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 <dsterba@suse.com>
Reviewed-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 17f2dd8..01a4eab6 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;