Recent qemu has added a VIRTIO_BLK_F_FLUSH flag to advertise that the
virtual disk has a volatile write cache that needs to be flushed. In case
we see this feature implement tell the Linux block layer about the fact
and use the new VIRTIO_BLK_T_FLUSH to flush the cache when required. This
allows for an correct and simple implementation of write barriers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Virtio IDs are spread all over the tree which makes assigning new IDs
bothersome. Putting them together should make the process less error-prone.
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This API change means that virtio_net can tell how much capacity
remains for buffers. It's necessarily fuzzy, since
VIRTIO_RING_F_INDIRECT_DESC means we can fit any number of descriptors
in one, *if* we can kmalloc.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dinesh Subhraveti <dineshs@us.ibm.com>
* 'tj-block-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc:
virtio_blk: mark virtio_blk with __refdata to kill spurious section mismatch
block: sysfs fix mismatched queue_var_{store,show} in 64bit kernel
ataflop: adjust NULL test
block: fix failfast merge testing in elv_rq_merge_ok()
z2ram: Small cleanup for z2ram.c
The variable virtio_blk references the function virtblk_probe() (which
is in .devinit section) and also references the function
virtblk_remove() ( which is in .devexit section). So, virtio_blk
simultaneously refers .devinit and .devexit section. To avoid this
messup, we mark virtio_blk as __refdata.
We were warned by the following warning:
LD drivers/block/built-in.o
WARNING: drivers/block/built-in.o(.data+0xc8dc): Section mismatch in
reference from the variable virtio_blk to the function
.devinit.text:virtblk_probe()
The variable virtio_blk references
the function __devinit virtblk_probe()
If the reference is valid then annotate the
variable with __init* or __refdata (see linux/init.h) or name the variable:
*driver, *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console,
WARNING: drivers/block/built-in.o(.data+0xc8e0): Section mismatch in
reference from the variable virtio_blk to the function
.devexit.text:virtblk_remove()
The variable virtio_blk references
the function __devexit virtblk_remove()
If the reference is valid then annotate the
variable with __exit* (see linux/init.h) or name the variable:
*driver, *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console,
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Block driver ioctl methods must return ENOTTY and not -ENOIOCTLCMD if
they expect the block layer to handle generic ioctls.
This triggered a BLKROSET failure in xfsqa #200.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
By default a block driver bounces highmem requests, but virtio-blk is
perfectly fine with any request that fit into it's 64 bit addressing scheme,
mapped in the kernel virtual space or not.
Besides improving performance on highmem systems this also makes the
reproducible oops in __bounce_end_io go away (but hiding the real cause).
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The remove member of the virtio_driver structure uses __devexit_p(), so
the remove function itself should be marked with __devexit. And where
there be __devexit on the remove, so is there __devinit on the probe.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This replaces find_vq/del_vq with find_vqs/del_vqs virtio operations,
and updates all drivers. This is needed for MSI support, because MSI
needs to know the total number of vectors upfront.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ lguest/9p compile fixes)
Add a linked list of all virtqueues for a virtio device: this helps for
debugging and is also needed for upcoming interface change.
Also, add a "name" field for clearer debug messages.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This patch extracts the opaque data from pci i/o
region 0 via the added VIRTIO_BLK_F_IDENTIFY
field. By convention this data takes the form of
that returned by an ATA IDENTIFY DEVICE command,
however the driver (except for structure size)
makes no interpretation of the data. The structure
data is copied wholesale to userspace via a
HDIO_GET_IDENTITY ioctl command (eg: hdparm -i <dev>).
Signed-off-by: john cooper <john.cooper@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Until now we have had a 1:1 mapping between storage device physical
block size and the logical block sized used when addressing the device.
With SATA 4KB drives coming out that will no longer be the case. The
sector size will be 4KB but the logical block size will remain
512-bytes. Hence we need to distinguish between the physical block size
and the logical ditto.
This patch renames hardsect_size to logical_block_size.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Add support for SG_IO passthru to virtio_blk. We add the scsi command
block after the normal outhdr, and the scsi inhdr with full status
information aswell as the sense buffer before the regular inhdr.
[hch: forward ported, added the VIRTIO_BLK_F_SCSI flags, some comments
and tested the whole beast]
[axboe: updated to use ->resid and not dual-path the byte count]
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ checkpatch.pl tweak)
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
request->rq_disk is only set for FS requests or BLOCK_PC requests
originating from the generic block layer scsi ioctls. It's not set
for requests origination from other soures or internal cache flush
commands implemented by the patch I'll send after this.
