Bug#670593: linux-image-3.2.0-2-amd64: max_batch_time not honoured or incorrect in /proc/mounts

["Joshua Charles Campbell" <wz@wza.us>]

Package: linux-image-3.2.0-2-amd64
Version: 3.2.15-1
Severity: normal


This happens on both 3.2 from backports and 3.2 in wheezy, tested on both.
Might happen in earlier kernels too.

umount /test; mount -o max_batch_time=14000 /test; grep test /proc/mounts
produces:
/dev/mapper/test /test ext4
rw,noatime,user_xattr,acl,commit=600,max_batch_time=0,barrier=0,journal_async_commit,stripe=768,data=writeback

Note max_batch_time=0 means "batching off" according to ext4.txt from the linux
kernel documentation.

umount /test; mount -o max_batch_time=15000 /test; grep test /proc/mounts
produces:
/dev/mapper/test /test ext4
rw,noatime,user_xattr,acl,commit=600,barrier=0,journal_async_commit,stripe=768,data=writeback

This is correct since 15000 is the default.

umount /test; mount -o max_batch_time=15000,min_batch_time=42 /test; grep test
/proc/mounts
produces:
/dev/mapper/test /test ext4
rw,noatime,user_xattr,acl,commit=600,min_batch_time=42,max_batch_time=42,barrier=0,journal_async_commit,stripe=768,data=writeback

Now they are both 42!

So either the reporting of /proc/mounts or parsing when mount options are set
is broken.


-- System Information:
Debian Release: 6.0.4
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.2.0-0.bpo.1-amd64 (SMP w/6 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash