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Re: ACL limit

To: Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx>
Subject: Re: ACL limit
From: Timothy Shimmin <tes@xxxxxxx>
Date: Mon, 03 Dec 2007 10:47:07 +1100
Cc: David Chinner <dgc@xxxxxxx>, xfs@xxxxxxxxxxx
In-reply-to: <20071202223105.GS119954183@xxxxxxx>
References: <Pine.LNX.4.64.0711301902360.18767@xxxxxxxxxxxxxxxxxxxxxxxxx> <20071202223105.GS119954183@xxxxxxx>
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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


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