scsi-disk: Improve error messager if can't get version number

More often it is that bdrv_ioctl fails due to not supported by driver or
whatever reason, in this case we should be specific, because "interface
too old" is very confusing.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
scsi: Improve error messages more

Remove the "scsi-block:" prefix for error messages as suggested
by Markus.

Improve the previous patch by making the message the same for both
scsi-block and scsi-generic, including the strerror() output in both
and making an explicit reference to SG_IO.  Also s/can not/cannot/.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
megasas: Implement LD_LIST_QUERY

Newer firmware implement a LD_LIST_QUERY command, and due to a driver
issue no drives might be detected if this command isn't supported.
So add emulation for this command, too.

Cc: qemu-stable@nongnu.org
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
megasas: Enable MSI-X support

MSI-X support has been fixed in qemu, so we can enable it again.

Signed-off-by: Hannes Reinecke <hare@suse.de>
[Do not change VMSTATE_PCI_DEVICE to PCIE. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
megasas: Add MSI support

Some hardware instances do support MSI, so we should do likewise.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MAINTAINERS: mark megasas as maintained

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
block/iscsi: allow fall back to WRITE SAME without UNMAP

if the iscsi driver receives a write zeroes request with
the BDRV_REQ_MAY_UNMAP flag set it fails with -ENOTSUP
if the iscsi target does not support WRITE SAME with
UNMAP. However, the BDRV_REQ_MAY_UNMAP is only a hint
and writing zeroes with WRITE SAME will still be
better than falling back to writing zeroes with WRITE16.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
block/iscsi: speed up read for unallocated sectors

this patch implements a cache that tracks if a page on the
iscsi target is allocated or not. The cache is implemented in
a way that it allows for false positives
(e.g. pretending a page is allocated, but it isn't), but
no false negatives.

The cached allocation info is then used to speed up the
read process for unallocated sectors by issueing a GET_LBA_STATUS
request for all sectors that are not yet known to be allocated.
If the read request is confirmed to fall into an unallocated
range we directly return zeroes and do not transfer the
data over the wire.

Tests have shown that a relatively small amount of GET_LBA_STATUS
requests happens a vServer boot time to fill the allocation cache
(all those blocks are not queried again).

Not to transfer all the data of unallocated sectors saves a lot
of time, bandwidth and storage I/O load during block jobs or storage
migration and it saves a lot of bandwidth as well for any big sequential
read of the whole disk (e.g. block copy or speed tests) if a significant
number of blocks is unallocated.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
block/iscsi: clarify the meaning of ISCSI_CHECKALLOC_THRES

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
block/iscsi: allow cluster_size of 4K and greater

depending on the target the opt_unmap_gran might be as low
as 4K. As we know use this also as a knob to activate the allocationmap
feature lower the barrier. The limit 4K (and not 512) is choosen
to avoid a potentially too big allocationmap.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[PATCH] block/iscsi: bump year in copyright notice

Signed-off-by: Peter Lieven <pl@kamp.de>
qapi: Update qapi-code-gen.txt example to match current code

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
qapi: Normalize marshalling's visitor initialization and cleanup

Input and output marshalling functions do it differently.  Change them
to work the same: initialize the I/O visitor, use it, clean it up,
initialize the dealloc visitor, use it, clean it up.

This delays dealloc visitor initialization in output marshalling
functions, and input visitor cleanup in input marshalling functions.
No functional change, but the latter will be convenient when I change
the error handling.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
qapi: Remove unused Visitor callbacks start_handle(), end_handle()

These have never been called or implemented by anything, and their
intended use is undocumented, like all of the visitor API.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
qapi: Replace start_optional()/end_optional() by optional()

Semantics of end_optional() differ subtly from the other end_FOO()
callbacks: when start_FOO() succeeds, the matching end_FOO() gets
called regardless of what happens in between.  end_optional() gets
called only when everything in between succeeds as well.  Entirely
undocumented, like all of the visitor API.

The only user of Visitor Callback end_optional() never did anything,
and was removed in commit 9f9ab46.

I'm about to clean up error handling in the generated visitor code,
and end_optional() is in my way.  No users mean no test cases, and
making non-trivial cleanup transformations without test cases doesn't
strike me as a good idea.

Drop end_optional(), and rename start_optional() to optional().  We
can always go back to a pair of callbacks when we have an actual need.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
qapi-visit.py: Clean up confusing push_indent() / pop_indent() use

Changing implicit indentation in the middle of generating a block
makes following the code being generated unnecessarily hard.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
qapi: Clean up shadowing of parameters and locals in inner scopes

By un-inlining the visit of nested complex types.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
qapi-visit.py: Clean up a sloppy use of field prefix

generate_visit_struct_fields() generates the base type's struct member
name both with and without the field prefix.  Harmless, because the
field prefix is always empty there: only unboxed complex members have
a prefix, and those can't have a base type.

Clean it up anyway.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
qapi: Un-inline visit of implicit struct

In preparation of error handling changes.  Bonus: generates less
duplicated code.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
hmp: Call visit_end_struct() after visit_start_struct() succeeds

When visit_start_struct() succeeds, visit_end_struct() must be called.
hmp_object_add() doesn't when a member visit fails.  As far as I can
tell, the opts visitor copes okay with the misuse.  Fix it anyway.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>