UBIFS is not remounted read-only from within do_emergency_remount
Alexander Stein
alexander.stein at systec-electronic.com
Tue Jul 31 07:24:19 EDT 2012
Hello,
upon testing do_emergency_remount from a power fail interrupt (using the
workqueue of course), we noticed UBIFS is not remounted read-only afterwards.
The current code in do_emergency_remount checks if the kernel actually needs
to remount a filesystem using the following code:
> if (sb->s_root && sb->s_bdev && (sb->s_flags & MS_BORN) &&
> !(sb->s_flags & MS_RDONLY)) {
> /*
> * What lock protects sb->s_flags??
> */
> do_remount_sb(sb, MS_RDONLY, NULL, 1);
> }
I'm not in the details of this part of the kernel, but I suspect that sb-
>s_bdev is NULL for UBIFS as it has no block device, but the character device
/dev/ubiX_Y instead. I have the information from a collegue that removing the
check for testing purposes for sb->s_bdev mounts UBIFS read-only.
Any comments/ideas how to remount UBIFS as read-only from
do_emergency_remount?
Best regards,
Alexander
More information about the linux-mtd
mailing list