When the path argument to "zfs list -Ho name <path>" (or any caller of
zfs_path_to_zhandle()) is a symlink that crosses a mount boundary, the
wrong dataset is returned. Instead of returning the dataset that owns
the symlink's target, getextmntent() matches the dataset containing the
symlink itself.
For example, given two ZFS datasets "tank/ds1" and "tank/ds2", and a
symlink "/tank/ds1/link" pointing into "/tank/ds2":
$ sudo zfs list -Ho name /tank/ds1/link
tank/ds1
The expected (and previous) behavior is to return "tank/ds2", since the
symlink's target resides in that dataset.
The problem is in getextmntent(), in lib/libspl/os/linux/mnttab.c. That
function calls statx() on the caller-supplied path to obtain its mnt_id
(used to match against the mnt_id of each entry in /proc/self/mounts),
and it passes AT_SYMLINK_NOFOLLOW to that statx() call. As a result,
the mnt_id returned reflects the symlink's location rather than the
symlink target's mount, and the wrong /proc/self/mounts entry is
matched.
The same function also calls stat64() on the caller-supplied path
(used as a fallback when STATX_MNT_ID is not available, and to populate
the statbuf out-parameter). stat64() always follows symlinks, so the
statx() and stat64() calls were inconsistent: one resolved the symlink,
the other didn't. The AT_SYMLINK_NOFOLLOW behavior may be appropriate
when statx() is called on a mount entry from /proc/self/mounts (which
is always a real directory), but it is wrong for caller-supplied paths,
which may be symlinks.
This bug was introduced by 523d9d6007 ("Validate mountpoint on
path-based unmount using statx"), which added the STATX_MNT_ID code
path. However, the bug was latent: config/user-statx.m4 omitted
"#define _GNU_SOURCE" when checking for STATX_MNT_ID in <sys/stat.h>,
so HAVE_STATX_MNT_ID was never defined, and the buggy statx() path was
never compiled in. getextmntent() always fell back to the dev_t
comparison via stat64(), which correctly follows symlinks.
The fix to that autoconf check, in 2b930f63f8 ("config: fix
STATX_MNT_ID detection"), caused HAVE_STATX_MNT_ID to be properly
defined on kernels that support it, activating the broken
AT_SYMLINK_NOFOLLOW path for the first time and exposing the
regression.
The fix is to drop AT_SYMLINK_NOFOLLOW from the statx() call so that
symlinks are followed, matching the behavior of stat64() on the same
path.
Verified with a minimal reproducer: created two ZFS datasets, placed a
symlink inside the first pointing into the second, and confirmed that
"zfs list -Ho name <symlink>" returns the dataset containing the
symlink's target rather than the dataset containing the symlink.
Signed-off-by: Prakash Surya <prakash.surya@perforce.com>
Reviewed-by: Ameer Hamza <ahamza@ixsystems.com>
Reviewed-by: Mark Maybee <mark.maybee@delphix.com>
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
ZFS Test Suite README
1) Building and installing the ZFS Test Suite
The ZFS Test Suite runs under the test-runner framework. This framework is built along side the standard ZFS utilities and is included as part of zfs-test package. The zfs-test package can be built from source as follows:
$ ./configure
$ make pkg-utils
The resulting packages can be installed using the rpm or dpkg command as appropriate for your distributions. Alternately, if you have installed ZFS from a distributions repository (not from source) the zfs-test package may be provided for your distribution.
- Installed from source
$ rpm -ivh ./zfs-test*.rpm, or
$ dpkg -i ./zfs-test*.deb,
- Installed from package repository
$ yum install zfs-test
$ apt-get install zfs-test
2) Running the ZFS Test Suite
The pre-requisites for running the ZFS Test Suite are:
- Three scratch disks
- Specify the disks you wish to use in the $DISKS variable, as a space delimited list like this: DISKS='vdb vdc vdd'. By default the zfs-tests.sh script will construct three loopback devices to be used for testing: DISKS='loop0 loop1 loop2'.
