Re: ACL limit

[Timothy Shimmin <tes@sgi.com>]

David Chinner wrote:
> On Fri, Nov 30, 2007 at 07:07:26PM +0100, Jan Engelhardt wrote:
>> Hi,
>>
>>
>> is there any way to raise the number of ACLs that can be stored? The 
>> current limit of 25 is quite tight, where ext3 allows 124 and jfs 8192.
>> Would increasing XFS_ACL_MAX_ENTRIES work (yes, using potentially more 
>> memory), i.e. not interfering with the on-disk format?
> 
> It would be an on disk format change - older kernels would error out
> (-EINVAL) on > 25 ACLs and not check any of them. Hence we'd
> probably need a superblock feature bit to indicate that >25 ACEs are
> supported in a given ACL.
> 
> But we can work around that (superblock feature bit) and should
> be able to extend this out to ~8190 entries. We're doing an ACL
> rework ATM, so > 25 entry support should fall out of that....
> 
> Cheers,
> 
> Dave.

Yeah, it's just an array of entries in an EA value.
The EA value is limited to 64K so it's a question of how
many entries you can fit into that.
(64K - 4)/12 = 5461

(So just have to sort out the ondisk change as mentioned above)

--Tim