[PATCH 4/5] Hibernation: Switch to preallocating swap.

Nigel Cunningham
2010-05-26T07:10:18Z

Switch from allocating swap as the image is written to allocating
storage prior to writing the image.

Signed-off-by: Nigel Cunningham <nigel@tuxonice.net>
---
kernel/power/swap.c | 62
++++++++++++++++++++++++++++++--------------------
1 files changed, 37 insertions(+), 25 deletions(-)

diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 550c1ed..ff2fc15 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -201,6 +201,33 @@ int alloc_swapdev_blocks(int needed)
}

/**
+ * allocate_swap - Allocate enough swap to save the image.
+ *
+ * Calculates the number of swap pages actually needed and seeks
+ * to allocate that many from the resume partition. Returns TRUE
+ * or FALSE to indicate whether we got enough storage.
+ */
+
+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);
+
+ pr_debug("PM: Free swap pages: %u\n", free_swap);
+ if (free_swap < nr_pages)
+ return 0;
+
+ if (alloc_swapdev_blocks(nr_pages) < nr_pages) {
+ free_all_swap_pages(root_swap);
+ return 0;
+ }
+
+ reset_storage_pos();
+ return 1;
+}
+
+/**
* free_all_swap_pages - free swap pages allocated for saving image data.
* It also frees the extents used to register which swap entres had been
* allocated.
@@ -321,7 +348,7 @@ static void release_swap_writer(struct
swap_map_handle *handle)
handle->cur = NULL;
}

-static int get_swap_writer(struct swap_map_handle *handle)
+static int get_swap_writer(struct swap_map_handle *handle, unsigned
long pages)
{
int ret;

@@ -337,7 +364,12 @@ static int get_swap_writer(struct swap_map_handle
*handle)
ret = -ENOMEM;
goto err_close;
}
- handle->cur_swap = alloc_swapdev_block(root_swap);
+ if (!allocate_swap(pages)) {
+ printk(KERN_ERR "PM: Not enough free swap\n");
+ ret = -ENOSPC;
+ goto err_close;
+ }
+ handle->cur_swap = next_swapdev_block();
if (!handle->cur_swap) {
ret = -ENOSPC;
goto err_rel;
@@ -360,7 +392,7 @@ static int swap_write_page(struct swap_map_handle
*handle, void *buf,

if (!handle->cur)
return -EINVAL;
- offset = alloc_swapdev_block(root_swap);
+ offset = next_swapdev_block();
error = write_page(buf, offset, bio_chain);
if (error)
return error;
@@ -369,7 +401,7 @@ static int swap_write_page(struct swap_map_handle
*handle, void *buf,
error = hib_wait_on_bio_chain(bio_chain);
if (error)
goto out;
- offset = alloc_swapdev_block(root_swap);
+ offset = next_swapdev_block();
if (!offset)
return -ENOSPC;
handle->cur->next_swap = offset;
@@ -458,21 +490,6 @@ static int save_image(struct swap_map_handle *handle,
}

/**
- * enough_swap - Make sure we have enough swap to save the image.
- *
- * Returns TRUE or FALSE after checking the total amount of swap
- * space avaiable from the resume partition.
- */
-
-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;
-}
-
-/**
* swsusp_write - Write entire image and metadata.
* @flags: flags to pass to the "boot" kernel in the image header
*
@@ -491,16 +508,11 @@ int swsusp_write(unsigned int flags)
int error;

pages = snapshot_get_image_size();
- error = get_swap_writer(&handle);
+ error = get_swap_writer(&handle, pages);
if (error) {
printk(KERN_ERR "PM: Cannot get swap writer\n");
return error;
}
- if (!enough_swap(pages)) {
- printk(KERN_ERR "PM: Not enough free swap\n");
- error = -ENOSPC;
- goto out_finish;
- }
memset(&snapshot, 0, sizeof(struct snapshot_handle));
error = snapshot_read_next(&snapshot);
if (error < PAGE_SIZE) {
--
1.7.0.4