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panic in removal_remap test on 4K devices

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If the zfs_remove_max_segment tunable is changed to be not a multiple of
the sector size, then the device removal code will malfunction and try
to create mappings that are smaller than one sector, leading to a panic.

On debug bits this assertion will fail in spa_vdev_copy_segment():
    ASSERT3U(DVA_GET_ASIZE(&dst), ==, size);

On nondebug, the system panics with a stack like:
    metaslab_free_concrete()
    metaslab_free_impl()
    metaslab_free_impl_cb()
    vdev_indirect_remap()
    free_from_removing_vdev()
    metaslab_free_impl()
    metaslab_free_dva()
    metaslab_free()

Fortunately, the default for zfs_remove_max_segment is 1MB, so this
can't occur by default.  We hit it during this test because
removal_remap.ksh changes zfs_remove_max_segment to 1KB. When testing on
4KB-sector disks, we hit the bug.

This change makes the zfs_remove_max_segment tunable more robust,
automatically rounding it up to a multiple of the sector size. We also
turn some key assertions into VERIFY's so that similar bugs would be
caught before they are encoded on disk (and thus avoid a
panic-reboot-loop).

Reviewed-by: Sean Eric Fagan <sef@ixsystems.com>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed-by: Sebastien Roy <sebastien.roy@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
External-issue: DLPX-61342
Closes #8893
This commit is contained in:
Matthew Ahrens
2019-06-13 13:12:39 -07:00
committed by Brian Behlendorf
parent be89734a29
commit 53dce5acc6
4 changed files with 59 additions and 14 deletions
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module/zfs/vdev_label.c
+2 -3
View File
@@ -21,8 +21,7 @@
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2018 by Delphix. All rights reserved.
* Copyright (c) 2012, 2016 by Delphix. All rights reserved.
* Copyright (c) 2012, 2019 by Delphix. All rights reserved.
* Copyright (c) 2017, Intel Corporation.
*/
@@ -613,7 +612,7 @@ vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats,
* zfs_remove_max_segment, so we need at least one entry
* per zfs_remove_max_segment of allocated data.
*/
seg_count += to_alloc / zfs_remove_max_segment;
seg_count += to_alloc / spa_remove_max_segment(spa);
fnvlist_add_uint64(nv, ZPOOL_CONFIG_INDIRECT_SIZE,
seg_count *