a10e552b99
Adding O_DIRECT support to ZFS to bypass the ARC for writes/reads. O_DIRECT support in ZFS will always ensure there is coherency between buffered and O_DIRECT IO requests. This ensures that all IO requests, whether buffered or direct, will see the same file contents at all times. Just as in other FS's , O_DIRECT does not imply O_SYNC. While data is written directly to VDEV disks, metadata will not be synced until the associated TXG is synced. For both O_DIRECT read and write request the offset and request sizes, at a minimum, must be PAGE_SIZE aligned. In the event they are not, then EINVAL is returned unless the direct property is set to always (see below). For O_DIRECT writes: The request also must be block aligned (recordsize) or the write request will take the normal (buffered) write path. In the event that request is block aligned and a cached copy of the buffer in the ARC, then it will be discarded from the ARC forcing all further reads to retrieve the data from disk. For O_DIRECT reads: The only alignment restrictions are PAGE_SIZE alignment. In the event that the requested data is in buffered (in the ARC) it will just be copied from the ARC into the user buffer. For both O_DIRECT writes and reads the O_DIRECT flag will be ignored in the event that file contents are mmap'ed. In this case, all requests that are at least PAGE_SIZE aligned will just fall back to the buffered paths. If the request however is not PAGE_SIZE aligned, EINVAL will be returned as always regardless if the file's contents are mmap'ed. Since O_DIRECT writes go through the normal ZIO pipeline, the following operations are supported just as with normal buffered writes: Checksum Compression Encryption Erasure Coding There is one caveat for the data integrity of O_DIRECT writes that is distinct for each of the OS's supported by ZFS. FreeBSD - FreeBSD is able to place user pages under write protection so any data in the user buffers and written directly down to the VDEV disks is guaranteed to not change. There is no concern with data integrity and O_DIRECT writes. Linux - Linux is not able to place anonymous user pages under write protection. Because of this, if the user decides to manipulate the page contents while the write operation is occurring, data integrity can not be guaranteed. However, there is a module parameter `zfs_vdev_direct_write_verify` that controls the if a O_DIRECT writes that can occur to a top-level VDEV before a checksum verify is run before the contents of the I/O buffer are committed to disk. In the event of a checksum verification failure the write will return EIO. The number of O_DIRECT write checksum verification errors can be observed by doing `zpool status -d`, which will list all verification errors that have occurred on a top-level VDEV. Along with `zpool status`, a ZED event will be issues as `dio_verify` when a checksum verification error occurs. ZVOLs and dedup is not currently supported with Direct I/O. A new dataset property `direct` has been added with the following 3 allowable values: disabled - Accepts O_DIRECT flag, but silently ignores it and treats the request as a buffered IO request. standard - Follows the alignment restrictions outlined above for write/read IO requests when the O_DIRECT flag is used. always - Treats every write/read IO request as though it passed O_DIRECT and will do O_DIRECT if the alignment restrictions are met otherwise will redirect through the ARC. This property will not allow a request to fail. There is also a module parameter zfs_dio_enabled that can be used to force all reads and writes through the ARC. By setting this module parameter to 0, it mimics as if the direct dataset property is set to disabled. Reviewed-by: Brian Behlendorf <behlendorf@llnl.gov> Reviewed-by: Alexander Motin <mav@FreeBSD.org> Reviewed-by: Tony Hutter <hutter2@llnl.gov> Signed-off-by: Brian Atkinson <batkinson@lanl.gov> Co-authored-by: Mark Maybee <mark.maybee@delphix.com> Co-authored-by: Matt Macy <mmacy@FreeBSD.org> Co-authored-by: Brian Behlendorf <behlendorf@llnl.gov> Closes #10018 |
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runfiles | ||
test-runner | ||
zfs-tests | ||
Makefile.am | ||
README.md |
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/exports
as one of its export files – by default this can be done by settingzfs_enable=yes
in/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