On 11/06/2011 06:24 PM, Matt Parnell wrote:
On 10/22/2011 02:32 AM, Ted Ts'o wrote:
On Sat, Oct 22, 2011 at 02:51:35AM -0500, Matt Parnell wrote:
That doesn't really help me at all, it's not
rootflags=data=writeback causing this, it's starting to make me
think that arch's init may be to blame, although I previously ruled
it out...
Well, it looks like rootflags=data=writeback is not making it to the
file system. That's why it's not showing up in /proc/mounts, from you
showed us. Can you look at the kernel dmesg?
You should see something like this:
[ 1.421146] EXT3-fs (vda): error: couldn't mount because of
unsupported optional features (240)
[ 1.434057] EXT4-fs (vda): couldn't mount as ext2 due to feature
incompatibilities
[ 1.454631] EXT4-fs (vda): mounted filesystem with writeback data
mode. Opts: data=writeback
[ 1.455966] VFS: Mounted root (ext4 filesystem) readonly on device
254:0.
The first line is the failure to mount the root file system as ext3.
The 2nd is the failure to mount the file system as ext2, using the
ext4 file system driver. The last two lines show the options show the
mount as ext4.
What do those two lines look to you. If you don't see "Opts:
data=writeback", then somehow the rootflags option isn't getting passed
down to the file system. Then when you try to remount the file system
read/write, the fact that you have "data=writeback" in your /etc/fstab
causes the failure to remount.
If you simply remove that from /etc/fstab, things should work better.
The remount will preserve whatever data=journalling mode was in use
when the root file system was originallymounted as. If rootflags is
non-functional, then the file system won't be mounted as
data=writeback, but at least the boot sequence will continue without
blowing out.
- Ted
Looks like the kernel isn't creating the /dev/root link/block device,
either all of the time or some of the time, I'm confused.
I figured it out. data=writeback isn't needed and is done by default if
there's no journal, as per commit
373cd5c53d5ea6622c319ecd84e29e2737d488bd
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=373cd5c53d5ea6622c319ecd84e29e2737d488bd
...sorry about throwing you guys through loops over this, although I'm
guessing there's still a bug in that the kernel should just warn the
user about the option when it's used and otherwise ignore it instead of
breaking if there's no journal.
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