map_header {
__le16 h_reserved1;

1
fs/erofs/internal.h
View File

@ -420,6 +420,7 @@ struct erofs_map_blocks {
enum {
Z_EROFS_COMPRESSION_SHIFTED = Z_EROFS_COMPRESSION_MAX,
Z_EROFS_COMPRESSION_INTERLACED,
Z_EROFS_COMPRESSION_RUNTIME_MAX
};

14
fs/erofs/zmap.c
View File

@ -679,12 +679,18 @@ static int z_erofs_do_map_blocks(struct inode *inode,
goto out;
}
if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN)
map->m_algorithmformat = Z_EROFS_COMPRESSION_SHIFTED;
else if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2)
if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN) {
if (vi->z_advise & Z_EROFS_ADVISE_INTERLACED_PCLUSTER)
map->m_algorithmformat =
Z_EROFS_COMPRESSION_INTERLACED;
else
map->m_algorithmformat =
Z_EROFS_COMPRESSION_SHIFTED;
} else if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_HEAD2) {
map->m_algorithmformat = vi->z_algorithmtype[1];
else
} else {
map->m_algorithmformat = vi->z_algorithmtype[0];
}
if ((flags & EROFS_GET_BLOCKS_FIEMAP) ||
((flags & EROFS_GET_BLOCKS_READMORE) &&