So instead of using it to get at the private data in do_virtblk_request
setup queue->queuedata and use it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Till now block layer allowed two separate modes of request execution.
A request is always acquired from the request queue via
elv_next_request(). After that, drivers are free to either dequeue it
or process it without dequeueing. Dequeue allows elv_next_request()
to return the next request so that multiple requests can be in flight.
Executing requests without dequeueing has its merits mostly in
allowing drivers for simpler devices which can't do sg to deal with
segments only without considering request boundary. However, the
benefit this brings is dubious and declining while the cost of the API
ambiguity is increasing. Segment based drivers are usually for very
old or limited devices and as converting to dequeueing model isn't
difficult, it doesn't justify the API overhead it puts on block layer
and its more modern users.
Previous patches converted all block low level drivers to dequeueing
model. This patch completes the API transition by...
* renaming elv_next_request() to blk_peek_request()
* renaming blkdev_dequeue_request() to blk_start_request()
* adding blk_fetch_request() which is combination of peek and start
* disallowing completion of queued (not started) requests
* applying new API to all LLDs
Renamings are for consistency and to break out of tree code so that
it's apparent that out of tree drivers need updating.
[ Impact: block request issue API cleanup, no functional change ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Mike Miller <mike.miller@hp.com>
Cc: unsik Kim <donari75@gmail.com>
Cc: Paul Clements <paul.clements@steeleye.com>
Cc: Tim Waugh <tim@cyberelk.net>
Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Laurent Vivier <Laurent@lvivier.info>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Borislav Petkov <petkovbb@googlemail.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: Pierre Ossman <drzeus@drzeus.cx>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Markus Lidel <Markus.Lidel@shadowconnect.com>
Cc: Stefan Weinhuber <wein@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
With recent cleanups, there is no place where low level driver
directly manipulates request fields. This means that the 'hard'
request fields always equal the !hard fields. Convert all
rq->sectors, nr_sectors and current_nr_sectors references to
accessors.
While at it, drop superflous blk_rq_pos() < 0 test in swim.c.
[ Impact: use pos and nr_sectors accessors ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Tested-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Acked-by: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Acked-by: Mike Miller <mike.miller@hp.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Borislav Petkov <petkovbb@googlemail.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Eric Moore <Eric.Moore@lsi.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Paul Clements <paul.clements@steeleye.com>
Cc: Tim Waugh <tim@cyberelk.net>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Dario Ballabio <ballabio_dario@emc.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: unsik Kim <donari75@gmail.com>
Cc: Laurent Vivier <Laurent@lvivier.info>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
There are many [__]blk_end_request() call sites which call it with
full request length and expect full completion. Many of them ensure
that the request actually completes by doing BUG_ON() the return
value, which is awkward and error-prone.
This patch adds [__]blk_end_request_all() which takes @rq and @error
and fully completes the request. BUG_ON() is added to to ensure that
this actually happens.
Most conversions are simple but there are a few noteworthy ones.
* cdrom/viocd: viocd_end_request() replaced with direct calls to
__blk_end_request_all().
* s390/block/dasd: dasd_end_request() replaced with direct calls to
__blk_end_request_all().
* s390/char/tape_block: tapeblock_end_request() replaced with direct
calls to blk_end_request_all().
[ Impact: cleanup ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Mike Miller <mike.miller@hp.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
lguest: struct device - replace bus_id with dev_name()
lguest: move the initial guest page table creation code to the host
kvm-s390: implement config_changed for virtio on s390
virtio_console: support console resizing
virtio: add PCI device release() function
virtio_blk: fix type warning
virtio: block: dynamic maximum segments
virtio: set max_segment_size and max_sectors to infinite.
virtio: avoid implicit use of Linux page size in balloon interface
virtio: hand virtio ring alignment as argument to vring_new_virtqueue
virtio: use KVM_S390_VIRTIO_RING_ALIGN instead of relying on pagesize
virtio: use LGUEST_VRING_ALIGN instead of relying on pagesize
virtio: Don't use PAGE_SIZE for vring alignment in virtio_pci.
virtio: rename 'pagesize' arg to vring_init/vring_size
virtio: Don't use PAGE_SIZE in virtio_pci.c
virtio: struct device - replace bus_id with dev_name(), dev_set_name()
virtio-pci queue allocation not page-aligned
Fix parameter type warning:
linux-next-20081126/drivers/block/virtio_blk.c:307: warning: large integer implicitly truncated to unsigned type
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Enhance the driver to handle whatever maximum segment number the host
tells us to handle. Do to this, we need to allocate the scatterlist
dynamically.
