Re: fsync reliability

On 2011-04-22 21:55, Greg Smith wrote:
> On 04/22/2011 09:32 AM, Simon Riggs wrote:
>> OK, that's good, but ISTM we still have a hole during
>> RemoveOldXlogFiles() where we don't fsync or open/close the file, just
>> rename it.
>
> This is also something that many applications rely upon working as hoped
> for here, even though it's not technically part of POSIX. Early
> versions of ext4 broke that, and it caused a giant outcry of
> complaints.
> http://www.h-online.com/open/news/item/Ext4-data-loss-explanations-and-workarounds-740671.html
> has a good summary. This was broken on ext4 from around 2.6.28 to
> 2.6.30, but the fix for it was so demanded that it's even been ported by
> the relatively lazy distributions to their 2.6.28/2.6.29 kernels.

As far as I can make out, the current situation is that this fix (the
auto_da_alloc mount option) doesn't work as advertised, and the ext4
maintainers are not treating this as a bug.

See https://bugzilla.kernel.org/show_bug.cgi?id=15910

-M-