- rather than embedding bufq_state in driver softc,
have a pointer to the former.
- move bufq related functions from kern/subr_disk.c to kern/subr_bufq.c.
- rename method to strategy for consistency.
- move some definitions which don't need to be exposed to the rest of kernel
from sys/bufq.h to sys/bufq_impl.h.
(is it better to move it to kern/ or somewhere?)
- fix some obvious breakage in dev/qbus/ts.c. (not tested)
sd3(mpt0:0:1:0): unable to allocate scsipi_xfer
sd3: not queued, error 12
Havard Eidnes's analysis of this problem is that the scsipi_xfer pool is
competing for resources with other pools, including the the inode and vnode
pools which can grow quite large.
*_scsipi_cmd(): don't biodone the buffer if scsipi_make_xs() fails, let the
caller deal with the problem
start function of block devices drivers: dequeue the buffer after the
scsipi_command() call. If scsipi_command() fails with ENOMEM don't dequeue
the buffer, and schedule a callout to call the start function after
some delay.
scsipi_init(): prime the scsipi_xfer_pool with one page. This ensure that
there is always some scsipi_xfer to play with. If scsipi_command() fails
because of pool_get(), we're sure there will be resources available later,
when the pending commands have completed.
Reviewed by Jason Thorpe and Havard Eidnes.
Todo: remove the "unable to allocate scsipi_xfer" and "not queued, error %d"
printfs, but I choose to keep them for now, to help make sure the code does
what it should.
st0 at atapibus0 drive 1: <Seagate STT8000A, , 5.51> type 1 sequential
removable
Major changes may still happen in order to properly support other ATAPI
tape drives.
