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Commit 431e9822 authored by David Sterba's avatar David Sterba
Browse files

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: default avatarDavid Sterba <dsterba@suse.com>
Reviewed-by: default avatarNick Terrell <terrelln@fb.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 5302e089

fs/btrfs/zstd.c

+67 −65
Original line number Diff line number Diff line
@@ -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;