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Prakash Surya 5549a537dd Fix device expansion when VM is powered off
When running on an ESXi based VM, I've found that "zpool online -e" will
not expand the zpool, if the disk was expanded in ESXi while the VM was
powered off.

For example, take the following scenario:

 1. VM running on top of VMware ESXi
 2. ZFS pool created with a given device "sda" of size 8GB
 3. VM powered off
 4. Device "sda" size expanded to 16GB
 5. VM powered on
 6. "zpool online -e" used on device "sda"

In this situation, after (2) the zpool will be roughly 8GB in size.
After (6), the expectation is the zpool's size will expand to roughly
16GB in size; i.e. expand to the new size of the "sda" device.
Unfortunately, I've seen that after (6), the zpool size does not change.

What's happening is after (5), the EFI label of the "sda" device will be
such that fields "efi_last_u_lba", "efi_last_lba", and "efi_altern_lba"
all reflect the new size of the disk; i.e. "33554398", "33554431", and
"33554431" respectively.

Thus, the check that we perform in "efi_use_whole_disk":

    if ((efi_label->efi_altern_lba == 1) || (efi_label->efi_altern_lba
        >= efi_label->efi_last_lba)) {

This will return true, and then we return from the function without
having expanded the size of the zpool/device.

In contrast, if we remove steps (3) and (5) in the sequence above, i.e.
the device is expanded while the VM is powered on, things change. In
that case, the fields "efi_last_u_lba" and "efi_altern_lba" do not
change (i.e. they still reflect the old 8GB device size), but the
"efi_last_lba" field does change (i.e. it now reflects the new 16GB
device size). Thus, when we evaluate the same conditional in
"efi_use_whole_disk", it'll return false, so the zpool is expanded.

Taking all of this into account, this PR updates "efi_use_whole_disk" to
properly expand the zpool when the underlying disk is expanded while the
VM is powered off.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Don Brady <don.brady@delphix.com>
Signed-off-by: Prakash Surya <prakash.surya@delphix.com>
Closes #9111
2020-01-22 13:48:57 -08:00
.github Update CONTRIBUTING to point users to IRC as well as mailing list 2019-03-13 11:57:57 -07:00
cmd spa_load_verify() may consume too much memory 2020-01-22 13:48:57 -08:00
config Minor style cleanup 2019-09-25 11:27:49 -07:00
contrib Add channel program for property based snapshots 2020-01-22 13:48:57 -08:00
etc New service that waits on zvol links to be created 2019-09-25 11:27:51 -07:00
include spa_load_verify() may consume too much memory 2020-01-22 13:48:57 -08:00
lib Fix device expansion when VM is powered off 2020-01-22 13:48:57 -08:00
man spa_load_verify() may consume too much memory 2020-01-22 13:48:57 -08:00
module spa_load_verify() may consume too much memory 2020-01-22 13:48:57 -08:00
rpm install path fixes 2020-01-22 13:48:57 -08:00
scripts kmodtool: depmod path 2019-09-25 11:27:51 -07:00
tests Test cancelling a removal in ZTS 2020-01-22 13:48:57 -08:00
udev Add enclosure_symlinks option to vdev_id 2018-12-14 17:27:49 -08:00
.gitignore Linux 5.3 compat: Makefile subdir-m no longer supported 2019-09-25 11:27:50 -07:00
.gitmodules Add zimport.sh compatibility test script 2014-02-21 12:10:31 -08:00
.travis.yml Add .travis.yml 2017-11-13 09:18:18 -08:00
AUTHORS Update build system and packaging 2018-05-29 16:00:33 -07:00
autogen.sh Cause autogen.sh to fail if autoreconf fails 2018-07-06 09:27:37 -07:00
CODE_OF_CONDUCT.md Add CODE_OF_CONDUCT.md 2019-04-30 10:58:45 -07:00
configure.ac Add channel program for property based snapshots 2020-01-22 13:48:57 -08:00
copy-builtin Allow copy-builtin to work with modified sources 2018-10-17 12:06:05 -07:00
COPYRIGHT Update build system and packaging 2018-05-29 16:00:33 -07:00
LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
Makefile.am Fix out-of-tree build failures 2019-09-25 11:27:48 -07:00
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NOTICE Update build system and packaging 2018-05-29 16:00:33 -07:00
README.md Explicitly state supported Linux versions 2018-05-30 20:11:19 -07:00
TEST Update build system and packaging 2018-05-29 16:00:33 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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