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SubjectRe: [PATCH] 2.6.6 swsusp.c: allow device aliasing
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Here is an updated patch. I thank Pavel for his suggestions.

>> (Does swsusp support swap files? If so, should we also support
>> file aliasing? How?)

Pavel> No, swsusp only supports swap devices. That means that you
Pavel> probably should kill d_path and name handling; that will
Pavel> slean the code up as well.



--- linux-2.6.6/kernel/power/swsusp.c 2004/05/10 14:11:17 1.1
+++ linux-2.6.6-swsusp-dev-aliasing/kernel/power/swsusp.c 2004/05/11 08:14:40 1.4
@@ -215,47 +215,69 @@
else if ((!memcmp("SWAPSPACE2",cur->swh.magic.magic,10)))
memcpy(cur->swh.magic.magic,"S2SUSP....",10);
else panic("\nSwapspace is not swapspace (%.10s)\n", cur->swh.magic.magic);
cur->link.next = prev; /* prev is the first/last swap page of the resume area */
/* link.next lies *no more* in last 4/8 bytes of magic */
}
rw_swap_page_sync(WRITE, entry, page);
__free_page(page);
}

+static int is_resume_file(const struct swap_info_struct *swap_info)
+{
+ /*
+ Check whether the swap device is the specified resume
+ device, irrespective of whether they are specified by
+ identical names.
+
+ (Thus, device inode aliasing is allowed. You can say
+ /dev/hda4 instead of /dev/ide/host0/bus0/target0/lun0/part4
+ [if using devfs] and they'll be considered the same device.
+ This is *necessary* for devfs, since the resume code can
+ only recognize the form /dev/hda4, but the suspend code
+ would like the long name [as shown in 'cat /proc/mounts'].)
+ */
+
+ struct file *file = swap_info->swap_file;
+ struct inode *inode = file->f_dentry->d_inode;
+
+ /* See if it is a swap (block) device. If so, we compare
+ the device (MAJOR,MINOR).
+
+ Note: Swap files are not supported by swsusp.
+ */
+ return S_ISBLK(inode->i_mode) &&
+ resume_device == MKDEV(imajor(inode), iminor(inode));
+}
+
static void read_swapfiles(void) /* This is called before saving image */
{
int i, len;
- static char buff[sizeof(resume_file)], *sname;

len=strlen(resume_file);
root_swap = 0xFFFF;

swap_list_lock();
for(i=0; i<MAX_SWAPFILES; i++) {
if (swap_info[i].flags == 0) {
swapfile_used[i]=SWAPFILE_UNUSED;
} else {
if(!len) {
printk(KERN_WARNING "resume= option should be used to set suspend device" );
if(root_swap == 0xFFFF) {
swapfile_used[i] = SWAPFILE_SUSPEND;
root_swap = i;
} else
swapfile_used[i] = SWAPFILE_IGNORED;
} else {
/* we ignore all swap devices that are not the resume_file */
- sname = d_path(swap_info[i].swap_file->f_dentry,
- swap_info[i].swap_file->f_vfsmnt,
- buff,
- sizeof(buff));
- if (!strcmp(sname, resume_file)) {
+ if (is_resume_file(&swap_info[i])) {
swapfile_used[i] = SWAPFILE_SUSPEND;
root_swap = i;
} else {
#if 0
printk( "Resume: device %s (%x != %x) ignored\n", swap_info[i].swap_file->d_name.name, swap_info[i].swap_device, resume_device );
#endif
swapfile_used[i] = SWAPFILE_IGNORED;
}
}
}


--
Sau Dan LEE 李守敦(Big5) ~{@nJX6X~}(HZ)
E-mail: danlee@informatik.uni-freiburg.de
Home page: http://www.informatik.uni-freiburg.de/~danlee

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