1) Off-by-one in block allocation when block size != 1 KB
Due to a quirk in the on-disk layout of ext2, file systems with a block
size of 1 KB have block #1 as their first block, while all others start
on block #0.
2) We had no fallback mechanism when the preferred group was full
We now allocate blocks from the preferred block group as long as it's
possible, and fall back to a simple scan through all groups when the
preferred one is full.
It is now possible to unmount file systems from the VFS via `umount`.
It works via looking up the `fsid` of the filesystem from the `Inode`'s
metatdata so I'm not sure how fragile it is. It seems to work for now
though as something to get us going.
This is obviously more readable. If we ever run into a situation where
ref count churn is actually causing trouble in the future, we can deal with
it then. For now, let's keep it simple. :^)
After reading a bunch of POSIX specs, I've learned that a file descriptor
is the number that refers to a file description, not the description itself.
So this patch renames FileDescriptor to FileDescription, and Process now has
FileDescription* file_description(int fd).
Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
Factor out inode resizing into a separate Ext2FSInode::resize() function.
This is then called both from write_bytes() and truncate().
This patch finally implements freeing of blocks when an inode shrinks.
