From: David Sterba Date: Wed, 15 Nov 2017 17:27:39 +0000 (+0100) Subject: btrfs: move some zstd work data from stack to workspace X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=431e98226cbcaab40b77aeef2e6ba20a47649962;p=openwrt%2Fstaging%2Fblogic.git btrfs: move some zstd work data from stack to workspace * ZSTD_inBuffer in_buf * ZSTD_outBuffer out_buf are used in all functions to pass the compression parameters and the local variables consume some space. We can move them to the workspace and reduce the stack consumption: zstd.c:zstd_decompress -24 (136 -> 112) zstd.c:zstd_decompress_bio -24 (144 -> 120) zstd.c:zstd_compress_pages -24 (264 -> 240) Signed-off-by: David Sterba Reviewed-by: Nick Terrell Signed-off-by: David Sterba --- diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c index 17f2dd8fddb8..01a4eab602a3 100644 --- a/fs/btrfs/zstd.c +++ b/fs/btrfs/zstd.c @@ -43,6 +43,8 @@ struct workspace { size_t size; char *buf; struct list_head list; + ZSTD_inBuffer in_buf; + ZSTD_outBuffer out_buf; }; static void zstd_free_workspace(struct list_head *ws) @@ -94,8 +96,6 @@ static int zstd_compress_pages(struct list_head *ws, int nr_pages = 0; struct page *in_page = NULL; /* The current page to read */ struct page *out_page = NULL; /* The current page to write to */ - ZSTD_inBuffer in_buf = { NULL, 0, 0 }; - ZSTD_outBuffer out_buf = { NULL, 0, 0 }; unsigned long tot_in = 0; unsigned long tot_out = 0; unsigned long len = *total_out; @@ -118,9 +118,9 @@ static int zstd_compress_pages(struct list_head *ws, /* map in the first page of input data */ in_page = find_get_page(mapping, start >> PAGE_SHIFT); - in_buf.src = kmap(in_page); - in_buf.pos = 0; - in_buf.size = min_t(size_t, len, PAGE_SIZE); + workspace->in_buf.src = kmap(in_page); + workspace->in_buf.pos = 0; + workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE); /* Allocate and map in the output buffer */ @@ -130,14 +130,15 @@ static int zstd_compress_pages(struct list_head *ws, goto out; } pages[nr_pages++] = out_page; - out_buf.dst = kmap(out_page); - out_buf.pos = 0; - out_buf.size = min_t(size_t, max_out, PAGE_SIZE); + workspace->out_buf.dst = kmap(out_page); + workspace->out_buf.pos = 0; + workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE); while (1) { size_t ret2; - ret2 = ZSTD_compressStream(stream, &out_buf, &in_buf); + ret2 = ZSTD_compressStream(stream, &workspace->out_buf, + &workspace->in_buf); if (ZSTD_isError(ret2)) { pr_debug("BTRFS: ZSTD_compressStream returned %d\n", ZSTD_getErrorCode(ret2)); @@ -146,22 +147,22 @@ static int zstd_compress_pages(struct list_head *ws, } /* Check to see if we are making it bigger */ - if (tot_in + in_buf.pos > 8192 && - tot_in + in_buf.pos < - tot_out + out_buf.pos) { + if (tot_in + workspace->in_buf.pos > 8192 && + tot_in + workspace->in_buf.pos < + tot_out + workspace->out_buf.pos) { ret = -E2BIG; goto out; } /* We've reached the end of our output range */ - if (out_buf.pos >= max_out) { - tot_out += out_buf.pos; + if (workspace->out_buf.pos >= max_out) { + tot_out += workspace->out_buf.pos; ret = -E2BIG; goto out; } /* Check if we need more output space */ - if (out_buf.pos == out_buf.size) { + if (workspace->out_buf.pos == workspace->out_buf.size) { tot_out += PAGE_SIZE; max_out -= PAGE_SIZE; kunmap(out_page); @@ -176,19 +177,20 @@ static int zstd_compress_pages(struct list_head *ws, goto out; } pages[nr_pages++] = out_page; - out_buf.dst = kmap(out_page); - out_buf.pos = 0; - out_buf.size = min_t(size_t, max_out, PAGE_SIZE); + workspace->out_buf.dst = kmap(out_page); + workspace->out_buf.pos = 0; + workspace->out_buf.size = min_t(size_t, max_out, + PAGE_SIZE); } /* We've reached the end of the input */ - if (in_buf.pos >= len) { - tot_in += in_buf.pos; + if (workspace->in_buf.pos >= len) { + tot_in += workspace->in_buf.pos; break; } /* Check if we need more input */ - if (in_buf.pos == in_buf.size) { + if (workspace->in_buf.pos == workspace->in_buf.size) { tot_in += PAGE_SIZE; kunmap(in_page); put_page(in_page); @@ -196,15 +198,15 @@ static int zstd_compress_pages(struct list_head *ws, start += PAGE_SIZE; len -= PAGE_SIZE; in_page = find_get_page(mapping, start >> PAGE_SHIFT); - in_buf.src = kmap(in_page); - in_buf.pos = 0; - in_buf.size = min_t(size_t, len, PAGE_SIZE); + workspace->in_buf.src = kmap(in_page); + workspace->in_buf.pos = 0; + workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE); } } while (1) { size_t ret2; - ret2 = ZSTD_endStream(stream, &out_buf); + ret2 = ZSTD_endStream(stream, &workspace->out_buf); if (ZSTD_isError(ret2)) { pr_debug("BTRFS: ZSTD_endStream returned %d\n", ZSTD_getErrorCode(ret2)); @@ -212,11 +214,11 @@ static int zstd_compress_pages(struct list_head *ws, goto out; } if (ret2 == 0) { - tot_out += out_buf.pos; + tot_out += workspace->out_buf.pos; break; } - if (out_buf.pos >= max_out) { - tot_out += out_buf.pos; + if (workspace->out_buf.pos >= max_out) { + tot_out += workspace->out_buf.pos; ret = -E2BIG; goto out; } @@ -235,9 +237,9 @@ static int zstd_compress_pages(struct list_head *ws, goto out; } pages[nr_pages++] = out_page; - out_buf.dst = kmap(out_page); - out_buf.pos = 0; - out_buf.size = min_t(size_t, max_out, PAGE_SIZE); + workspace->out_buf.dst = kmap(out_page); + workspace->out_buf.pos = 0; + workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE); } if (tot_out >= tot_in) { @@ -273,8 +275,6 @@ static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE); unsigned long buf_start; unsigned long total_out = 0; - ZSTD_inBuffer in_buf = { NULL, 0, 0 }; - ZSTD_outBuffer out_buf = { NULL, 0, 0 }; stream = ZSTD_initDStream( ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size); @@ -284,18 +284,19 @@ static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) goto done; } - in_buf.src = kmap(pages_in[page_in_index]); - in_buf.pos = 0; - in_buf.size = min_t(size_t, srclen, PAGE_SIZE); + workspace->in_buf.src = kmap(pages_in[page_in_index]); + workspace->in_buf.pos = 0; + workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE); - out_buf.dst = workspace->buf; - out_buf.pos = 0; - out_buf.size = PAGE_SIZE; + workspace->out_buf.dst = workspace->buf; + workspace->out_buf.pos = 0; + workspace->out_buf.size = PAGE_SIZE; while (1) { size_t ret2; - ret2 = ZSTD_decompressStream(stream, &out_buf, &in_buf); + ret2 = ZSTD_decompressStream(stream, &workspace->out_buf, + &workspace->in_buf); if (ZSTD_isError(ret2)) { pr_debug("BTRFS: ZSTD_decompressStream returned %d\n", ZSTD_getErrorCode(ret2)); @@ -303,38 +304,38 @@ static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb) goto done; } buf_start = total_out; - total_out += out_buf.pos; - out_buf.pos = 0; + total_out += workspace->out_buf.pos; + workspace->out_buf.pos = 0; - ret = btrfs_decompress_buf2page(out_buf.dst, buf_start, - total_out, disk_start, orig_bio); + ret = btrfs_decompress_buf2page(workspace->out_buf.dst, + buf_start, total_out, disk_start, orig_bio); if (ret == 0) break; - if (in_buf.pos >= srclen) + if (workspace->in_buf.pos >= srclen) break; /* Check if we've hit the end of a frame */ if (ret2 == 0) break; - if (in_buf.pos == in_buf.size) { + if (workspace->in_buf.pos == workspace->in_buf.size) { kunmap(pages_in[page_in_index++]); if (page_in_index >= total_pages_in) { - in_buf.src = NULL; + workspace->in_buf.src = NULL; ret = -EIO; goto done; } srclen -= PAGE_SIZE; - in_buf.src = kmap(pages_in[page_in_index]); - in_buf.pos = 0; - in_buf.size = min_t(size_t, srclen, PAGE_SIZE); + workspace->in_buf.src = kmap(pages_in[page_in_index]); + workspace->in_buf.pos = 0; + workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE); } } ret = 0; zero_fill_bio(orig_bio); done: - if (in_buf.src) + if (workspace->in_buf.src) kunmap(pages_in[page_in_index]); return ret; } @@ -348,8 +349,6 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in, ZSTD_DStream *stream; int ret = 0; size_t ret2; - ZSTD_inBuffer in_buf = { NULL, 0, 0 }; - ZSTD_outBuffer out_buf = { NULL, 0, 0 }; unsigned long total_out = 0; unsigned long pg_offset = 0; char *kaddr; @@ -364,16 +363,17 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in, destlen = min_t(size_t, destlen, PAGE_SIZE); - in_buf.src = data_in; - in_buf.pos = 0; - in_buf.size = srclen; + workspace->in_buf.src = data_in; + workspace->in_buf.pos = 0; + workspace->in_buf.size = srclen; - out_buf.dst = workspace->buf; - out_buf.pos = 0; - out_buf.size = PAGE_SIZE; + workspace->out_buf.dst = workspace->buf; + workspace->out_buf.pos = 0; + workspace->out_buf.size = PAGE_SIZE; ret2 = 1; - while (pg_offset < destlen && in_buf.pos < in_buf.size) { + while (pg_offset < destlen + && workspace->in_buf.pos < workspace->in_buf.size) { unsigned long buf_start; unsigned long buf_offset; unsigned long bytes; @@ -384,7 +384,8 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in, ret = -EIO; goto finish; } - ret2 = ZSTD_decompressStream(stream, &out_buf, &in_buf); + ret2 = ZSTD_decompressStream(stream, &workspace->out_buf, + &workspace->in_buf); if (ZSTD_isError(ret2)) { pr_debug("BTRFS: ZSTD_decompressStream returned %d\n", ZSTD_getErrorCode(ret2)); @@ -393,8 +394,8 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in, } buf_start = total_out; - total_out += out_buf.pos; - out_buf.pos = 0; + total_out += workspace->out_buf.pos; + workspace->out_buf.pos = 0; if (total_out <= start_byte) continue; @@ -405,10 +406,11 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in, buf_offset = 0; bytes = min_t(unsigned long, destlen - pg_offset, - out_buf.size - buf_offset); + workspace->out_buf.size - buf_offset); kaddr = kmap_atomic(dest_page); - memcpy(kaddr + pg_offset, out_buf.dst + buf_offset, bytes); + memcpy(kaddr + pg_offset, workspace->out_buf.dst + buf_offset, + bytes); kunmap_atomic(kaddr); pg_offset += bytes;