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From: Trond Myklebust <trondmy@hammerspace.com>
To: "tigran.mkrtchyan@desy.de" <tigran.mkrtchyan@desy.de>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v2 16/16] NFS: Improve handling of directory verifiers
Date: Wed, 4 Nov 2020 17:21:05 +0000
Message-ID: <fc3b4ff48d315674f9b076187dc2a1c056cf5744.camel@hammerspace.com> (raw)
In-Reply-To: <1868756897.5941283.1604484769947.JavaMail.zimbra@desy.de>

Hi Tigran,

On Wed, 2020-11-04 at 11:12 +0100, Mkrtchyan, Tigran wrote:
> 
> 
> ----- Original Message -----
> > From: trondmy@kernel.org
> > To: "linux-nfs" <linux-nfs@vger.kernel.org>
> > Sent: Tuesday, 3 November, 2020 16:33:29
> > Subject: [PATCH v2 16/16] NFS: Improve handling of directory
> > verifiers
> 
> > From: Trond Myklebust <trond.myklebust@hammerspace.com>
<snip>
> > @@ -89,6 +94,7 @@ struct nfs_open_context {
> > struct nfs_open_dir_context {
> >         struct list_head list;
> >         unsigned long attr_gencount;
> > +       __be32  verf[NFS_DIR_VERIFIER_SIZE];
> >         __u64 dir_cookie;
> >         __u64 dup_cookie;
> >         signed char duped;
> > @@ -156,7 +162,7 @@ struct nfs_inode {
> >          * This is the cookie verifier used for NFSv3 readdir
> >          * operations
> >          */
> > -       __be32                  cookieverf[2];
> > +       __be32                  cookieverf[NFS_DIR_VERIFIER_SIZE];
> 
> Just for my education. Why we use 2x32 bit BE encoded ints instead of
> raw 8 bytes?
> And if it's treaded as a number, as spec sometimes does ("The
> request's cookieverf
> field should be set to 0"), then why it's not then __be64?

The main reason for often using __be32 on these identifiers is to tag
them as being opaque RPC objects (since RPC objects are always in units
of 32-bits and are big endian encoded).

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com



  reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-03 15:33 [PATCH v2 00/16] Readdir enhancements trondmy
2020-11-03 15:33 ` [PATCH v2 01/16] NFS: Ensure contents of struct nfs_open_dir_context are consistent trondmy
2020-11-03 15:33   ` [PATCH v2 02/16] NFS: Clean up readdir struct nfs_cache_array trondmy
2020-11-03 15:33     ` [PATCH v2 03/16] NFS: Clean up nfs_readdir_page_filler() trondmy
2020-11-03 15:33       ` [PATCH v2 04/16] NFS: Clean up directory array handling trondmy
2020-11-03 15:33         ` [PATCH v2 05/16] NFS: Don't discard readdir results trondmy
2020-11-03 15:33           ` [PATCH v2 06/16] NFS: Remove unnecessary kmap in nfs_readdir_xdr_to_array() trondmy
2020-11-03 15:33             ` [PATCH v2 07/16] NFS: Replace kmap() with kmap_atomic() in nfs_readdir_search_array() trondmy
2020-11-03 15:33               ` [PATCH v2 08/16] NFS: Simplify struct nfs_cache_array_entry trondmy
2020-11-03 15:33                 ` [PATCH v2 09/16] NFS: Support larger readdir buffers trondmy
2020-11-03 15:33                   ` [PATCH v2 10/16] NFS: More readdir cleanups trondmy
2020-11-03 15:33                     ` [PATCH v2 11/16] NFS: nfs_do_filldir() does not return a value trondmy
2020-11-03 15:33                       ` [PATCH v2 12/16] NFS: Reduce readdir stack usage trondmy
2020-11-03 15:33                         ` [PATCH v2 13/16] NFS: Cleanup to remove nfs_readdir_descriptor_t typedef trondmy
2020-11-03 15:33                           ` [PATCH v2 14/16] NFS: Allow the NFS generic code to pass in a verifier to readdir trondmy
2020-11-03 15:33                             ` [PATCH v2 15/16] NFS: Handle NFS4ERR_NOT_SAME and NFSERR_BADCOOKIE from readdir calls trondmy
2020-11-03 15:33                               ` [PATCH v2 16/16] NFS: Improve handling of directory verifiers trondmy
2020-11-04 10:12                                 ` Mkrtchyan, Tigran
2020-11-04 17:21                                   ` Trond Myklebust [this message]
2020-11-03 15:55           ` [PATCH v2 05/16] NFS: Don't discard readdir results Benjamin Coddington
2020-11-03 16:14             ` Trond Myklebust
2020-11-04 16:14 ` [PATCH v2 00/16] Readdir enhancements Benjamin Coddington
2020-11-04 17:04   ` Trond Myklebust
2020-11-04 17:19     ` Benjamin Coddington

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