From fa6ac76083b8ffc1309876459f54f9f0e2843731 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Tue, 30 Dec 2014 20:57:53 +0100 Subject: journald: process SIGBUS for the memory maps we set up Even though we use fallocate() it appears that file systems like btrfs will trigger SIGBUS on certain low-disk-space situation. We should handle that, hence catch the signal, add it to a list of invalidated pages, and replace the page with an empty memory area. After each write check if SIGBUS was triggered, and consider the write invalid if it was. This should make journald a lot more robust with file systems where fallocate() is not reliable, for example all CoW file systems (btrfs...), where changing written data can fail with disk full errors. https://bugzilla.redhat.com/show_bug.cgi?id=1045810 --- src/test/test-sigbus.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 src/test/test-sigbus.c (limited to 'src/test') diff --git a/src/test/test-sigbus.c b/src/test/test-sigbus.c new file mode 100644 index 0000000000..39d0fec894 --- /dev/null +++ b/src/test/test-sigbus.c @@ -0,0 +1,62 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2014 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see . +***/ + +#include + +#include "util.h" +#include "sigbus.h" + +int main(int argc, char *argv[]) { + _cleanup_close_ int fd = -1; + char template[] = "/tmp/sigbus-test-XXXXXX"; + void *addr = NULL; + uint8_t *p; + + sigbus_install(); + + assert(sigbus_pop(&addr) == 0); + + assert_se((fd = mkostemp(template, O_RDWR|O_CREAT|O_EXCL)) >= 0); + assert_se(unlink(template) >= 0); + assert_se(fallocate(fd, 0, 0, page_size() * 8) >= 0); + + p = mmap(NULL, page_size() * 16, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); + assert_se(p != MAP_FAILED); + + assert_se(sigbus_pop(&addr) == 0); + + p[0] = 0xFF; + assert_se(sigbus_pop(&addr) == 0); + + p[page_size()] = 0xFF; + assert_se(sigbus_pop(&addr) == 0); + + p[page_size()*8] = 0xFF; + p[page_size()*8+1] = 0xFF; + p[page_size()*10] = 0xFF; + assert_se(sigbus_pop(&addr) > 0); + assert_se(addr == p + page_size() * 8); + assert_se(sigbus_pop(&addr) > 0); + assert_se(addr == p + page_size() * 10); + assert_se(sigbus_pop(&addr) == 0); + + sigbus_reset(); +} -- cgit v1.2.3-54-g00ecf