devsd: cache SDunit pointer in Chan.aux, improve error handling

Avoid calling sdgetdev() for every I/O. Instead,
put the SDunit pointer for #S/sdXX/* files in Chan.aux
and keep a reference to SDev between sdopen()/sdclose().

This avoids having to do the sdindex() lookup and
qlock(),incref(),decref() on every read/write
operation. Removal of SDev's is quite rare and only
can happen with pcmcia ide controllers, and i assume
that for that we can assume thet fileservers having
been exited properly and closed their files before
we attempt to remove a device.

The rest is improving waserror() codepaths, making
sure we release the locks for any of the interface
callbacks (verify/online).

Also get rid of tas() and instead only change the
unit's rawopen flag while holding raw qlock.

0 files changed, 0 insertions, 0 deletions