Add descriptions to undocumented sysctls (vfs)

[mhorne063_gmail.com]

Summary

An attempt to reduce the number of sysctls in the system that are missing descriptions.

I've taken some effort to examine each of the sysctls to determine their purpose, but due
to the range and quanitity of changes some descriptions may require additional detail. Input
is appreciated from anyone with relevant knowledge.

In addition to the grammar and functional accuracy of the descriptions added, there will
undoubtedly be some sysctls that I have missed. Please feel free to mention them in the
appropriate thread and I will add those descriptions.

This patch covers filesystem related sysctls under vfs.
Some of the areas touched by this patch:

• e2fs
• zfs
• ffs
• fuse
• nandfs
• nfs
• smbfs

[mhorne063_gmail.com]

Updated some descriptions to match desired style.

Added missing descriptions for ffs.

[rmacklem]

The NFS ones look ok to me. To be honest, some of them were inherited from the old NFS
and I'm not even sure what the do (without looking at the code). However, the descriptions
look reasonable to me.

Thanks for doing this, rick

[julian]

was this ever done?

[asomers]

It wasn't committed as-is, but all of the fusefs sysctls have since been described by separate commits.

[mhorne]

Indeed, this never landed in its entirety. I have it on a git branch somewhere...

Some of these descriptions could be improved still. I could split out the interesting pieces and handle those one at a time, e.g. NFS first.