[PATCH] btrfs compression: merge inflate and deflate z_streams

From: Sergey Senozhatsky
Date: Mon Jun 30 2014 - 11:33:00 EST

`struct workspace' used for zlib compression contains two zlib
z_stream-s: `def_strm' used in zlib_compress_pages(), and `inf_strm'
used in zlib_decompress/zlib_decompress_biovec(). None of these
functions use `inf_strm' and `def_strm' simultaniously, meaning that
for every compress/decompress operation we need only one z_stream
(out of two available).

`inf_strm' and `def_strm' are different in size of ->workspace. For
inflate stream we vmalloc() zlib_inflate_workspacesize() bytes, for
deflate stream - zlib_deflate_workspacesize() bytes. On my system zlib
returns the following workspace sizes, correspondingly: 42312 and 268104
(+ guard pages).

Keep only one `z_stream' in `struct workspace' and use it for both
compression and decompression. Hence, instead of vmalloc() of two
z_stream->worskpace-s, allocate only one of size:
max(zlib_deflate_workspacesize(), zlib_inflate_workspacesize())

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
---
fs/btrfs/zlib.c | 138 ++++++++++++++++++++++++++++----------------------------
1 file changed, 68 insertions(+), 70 deletions(-)

diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 4f19631..280123c 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -33,8 +33,7 @@
#include "compression.h"

struct workspace {
- z_stream inf_strm;
- z_stream def_strm;
+ z_stream strm;
char *buf;
struct list_head list;
};
@@ -43,8 +42,7 @@ static void zlib_free_workspace(struct list_head *ws)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);

- vfree(workspace->def_strm.workspace);
- vfree(workspace->inf_strm.workspace);
+ vfree(workspace->strm.workspace);
kfree(workspace->buf);
kfree(workspace);
}
@@ -52,17 +50,17 @@ static void zlib_free_workspace(struct list_head *ws)
static struct list_head *zlib_alloc_workspace(void)
{
struct workspace *workspace;
+ int workspacesize;

workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
if (!workspace)
return ERR_PTR(-ENOMEM);

- workspace->def_strm.workspace = vmalloc(zlib_deflate_workspacesize(
- MAX_WBITS, MAX_MEM_LEVEL));
- workspace->inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
+ workspacesize = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
+ zlib_inflate_workspacesize());
+ workspace->strm.workspace = vmalloc(workspacesize);
workspace->buf = kmalloc(PAGE_CACHE_SIZE, GFP_NOFS);
- if (!workspace->def_strm.workspace ||
- !workspace->inf_strm.workspace || !workspace->buf)
+ if (!workspace->strm.workspace || !workspace->buf)
goto fail;

INIT_LIST_HEAD(&workspace->list);
@@ -96,14 +94,14 @@ static int zlib_compress_pages(struct list_head *ws,
*total_out = 0;
*total_in = 0;

- if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) {
+ if (Z_OK != zlib_deflateInit(&workspace->strm, 3)) {
printk(KERN_WARNING "BTRFS: deflateInit failed\n");
ret = -EIO;
goto out;
}

- workspace->def_strm.total_in = 0;
- workspace->def_strm.total_out = 0;
+ workspace->strm.total_in = 0;
+ workspace->strm.total_out = 0;

in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
data_in = kmap(in_page);
@@ -117,25 +115,25 @@ static int zlib_compress_pages(struct list_head *ws,
pages[0] = out_page;
nr_pages = 1;

- workspace->def_strm.next_in = data_in;
- workspace->def_strm.next_out = cpage_out;
- workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
- workspace->def_strm.avail_in = min(len, PAGE_CACHE_SIZE);
+ workspace->strm.next_in = data_in;
+ workspace->strm.next_out = cpage_out;
+ workspace->strm.avail_out = PAGE_CACHE_SIZE;
+ workspace->strm.avail_in = min(len, PAGE_CACHE_SIZE);

- while (workspace->def_strm.total_in < len) {
- ret = zlib_deflate(&workspace->def_strm, Z_SYNC_FLUSH);
+ while (workspace->strm.total_in < len) {
+ ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
if (ret != Z_OK) {
printk(KERN_DEBUG "BTRFS: deflate in loop returned %d\n",
ret);
- zlib_deflateEnd(&workspace->def_strm);
+ zlib_deflateEnd(&workspace->strm);
ret = -EIO;
goto out;
}

