Date: Sun, 12 Nov 2006 03:54:52 +0700 (KRAT) From: Eugene Grosbein <eugen@grosbein.pp.ru> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/105412: [msdosfs] msdosfs mounted as r/o cannot be remounted to r/w Message-ID: <200611112054.kABKsqnM002902@grosbein.pp.ru> Resent-Message-ID: <200611112100.kABL0g8f057318@freefall.freebsd.org>
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>Number: 105412
>Category: kern
>Synopsis: [msdosfs] msdosfs mounted as r/o cannot be remounted to r/w
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sat Nov 11 21:00:41 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator: Eugene Grosbein
>Release: FreeBSD 6.2-PRERELEASE i386
>Organization:
Svyaz Service JSC
>Environment:
System: FreeBSD grosbein.pp.ru 6.2-PRERELEASE FreeBSD 6.2-PRERELEASE #20: Fri Nov 10 20:05:19 KRAT 2006 eu@grosbein.pp.ru:/mnt/home/obj/usr/local/src/sys/DADV i386
>Description:
It must be possible to remount msdosfs from r/o to r/w
>How-To-Repeat:
Let's make an image for file system to play with:
# dd if=/dev/zero bs=1k count=1440 of=image
Then make it device /dev/md0:
# mdconfig -a -t vnode -f image
Then make new filesystem to mount:
# newfs_msdos -f 1440 /dev/md0
Then mount it read-only:
# mount_msdosfs -o ro /dev/md0 /mnt/tmp
Now look at this:
# mount | grep md0
/dev/md0 on /mnt/tmp (msdosfs, local, read-only)
Still good. Now try to remount it r/w:
# mount -u -o rw /dev/md0; echo $?
0
It pretends to finish with success. But it has failed:
# echo test > /mnt/tmp/test; mount | grep md0
bash: /mnt/tmp/test: Read-only file system
/dev/md0 on /mnt/tmp (msdosfs, local, read-only)
>Fix:
Unknown. There are two problems really.
First, mount(8) does not treat msdosfs as remountable.
This should be fixed with the following patch:
--- sbin/mount/mount.c.orig Sun Nov 12 01:16:13 2006
+++ sbin/mount/mount.c Sun Nov 12 01:16:23 2006
@@ -116,7 +116,7 @@
*/
static const char *
remountable_fs_names[] = {
- "ufs", "ffs", "ext2fs",
+ "ufs", "ffs", "ext2fs","msdosfs",
0
};
Second, "mount -o update,noro /dev/md0" results in
a call to msdosfs_mount() that for some reason finds "export"
option in its arguments and just returns 0 effectively ignoring
the request for upgrade to r/w.
Eugene Grosbein
>Release-Note:
>Audit-Trail:
>Unformatted:
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