FileInfo quorum shouldn't be passed down, instead
inferred after obtaining a maximally occurring FileInfo.
This PR also changes other functions that rely on
wrong quorum calculation.
Update tests as well to handle the proper requirement. All
these changes are needed when migrating from older deployments
where we used to set N/2 quorum for reads to EC:4 parity in
newer releases.
dataDir loosely based on maxima is incorrect and does not
work in all situations such as disks in the following order
- xl.json migration to xl.meta there may be partial xl.json's
leftover if some disks are not yet connected when the disk
is yet to come up, since xl.json mtime and xl.meta is
same the dataDir maxima doesn't work properly leading to
quorum issues.
- its also possible that XLV1 might be true among the disks
available, make sure to keep FileInfo based on common quorum
and skip unexpected disks with the older data format.
Also, this PR tests upgrade from older to a newer release if the
data is readable and matches the checksum.
NOTE: this is just initial work we can build on top of this to do further tests.
Harshavardhana