From: Theodore Ts'o <tytso@mit.edu>
To: Chen Gang <gang.chen@asianux.com>
Cc: jack@suse.cz, akpm@linux-foundation.org, linux-ext4@vger.kernel.org
Subject: Re: [PATCH] fs/ext3: use kzalloc instead of kmalloc
Date: Tue, 25 Dec 2012 23:45:32 -0500 [thread overview]
Message-ID: <20121226044532.GB16669@thunk.org> (raw)
In-Reply-To: <50DA6BC7.1000804@asianux.com>
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
next prev parent reply other threads:[~2012-12-26 4:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-24 5:28 [PATCH] fs/ext3: use kzalloc instead of kmalloc Chen Gang
2012-12-25 18:48 ` Theodore Ts'o
2012-12-26 3:15 ` Chen Gang
2012-12-26 4:45 ` Theodore Ts'o [this message]
2012-12-26 5:08 ` Chen Gang
2012-12-26 5:34 ` Chen Gang
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