/* we're making it bigger, give up */
- if (workspace->def_strm.total_in > 8192 &&
- workspace->def_strm.total_in <
- workspace->def_strm.total_out) {
+ if (workspace->strm.total_in > 8192 &&
+ workspace->strm.total_in <
+ workspace->strm.total_out) {
ret = -EIO;
goto out;
}
@@ -143,7 +141,7 @@ static int zlib_compress_pages(struct list_head *ws,
* before the total_in so we will pull in a new page for
* the stream end if required
*/
- if (workspace->def_strm.avail_out == 0) {
+ if (workspace->strm.avail_out == 0) {
kunmap(out_page);
if (nr_pages == nr_dest_pages) {
out_page = NULL;
@@ -158,19 +156,19 @@ static int zlib_compress_pages(struct list_head *ws,
cpage_out = kmap(out_page);
pages[nr_pages] = out_page;
nr_pages++;
- workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
- workspace->def_strm.next_out = cpage_out;
+ workspace->strm.avail_out = PAGE_CACHE_SIZE;
+ workspace->strm.next_out = cpage_out;
}
/* we're all done */
- if (workspace->def_strm.total_in >= len)
+ if (workspace->strm.total_in >= len)
break;

/* we've read in a full page, get a new one */
- if (workspace->def_strm.avail_in == 0) {
- if (workspace->def_strm.total_out > max_out)
+ if (workspace->strm.avail_in == 0) {
+ if (workspace->strm.total_out > max_out)
break;

- bytes_left = len - workspace->def_strm.total_in;
+ bytes_left = len - workspace->strm.total_in;
kunmap(in_page);
page_cache_release(in_page);

@@ -178,28 +176,28 @@ static int zlib_compress_pages(struct list_head *ws,
in_page = find_get_page(mapping,
start >> PAGE_CACHE_SHIFT);
data_in = kmap(in_page);
- workspace->def_strm.avail_in = min(bytes_left,
+ workspace->strm.avail_in = min(bytes_left,
PAGE_CACHE_SIZE);
- workspace->def_strm.next_in = data_in;
+ workspace->strm.next_in = data_in;
}
}
- workspace->def_strm.avail_in = 0;
- ret = zlib_deflate(&workspace->def_strm, Z_FINISH);
- zlib_deflateEnd(&workspace->def_strm);
+ workspace->strm.avail_in = 0;
+ ret = zlib_deflate(&workspace->strm, Z_FINISH);
+ zlib_deflateEnd(&workspace->strm);

if (ret != Z_STREAM_END) {
ret = -EIO;
goto out;
}

- if (workspace->def_strm.total_out >= workspace->def_strm.total_in) {
+ if (workspace->strm.total_out >= workspace->strm.total_in) {
ret = -E2BIG;
goto out;
}

ret = 0;
- *total_out = workspace->def_strm.total_out;
- *total_in = workspace->def_strm.total_in;
+ *total_out = workspace->strm.total_out;
+ *total_in = workspace->strm.total_in;
out:
*out_pages = nr_pages;
if (out_page)
@@ -231,13 +229,13 @@ static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in,
unsigned long pg_offset;

data_in = kmap(pages_in[page_in_index]);
- workspace->inf_strm.next_in = data_in;
- workspace->inf_strm.avail_in = min_t(size_t, srclen, PAGE_CACHE_SIZE);
- workspace->inf_strm.total_in = 0;
+ workspace->strm.next_in = data_in;
+ workspace->strm.avail_in = min_t(size_t, srclen, PAGE_CACHE_SIZE);
+ workspace->strm.total_in = 0;

- workspace->inf_strm.total_out = 0;
- workspace->inf_strm.next_out = workspace->buf;
- workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
+ workspace->strm.total_out = 0;
+ workspace->strm.next_out = workspace->buf;
+ workspace->strm.avail_out = PAGE_CACHE_SIZE;
pg_offset = 0;

