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Date: Wed, 04 Aug 2010 14:04:18 +1000
From: Bojan Smojver <bojan@...ursive.com>
To: Nigel Cunningham <nigel@...onice.net>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH]: Compress hibernation image with LZO (in-kernel)
On Wed, 2010-08-04 at 12:47 +1000, Bojan Smojver wrote:
> Points taken for all the other comments. Thank you.
Style wise, does this look better?
PS. Don't worry about contents yet - still working out the kinks.
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index ca6066a..cb57eb9 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -137,6 +137,8 @@ config SUSPEND_FREEZER
config HIBERNATION
bool "Hibernation (aka 'suspend to disk')"
depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
+ select LZO_COMPRESS
+ select LZO_DECOMPRESS
select SUSPEND_NVS if HAS_IOMEM
---help---
Enable the suspend to disk (STD) functionality, which is usually
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index b0bb217..1515e2c 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -24,6 +24,7 @@
#include <linux/swapops.h>
#include <linux/pm.h>
#include <linux/slab.h>
+#include <linux/lzo.h>
#include "power.h"
@@ -357,6 +358,30 @@ static int swap_writer_finish(struct swap_map_handle *handle,
return error;
}
+/* We need to remember how much compressed data we need to read. */
+#define LZO_HEADER sizeof(size_t)
+
+/* Number of pages/bytes we'll compress at a time. */
+#define LZO_UNC_PAGES 64
+#define LZO_UNC_SIZE (LZO_UNC_PAGES * PAGE_SIZE)
+
+/* Number of pages/bytes we need for compressed data (worst case). */
+#define LZO_CMP_PAGES DIV_ROUND_UP(lzo1x_worst_compress(LZO_UNC_SIZE) + \
+ LZO_HEADER, PAGE_SIZE)
+#define LZO_CMP_SIZE (LZO_CMP_PAGES * PAGE_SIZE)
+
+/* As per examples/overlap.c in lzo distribution, we need to add more space
+ * to the end of the buffer in order to perform overlapping compression. We
+ * also add LZO_HEADER, because our compressed data starts at that offset.
+ * Then we round it off on PAGE_SIZE boundary, so that we can copy full pages
+ * safely. We call this overhead. Magic numbers and formula below.
+ */
+#define LZO_OVH_PAGES DIV_ROUND_UP((LZO_UNC_SIZE > 0xBFFF ? \
+ 0xBFFF : LZO_UNC_SIZE) + \
+ LZO_UNC_SIZE / 16 + 64 + 3 + \
+ LZO_HEADER, PAGE_SIZE)
+#define LZO_OVH_SIZE (LZO_OVH_PAGES + PAGE_SIZE)
+
/**
* save_image - save the suspend image data
*/
@@ -372,6 +397,29 @@ static int save_image(struct swap_map_handle *handle,
struct bio *bio;
struct timeval start;
struct timeval stop;
+ size_t i, unc_len, cmp_len;
+ unsigned char *buf, *wrk, *page;
+
+ page = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
+ if (!page) {
+ printk(KERN_ERR "PM: Failed to allocate LZO page\n");
+ return -ENOMEM;
+ }
+
+ wrk = vmalloc(LZO1X_1_MEM_COMPRESS);
+ if (!wrk) {
+ printk(KERN_ERR "PM: Failed to allocate LZO workspace\n");
+ free_page((unsigned long)page);
+ return -ENOMEM;
+ }
+
+ buf = vmalloc(LZO_UNC_SIZE + LZO_OVH_SIZE);
+ if (!buf) {
+ printk(KERN_ERR "PM: Failed to allocate LZO buffer\n");
+ vfree(wrk);
+ free_page((unsigned long)page);
+ return -ENOMEM;
+ }
printk(KERN_INFO "PM: Saving image data pages (%u pages) ... ",
nr_to_write);
@@ -382,16 +430,59 @@ static int save_image(struct swap_map_handle *handle,
bio = NULL;
do_gettimeofday(&start);
while (1) {
- ret = snapshot_read_next(snapshot);
- if (ret <= 0)
+ for (unc_len = 0;
+ unc_len < LZO_UNC_SIZE; unc_len += PAGE_SIZE) {
+ ret = snapshot_read_next(snapshot);
+ if (ret < 0)
+ goto out_finish;
+
+ if (!ret)
+ break;
+
+ /* Copy uncompressed data to the top of the buffer. */
+ memcpy(buf + LZO_OVH_SIZE + unc_len,
+ data_of(*snapshot), PAGE_SIZE);
+
+ if (!(nr_pages % m))
+ printk(KERN_CONT "\b\b\b\b%3d%%", nr_pages / m);
+ nr_pages++;
+ }
+
+ if (!unc_len)
break;
- ret = swap_write_page(handle, data_of(*snapshot), &bio);
- if (ret)
+
+ ret = lzo1x_1_compress(buf + LZO_OVH_SIZE, unc_len,
+ buf + LZO_HEADER, &cmp_len, wrk);
+ if (ret < 0) {
+ printk(KERN_ERR "PM: LZO compression failed\n");
+ break;
+ }
+
+ if (unlikely(!cmp_len ||
+ cmp_len > lzo1x_worst_compress(unc_len))) {
+ printk(KERN_ERR "PM: Invalid LZO length\n");
+ ret = -1;
break;
- if (!(nr_pages % m))
- printk(KERN_CONT "\b\b\b\b%3d%%", nr_pages / m);
- nr_pages++;
+ }
+
+ *(size_t *)buf = cmp_len;
+
+ /* Given we are writing one page at a time to disk, we copy
+ * that much from the buffer, although the last bit will likely
+ * be smaller than full page. This is OK - we saved the length
+ * of the compressed data, so any garbage at the end will be
+ * discarded when we read it.
