Re: swsusp: fix devfs breakage introduced in 2.6.6

Re: swsusp: fix devfs breakage introduced in 2.6.6

[Sau Dan Lee]

>>>>> "Pavel" == Pavel Machek <pavel@ucw.cz> writes:

    Pavel> Hi!  This fixes bad interaction between devfs and swsusp.

    Pavel>  Check whether the swap device is the specified resume
    Pavel> device, irrespective of whether they are specified by
    Pavel> identical names.

    Pavel>  (Thus, device inode aliasing is allowed.  You can say
    Pavel> /dev/hda4 instead of /dev/ide/host0/bus0/target0/lun0/part4
    Pavel> [if using devfs] and they'll be considered the same device.
    Pavel> This is *necessary* for devfs, since the resume code can
    Pavel> only recognize the form /dev/hda4, but the suspend code
    Pavel> would like the long name [as shown in 'cat /proc/mounts'].)

    Pavel> [Thanks to devfs hero whose name I forgot.]  Pavel

The patch  was submitted by  me.  But I'm  no devfs hero at  all.  I'm
just a  happy user of devfs who  gets unhappy due to  this swsusp bug.
:)



-- 
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

Re: swsusp: fix devfs breakage introduced in 2.6.6

[Valdis.Kletnieks]

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On Fri, 21 May 2004 20:05:01 +0200, Sau Dan Lee said:

> The patch  was submitted by  me.  But I'm  no devfs hero at  all.  I'm
> just a  happy user of devfs who  gets unhappy due to  this swsusp bug.
> :)

Congratulate yourself anyhow. It's that type of hero that makes Linux (or open
source in general, for that matter) work as well as it does.  Yes, there's a
core crew of several dozen maintainers (who all deserve our thanks too), but
they can't develop a great operating system in a vacuum - without good bug
reports and the occasional user-provided patch, it all grinds to a halt very
quickly....

(OK, *everybody* who's ever contributed, take a bow now. :)

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swsusp: fix devfs breakage introduced in 2.6.6

[Pavel Machek]

Hi!

This fixes bad interaction between devfs and swsusp.

 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'].)

[Thanks to devfs hero whose name I forgot.]
								Pavel

--- clean/kernel/power/swsusp.c	2004-05-20 23:08:36.000000000 +0200
+++ linux/kernel/power/swsusp.c	2004-05-21 12:26:43.000000000 +0200
@@ -222,10 +224,30 @@
 	__free_page(page);
 }
 
+
+/*
+ * 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 see the long name.)
+ */
+static int is_resume_device(const struct swap_info_struct *swap_info)
+{
+	struct file *file = swap_info->swap_file;
+	struct inode *inode = file->f_dentry->d_inode;
+
+	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;
@@ -244,17 +266,10 @@
 					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_device(&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;
 				}
 			}

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