We set max_phys_segments and max_hw_segments to the same value (1 if
the host doesn't tell us, since that's safest and all known hosts do
tell us).
Note that kmalloc'ing the structure for large sg_elems might be
problematic: the fix for this is sg_table, but that requires more
work.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Setting max_segment_size allows more than 64k per sg element, unless
the host specified a limit. Setting max_sectors indicates that our
max_hw_segments is the only limit.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
As a paravirt front-end driver, virtio_blk is not a rotational device so
we want do avoid idling in AS/CFQ. Tell the block layer about this.
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
To keep the size of changesets sane we split the switch by drivers;
to keep the damn thing bisectable we do the following:
1) rename the affected methods, add ones with correct
prototypes, make (few) callers handle both. That's this changeset.
2) for each driver convert to new methods. *ALL* drivers
are converted in this series.
3) kill the old (renamed) methods.
Note that it _is_ a flagday; all in-tree drivers are converted and by the
end of this series no trace of old methods remain. The only reason why
we do that this way is to keep the damn thing bisectable and allow per-driver
debugging if anything goes wrong.
New methods:
open(bdev, mode)
release(disk, mode)
ioctl(bdev, mode, cmd, arg) /* Called without BKL */
compat_ioctl(bdev, mode, cmd, arg)
locked_ioctl(bdev, mode, cmd, arg) /* Called with BKL, legacy */
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This patch converts virtio_blk to use __blk_end_request() directly
so that end_{queued|dequeued}_request() can be removed.
Related 'uptodate' argument is converted to 'error'.
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
struct request has an ioprio member but it is never updated because
currently bios do not hold io context information. The implication of
this is that virtio_blk ends up passing useless information to the
backend driver.
That said, some IO schedulers such as CFQ do store io context
information in struct request, but use private members for that, which
means that that information cannot be directly accessed in a IO
scheduler-independent way.
This patch adds a function to obtain the ioprio of a request. We should
avoid accessing ioprio directly and use this function instead, so that
its users do not have to care about future changes in block layer
structures or what the currently active IO controller is.
This patch does not introduce any functional changes but paves the way
for future clean-ups and enhancements.
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Currently virtio_blk assumes a 512 byte hard sector size. This can cause
trouble / performance issues if the backing has a different block size
(like a file on an ext3 file system formatted with 4k block size or a dasd).
Lets add a feature flag that tells the guest to use a different hard sector
size than 512 byte.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Hello Rusty,
sometimes it is useful to share a disk (e.g. usr). To avoid file system
corruption, the disk should be mounted read-only in that case. This patch
adds a new feature flag, that allows the host to specify, if the disk should
be considered read-only.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fix a modprobe virtio_blk ; rmmod virtio_blk ; modprobe virtio_blk crash; this
was basically because we weren't doing "del_gendisk()" in the remove path.
Signed-off-by: Chris Lalancette <clalance@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (moved del_gendisk up)
Rather than faking up some geometry, allow the backend to push the disk
geometry via virtio pci config option. Keep the old geo code around for
compatibility.
Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (modified to single struct)
A recent proposed feature addition to the virtio block driver revealed
some flaws in the API: in particular, we assume that feature
negotiation is complete once a driver's probe function returns.
There is nothing in the API to require this, however, and even I
didn't notice when it was violated.
So instead, we require the driver to specify what features it supports
in a table, we can then move the feature negotiation into the virtio
core. The intersection of device and driver features are presented in
a new 'features' bitmap in the struct virtio_device.
Note that this highlights the difference between Linux unsigned-long
bitmaps where each unsigned long is in native endian, and a
straight-forward little-endian array of bytes.
Drivers can still remove feature bits in their probe routine if they
really have to.
API changes:
- dev->config->feature() no longer gets and acks a feature.
- drivers should advertise their features in the 'feature_table' field
- use virtio_has_feature() for extra sanity when checking feature bits
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
A recent proposed feature addition to the virtio block driver revealed
some flaws in the API, in particular how easy it is to break big
endian machines.