+ */
+ for (i = 0; i < LZO_HEADER + cmp_len; i += PAGE_SIZE) {
+ memcpy(page, buf + i, PAGE_SIZE);
+
+ ret = swap_write_page(handle, page, &bio);
+ if (ret)
+ goto out_finish;
+ }
}
+
+out_finish:
err2 = hib_wait_on_bio_chain(&bio);
do_gettimeofday(&stop);
if (!ret)
@@ -401,6 +492,11 @@ static int save_image(struct swap_map_handle *handle,
else
printk(KERN_CONT "\n");
swsusp_show_speed(&start, &stop, nr_to_write, "Wrote");
+
+ vfree(buf);
+ vfree(wrk);
+ free_page((unsigned long)page);
+
return ret;
}
@@ -416,7 +512,8 @@ static int enough_swap(unsigned int nr_pages)
unsigned int free_swap = count_swap_pages(root_swap, 1);
pr_debug("PM: Free swap pages: %u\n", free_swap);
- return free_swap > nr_pages + PAGES_FOR_IO;
+ return free_swap >
+ (nr_pages * LZO_CMP_PAGES) / LZO_UNC_PAGES + 1 + PAGES_FOR_IO;
}
/**
@@ -547,9 +644,22 @@ static int load_image(struct swap_map_handle *handle,
int error = 0;
struct timeval start;
struct timeval stop;
- struct bio *bio;
- int err2;
unsigned nr_pages;
+ size_t i, off, unc_len, cmp_len;
+ unsigned char *buf, *page;
+
+ page = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
+ if (!page) {
+ printk(KERN_ERR "PM: Failed to allocate LZO page\n");
+ return -ENOMEM;
+ }
+
+ buf = vmalloc(LZO_CMP_SIZE);
+ if (!buf) {
+ printk(KERN_ERR "PM: Failed to allocate LZO buffer\n");
+ free_page((unsigned long)page);
+ return -ENOMEM;
+ }
printk(KERN_INFO "PM: Loading image data pages (%u pages) ... ",
nr_to_read);
@@ -557,27 +667,73 @@ static int load_image(struct swap_map_handle *handle,
if (!m)
m = 1;
nr_pages = 0;
- bio = NULL;
do_gettimeofday(&start);
+
+ error = snapshot_write_next(snapshot);
+ if (error <= 0)
+ goto out_finish;
+
for ( ; ; ) {
- error = snapshot_write_next(snapshot);
- if (error <= 0)
- break;
- error = swap_read_page(handle, data_of(*snapshot), &bio);
+ error = swap_read_page(handle, page, NULL); /* sync */
if (error)
break;
- if (snapshot->sync_read)
- error = hib_wait_on_bio_chain(&bio);
- if (error)
+
+ cmp_len = *(size_t *)page;
+ if (unlikely(!cmp_len ||
+ cmp_len > lzo1x_worst_compress(LZO_UNC_SIZE))) {
+ printk(KERN_ERR "PM: Invalid LZO length\n");
+ error = -1;
break;
- if (!(nr_pages % m))
- printk("\b\b\b\b%3d%%", nr_pages / m);
- nr_pages++;
+ }
+
+ /* As per examples/overlap.c in lzo distribution, we copy
+ * compressed data to the top of the in-place decompression
+ * buffer. */
+ off = LZO_CMP_SIZE - cmp_len;
+ memcpy(buf + off, page + LZO_HEADER,
+ (cmp_len < PAGE_SIZE - LZO_HEADER ?
+ cmp_len : PAGE_SIZE - LZO_HEADER));
+
+ for (i = PAGE_SIZE - LZO_HEADER; i < cmp_len; i += PAGE_SIZE) {
+ error = swap_read_page(handle, page, NULL); /* sync */
+ if (error)
+ goto out_finish;
+
+ memcpy(buf + off + i, page,
+ (cmp_len - unc_len < PAGE_SIZE ?
+ cmp_len - unc_len : PAGE_SIZE));
+ }
+
+ unc_len = LZO_UNC_SIZE;
+ error = lzo1x_decompress_safe(buf + off, cmp_len,
+ buf, &unc_len);
+ if (error < 0) {
+ printk(KERN_ERR "PM: LZO decompression failed\n");
+ break;
+ }
+
+ if (unlikely(!unc_len ||
+ unc_len > LZO_UNC_SIZE || unc_len % PAGE_SIZE)) {
+ printk(KERN_ERR "PM: Invalid LZO length\n");
+ error = -1;
+ break;
+ }
+
+ for (i = 0; i < unc_len; i += PAGE_SIZE) {
+ memcpy(data_of(*snapshot), buf + i, PAGE_SIZE);
+
+ if (!(nr_pages % m))
+ printk("\b\b\b\b%3d%%", nr_pages / m);
+ nr_pages++;
+
+ error = snapshot_write_next(snapshot);
+ if (error <= 0)
+ goto out_finish;
+ }
}
- err2 = hib_wait_on_bio_chain(&bio);
+
+out_finish:
do_gettimeofday(&stop);
- if (!error)
- error = err2;
if (!error) {
printk("\b\b\b\bdone\n");
snapshot_write_finalize(snapshot);
@@ -586,6 +742,10 @@ static int load_image(struct swap_map_handle *handle,
} else
printk("\n");
swsusp_show_speed(&start, &stop, nr_to_read, "Read");
+
+ vfree(buf);
+ free_page((unsigned long)page);
+
return error;
}
--
Bojan
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