From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753623AbdECSoB (ORCPT ); Wed, 3 May 2017 14:44:01 -0400 Received: from smtprelay0210.hostedemail.com ([216.40.44.210]:46897 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751494AbdECSnw (ORCPT ); Wed, 3 May 2017 14:43:52 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::::::,RULES_HIT:41:355:379:541:599:800:960:966:973:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2196:2199:2393:2559:2562:2828:2914:3138:3139:3140:3141:3142:3352:3622:3865:3867:3868:3870:3871:3872:3873:3874:4321:4385:5007:10004:10400:10848:11232:11658:11914:12740:12760:12895:13069:13311:13357:13439:14181:14659:14721:21080:21627:30054:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:2,LUA_SUMMARY:none X-HE-Tag: man18_4425110ddf01 X-Filterd-Recvd-Size: 2145 Message-ID: <1493837027.22125.17.camel@perches.com> Subject: Re: [PATCH 3/9] VFS: Introduce a mount context From: Joe Perches To: David Howells Cc: Jeff Layton , viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, mszeredi@redhat.com Date: Wed, 03 May 2017 11:43:47 -0700 In-Reply-To: <4597.1493836661@warthog.procyon.org.uk> References: <1493835998.22125.15.camel@perches.com> <149382747487.30481.15428192741961545429.stgit@warthog.procyon.org.uk> <149382749941.30481.11685229083280551867.stgit@warthog.procyon.org.uk> <1493835238.3180.7.camel@poochiereds.net> <4597.1493836661@warthog.procyon.org.uk> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.22.6-1ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2017-05-03 at 19:37 +0100, David Howells wrote: > Joe Perches wrote: > > > krealloc would probably be more efficient and possible > > readable as likely there's already padding in the original > > allocation. > > The problem is if krealloc() fails: you've lost all those pointers to things > you then need to free. Huh? How could that happen? krealloc must always use a temporary. If krealloc returns NULL, the original allocation is kept. > > Are there no locking constraints? > > Generally, no, not until you do the ->mount() op. Also remounting needs a > lock, but that's already done with the sb->s_umount lock. > > However, that said, if you do: > > fd = fsopen("foofs"); > write(fd, "o foo=bar", ...); > fsmount(fd, "/foo"); > > then the fsmount() and write() calls have to lock against other fsmount() and > write() calls. I use the inode lock for this. [Note that it probably should > be interruptible rather than just killable, but there's no primitive for that > as yet]. > > David