mirror_zfs/tests/runfiles
Allan Jude fc34dfba8e
Fix L2ARC reads when compressed ARC disabled
When reading compressed blocks from the L2ARC, with
compressed ARC disabled, arc_hdr_size() returns
LSIZE rather than PSIZE, but the actual read is PSIZE.
This causes l2arc_read_done() to compare the checksum
against the wrong size, resulting in checksum failure.

This manifests as an increase in the kstat l2_cksum_bad
and the read being retried from the main pool, making the
L2ARC ineffective.

Add new L2ARC tests with Compressed ARC enabled/disabled

Blocks are handled differently depending on the state of the
zfs_compressed_arc_enabled tunable.

If a block is compressed on-disk, and compressed_arc is enabled:
- the block is read from disk
- It is NOT decompressed
- It is added to the ARC in its compressed form
- l2arc_write_buffers() may write it to the L2ARC (as is)
- l2arc_read_done() compares the checksum to the BP (compressed)

However, if compressed_arc is disabled:
- the block is read from disk
- It is decompressed
- It is added to the ARC (uncompressed)
- l2arc_write_buffers() will use l2arc_apply_transforms() to
  recompress the block, before writing it to the L2ARC
- l2arc_read_done() compares the checksum to the BP (compressed)
- l2arc_read_done() will use l2arc_untransform() to uncompress it

This test writes out a test file to a pool consisting of one disk
and one cache device, then randomly reads from it. Since the arc_max
in the tests is low, this will feed the L2ARC, and result in reads
from the L2ARC.

We compare the value of the kstat l2_cksum_bad before and after
to determine if any blocks failed to survive the trip through the
L2ARC.

Sponsored-by: The FreeBSD Foundation
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Allan Jude <allanjude@freebsd.org>
Closes #10693
2020-08-13 23:31:20 -07:00
..
common.run Fix L2ARC reads when compressed ARC disabled 2020-08-13 23:31:20 -07:00
freebsd.run FreeBSD: Fix zfs jail and add a test 2020-08-01 08:44:54 -07:00
linux.run Remove dependency on sharetab file and refactor sharing logic 2020-07-13 09:19:18 -07:00
longevity.run OpenZFS 9166 - zfs storage pool checkpoint 2018-06-26 10:07:42 -07:00
Makefile.am Add FreeBSD support to OpenZFS 2020-04-14 11:36:28 -07:00
perf-regression.run OpenZFS 9184 - Add ZFS performance test for fixed blocksize random read/write IO 2018-07-02 13:46:06 -07:00
sunos.run ZTS: Add a failsafe callback to run after each test 2020-03-10 11:00:56 -07:00