Re: ext4: indirect block allocations not sequential in 3.4.67 and 3.11.7

[Eric Sandeen <sandeen@redhat.com>]

On 1/16/14, 1:12 PM, Theodore Ts'o wrote:
> On Thu, Jan 16, 2014 at 01:48:26PM -0500, Benjamin LaHaise wrote:
>>
>> Any idea when this commit was made or titled?  I care about random 
>> performance as well, but that can't be at the cost of making sequential 
>> reads suck.
> 
> Thinking about this some more, I think it was made as part of the
> changes to better take advantage of the flex_bg feature in ext4.  The
> idea was to keep metadata blocks such as directory blocks and extent
> trees closer together.  I don't think when we made that change we
> really consciously thought that much about indirect block support,
> since that was viewed as a legacy feature for backwards compatibility
> support in ext4.  (This was years ago, before distributions started
> wanting to support only one code base for ext3 and ext4 file systems.)

Just to nitpick, wasn't this always the plan?  ;)

https://lkml.org/lkml/2006/6/28/454 :

> 4) At some point, probably in 6-9 months when we are satisified with the
> set of features that have been added to fs/ext4, and confident that the
> filesystem format has stablized, we will submit a patch which causes the
> fs/ext4 code to register itself as the ext4 filesystem.

-Eric

p.s. "6-9 months"  ;)