zpool import -m also removing spare and cache when log device is missing

[ixhamza]

spa_import() relies on a pool config fetched by spa_try_import() for spare/cache devices. Import flags are not passed to spa_tryimport(), which makes it return early due to a missing log device and missing retrieving the cache device and spare eventually. Passing ZFS_IMPORT_MISSING_LOG to spa_tryimport() makes it fetch the correct configuration regardless of the missing log device.

How Has This Been Tested?

• Create a zfs pool: zpool create -f tank nvme0n1 cache nvme1n1 spare nvme2n1 log nvme3n1
• Check pool status:

$ zpool status tank
	NAME        STATE     READ WRITE CKSUM
	tank        ONLINE       0     0     0
	  nvme0n1   ONLINE       0     0     0
	logs	
	  nvme3n1   ONLINE       0     0     0
	cache
	  nvme1n1   ONLINE       0     0     0
	spares
	  nvme2n1   AVAIL    

• Export the pool: zpool export tank
• Pull nvme3n1 drive, i.e., log device.
• Import the pool: zpool import -m tank
• Check the pool status again:

$ zpool status tank
	NAME                   STATE     READ WRITE CKSUM
	tank                   DEGRADED     0     0     0
	  nvme0n1              ONLINE       0     0     0
	logs	
	  1797033476626228610  UNAVAIL      0     0     0  was /dev/nvme3n1p1

• Expected pool status:

$ zpool status tank
	NAME                    STATE     READ WRITE CKSUM
	tank                    DEGRADED     0     0     0
	  nvme0n1               ONLINE       0     0     0
	logs	
	  15191547688177894754  UNAVAIL      0     0     0  was /dev/nvme3n1p1
	cache
	  nvme1n1               ONLINE       0     0     0
	spares
	  nvme2n1               AVAIL   

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)
• 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.

[ixhamza]

cc: @amotin

[ixhamza]

After discussing with @amotin internally, passing ZFS_IMPORT_MISSING_LOG to spa_tryimport() makes it fetch the correct configuration without any obvious side effects. It also shows the correct spare/cache configuration through the zpool import command. Updated the PR.

[behlendorf]

@ixhamza the fix here seems reasonable. How about also adding your test case from the top comment to the test suite as part of this PR.

[ixhamza]

@behlendorf sure

[ixhamza]

@behlendorf Added a test case.

[behlendorf]

@ixhamza great! It looks like the zloop failures were caused by a known leak which was resolved. Please just rebase this on master so we can get a clean run then this is good to go.