Fix history logging for zpool create -t

[delan]

Motivation and Context

zpool create is supposed to log the command to the new pool’s history, as a special record that never gets evicted from the ring buffer. but when you create a pool with zpool create -t, no such record is ever logged (#18102). that bug may be the cause of issues like #16408.

Description

zpool create -t (83e9986) and zpool import -t (26b42f3) are both designed to override the on-disk zpool property name with an in-core “temporary” name, but they work somewhat differently under the hood.

importing with a temporary name sets spa->spa_import_flags |= ZFS_IMPORT_TEMP_NAME in ZFS_IOC_POOL_IMPORT, which tells spa_write_cachefile() and spa_config_generate() to use the ZPOOL_CONFIG_POOL_NAME in spa->spa_config instead of spa->spa_name.

creating with a temporary name permanently(!) sets the internal zpool property tname (ZPOOL_PROP_TNAME) in the zc->zc_nvlist_src of ZFS_IOC_POOL_CREATE, which tells zfs_ioc_pool_create() (4ceb8dd) and spa_create() to use that name instead of zc->zc_name, then sets spa->spa_import_flags |= ZFS_IMPORT_TEMP_NAME like an import.

but zfsdev_ioctl_common() fails to check for tname when saving the pool name to zfs_allow_log_key, so when we call ZFS_IOC_LOG_HISTORY, we call spa_open() on the wrong pool name and get ENOENT, so the logging silently fails.

this patch fixes #18102 by checking for tname in zfsdev_ioctl_common() like we do in zfs_ioc_pool_create().

How Has This Been Tested?

tested using quiz, on linux 6.12.44:

$ ./quiz -k 6.12.44 -p zfs,ztest /usr/local/share/zfs/zfs-tests.sh -t tests/functional/cli_root/zpool_create/zpool_create_tempname.ksh
$ ./quiz -k 6.12.44 -p memdev,zfs /usr/local/zfs-18102-repro.sh

zfs-18102-repro.sh:

#!/bin/sh
set -euvx
zpool create -t test2 test /dev/quizm0
zpool history test2

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Quality assurance (non-breaking change which makes the code more robust against bugs)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.