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Subject[PATCH v4 1/5] erofs: tidy up z_erofs_lz4_decompress
Date
To prepare for the upcoming ztailpacking feature and further
cleanups, introduce a unique z_erofs_lz4_decompress_ctx to keep
the context, including inpages, outpages and oend, which are
frequently used by the lz4 decompressor.

No logic changes.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
fs/erofs/decompressor.c | 83 ++++++++++++++++++++++-------------------
1 file changed, 44 insertions(+), 39 deletions(-)

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index c373a199c407..1d137fd42306 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -16,6 +16,14 @@
#define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize) (((srcsize) >> 8) + 32)
#endif

+struct z_erofs_lz4_decompress_ctx {
+ struct z_erofs_decompress_req *rq;
+ /* # of encoded, decoded pages */
+ unsigned int inpages, outpages;
+ /* decoded block total length (used for in-place decompression) */
+ unsigned int oend;
+};
+
int z_erofs_load_lz4_config(struct super_block *sb,
struct erofs_super_block *dsb,
struct z_erofs_lz4_cfgs *lz4, int size)
@@ -56,11 +64,10 @@ int z_erofs_load_lz4_config(struct super_block *sb,
* 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,
+static int z_erofs_lz4_prepare_dstpages(struct z_erofs_lz4_decompress_ctx *ctx,
struct page **pagepool)
{
- const unsigned int nr =
- PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
+ struct z_erofs_decompress_req *rq = ctx->rq;
struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
BITS_PER_LONG)] = { 0 };
@@ -70,7 +77,7 @@ static int z_erofs_lz4_prepare_dstpages(struct z_erofs_decompress_req *rq,
unsigned int i, j, top;

top = 0;
- for (i = j = 0; i < nr; ++i, ++j) {
+ for (i = j = 0; i < ctx->outpages; ++i, ++j) {
struct page *const page = rq->out[i];
struct page *victim;

@@ -112,41 +119,36 @@ static int z_erofs_lz4_prepare_dstpages(struct z_erofs_decompress_req *rq,
return kaddr ? 1 : 0;
}

-static void *z_erofs_lz4_handle_inplace_io(struct z_erofs_decompress_req *rq,
+static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,
void *inpage, unsigned int *inputmargin, int *maptype,
bool support_0padding)
{
- unsigned int nrpages_in, nrpages_out;
- unsigned int ofull, oend, inputsize, total, i, j;
+ struct z_erofs_decompress_req *rq = ctx->rq;
+ unsigned int omargin, total, i, j;
struct page **in;
void *src, *tmp;

- inputsize = rq->inputsize;
- nrpages_in = PAGE_ALIGN(inputsize) >> PAGE_SHIFT;
- oend = rq->pageofs_out + rq->outputsize;
- ofull = PAGE_ALIGN(oend);
- nrpages_out = ofull >> PAGE_SHIFT;
-
if (rq->inplace_io) {
+ omargin = PAGE_ALIGN(ctx->oend) - ctx->oend;
if (rq->partial_decoding || !support_0padding ||
- ofull - oend < LZ4_DECOMPRESS_INPLACE_MARGIN(inputsize))
+ omargin < LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize))
goto docopy;

- for (i = 0; i < nrpages_in; ++i) {
+ for (i = 0; i < ctx->inpages; ++i) {
DBG_BUGON(rq->in[i] == NULL);
- for (j = 0; j < nrpages_out - nrpages_in + i; ++j)
+ for (j = 0; j < ctx->outpages - ctx->inpages + i; ++j)
if (rq->out[j] == rq->in[i])
goto docopy;
}
}

