[PATCH 6/7] erofs: rename some generic methods in decompressor

Gao Xiang
2021-10-10T21:32:56Z

From: Gao Xiang <hsiangkao@linux.alibaba.com>

Previously, some LZ4 methods were named with `generic'. However, while
evaluating the effective LZMA approach, it seems they aren't quite
generic at all (e.g. no need preparing dstpages for most LZMA cases.)

Avoid such naming instead.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
fs/erofs/decompressor.c | 65 ++++++++++++++++++++---------------------
1 file changed, 31 insertions(+), 34 deletions(-)

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index a5bc4b1b7813..bceaa2b06b17 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -17,13 +17,8 @@
#endif

struct z_erofs_decompressor {
- /*
- * if destpages have sparsed pages, fill them with bounce pages.
- * it also check whether destpages indicate continuous physical memory.
- */
- int (*prepare_destpages)(struct z_erofs_decompress_req *rq,
- struct list_head *pagepool);
- int (*decompress)(struct z_erofs_decompress_req *rq, u8 *out);
+ int (*decompress)(struct z_erofs_decompress_req *rq,
+ struct list_head *pagepool);
char *name;
};

@@ -63,8 +58,12 @@ int z_erofs_load_lz4_config(struct super_block *sb,
return erofs_pcpubuf_growsize(sbi->lz4.max_pclusterblks);
}

-static int z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req *rq,
- struct list_head *pagepool)
+/*
+ * Fill all gaps with bounce pages if it's a sparse page list. Also check if
+ * all physical pages are consecutive, which can be seen for moderate CR.
+ */
+static int z_erofs_lz4_prepare_dstpages(struct z_erofs_decompress_req *rq,
+ struct list_head *pagepool)
{
const unsigned int nr =
PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
@@ -119,7 +118,7 @@ static int z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req *rq,
return kaddr ? 1 : 0;
}

-static void *z_erofs_handle_inplace_io(struct z_erofs_decompress_req *rq,
+static void *z_erofs_lz4_handle_inplace_io(struct z_erofs_decompress_req *rq,
void *inpage, unsigned int *inputmargin, int *maptype,
bool support_0padding)
{
@@ -189,7 +188,8 @@ static void *z_erofs_handle_inplace_io(struct z_erofs_decompress_req *rq,
return src;
}

-static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
+static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq,
+ u8 *out)
{
unsigned int inputmargin;
u8 *headpage, *src;
@@ -216,8 +216,8 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
}

rq->inputsize -= inputmargin;
- src = z_erofs_handle_inplace_io(rq, headpage, &inputmargin, &maptype,
- support_0padding);
+ src = z_erofs_lz4_handle_inplace_io(rq, headpage, &inputmargin,
+ &maptype, support_0padding);
if (IS_ERR(src))
return PTR_ERR(src);

@@ -257,17 +257,6 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
return ret;
}

-static struct z_erofs_decompressor decompressors[] = {
- [Z_EROFS_COMPRESSION_SHIFTED] = {
- .name = "shifted"
- },
- [Z_EROFS_COMPRESSION_LZ4] = {
- .prepare_destpages = z_erofs_lz4_prepare_destpages,
- .decompress = z_erofs_lz4_decompress,
- .name = "lz4"
- },
-};
-
static void copy_from_pcpubuf(struct page **out, const char *dst,
unsigned short pageofs_out,
unsigned int outputsize)
@@ -295,12 +284,11 @@ static void copy_from_pcpubuf(struct page **out, const char *dst,
}
}

-static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
- struct list_head *pagepool)
+static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
+ struct list_head *pagepool)
{
const unsigned int nrpages_out =
PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
- const struct z_erofs_decompressor *alg = decompressors + rq->alg;
unsigned int dst_maptype;
void *dst;
int ret;
@@ -325,7 +313,7 @@ static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
return PTR_ERR(dst);

rq->inplace_io = false;
- ret = alg->decompress(rq, dst);
+ ret = z_erofs_lz4_decompress_mem(rq, dst);
if (!ret)
copy_from_pcpubuf(rq->out, dst, rq->pageofs_out,
rq->outputsize);
@@ -336,7 +324,7 @@ static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
}

/* general decoding path which can be used for all cases */
- ret = alg->prepare_destpages(rq, pagepool);
+ ret = z_erofs_lz4_prepare_dstpages(rq, pagepool);
if (ret < 0)
return ret;
if (ret) {
@@ -351,7 +339,7 @@ static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
dst_maptype = 2;

dstmap_out:
- ret = alg->decompress(rq, dst + rq->pageofs_out);
+ ret = z_erofs_lz4_decompress_mem(rq, dst + rq->pageofs_out);

if (!dst_maptype)
kunmap_atomic(dst);
@@ -360,7 +348,7 @@ static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
return ret;
}

-static int z_erofs_shifted_transform(const struct z_erofs_decompress_req *rq,
+static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq,
struct list_head *pagepool)
{
const unsigned int nrpages_out =
@@ -399,10 +387,19 @@ static int z_erofs_shifted_transform(const struct z_erofs_decompress_req *rq,
return 0;
}

+static struct z_erofs_decompressor decompressors[] = {
+ [Z_EROFS_COMPRESSION_SHIFTED] = {
+ .decompress = z_erofs_shifted_transform,
+ .name = "shifted"
+ },
+ [Z_EROFS_COMPRESSION_LZ4] = {
+ .decompress = z_erofs_lz4_decompress,
+ .name = "lz4"
+ },
+};
+
int z_erofs_decompress(struct z_erofs_decompress_req *rq,
struct list_head *pagepool)
{
- if (rq->alg == Z_EROFS_COMPRESSION_SHIFTED)
- return z_erofs_shifted_transform(rq, pagepool);
- return z_erofs_decompress_generic(rq, pagepool);
+ return decompressors[rq->alg].decompress(rq, pagepool);
}
--
2.20.1