- A non-root user with a full set of basic privileges and the ability to sudo(8) to root without a password to run the test.
- Specify any pools you wish to preserve as a space delimited list in the $KEEP variable. All pools detected at the start of testing are added automatically.
- The ZFS Test Suite will add users and groups to test machine to verify functionality. Therefore it is strongly advised that a dedicated test machine, which can be a VM, be used for testing.
- On FreeBSD, mountd(8) must use
/etc/zfs/exportsas one of its export files – by default this can be done by settingzfs_enable=yesin/etc/rc.conf.
Once the pre-requisites are satisfied simply run the zfs-tests.sh script:
$ /usr/share/zfs/zfs-tests.sh
Alternately, the zfs-tests.sh script can be run from the source tree to allow developers to rapidly validate their work. In this mode the ZFS utilities and modules from the source tree will be used (rather than those installed on the system). In order to avoid certain types of failures you will need to ensure the ZFS udev rules are installed. This can be done manually or by ensuring some version of ZFS is installed on the system.
$ ./scripts/zfs-tests.sh
The following zfs-tests.sh options are supported:
-v Verbose zfs-tests.sh output When specified additional
information describing the test environment will be logged
prior to invoking test-runner. This includes the runfile
being used, the DISKS targeted, pools to keep, etc.
-q Quiet test-runner output. When specified it is passed to
test-runner(1) which causes output to be written to the
console only for tests that do not pass and the results
summary.
-x Remove all testpools, dm, lo, and files (unsafe). When
specified the script will attempt to remove any leftover
configuration from a previous test run. This includes
destroying any pools named testpool, unused DM devices,
and loopback devices backed by file-vdevs. This operation
can be DANGEROUS because it is possible that the script
will mistakenly remove a resource not related to the testing.
-k Disable cleanup after test failure. When specified the
zfs-tests.sh script will not perform any additional cleanup
when test-runner exists. This is useful when the results of
a specific test need to be preserved for further analysis.
-f Use sparse files directly instead of loopback devices for
the testing. When running in this mode certain tests will
be skipped which depend on real block devices.
-c Only create and populate constrained path
-I NUM Number of iterations
-d DIR Create sparse files for vdevs in the DIR directory. By
default these files are created under /var/tmp/.
This directory must be world-writable.
-s SIZE Use vdevs of SIZE (default: 4G)
-r RUNFILES Run tests in RUNFILES (default: common.run,linux.run)
-t PATH Run single test at PATH relative to test suite
-T TAGS Comma separated list of tags (default: 'functional')
-u USER Run single test as USER (default: root)
The ZFS Test Suite allows the user to specify a subset of the tests via a runfile or list of tags.
The format of the runfile is explained in test-runner(1), and the files that zfs-tests.sh uses are available for reference under /usr/share/zfs/runfiles. To specify a custom runfile, use the -r option:
$ /usr/share/zfs/zfs-tests.sh -r my_tests.run
Otherwise user can set needed tags to run only specific tests.
3) Test results
While the ZFS Test Suite is running, one informational line is printed at the
end of each test, and a results summary is printed at the end of the run. The
results summary includes the location of the complete logs, which is logged in
the form /var/tmp/test_results/[ISO 8601 date]. A normal test run launched
with the zfs-tests.sh wrapper script will look something like this:
$ /usr/share/zfs/zfs-tests.sh -v -d /tmp/test
--- Configuration ---
Runfile: /usr/share/zfs/runfiles/linux.run
STF_TOOLS: /usr/share/zfs/test-runner
STF_SUITE: /usr/share/zfs/zfs-tests
STF_PATH: /var/tmp/constrained_path.G0Sf
FILEDIR: /tmp/test
FILES: /tmp/test/file-vdev0 /tmp/test/file-vdev1 /tmp/test/file-vdev2
LOOPBACKS: /dev/loop0 /dev/loop1 /dev/loop2
DISKS: loop0 loop1 loop2
NUM_DISKS: 3
FILESIZE: 4G
ITERATIONS: 1
TAGS: functional
Keep pool(s): rpool
/usr/share/zfs/test-runner/bin/test-runner.py -c /usr/share/zfs/runfiles/linux.run \
-T functional -i /usr/share/zfs/zfs-tests -I 1
Test: /usr/share/zfs/zfs-tests/tests/functional/arc/setup (run as root) [00:00] [PASS]
...more than 1100 additional tests...
