QA test attempting to reproduce multiple directory entries problem.

This commit is contained in:
fsgqa
2004-04-22 03:06:52 +00:00
parent d0d6ac2d43
commit abdf9cb068
5 changed files with 349 additions and 1 deletions
Executable
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@@ -0,0 +1,75 @@
#! /bin/sh
# XFS QA Test No. 089
#
# Emulate the way Linux mount manipulates /etc/mtab to attempt to
# reproduce a possible bug in rename (see src/t_mtab.c).
#
#-----------------------------------------------------------------------
# Copyright (c) 2000-2004 Silicon Graphics, Inc. All Rights Reserved.
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of version 2 of the GNU General Public License as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it would be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
#
# Further, this software is distributed without any warranty that it is
# free of the rightful claim of any third person regarding infringement
# or the like. Any license provided herein, whether implied or
# otherwise, applies only to this software file. Patent licenses, if
# any, provided herein do not apply to combinations of this program with
# other software, or any other product whatsoever.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write the Free Software Foundation, Inc., 59
# Temple Place - Suite 330, Boston MA 02111-1307, USA.
#
# Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
# Mountain View, CA 94043, or:
#
# http://www.sgi.com
#
# For further information regarding this notice, see:
#
# http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
#-----------------------------------------------------------------------
#
# creator
owner=nathans@sgi.com
seq=`basename $0`
echo "QA output created by $seq"
here=`pwd`
tmp=/tmp/$$
status=1 # failure is the default!
trap "rm -f $tmp.*; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
# real QA test starts here
[ "X$TEST_DIR" = "X" ] && exit 1
cd $TEST_DIR
rm -fr test
mkdir test || exit 1
cd $TEST_DIR/test
mount > t_mtab
$here/src/t_mtab 2 &
$here/src/t_mtab 2 &
$here/src/t_mtab 2 &
wait
$here/src/t_mtab 10000
echo directory entries:
ls
ls -li > $seq.full
# success, all done
status=0
exit
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@@ -0,0 +1,7 @@
QA output created by 089
completed 2 iterations
completed 2 iterations
completed 2 iterations
completed 10000 iterations
directory entries:
t_mtab
+1
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@@ -155,3 +155,4 @@ ioctl nathans@sgi.com
086 log auto
087 log auto
088 perms
089 metadata auto
+1 -1
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@@ -38,7 +38,7 @@ TARGETS = alloc acl_get bstat devzero dirstress fault feature \
nametest permname randholes runas truncfile usemem \
fstest mmapcat append_reader append_writer \
dirperf metaperf enospc_unlink resvtest scaleread \
godown t_access_root
godown t_access_root t_mtab
ifeq ($(ENABLE_DBM), yes)
TARGETS += dbtest
endif
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/*
* Test program based on Linux mount(8) source attempting to
* trigger a suspected problem in rename(2) code paths - its
* symptoms have been multiple mtab entries in /etc... hence
* use of the actual mount code here.
*/
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <sys/stat.h>
#include <mntent.h>
#include <limits.h>
#define LOCK_TIMEOUT 10
#define _(x) (x)
static char *mounted = "t_mtab";
static char *mounted_lock = "t_mtab~";
static char *mounted_temp = "t_mtab.tmp";
/* Updating mtab ----------------------------------------------*/
/* Flag for already existing lock file. */
static int we_created_lockfile = 0;
/* Flag to indicate that signals have been set up. */
static int signals_have_been_setup = 0;
/* Ensure that the lock is released if we are interrupted. */
static void
handler (int sig) {
fprintf(stderr, "%s", sys_siglist[sig]);
exit(1);
}
static void
setlkw_timeout (int sig) {
/* nothing, fcntl will fail anyway */
}
/* Create the lock file.
The lock file will be removed if we catch a signal or when we exit. */
/* The old code here used flock on a lock file /etc/mtab~ and deleted
this lock file afterwards. However, as rgooch remarks, that has a
race: a second mount may be waiting on the lock and proceed as
soon as the lock file is deleted by the first mount, and immediately
afterwards a third mount comes, creates a new /etc/mtab~, applies
flock to that, and also proceeds, so that the second and third mount
now both are scribbling in /etc/mtab.
The new code uses a link() instead of a creat(), where we proceed
only if it was us that created the lock, and hence we always have
to delete the lock afterwards. Now the use of flock() is in principle
superfluous, but avoids an arbitrary sleep(). */
void
lock_mtab (void) {
int tries = 3;
char linktargetfile[PATH_MAX + 20];
if (!signals_have_been_setup) {
int sig = 0;
struct sigaction sa;
sa.sa_handler = handler;
sa.sa_flags = 0;
sigfillset (&sa.sa_mask);
while (sigismember (&sa.sa_mask, ++sig) != -1
&& sig != SIGCHLD) {
if (sig == SIGALRM)
sa.sa_handler = setlkw_timeout;
else
sa.sa_handler = handler;
sigaction (sig, &sa, (struct sigaction *) 0);
}
signals_have_been_setup = 1;
}
/* use 20 as upper bound for the length of %d output */
snprintf(linktargetfile, PATH_MAX+20, "%s%d", mounted_lock, getpid());
/* Repeat until it was us who made the link */
while (!we_created_lockfile) {
struct flock flock;
int fd, errsv, i, j;
i = open (linktargetfile, O_WRONLY|O_CREAT, 0);
if (i < 0) {
int errsv = errno;
/* linktargetfile does not exist (as a file)
and we cannot create it. Read-only filesystem?