- if (nrpages_in <= 1) {
+ if (ctx->inpages <= 1) {
*maptype = 0;
return inpage;
}
kunmap_atomic(inpage);
might_sleep();
- src = erofs_vm_map_ram(rq->in, nrpages_in);
+ src = erofs_vm_map_ram(rq->in, ctx->inpages);
if (!src)
return ERR_PTR(-ENOMEM);
*maptype = 1;
@@ -155,7 +157,7 @@ static void *z_erofs_lz4_handle_inplace_io(struct z_erofs_decompress_req *rq,
docopy:
/* Or copy compressed data which can be overlapped to per-CPU buffer */
in = rq->in;
- src = erofs_get_pcpubuf(nrpages_in);
+ src = erofs_get_pcpubuf(ctx->inpages);
if (!src) {
DBG_BUGON(1);
kunmap_atomic(inpage);
@@ -182,9 +184,10 @@ static void *z_erofs_lz4_handle_inplace_io(struct z_erofs_decompress_req *rq,
return src;
}

-static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq,
+static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
u8 *out)
{
+ struct z_erofs_decompress_req *rq = ctx->rq;
unsigned int inputmargin;
u8 *headpage, *src;
bool support_0padding;
@@ -210,8 +213,8 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq,
}

rq->inputsize -= inputmargin;
- src = z_erofs_lz4_handle_inplace_io(rq, headpage, &inputmargin,
- &maptype, support_0padding);
+ src = z_erofs_lz4_handle_overlap(ctx, headpage, &inputmargin,
+ &maptype, support_0padding);
if (IS_ERR(src))
return PTR_ERR(src);

@@ -240,9 +243,9 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq,
}

if (maptype == 0) {
- kunmap_atomic(src);
+ kunmap_atomic(headpage);
} else if (maptype == 1) {
- vm_unmap_ram(src, PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT);
+ vm_unmap_ram(src, ctx->inpages);
} else if (maptype == 2) {
erofs_put_pcpubuf(src);
} else {
@@ -255,14 +258,18 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_decompress_req *rq,
static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
struct page **pagepool)
{
- const unsigned int nrpages_out =
- PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
+ struct z_erofs_lz4_decompress_ctx ctx;
unsigned int dst_maptype;
void *dst;
int ret;

+ ctx.rq = rq;
+ ctx.oend = rq->pageofs_out + rq->outputsize;
+ ctx.outpages = PAGE_ALIGN(ctx.oend) >> PAGE_SHIFT;
+ ctx.inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
+
/* one optimized fast path only for non bigpcluster cases yet */
- if (rq->inputsize <= PAGE_SIZE && nrpages_out == 1 && !rq->inplace_io) {
+ if (ctx.inpages == 1 && ctx.outpages == 1 && !rq->inplace_io) {
DBG_BUGON(!*rq->out);
dst = kmap_atomic(*rq->out);
dst_maptype = 0;
@@ -270,27 +277,25 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
}

/* general decoding path which can be used for all cases */
- ret = z_erofs_lz4_prepare_dstpages(rq, pagepool);
- if (ret < 0)
+ ret = z_erofs_lz4_prepare_dstpages(&ctx, pagepool);
+ if (ret < 0) {
return ret;
- if (ret) {
+ } else if (ret > 0) {
dst = page_address(*rq->out);
dst_maptype = 1;
- goto dstmap_out;
+ } else {
+ dst = erofs_vm_map_ram(rq->out, ctx.outpages);
+ if (!dst)
+ return -ENOMEM;
+ dst_maptype = 2;
}

- dst = erofs_vm_map_ram(rq->out, nrpages_out);
- if (!dst)
- return -ENOMEM;
- dst_maptype = 2;
-
dstmap_out:
- ret = z_erofs_lz4_decompress_mem(rq, dst + rq->pageofs_out);
-
+ ret = z_erofs_lz4_decompress_mem(&ctx, dst + rq->pageofs_out);
if (!dst_maptype)
kunmap_atomic(dst);
else if (dst_maptype == 2)
- vm_unmap_ram(dst, nrpages_out);
+ vm_unmap_ram(dst, ctx.outpages);
return ret;
}

--
2.24.4
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