From: Eric Sandeen <sandeen@redhat.com>
To: Jordan Russell <jr-list-2010@quo.to>
Cc: linux-ext4@vger.kernel.org
Subject: Re: Garbage returned in nanosecond component of timestamps
Date: Sat, 20 Nov 2010 01:53:24 -0600 [thread overview]
Message-ID: <4CE77E74.2070006@redhat.com> (raw)
In-Reply-To: <4CE76938.8050304@quo.to>
On 11/20/10 12:22 AM, Jordan Russell wrote:
> [Fedora 14 with vendor kernel 2.6.35.6-48.fc14.i686.PAE]
>
> When nanosecond timestamp resolution isn't supported on an ext4
> partition (inode size = 128), stat() appears to be returning
> uninitialized garbage in the nanosecond component of timestamps.
>
> See the following tests.
> Expected: All timestamps should end with '.0000000000'.
> Actual: '.0026721629' popping up on a different file each time.
>
>> # tune2fs -l /dev/md0 | fgrep 'Inode size'
>> Inode size: 128
>> # echo 3 >/proc/sys/vm/drop_caches
>> # find / -xdev -type f -printf '%t - %p\n' | fgrep -v '.0000000000'
>> Wed Nov 4 16:53:20.0026721629 2009 - /boot/oldconfigs/config-2.6.27.38-170.2.113.fc10.i686.PAE
>> # echo 3 >/proc/sys/vm/drop_caches
>> # find / -xdev -type f -printf '%t - %p\n' | fgrep -v '.0000000000'
>> Thu Nov 8 20:38:30.0026721629 2007 - /boot/oldconfigs/config-2.6.23.1-49.fc8PAE
>> # echo 3 >/proc/sys/vm/drop_caches
>> # find / -xdev -type f -printf '%t - %p\n' | fgrep -v '.0000000000'
>> Thu Aug 12 17:44:51.0026721629 2010 - /lib/firmware/emi26/bitstream.fw
>> # echo 3 >/proc/sys/vm/drop_caches
>> # find / -xdev -type f -printf '%t - %p\n' | fgrep -v '.0000000000'
>> Thu Aug 12 17:44:51.0026721629 2010 - /lib/firmware/slicoss/gbdownload.sys
>> # echo 3 >/proc/sys/vm/drop_caches
>> # find / -xdev -type f -printf '%t - %p\n' | fgrep -v '.0000000000'
>> Fri Nov 5 01:16:32.0026721629 2010 - /boot/grub/e2fs_stage1_5
>
>
> Shouldn't EXT4_INODE_GET_XTIME zero out tv_nsec when EXT4_FITS_IN_INODE
> evaluates to false...?
Yep I think so, good catch...
-Eric
>> #define EXT4_INODE_GET_XTIME(xtime, inode, raw_inode) \
>> do { \
>> (inode)->xtime.tv_sec = (signed)le32_to_cpu((raw_inode)->xtime); \
>> if (EXT4_FITS_IN_INODE(raw_inode, EXT4_I(inode), xtime ## _extra)) \
>> ext4_decode_extra_time(&(inode)->xtime, \
>> raw_inode->xtime ## _extra); \
>> } while (0)
>
next prev parent reply other threads:[~2010-11-20 7:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-20 6:22 Garbage returned in nanosecond component of timestamps Jordan Russell
2010-11-20 7:53 ` Eric Sandeen [this message]
2010-11-22 17:45 ` [PATCH] ext4: zero out nanosecond timestamps for small inodes Eric Sandeen
2010-12-20 3:11 ` Ted Ts'o
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