From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 36556 invoked by alias); 8 Feb 2019 11:37:57 -0000 Mailing-List: contact cygwin-cvs-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: cygwin-cvs-owner@cygwin.com Received: (qmail 36261 invoked by uid 9078); 8 Feb 2019 11:37:57 -0000 Date: Fri, 08 Feb 2019 11:37:00 -0000 Message-ID: <20190208113757.36260.qmail@sourceware.org> Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Corinna Vinschen To: cygwin-cvs@sourceware.org Subject: [newlib-cygwin] forkables: Keep hardlinks disabled via shared mem. X-Act-Checkin: newlib-cygwin X-Git-Author: Michael Haubenwallner X-Git-Refname: refs/heads/master X-Git-Oldrev: ece7282f329fd3616a9a1089aa0f0c26a5c01cc1 X-Git-Newrev: 5a41aa6f4d5eb12a1fc2ef084d98f63d65f5fcc3 X-SW-Source: 2019-q1/txt/msg00141.txt.bz2 https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=5a41aa6f4d5eb12a1fc2ef084d98f63d65f5fcc3 commit 5a41aa6f4d5eb12a1fc2ef084d98f63d65f5fcc3 Author: Michael Haubenwallner Date: Wed Dec 7 11:58:29 2016 +0100 forkables: Keep hardlinks disabled via shared mem. To avoid the need for each process to check the filesystem to detect that hardlink creation is impossible or disabled, cache this fact in shared memory. Removing cygfork directory while in use does disable hardlinks creation. To (re-)enable hardlinks creation, the cygfork directory has to exist before the first cygwin process does fork. * forkable.cc (dll_list::forkable_ntnamesize): Short cut forkables needs to impossible when disabled via shared memory. (dll_list::update_forkables_needs): When detecting hardlink creation as impossible (not on NTFS) while still (we are the first one checking) enabled via shared memory, disable the shared memory value. (dll_list::request_forkables): Disable the shared memory value when hardlinks creation became disabled, that is when the cygfork directory was removed. * include/cygwin/version.h: Bump CYGWIN_VERSION_SHARED_DATA 6. * shared_info.h (struct shared_info): Add member prefer_forkable_hardlinks. Update CURR_SHARED_MAGIC. * shared.cc (shared_info::initialize): Initialize prefer_forkable_hardlinks to 1 (Yes). Diff: --- winsup/cygwin/forkable.cc | 13 +++++++++++++ winsup/cygwin/include/cygwin/version.h | 2 +- winsup/cygwin/shared_info.h | 3 ++- 3 files changed, 16 insertions(+), 2 deletions(-) diff --git a/winsup/cygwin/forkable.cc b/winsup/cygwin/forkable.cc index cc28f9f..da45643 100644 --- a/winsup/cygwin/forkable.cc +++ b/winsup/cygwin/forkable.cc @@ -522,6 +522,11 @@ dll::create_forkable () size_t dll_list::forkable_ntnamesize (dll_type type, PCWCHAR fullntname, PCWCHAR modname) { + /* per process, this is the first forkables-method ever called */ + if (forkables_needs == forkables_unknown && + !cygwin_shared->prefer_forkable_hardlinks) + forkables_needs = forkables_impossible; /* short cut */ + if (forkables_needs == forkables_impossible) return 0; @@ -667,6 +672,7 @@ dll_list::update_forkables_needs () { debug_printf ("impossible, not on NTFS %W", fn.Buffer); forkables_needs = forkables_impossible; + cygwin_shared->prefer_forkable_hardlinks = 0; } } @@ -1056,6 +1062,13 @@ dll_list::request_forkables () set_forkables_inheritance (true); + if (forkables_needs == forkables_disabled) + { + /* we do not support (re-)enabling on the fly */ + forkables_needs = forkables_impossible; + cygwin_shared->prefer_forkable_hardlinks = 0; + } + if (forkables_needs <= forkables_needless) return; diff --git a/winsup/cygwin/include/cygwin/version.h b/winsup/cygwin/include/cygwin/version.h index 8926d49..f7ed351 100644 --- a/winsup/cygwin/include/cygwin/version.h +++ b/winsup/cygwin/include/cygwin/version.h @@ -518,7 +518,7 @@ details. */ regions. It is incremented when incompatible changes are made to the shared memory region *or* to any named shared mutexes, semaphores, etc. */ -#define CYGWIN_VERSION_SHARED_DATA 5 +#define CYGWIN_VERSION_SHARED_DATA 6 /* An identifier used in the names used to create shared objects. The full names include the CYGWIN_VERSION_SHARED_DATA version as well as this diff --git a/winsup/cygwin/shared_info.h b/winsup/cygwin/shared_info.h index 1a5648b..8f0954f 100644 --- a/winsup/cygwin/shared_info.h +++ b/winsup/cygwin/shared_info.h @@ -33,7 +33,7 @@ public: /* Data accessible to all tasks */ -#define CURR_SHARED_MAGIC 0x6758de88U +#define CURR_SHARED_MAGIC 0x3a6025edU #define USER_VERSION 1 @@ -51,6 +51,7 @@ class shared_info mtinfo mt; loadavginfo loadavg; LONG pid_src; + char prefer_forkable_hardlinks; /* single byte access always is atomic */ void initialize (); void init_obcaseinsensitive ();