[PATCH 11/22] Hibernation: Move block i/o fns to block_io.c

From: Nigel Cunningham
Date: Sat Sep 25 2010 - 00:17:34 EST

Move the functions that specifically deal with submitting I/O
to block_io.c. This helps us in working towards having a clean
separation between swap specific functions (which will be all
that will be in swap.c eventually) and low level block i/o
functions (block_io.c) that are/will be agnostic with regard to
the source of the storage. The block_io.c functions will thus
also be useable when support for storing an image in a generic
file (non swap) is added later.

Signed-off-by: Nigel Cunningham <nigel@xxxxxxxxxxxx>
---
kernel/power/block_io.c | 199 ++++++++++++++++++++++++++++++++++++++++++++++
kernel/power/block_io.h | 23 ++++++
kernel/power/swap.c | 202 +++--------------------------------------------
3 files changed, 235 insertions(+), 189 deletions(-)
create mode 100644 kernel/power/block_io.h

diff --git a/kernel/power/block_io.c b/kernel/power/block_io.c
index aa239a2..5edcb08 100644
--- a/kernel/power/block_io.c
+++ b/kernel/power/block_io.c
@@ -13,6 +13,7 @@
#include <linux/swap.h>

#include "power.h"
+#include "extents.h"

static struct bio *bio_chain;

