use zpool.cache when importing pools at boot

[nt1]

Fixes issue #7553

[fichtner]

Thanks. Ideally hardcoding cache files should be avoided. It just looks like a maintenance spot further down the road. As said I’ll take a look when I’m back.

[nt1]

Minimally, I'll move those string constants to a better place for the sake of maintainability. This would also be a good place for a link to openzfs zpool cache documentation.

[fichtner]

To be frank I'd prefer something like

ZPOOL_IMPORT_PATH="/dir1:/dir2"
export ZPOOL_IMPORT_PATH

The docs say:

ZPOOL_IMPORT_PATH The search path for devices or files to use with the pool. This is a colon-separated list of directories in which zpool looks for device nodes and files. Similar to the -d option in zpool import.

But the fun part is nothing really says what the compatible directory default is nor does the code make an effort to bootstrap a default.

Cheers,
Franco

[fichtner]

Ok from the old code "/dev" should suffice so if you can let me know if this works as well... e7d8052

[fichtner]

Shipping 701dff4 can't hurt so I will.