[PATCH 6/9] PM / Hibernate: split snapshot_read_next

Jiri Slaby
2010-06-02T08:54:27Z

When writing the snapshot, do the initialization and header write in
a separate function. This makes the code more readable and lowers
complexity of snapshot_read_next.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
---
kernel/power/power.h | 2 +
kernel/power/snapshot.c | 65 ++++++++++++++++++++++++++++++----------------
kernel/power/swap.c | 14 +++-------
3 files changed, 48 insertions(+), 33 deletions(-)

diff --git a/kernel/power/power.h b/kernel/power/power.h
index 812b66c..ff3f63f 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -171,6 +171,8 @@ struct hibernate_io_ops {

extern unsigned int snapshot_additional_pages(struct zone *zone);
extern unsigned long snapshot_get_image_size(void);
+extern int snapshot_write_init(struct hibernate_io_handle *io_handle,
+ struct snapshot_handle *handle);
extern int snapshot_read_next(struct snapshot_handle *handle);
extern int snapshot_write_next(struct snapshot_handle *handle);
extern void snapshot_write_finalize(struct snapshot_handle *handle);
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 25ce010..4600d15 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1598,10 +1598,46 @@ pack_pfns(unsigned long *buf, struct memory_bitmap *bm)
}

/**
+ * snapshot_write_init - initialization before writing the snapshot to
+ * a backing storage
+ *
+ * This function *must* be called before snapshot_read_next to initialize
+ * @handle and write a header.
+ *
+ * @io_handle: handle used when writing the initial info onto storage
+ * @handle: snapshot handle to init
+ */
+int snapshot_write_init(struct hibernate_io_handle *io_handle,
+ struct snapshot_handle *handle)
+{
+ int ret;
+
+ /* This makes the buffer be freed by swsusp_free() */
+ buffer = get_image_page(GFP_ATOMIC, PG_ANY);
+ if (!buffer)
+ return -ENOMEM;
+ init_header(buffer);
+ ret = hib_buffer_init_write(io_handle);
+ if (ret)
+ return ret;
+ ret = hib_buffer_write(io_handle, buffer, sizeof(struct swsusp_info));
+ if (ret)
+ goto finish;
+ hib_buffer_finish_write(io_handle);
+ memory_bm_position_reset(&orig_bm);
+ memory_bm_position_reset(&copy_bm);
+ handle->buffer = buffer;
+ return 0;
+finish:
+ hib_buffer_finish_write(io_handle);
+ return ret;
+}
+
+/**
* snapshot_read_next - used for reading the system memory snapshot.
*
- * On the first call to it @handle should point to a zeroed
- * snapshot_handle structure. The structure gets updated and a pointer
+ * Before calling this function, snapshot_write_init has to be called with
+ * handle passed as @handle here. The structure gets updated and a pointer
* to it should be passed to this function every next time.
*
* On success the function returns a positive number. Then, the caller
@@ -1613,31 +1649,12 @@ pack_pfns(unsigned long *buf, struct memory_bitmap *bm)
* structure pointed to by @handle is not updated and should not be used
* any more.
*/
-
int snapshot_read_next(struct snapshot_handle *handle)
{
- if (handle->cur > nr_meta_pages + nr_copy_pages)
- return 0;
-
- if (!buffer) {
- /* This makes the buffer be freed by swsusp_free() */
- buffer = get_image_page(GFP_ATOMIC, PG_ANY);
- if (!buffer)
- return -ENOMEM;
- }
- if (!handle->cur) {
- int error;
-
- error = init_header((struct swsusp_info *)buffer);
- if (error)
- return error;
- handle->buffer = buffer;
- memory_bm_position_reset(&orig_bm);
- memory_bm_position_reset(&copy_bm);
- } else if (handle->cur <= nr_meta_pages) {
+ if (handle->cur < nr_meta_pages) {
memset(buffer, 0, PAGE_SIZE);
pack_pfns(buffer, &orig_bm);
- } else {
+ } else if (handle->cur < nr_meta_pages + nr_copy_pages) {
struct page *page;

page = pfn_to_page(memory_bm_next_pfn(&copy_bm));
@@ -1655,6 +1672,8 @@ int snapshot_read_next(struct snapshot_handle *handle)
} else {
handle->buffer = page_address(page);
}
+ } else {
+ return 0;
}
handle->cur++;
return PAGE_SIZE;
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index f09494e..9b319f1 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -448,7 +448,6 @@ int swsusp_write(unsigned int flags)
{
struct hibernate_io_handle *io_handle;
struct snapshot_handle snapshot;
- struct swsusp_info *header;
unsigned long pages;
int error;

@@ -464,17 +463,12 @@ int swsusp_write(unsigned int flags)
goto out_finish;
}
memset(&snapshot, 0, sizeof(struct snapshot_handle));
- error = snapshot_read_next(&snapshot);
- if (error < PAGE_SIZE) {
- if (error >= 0)
- error = -EFAULT;
-
+ error = snapshot_write_init(io_handle, &snapshot);
+ if (error) {
+ printk(KERN_ERR "PM: Cannot init writer\n");
goto out_finish;
}
- header = (struct swsusp_info *)data_of(snapshot);
- error = hibernate_io_ops->write_page(io_handle, header, NULL);
- if (!error)
- error = save_image(io_handle, &snapshot, pages - 1);
+ error = save_image(io_handle, &snapshot, pages - 1);
out_finish:
error = hibernate_io_ops->writer_finish(io_handle, flags, error);
return error;
--
1.7.1