/* If it's deflate, and it's got no preset dictionary, then
@@ -247,21 +245,21 @@ static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in,
!(((data_in[0]<<8) + data_in[1]) % 31)) {

wbits = -((data_in[0] >> 4) + 8);
- workspace->inf_strm.next_in += 2;
- workspace->inf_strm.avail_in -= 2;
+ workspace->strm.next_in += 2;
+ workspace->strm.avail_in -= 2;
}

- if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
+ if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
printk(KERN_WARNING "BTRFS: inflateInit failed\n");
return -EIO;
}
- while (workspace->inf_strm.total_in < srclen) {
- ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
+ while (workspace->strm.total_in < srclen) {
+ ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END)
break;

buf_start = total_out;
- total_out = workspace->inf_strm.total_out;
+ total_out = workspace->strm.total_out;

/* we didn't make progress in this inflate call, we're done */
if (buf_start == total_out)
@@ -276,10 +274,10 @@ static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in,
goto done;
}

- workspace->inf_strm.next_out = workspace->buf;
- workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
+ workspace->strm.next_out = workspace->buf;
+ workspace->strm.avail_out = PAGE_CACHE_SIZE;

- if (workspace->inf_strm.avail_in == 0) {
+ if (workspace->strm.avail_in == 0) {
unsigned long tmp;
kunmap(pages_in[page_in_index]);
page_in_index++;
@@ -288,9 +286,9 @@ static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in,
break;
}
data_in = kmap(pages_in[page_in_index]);
- workspace->inf_strm.next_in = data_in;
- tmp = srclen - workspace->inf_strm.total_in;
- workspace->inf_strm.avail_in = min(tmp,
+ workspace->strm.next_in = data_in;
+ tmp = srclen - workspace->strm.total_in;
+ workspace->strm.avail_in = min(tmp,
PAGE_CACHE_SIZE);
}
}
@@ -299,7 +297,7 @@ static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in,
else
ret = 0;
done:
- zlib_inflateEnd(&workspace->inf_strm);
+ zlib_inflateEnd(&workspace->strm);
if (data_in)
kunmap(pages_in[page_in_index]);
return ret;
@@ -317,13 +315,13 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
unsigned long total_out = 0;
char *kaddr;

- workspace->inf_strm.next_in = data_in;
- workspace->inf_strm.avail_in = srclen;
- workspace->inf_strm.total_in = 0;
+ workspace->strm.next_in = data_in;
+ workspace->strm.avail_in = srclen;
+ workspace->strm.total_in = 0;

- workspace->inf_strm.next_out = workspace->buf;
- workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
- workspace->inf_strm.total_out = 0;
+ workspace->strm.next_out = workspace->buf;
+ workspace->strm.avail_out = PAGE_CACHE_SIZE;
+ workspace->strm.total_out = 0;
/* If it's deflate, and it's got no preset dictionary, then
we can tell zlib to skip the adler32 check. */
if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
@@ -331,11 +329,11 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
!(((data_in[0]<<8) + data_in[1]) % 31)) {

wbits = -((data_in[0] >> 4) + 8);
- workspace->inf_strm.next_in += 2;
- workspace->inf_strm.avail_in -= 2;
+ workspace->strm.next_in += 2;
+ workspace->strm.avail_in -= 2;
}

- if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
+ if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
printk(KERN_WARNING "BTRFS: inflateInit failed\n");
return -EIO;
}
@@ -346,12 +344,12 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
unsigned long bytes;
unsigned long pg_offset = 0;

- ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
+ ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END)
break;

buf_start = total_out;
- total_out = workspace->inf_strm.total_out;
+ total_out = workspace->strm.total_out;

if (total_out == buf_start) {
ret = -EIO;
@@ -377,8 +375,8 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
pg_offset += bytes;
bytes_left -= bytes;
next:
- workspace->inf_strm.next_out = workspace->buf;
- workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
+ workspace->strm.next_out = workspace->buf;
+ workspace->strm.avail_out = PAGE_CACHE_SIZE;
}

if (ret != Z_STREAM_END && bytes_left != 0)
@@ -386,7 +384,7 @@ next:
else
ret = 0;

- zlib_inflateEnd(&workspace->inf_strm);
+ zlib_inflateEnd(&workspace->strm);
return ret;
}

--
2.0.1.570.gc6b0718

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