Test: /usr/share/zfs/zfs-tests/tests/functional/zvol/zvol_swap/cleanup (run as root) [00:00] [PASS]
Results Summary
SKIP 52
PASS 1129
Running Time: 02:35:33
Percent passed: 95.6%
Log directory: /var/tmp/test_results/20180515T054509
4) Example of adding and running test-case (zpool_example)
This broadly boils down to 5 steps
- Create/Set password-less sudo for user running test case.
- Edit configure.ac, Makefile.am appropriately
- Create/Modify .run files
- Create actual test-scripts
- Run Test case
Will look at each of them in depth.
-
Set password-less sudo for 'Test' user as test script cannot be run as root
-
Edit file configure.ac and include line under AC_CONFIG_FILES section
tests/zfs-tests/tests/functional/cli_root/zpool_example/Makefile -
Edit file tests/runfiles/Makefile.am and add line zpool_example.
pkgdatadir = $(datadir)/@PACKAGE@/runfiles dist_pkgdata_DATA = \ zpool_example.run \ common.run \ freebsd.run \ linux.run \ longevity.run \ perf-regression.run \ sanity.run \ sunos.run -
Create file tests/runfiles/zpool_example.run. This defines the most common properties when run with test-runner.py or zfs-tests.sh.
[DEFAULT] timeout = 600 outputdir = /var/tmp/test_results tags = ['functional'] tests = ['zpool_example_001_pos']If adding test-case to an already existing suite the runfile would already be present and it needs to be only updated. For example, adding zpool_example_002_pos to the above runfile only update the "tests =" section of the runfile as shown below
[DEFAULT] timeout = 600 outputdir = /var/tmp/test_results tags = ['functional'] tests = ['zpool_example_001_pos', 'zpool_example_002_pos'] -
Edit tests/zfs-tests/tests/functional/cli_root/Makefile.am and add line under SUBDIRS.
zpool_example \ (Make sure to escape the line end as there will be other folders names following) -
Create new file tests/zfs-tests/tests/functional/cli_root/zpool_example/Makefile.am the contents of the file could be as below. What it says it that now we have a test case zpool_example_001_pos.ksh
pkgdatadir = $(datadir)/@PACKAGE@/zfs-tests/tests/functional/cli_root/zpool_example dist_pkgdata_SCRIPTS = \ zpool_example_001_pos.ksh -
We can now create our test-case zpool_example_001_pos.ksh under tests/zfs-tests/tests/functional/cli_root/zpool_example/.
# DESCRIPTION: # zpool_example Test # # STRATEGY: # 1. Demo a very basic test case # DISKS_DEV1="/dev/loop0" DISKS_DEV2="/dev/loop1" TESTPOOL=EXAMPLE_POOL function cleanup { # Cleanup destroy_pool $TESTPOOL log_must rm -f $DISKS_DEV1 log_must rm -f $DISKS_DEV2 } log_assert "zpool_example" # Run function "cleanup" on exit log_onexit cleanup # Prep backend device log_must dd if=/dev/zero of=$DISKS_DEV1 bs=512 count=140000 log_must dd if=/dev/zero of=$DISKS_DEV2 bs=512 count=140000 # Create pool log_must zpool create $TESTPOOL $type $DISKS_DEV1 $DISKS_DEV2 log_pass "zpool_example" -
Run Test case, which can be done in two ways. Described in detail above in section 2.
- test-runner.py (This takes run file as input. See zpool_example.run)
- zfs-tests.sh. Can execute the run file or individual tests