btrfs compression: merge inflate and deflate z_streams

`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())

Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 77a0e5d..759fa4e 100644 (file)
--- 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 = -E2BIG;
                        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)
@@ -230,13 +228,13 @@ 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
@@ -246,21 +244,21 @@ 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)
@@ -275,10 +273,10 @@ 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++;
@@ -287,9 +285,9 @@ 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);
                }
        }
@@ -298,7 +296,7 @@ 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;
@@ -316,13 +314,13 @@ 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) &&
@@ -330,11 +328,11 @@ 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;
        }
@@ -345,12 +343,12 @@ 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;
@@ -376,8 +374,8 @@ 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)
@@ -385,7 +383,7 @@ next:
        else
                ret = 0;
 
-       zlib_inflateEnd(&workspace->inf_strm);
+       zlib_inflateEnd(&workspace->strm);
        return ret;
 }