Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755474AbYH0O2c (ORCPT ); Wed, 27 Aug 2008 10:28:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753563AbYH0O2Y (ORCPT ); Wed, 27 Aug 2008 10:28:24 -0400 Received: from vpnflf.ccur.com ([12.192.68.2]:36256 "EHLO gamx.iccur.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753506AbYH0O2X (ORCPT ); Wed, 27 Aug 2008 10:28:23 -0400 Date: Wed, 27 Aug 2008 10:28:20 -0400 From: Joe Korty To: Trond Myklebust Cc: Linux Kernel Subject: [PATCH] NFSv3: cached permissions subset enhancement Message-ID: <20080827142820.GA22661@tsunami.ccur.com> Reply-To: Joe Korty Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2422 Lines: 72 [NFSv3] cached permissions subset enhancement. NFSv3 allows file permissions to be cached on the client side. The Linux client, when fetching these permissions, makes the request for all permissions (rwx) in a single operation. However, for some NFSv3 server implementations (the only one currently known is PowerMAX OS), an incoming request for all rwx permissions in a single request, when all are not actually set in the file, returns an NFSERR_ACCES failure code to the client, rather than the subset of permissions actually available for that file. This patch modifies the Linux client side code to individually fetch the r, w, and x permissions (combining these for storage into the cache), if the original single-request method fails. This slower method will not affect performance of those client/server pairs for which the original single-request method works. In particular there is no performance penalty for linux/linux NFSv3 connections. Author: Linda Dunaphant Signed-off-by: Joe Korty Index: 2.6.27-rc4-git4/fs/nfs/dir.c =================================================================== --- 2.6.27-rc4-git4.orig/fs/nfs/dir.c 2008-08-26 17:44:34.000000000 -0400 +++ 2.6.27-rc4-git4/fs/nfs/dir.c 2008-08-26 18:21:27.000000000 -0400 @@ -1870,6 +1870,8 @@ { struct nfs_access_entry cache; int status; + int i; + int cmask = 0; status = nfs_access_get_cached(inode, cred, &cache); if (status == 0) @@ -1880,8 +1882,27 @@ cache.cred = cred; cache.jiffies = jiffies; status = NFS_PROTO(inode)->access(inode, &cache); - if (status != 0) + if (status == -NFSERR_ACCES) { + // + // Try again - one mode at a time & combine at the end + // + for (i = 0; i <= MAY_READ; i++) { + cache.mask = 1 << i; + status = NFS_PROTO(inode)->access(inode, &cache); + if (status == 0) + cmask |= cache.mask; + else if (status != -NFSERR_ACCES) { + return status; + } + } + + if (!cmask) + return -NFSERR_ACCES; + + cache.mask = cmask; + } else if (status) return status; + nfs_access_add_cache(inode, &cache); out: if ((mask & ~cache.mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/