[power] Cleanup pdmisk header.

- Create struct pmdisk_header, which can overlay a union suspend_header, but 
  keeps the swap entry of the suspend header just before the signature (so
  we can use the full 10 bytes for a signature and don't have to worry about
  getting too cramped in there).

- We also keep a field for the orignal signature. We don't need to change our
  signature based on what version of swap we're using, we just need to make
  sure that we reset it correctly. 

- Get rid of union diskpage::swh, and all ugly casts to get the swap entry 
  for the header.

1 files changed, 41 insertions, 48 deletions

diff --git a/kernel/power/pmdisk.c b/kernel/power/pmdisk.c
index 51029739af3d..736131aa7efa 100644
--- a/kernel/power/pmdisk.c
+++ b/kernel/power/pmdisk.c
@@ -75,11 +75,20 @@ struct link {
 };
 
 union diskpage {
-	union swap_header swh;
 	struct link link;
 	struct suspend_header sh;
 };
 
+
+#define PMDISK_SIG	"pmdisk-swap1"
+
+struct pmdisk_header {
+	char reserved[PAGE_SIZE - 20 - sizeof(swp_entry_t)];
+	swp_entry_t pmdisk_info;
+	char	orig_sig[10];
+	char	sig[10];
+};
+
 /*
  * XXX: We try to keep some more pages free so that I/O operations succeed
  * without paging. Might this be more?
@@ -98,10 +107,9 @@ static void fill_suspend_header(struct suspend_header *sh)
 	sh->num_physpages = num_physpages;
 	strncpy(sh->machine, system_utsname.machine, 8);
 	strncpy(sh->version, system_utsname.version, 20);
-	/* FIXME: Is this bogus? --RR */
+
 	sh->num_cpus = num_online_cpus();
 	sh->page_size = PAGE_SIZE;
-	sh->suspend_pagedir = pm_pagedir_nosave;
 	BUG_ON (pagedir_save != pm_pagedir_nosave);
 	sh->num_pbes = pmdisk_pages;
 	/* TODO: needed? mounted fs' last mounted date comparison
@@ -122,7 +130,7 @@ static unsigned short root_swap;
 static int mark_swapfiles(swp_entry_t prev)
 {
 	swp_entry_t entry;
-	union diskpage *cur;
+	struct pmdisk_header * hdr;
 	int error;
 
 	printk( "S" );
@@ -130,31 +138,28 @@ static int mark_swapfiles(swp_entry_t prev)
 	if (root_swap == 0xFFFF)  /* ignored */
 		return -EINVAL;
 
-	cur = (union diskpage *)get_zeroed_page(GFP_ATOMIC);
-	if (!cur)
+	hdr = (struct pmdisk_header *)get_zeroed_page(GFP_ATOMIC);
+	if (!hdr)
 		return -ENOMEM;
 
 	/* XXX: this is dirty hack to get first page of swap file */
 	entry = swp_entry(root_swap, 0);
-	rw_swap_page_sync(READ, entry, virt_to_page((unsigned long)cur));
+	rw_swap_page_sync(READ, entry, virt_to_page((unsigned long)hdr));
 
-	if ((!memcmp("SWAP-SPACE",cur->swh.magic.magic,10)))
-		memcpy(cur->swh.magic.magic,"P1DISK....",10);
-	else if ((!memcmp("SWAPSPACE2",cur->swh.magic.magic,10)))
-		memcpy(cur->swh.magic.magic,"P2DISK....",10);
-	else {
-		pr_debug("pmdisk: Partition is not swap space.\n");
-		return -ENODEV;
-	}
-
-	/* prev is the first/last swap page of the resume area */
-	cur->link.next = prev; 
 
-	/* link.next lies *no more* in last 4/8 bytes of magic */
+	if (!memcmp("SWAP-SPACE",hdr->sig,10) ||
+	    !memcmp("SWAPSPACE2",hdr->sig,10)) {
+		memcpy(hdr->orig_sig,hdr->sig,10);
+		memcpy(hdr->sig,PMDISK_SIG,10);
+		hdr->pmdisk_info = prev;
 
-	error = rw_swap_page_sync(WRITE, entry, 
-				  virt_to_page((unsigned long)cur));
-	free_page((unsigned long)cur);
+		error = rw_swap_page_sync(WRITE, entry,
+					  virt_to_page((unsigned long)hdr));
+	} else {
+		pr_debug("pmdisk: Partition is not swap space.\n");
+		error = -ENODEV;
+	}
+	free_page((unsigned long)hdr);
 	return error;
 }
 
@@ -934,42 +939,31 @@ extern dev_t __init name_to_dev_t(const char *line);
 
 static int __init check_sig(swp_entry_t * next)
 {
-	union swap_header * hdr;
+	struct pmdisk_header * hdr;
 	int error;
 
-	hdr = (union swap_header *)get_zeroed_page(GFP_ATOMIC);
+	hdr = (struct pmdisk_header *)get_zeroed_page(GFP_ATOMIC);
 	if (!hdr)
 		return -ENOMEM;
 
 	if ((error = read_page(0,hdr)))
-		return error;
-	/*
-	 * We have to read next position before we overwrite it
-	 */
-	*next = next_entry((union diskpage *)hdr);
-
-	if (!memcmp("P1",hdr->magic.magic,2))
-		memcpy(hdr->magic.magic,"SWAP-SPACE",10);
-	else if (!memcmp("P2",hdr->magic.magic,2))
-		memcpy(hdr->magic.magic,"SWAPSPACE2",10);
-	else if ((!memcmp("SWAP-SPACE",hdr->magic.magic,10)) ||
-		 (!memcmp("SWAPSPACE2",hdr->magic.magic,10))) {
-		pr_debug(KERN_ERR "pmdisk: Partition is normal swap space\n");
-		error = -EINVAL;
 		goto Done;
-	} else {
+
+	if (!memcmp(PMDISK_SIG,hdr->sig,10)) {
+		memcpy(hdr->sig,hdr->orig_sig,10);
+		*next = hdr->pmdisk_info;
+
+		/*
+		 * Reset swap signature now.
+		 */
+		error = write_page(0,hdr);
+	} else { 
 		pr_debug(KERN_ERR "pmdisk: Invalid partition type.\n");
 		error = -EINVAL;
-		goto Done;
 	}
 
-	/*
-	 * Reset swap signature now.
-	 */
-	if ((error = write_page(0,hdr)))
-		goto Done;
-
-	pr_debug("pmdisk: Signature found, resuming\n");
+	if (!error)
+		pr_debug("pmdisk: Signature found, resuming\n");
  Done:
 	free_page((unsigned long)hdr);
 	return error;
@@ -1020,7 +1014,6 @@ static int __init check_header(swp_entry_t * next)
 	}
 
 	*next = next_entry((union diskpage *)sh);
-	pagedir_save = sh->suspend_pagedir;
 	pmdisk_pages = sh->num_pbes;
  Done:
 	free_page((unsigned long)sh);