@@ -102,3 +103,201 @@ int hib_wait_on_bio_chain(void)
bio_chain = NULL;
return ret;
}
+
+/*
+ * The swap map is a data structure used for keeping track of each page
+ * written to a swap partition. It consists of many swap_map_page
+ * structures that contain each an array of MAP_PAGE_SIZE swap entries.
+ * These structures are stored on the swap and linked together with the
+ * help of the .next_swap member.
+ *
+ * The swap map is created during suspend. The swap map pages are
+ * allocated and populated one at a time, so we only need one memory
+ * page to set up the entire structure.
+ *
+ * During resume we also only need to use one swap_map_page structure
+ * at a time.
+ */
+
+#define MAP_PAGE_ENTRIES (PAGE_SIZE / sizeof(sector_t) - 1)
+
+struct swap_map_page {
+ sector_t entries[MAP_PAGE_ENTRIES];
+ sector_t next_swap;
+};
+
+/**
+ * The swap_map_handle structure is used for handling swap in
+ * a file-alike way
+ */
+
+struct swap_map_handle {
+ struct swap_map_page *cur;
+ sector_t cur_swap;
+ sector_t first_sector;
+ unsigned int k;
+};
+
+static struct swap_map_handle handle;
+
+extern struct hib_extent_state sector_extents;
+
+/* Calculate the overhead needed for storing n pages */
+unsigned int hib_bio_overhead(unsigned int nr_pages)
+{
+ return DIV_ROUND_UP(nr_pages, MAP_PAGE_ENTRIES);
+}
+
+/* Get the first sector of the image proper, for storing in the signature */
+sector_t hib_get_first_sector(void)
+{
+ return handle.first_sector;
+}
+
+/**
+ * write_page - Write one page to given swap location.
+ * @buf: Address we're writing.
+ * @offset: Offset of the swap page we're writing to.
+ * @sync: Whether to force synchronous i/o.
+ */
+
+static int write_page(void *buf, sector_t offset, int sync)
+{
+ void *src;
+
+ if (!offset)
+ return -ENOSPC;
+
+ if (!sync) {
+ src = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
+ if (src) {
+ memcpy(src, buf, PAGE_SIZE);
+ } else {
+ WARN_ON_ONCE(1);
+ sync = 1; /* Go synchronous */
+ src = buf;
+ }
+ } else {
+ src = buf;
+ }
+ return hib_bio_write_page(offset, src, sync);
+}
+
+void release_swap_writer(void)
+{
+ if (handle.cur)
+ free_page((unsigned long)handle.cur);
+ handle.cur = NULL;
+}
+
+int hib_bio_prepare_write(void)
+{
+ handle.cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
+
+ if (!handle.cur)
+ return -ENOMEM;
+
+ handle.cur_swap = hib_extent_next(&sector_extents);
+
+ if (!handle.cur_swap) {
+ release_swap_writer();
+ return -ENOSPC;
+ }
+
+ handle.k = 0;
+ handle.first_sector = handle.cur_swap;
+ return 0;
+}
+
+int swap_write_page(void *buf, int sync)
+{
+ int error = 0;
+ sector_t offset;
+
+ if (!handle.cur)
+ return -EINVAL;
+ offset = hib_extent_next(&sector_extents);
+ error = write_page(buf, offset, sync);
+ if (error)
+ return error;
+ handle.cur->entries[handle.k++] = offset;
+ if (handle.k >= MAP_PAGE_ENTRIES) {
+ error = hib_wait_on_bio_chain();
+ if (error)
+ goto out;
+ offset = hib_extent_next(&sector_extents);
+ if (!offset)
+ return -ENOSPC;
+ handle.cur->next_swap = offset;
+ error = write_page(handle.cur, handle.cur_swap, 1);
+ if (error)
+ goto out;
+ memset(handle.cur, 0, PAGE_SIZE);
+ handle.cur_swap = offset;
+ handle.k = 0;
+ }
+ out:
+ return error;
+}
+
+int flush_swap_writer(void)
+{
+ if (handle.cur && handle.cur_swap)
+ return write_page(handle.cur, handle.cur_swap, 1);
+ else
+ return -EINVAL;
+}
+
+/**
+ * The following functions allow us to read data using a swap map
+ * in a file-alike way
+ */
+
+void release_swap_reader(void)
+{
+ if (handle.cur)
+ free_page((unsigned long)handle.cur);
+ handle.cur = NULL;
+}
+
+int get_swap_reader(unsigned int *flags_p, sector_t first_page)
+{
+ int error;
+
+ handle.cur = (struct swap_map_page *)get_zeroed_page(__GFP_WAIT | __GFP_HIGH);
+ if (!handle.cur)
+ return -ENOMEM;
+
+ error = hib_bio_read_page(first_page, handle.cur, 1);
+ if (error) {
+ release_swap_reader();
+ return error;
+ }
+ handle.k = 0;
+ return 0;
+}
+
+int swap_read_page(void *buf, int sync)
+{
+ sector_t offset;
+ int error;
+
+ if (!handle.cur)
+ return -EINVAL;
+ offset = handle.cur->entries[handle.k];
+ if (!offset)
+ return -EFAULT;
+ error = hib_bio_read_page(offset, buf, sync);
+ if (error)
+ return error;
+ if (++handle.k >= MAP_PAGE_ENTRIES) {
+ error = hib_wait_on_bio_chain();
+ handle.k = 0;
+ offset = handle.cur->next_swap;
+ if (!offset)
+ release_swap_reader();
+ else if (!error)
+ error = hib_bio_read_page(offset, handle.cur, 1);
+ }
+ return error;
+}
diff --git a/kernel/power/block_io.h b/kernel/power/block_io.h
new file mode 100644
index 0000000..2f91d6d
--- /dev/null
+++ b/kernel/power/block_io.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@xxxxxx>
+ * Copyright (C) 2006 Rafael J. Wysocki <rjw@xxxxxxx>
+ * Copyright (C) 2010 Nigel Cunningham <nigel@xxxxxxxxxxxx>
+ *
+ * This file is released under the GPLv2.
+ */
+
+/* Low level routines */
+int hib_bio_read_page(pgoff_t page_off, void *addr, int sync);
+int hib_bio_write_page(pgoff_t page_off, void *addr, int sync);
+int hib_wait_on_bio_chain(void);
+
+unsigned int hib_bio_overhead(unsigned int nr_pages);
+sector_t hib_get_first_sector(void);
+extern struct hib_extent_state sector_extents;
+void release_swap_writer(void);
+int hib_bio_prepare_write(void);
+int flush_swap_writer(void);
+int swap_write_page(void *buf, int sync);
+int get_swap_reader(unsigned int *flags_p, sector_t first_page);
+void release_swap_reader(void);
+int swap_read_page(void *buf, int sync);
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index a881086..d217a6f 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -26,45 +26,10 @@