The virtio config space was originally chosen to be little-endian,
because we thought the config might be part of the PCI config space
for virtio_pci. It's actually a separate mmio region, so that
argument holds little water; as only x86 is currently using the virtio
mechanism, we can change this (but must do so now, before the
impending s390 merge).
API changes:
- __virtio_config_val() just becomes a striaght vdev->config_get() call.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Do not unregister the major at device remove, since there might be
another device instances around.
(qemu) pci_del 0 11
(qemu) ACPI: PCI interrupt for device 0000:00:0b.0 disabled
(qemu) pci_del 0 10
(qemu) ------------[ cut here ]------------
WARNING: at block/genhd.c:126 unregister_blkdev+0x74/0x9e()
ACPI: PCI interrupt for device 0000:00:0a.0 disabled
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Ron Minnich points out that a struct containing a char is not always
sizeof(char); simplest to remove the structure to avoid confusion.
Cc: "ron minnich" <rminnich@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fix up so that the virtio_blk devices in sysfs link correctly to their
block device. This then allows them to be detected by hal, etc
Signed-off-by: Jeremy Katz <katzj@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Am Freitag, 1. Februar 2008 schrieb Christian Borntraeger:
> Right. I will fix that with an additional patch.
This patch goes on top of the minor number patch. Please let me know if
you want a merged patch:
Currently virtio_blk creates the disk name combinging "vd" with 'a'++.
This will give strange names after vdz. I have implemented names up to
vdzzz - inspired by the sd.c code. That should be sufficient for now.
There is one driver in the kernel (driver/s390/block/dasd_genhd.c) that
implements names from dasda-dasdzzzz allowing even more disks. Maybe
a janitor can come up with a common implementation usable for all kind
of block device drivers.
I have tested this patch with 100 disks - seems to work.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Rusty,
currently virtio_blk uses one major number per device. While this works
quite well on most systems it is wasteful and will exhaust major numbers
on larger installations.
This patch allocates a major number on init and will use 16 minor numbers
for each disk. That will allow ~64k virtio_blk disks.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Rusty,
I currently try to make my guest boot from an virtio root device
without having an external kernel. Some of the tools that I tried
expect HDIO_GETGEO to work. The most interesting value is likely
the geo.start value to get the offset of a partition. This value
is filled by block/ioctl.c if fops->getgeo is set. This patch also
fills in some standard values for heads, sectors and cylinders.
Makes sense?
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
A reset function solves three problems:
1) It allows us to renegotiate features, eg. if we want to upgrade a
guest driver without rebooting the guest.
2) It gives us a clean way of shutting down virtqueues: after a reset,
we know that the buffers won't be used by the host, and
3) It helps the guest recover from messed-up drivers.
So we remove the ->shutdown hook, and the only way we now remove
feature bits is via reset.
We leave it to the driver to do the reset before it deletes queues:
the balloon driver, for example, needs to chat to the host in its
remove function.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
It seems that virtio_net wants to disable callbacks (interrupts) before
calling netif_rx_schedule(), so we can't use the return value to do so.
Rename "restart" to "cb_enable" and introduce "cb_disable" hook: callback
now returns void, rather than a boolean.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Previously we used a type/len pair within the config space, but this
seems overkill. We now simply define a structure which represents the
layout in the config space: the config space can now only be extended
at the end.
The main driver-visible changes:
1) We indicate what fields are present with an explicit feature bit.
2) Virtqueues are explicitly numbered, and not in the config space.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The virtio code never hooked through the ->remove callback. Although
noone supports device removal at the moment, this code is already
needed for module unloading.
This of course also revealed bugs in virtio_blk, virtio_net and lguest
unloading paths.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The block driver uses scatter-gather lists with sg[0] being the
request information (struct virtio_blk_outhdr) with the type, sector
and inbuf id. The next N sg entries are the bio itself, then the last
sg is the status byte. Whether the N entries are in or out depends on
whether it's a read or a write.
We accept the normal (SCSI) ioctls: they get handed through to the other
side which can then handle it or reply that it's unsupported. It's
not clear that this actually works in general, since I don't know
if blk_pc_request() requests have an accurate rq_data_dir().
Although we try to reply -ENOTTY on unsupported commands, ioctl(fd,
CDROMEJECT) returns success to userspace. This needs a separate
patch.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jens Axboe <jens.axboe@oracle.com>
Christoph Hellwig