increase inode reuse delay from 1 day to 30 days

[joelnn]

Increase inode reuse delay from 1 day to 30 days. This makes it much harder to run into inode reuse issues, as I did in my cluster.

[psarna]

It also potentially increases memory usage of your master server. What kind of inode reuse issues did you encounter? Maybe the problem is somewhere else, not precisely in master and inode management.

[psarna]

And the most important detail: which release caused the problem?

[joelnn]

This patch was initially applied to 2.5.4 a couple years ago when we switched from MooseFS. I believe the issue was as follows:

A directory is unlinked, but still open. After a day, the master reuses the inode, and the mount which still has the old directory open tries to access this inode which was reused too soon.