HAMMER Update - 16-July-2008

[Matthew Dillon]

    HAMMER is looking nice and stable for the release.  I've moved on to
    working through its error handling, getting rid of Debugger() calls
    and assertions in the I/O error path, and adjusting the code so a
    write error forces the mount into read-only mode.

    It's kinda fun.  I'm testing it by taking an external USB2 hard drive
    and mounting it w/ HAMMER, then unplugging it in the middle of a big
    cpdup.  I've found a couple of panics in CAM related to the device
    going away unexpectedly, and stuff like that, which I'm fixing as I
    go.

    I expect to get it working nicely by thursday afternoon and will commit
    and MFC it for 2.0 then.  Hopefully I'll get it to the point where
    I can pop the USB connector in and out without crashing the machine
    or corrupting the HAMMER filesystem.  Mind you, once you pull the drive
    you have to umount -f / remount HAMMER and will lose unflushed file
    data, but the filesystem itself shouldn't become corrupt.  I'm not
    pulling the disk's power, just its USB connector :-)

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>