From: Andreas Gruenbacher <agruen@suse.de>
To: Christoph Hellwig <hch@infradead.org>
Cc: jjohansen@suse.de, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [RFD 1/4] Pass no useless nameidata to the create, lookup, and permission IOPs
Date: Sat, 30 Jun 2007 18:13:57 +0200 [thread overview]
Message-ID: <200706301813.58435.agruen@suse.de> (raw)
In-Reply-To: <20070630091302.GA21784@infradead.org>
On Saturday 30 June 2007 11:13, Christoph Hellwig wrote:
> We need something like this, but I don't quite like the way you've done
> it. First the name is wrong, it's not a nameidata anymore but a lookup
> intent, so it should be named that way, struct lookup_intent.
Sure, that name was pretty random ... lookup_intent has gotten the majority of
votes so far, and I'm perfectly fine with that.
> Second the macro hackery is more than ugly, please keep the structures
> separate. With modern gcc it might be possible to embed the lookup_intent
> into the nameidata anonymously.
http://gcc.gnu.org/onlinedocs/gcc-4.2.0/gcc/Unnamed-Fields.html
If we can add the -fms-extensions gcc option we can get rid of the macro, and
the code becomes pretty clean (as shown below). If we cannot add this option,
then gcc would puke on ``struct lookup_intent;'' in the definition of struct
nameidata. The macro is the cleanest way to work around this I could come up
with, but maybe somebody knows another trick.
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -14,14 +14,10 @@ struct open_intent {
enum { MAX_NESTED_LINKS = 8 };
-struct nameidata {
+struct lookup_intent {
struct dentry *dentry;
struct vfsmount *mnt;
- struct qstr last;
unsigned int flags;
- int last_type;
- unsigned depth;
- char *saved_names[MAX_NESTED_LINKS + 1];
/* Intent data */
union {
@@ -29,6 +25,19 @@ struct nameidata {
} intent;
};
+struct nameidata {
+ struct lookup_intent;
+ struct qstr last;
+ int last_type;
+ unsigned depth;
+ char *saved_names[MAX_NESTED_LINKS + 1];
+};
> Also please either remove the dentry from struct lookup_entry or from the
> direct argument list of the functions and methods - there is no need to pass
> this one twice.
The dentry in the lookup_intent of the create inode operation is the parent
dentry right now, and the child dentry is passed as the separate parameter. I
would prefer the cleaner interface in which the lookup_intent refers to the
child dentry as well. (Getting from the child to the parent is trivial.) I
guess this can go in an incremental patch with the next version of these
patches.
Thanks,
Andreas
next prev parent reply other threads:[~2007-06-30 16:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-26 23:15 [RFD 0/4] AppArmor - Don't pass NULL nameidata to vfs_create/lookup/permission IOPs jjohansen
2007-06-26 23:15 ` [RFD 1/4] Pass no useless nameidata to the create, lookup, and permission IOPs jjohansen
2007-06-27 0:11 ` Erez Zadok
2007-06-30 9:14 ` Christoph Hellwig
2007-06-30 9:13 ` Christoph Hellwig
2007-06-30 16:13 ` Andreas Gruenbacher [this message]
2007-06-26 23:15 ` [RFD 2/4] Never pass a NULL nameidata to vfs_create() jjohansen
2007-06-26 23:15 ` [RFD 3/4] Dont use a NULL nameidata in xattr_permission() jjohansen
2007-06-26 23:15 ` [RFD 4/4] Pass nameidata2 to permission() from nfsd_permission() jjohansen
2007-06-26 23:46 ` [RFD 0/4] AppArmor - Don't pass NULL nameidata to vfs_create/lookup/permission IOPs Trond Myklebust
2007-06-27 20:42 ` Andreas Gruenbacher
2007-06-30 9:15 ` Christoph Hellwig
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