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Message-ID: <50DA8641.1030004@asianux.com>
Date: Wed, 26 Dec 2012 13:08:17 +0800
From: Chen Gang <gang.chen@...anux.com>
To: Theodore Ts'o <tytso@....edu>
CC: jack@...e.cz, akpm@...ux-foundation.org, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] fs/ext3: use kzalloc instead of kmalloc
于 2012年12月26日 12:45, Theodore Ts'o 写道:
> On Wed, Dec 26, 2012 at 11:15:19AM +0800, Chen Gang wrote:
>>
>> checking the ext3_acl_size, it does not like what you said above.
>> but we can say, the design for ext3_acl_size is really not quit well.
>> (maybe can cause issue).
>
> Ah, I see. What's there is OK, but it's not at all obvious that it's
> OK. A valid acl must have a very specific order of tags, as enforced
> by posix_acl_valid() in fs/posix_acl.c:
>
> ACL_USER_OBJ ACL_USER*[1] ACL_GROUP_OBJ ACL_GROUP*[1] ACL_MASK[2] ACL_OTHER
>
> [1] Where * is the regexp sense of "0 or more times"
> [2] Only if there is at least one ACL_USER or ACL_GROUP tag; otherwise
> skip ACL_MASK.
>
> Hence, a valid acl can have at most 4 short acl entry types
> (ACL_USER_OBJ, ACL_GROUP, ACL_MASK, and ACL_OTHER), and if there is
> less than 4 acl entries, they must all be short acl types.
>
> All I can say is, this is a horrible way of coding things, and I wish
> this was documented explicitly somewhere either in fs/posix_acl.c or
> in include/linux/posix_acl.h. Yuck, yuck, yuck....
>
> - Ted
learned.
:-)
also better to give a comment above the function ext3_acl_size.
thanks.
--
Chen Gang
Asianux Corporation
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