#include "power.h"
#include "extents.h"
+#include "block_io.h"

#define SWSUSP_SIG "S1SUSPEND"

-/*
- * The swap map is a data structure used for keeping track of each page
- * written to a swap partition. It consists of many swap_map_page
- * structures that contain each an array of MAP_PAGE_ENTRIES swap entries.
- * These structures are stored on the swap and linked together with the
- * help of the .next_swap member.
- *
- * The swap map is created during suspend. The swap map pages are
- * allocated and populated one at a time, so we only need one memory
- * page to set up the entire structure.
- *
- * During resume we also only need to use one swap_map_page structure
- * at a time.
- */
-
-#define MAP_PAGE_ENTRIES (PAGE_SIZE / sizeof(sector_t) - 1)
-
-struct swap_map_page {
- sector_t entries[MAP_PAGE_ENTRIES];
- sector_t next_swap;
-};
-
-/**
- * The swap_map_handle structure is used for handling swap in
- * a file-alike way
- */
-
-struct swap_map_handle {
- struct swap_map_page *cur;
- sector_t cur_swap;
- sector_t first_sector;
- unsigned int k;
-};
-
-static struct swap_map_handle handle;
-
static unsigned short root_swap = 0xffff;

struct swsusp_header {
@@ -79,7 +44,7 @@ struct swsusp_header {
static struct swsusp_header *swsusp_header;

static struct hib_extent_state swap_extents;
-static struct hib_extent_state sector_extents;
+struct hib_extent_state sector_extents;

/**
* alloc_swapdev_block - allocate a swap page and register that it has
@@ -127,7 +92,7 @@ static int allocate_swap(unsigned int nr_pages)
{
unsigned int free_swap = count_swap_pages(root_swap, 1);

- nr_pages += DIV_ROUND_UP(nr_pages, MAP_PAGE_ENTRIES);
+ nr_pages += hib_bio_overhead(nr_pages);

pr_debug("PM: Free swap pages: %u\n", free_swap);
if (free_swap < nr_pages)
@@ -185,7 +150,7 @@ static int mark_swapfiles(unsigned int flags)
memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
memcpy(swsusp_header->sig,SWSUSP_SIG, 10);
swsusp_header->write_speed = write_speed;
- swsusp_header->image = handle.first_sector;
+ swsusp_header->image = hib_get_first_sector();
swsusp_header->flags = flags;
error = hib_bio_write_page(swsusp_resume_block,
swsusp_header, 1);
@@ -223,42 +188,6 @@ static int swsusp_swap_check(void)
return res;
}

-/**
- * write_page - Write one page to given swap location.
- * @buf: Address we're writing.
- * @offset: Offset of the swap page we're writing to.
- * @sync: Whether to force synchronous i/o.
- */
-
-static int write_page(void *buf, sector_t offset, int sync)
-{
- void *src;
-
- if (!offset)
- return -ENOSPC;
-
- if (!sync) {
- src = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
- if (src) {
- memcpy(src, buf, PAGE_SIZE);
- } else {
- WARN_ON_ONCE(1);
- sync = 1; /* Go synchronous */
- src = buf;
- }
- } else {
- src = buf;
- }
- return hib_bio_write_page(offset, src, sync);
-}
-
-static void release_swap_writer(void)
-{
- if (handle.cur)
- free_page((unsigned long)handle.cur);
- handle.cur = NULL;
-}
-
static int get_swap_writer(unsigned long pages)
{
int ret;
@@ -270,70 +199,19 @@ static int get_swap_writer(unsigned long pages)
"swapon -a.\n");
return ret;
}
- handle.cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
- if (!handle.cur) {
- ret = -ENOMEM;
- goto err_close;
- }
if (!allocate_swap(pages)) {
printk(KERN_ERR "PM: Not enough free swap\n");
ret = -ENOSPC;
goto err_close;
}
- handle.cur_swap = hib_extent_next(&sector_extents);
- if (!handle.cur_swap) {
- ret = -ENOSPC;
- goto err_rel;
- }
- handle.k = 0;
- handle.first_sector = handle.cur_swap;
- return 0;
-err_rel:
- release_swap_writer();
+ ret = hib_bio_prepare_write();
+ if (!ret)
+ return 0;
err_close:
swsusp_close(FMODE_WRITE);
return ret;
}