Too many files open in the system?
Filesystem full? */
fprintf(stderr, "can't create lock file %s: %s "
"(use -n flag to override)",
linktargetfile, strerror (errsv));
exit(1);
}
close(i);
j = link(linktargetfile, mounted_lock);
errsv = errno;
(void) unlink(linktargetfile);
if (j < 0 && errsv != EEXIST) {
fprintf(stderr, "can't link lock file %s: %s "
"(use -n flag to override)",
mounted_lock, strerror (errsv));
exit(1);
}
fd = open (mounted_lock, O_WRONLY);
if (fd < 0) {
int errsv = errno;
/* Strange... Maybe the file was just deleted? */
if (errno == ENOENT && tries-- > 0)
continue;
fprintf(stderr, "can't open lock file %s: %s "
"(use -n flag to override)",
mounted_lock, strerror (errsv));
exit(1);
}
flock.l_type = F_WRLCK;
flock.l_whence = SEEK_SET;
flock.l_start = 0;
flock.l_len = 0;
if (j == 0) {
/* We made the link. Now claim the lock. */
if (fcntl (fd, F_SETLK, &flock) == -1) {
int errsv = errno;
printf(_("Can't lock lock file %s: %s\n"),
mounted_lock, strerror (errsv));
/* proceed anyway */
}
we_created_lockfile = 1;
} else {
static int tries = 0;
/* Someone else made the link. Wait. */
alarm(LOCK_TIMEOUT);
if (fcntl (fd, F_SETLKW, &flock) == -1) {
int errsv = errno;
fprintf(stderr, "can't lock lock file %s: %s",
mounted_lock, (errno == EINTR) ?
_("timed out") : strerror (errsv));
exit(1);
}
alarm(0);
/* Limit the number of iterations - maybe there
still is some old /etc/mtab~ */
if (tries++ > 3) {
if (tries > 5) {
fprintf(stderr, "Cant create link %s\n"
"Perhaps there is a stale lock file?\n",
mounted_lock);
exit(1);
}
sleep(1);
}
}
close (fd);
}
}
/* Remove lock file. */
void
unlock_mtab (void) {
if (we_created_lockfile) {
unlink (mounted_lock);
we_created_lockfile = 0;
}
}
/*
* Update the mtab.
* Used by umount with null INSTEAD: remove the last DIR entry.
* Used by mount upon a remount: update option part,
* and complain if a wrong device or type was given.
* [Note that often a remount will be a rw remount of /
* where there was no entry before, and we'll have to believe
* the values given in INSTEAD.]
*/
void
update_mtab (void)
{
FILE *mntent_fp, *mftmp;
char buffer[4096];
int size;
lock_mtab();
/* having locked mtab, read it again & write to mtemp */
mntent_fp = fopen(mounted, "r");
if (!mntent_fp) {
fprintf(stderr, "cannot open %s for reading\n", mounted);
exit(1);
}
mftmp = fopen(mounted_temp, "w");
if (!mftmp) {
fprintf(stderr, "cannot open %s for writing\n", mounted_temp);
exit(1);
}
while ((size = read(fileno(mntent_fp), buffer, sizeof(buffer))) > 0) {
if (write(fileno(mftmp), buffer, size) < 0) {
fprintf(stderr, "write failure: %s\n", strerror(errno));
exit(1);
}
}
if (size < 0) {
fprintf(stderr, "read failure: %s\n", strerror(errno));
exit(1);
}
fclose(mntent_fp);
if (fchmod (fileno (mftmp),
S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH) < 0) {
int errsv = errno;
fprintf(stderr, _("error changing mode of %s: %s\n"),
mounted_temp, strerror (errsv));
}
fclose(mftmp);
{ /*
* If mount is setuid and some non-root user mounts sth,
* then mtab.tmp might get the group of this user. Copy uid/gid
* from the present mtab before renaming.
*/
struct stat sbuf;
if (stat (mounted, &sbuf) == 0)
chown (mounted_temp, sbuf.st_uid, sbuf.st_gid);
}
/* rename mtemp to mtab */
if (rename (mounted_temp, mounted) < 0) {
int errsv = errno;
fprintf(stderr, _("can't rename %s to %s: %s\n"),
mounted_temp, mounted, strerror(errsv));
}
unlock_mtab();
}
int main(int argc, char **argv)
{
int i, stop = 100000;
if (argc > 1)
stop = atoi(argv[1]);
for (i = 0; i < stop; i++) {
update_mtab();
}
printf("completed %d iterations\n", stop);
return 0;
}