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getmntinfo(3): Scale faster, and return sooner
getmntinfo(3) is designed around a relatively static or slow growing set of current mounts. It tried to detect a race with somewhat concurrent mount and re-call getfsstat(2) in that case, looping indefinitely. It also allocated space for a single extra mount as slop. In the case where the user has a large number of mounts and is adding them at a rapid pace, it fell over. This patch makes two functional changes: 1. Allocate even more slop. Double whatever the last getfsstat(2) returned. 2. Abort and return some known results after looping a few times (arbitrarily, 3). If the list is constantly changing, we can't guarantee we return a full result to the user at any point anyways. While here, add very basic functional tests for getmntinfo(3) to the libc suite. PR: 221743 Submitted by: Peter Eriksson <peter AT ifm.liu.se> (earlier version) Sponsored by: Dell EMC Isilon
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/*- | ||
* Copyright (c) 2017 Conrad Meyer <cem@FreeBSD.org> | ||
* All rights reserved. | ||
* | ||
* Redistribution and use in source and binary forms, with or without | ||
* modification, are permitted provided that the following conditions | ||
* are met: | ||
* 1. Redistributions of source code must retain the above copyright | ||
* notice, this list of conditions and the following disclaimer. | ||
* 2. Redistributions in binary form must reproduce the above copyright | ||
* notice, this list of conditions and the following disclaimer in the | ||
* documentation and/or other materials provided with the distribution. | ||
* | ||
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND | ||
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | ||
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | ||
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE | ||
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | ||
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | ||
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | ||
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | ||
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | ||
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | ||
* SUCH DAMAGE. | ||
*/ | ||
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/* | ||
* Limited test program for getmntinfo(3), a non-standard BSDism. | ||
*/ | ||
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#include <sys/cdefs.h> | ||
__FBSDID("$FreeBSD$"); | ||
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#include <sys/param.h> | ||
#include <sys/mount.h> | ||
#include <sys/ucred.h> | ||
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#include <errno.h> | ||
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#include <atf-c.h> | ||
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static void | ||
check_mntinfo(struct statfs *mntinfo, int n) | ||
{ | ||
int i; | ||
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for (i = 0; i < n; i++) { | ||
ATF_REQUIRE_MSG(mntinfo[i].f_version == STATFS_VERSION, "%ju", | ||
(uintmax_t)mntinfo[i].f_version); | ||
ATF_REQUIRE(mntinfo[i].f_namemax <= sizeof(mntinfo[0].f_mntonname)); | ||
} | ||
} | ||
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ATF_TC_WITHOUT_HEAD(getmntinfo_test); | ||
ATF_TC_BODY(getmntinfo_test, tc) | ||
{ | ||
int nmnts; | ||
struct statfs *mntinfo; | ||
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/* Test bogus mode */ | ||
nmnts = getmntinfo(&mntinfo, 199); | ||
ATF_REQUIRE_MSG(nmnts == 0 && errno == EINVAL, | ||
"getmntinfo() succeeded; errno=%d", errno); | ||
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/* Valid modes */ | ||
nmnts = getmntinfo(&mntinfo, MNT_NOWAIT); | ||
ATF_REQUIRE_MSG(nmnts != 0, "getmntinfo(MNT_NOWAIT) failed; errno=%d", | ||
errno); | ||
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check_mntinfo(mntinfo, nmnts); | ||
memset(mntinfo, 0xdf, sizeof(*mntinfo) * nmnts); | ||
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nmnts = getmntinfo(&mntinfo, MNT_WAIT); | ||
ATF_REQUIRE_MSG(nmnts != 0, "getmntinfo(MNT_WAIT) failed; errno=%d", | ||
errno); | ||
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check_mntinfo(mntinfo, nmnts); | ||
} | ||
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ATF_TP_ADD_TCS(tp) | ||
{ | ||
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ATF_TP_ADD_TC(tp, getmntinfo_test); | ||
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return (atf_no_error()); | ||
} |