-static int swap_write_page(void *buf, int sync)
-{
- int error = 0;
- sector_t offset;
-
- if (!handle.cur)
- return -EINVAL;
- offset = hib_extent_next(&sector_extents);
- error = write_page(buf, offset, sync);
- if (error)
- return error;
- handle.cur->entries[handle.k++] = offset;
- if (handle.k >= MAP_PAGE_ENTRIES) {
- error = hib_wait_on_bio_chain();
- if (error)
- goto out;
- offset = hib_extent_next(&sector_extents);
- if (!offset)
- return -ENOSPC;
- handle.cur->next_swap = offset;
- error = write_page(handle.cur, handle.cur_swap, 1);
- if (error)
- goto out;
- memset(handle.cur, 0, PAGE_SIZE);
- handle.cur_swap = offset;
- handle.k = 0;
- }
- out:
- return error;
-}
-
-static int flush_swap_writer(void)
-{
- if (handle.cur && handle.cur_swap)
- return write_page(handle.cur, handle.cur_swap, 1);
- else
- return -EINVAL;
-}
-
static int swap_writer_finish(unsigned int flags, int error)
{
if (!error) {
@@ -437,65 +315,6 @@ out_finish:
return error;
}

-/**
- * The following functions allow us to read data using a swap map
- * in a file-alike way
- */
-
-static void release_swap_reader(void)
-{
- if (handle.cur)
- free_page((unsigned long)handle.cur);
- handle.cur = NULL;
-}
-
-static int get_swap_reader(unsigned int *flags_p)
-{
- int error;
-
- *flags_p = swsusp_header->flags;
-
- if (!swsusp_header->image) /* how can this happen? */
- return -EINVAL;
-
- handle.cur = (struct swap_map_page *)get_zeroed_page(__GFP_WAIT | __GFP_HIGH);
- if (!handle.cur)
- return -ENOMEM;
-
- error = hib_bio_read_page(swsusp_header->image, handle.cur, 1);
- if (error) {
- release_swap_reader();
- return error;
- }
- handle.k = 0;
- return 0;
-}
-
-static int swap_read_page(void *buf, int sync)
-{
- sector_t offset;
- int error;
-
- if (!handle.cur)
- return -EINVAL;
- offset = handle.cur->entries[handle.k];
- if (!offset)
- return -EFAULT;
- error = hib_bio_read_page(offset, buf, sync);
- if (error)
- return error;
- if (++handle.k >= MAP_PAGE_ENTRIES) {
- error = hib_wait_on_bio_chain();
- handle.k = 0;
- offset = handle.cur->next_swap;
- if (!offset)
- release_swap_reader();
- else if (!error)
- error = hib_bio_read_page(offset, handle.cur, 1);
- }
- return error;
-}
-
static int swap_reader_finish(void)
{
release_swap_reader();
@@ -574,7 +393,12 @@ int swsusp_read(unsigned int *flags_p)
if (error < PAGE_SIZE)
return error < 0 ? error : -EFAULT;
header = (struct swsusp_info *)data_of(snapshot);
- error = get_swap_reader(flags_p);
+ *flags_p = swsusp_header->flags;
+ if (!swsusp_header->image) { /* how can this happen? */
+ error = -EINVAL;
+ goto end;
+ }
+ error = get_swap_reader(flags_p, swsusp_header->image);
if (error)
goto end;
if (!error)
--
1.7.0.4

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