blk_eject is only used by scsi-disk and atapi, and in both cases we
only attempt to invoke blk_eject if we have a bona-fide change in
tray state.

The "issue" here is that the tray state does not generate a QMP event
unless there is a medium/BDS attached to the device, so if libvirt et al
are waiting for a tray event to occur from an empty-but-closed drive,
software opening that drive will not emit an event and libvirt will
wait forever.

Change this by modifying blk_eject to always emit an event, instead of
conditionally on a "real" backend eject.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1373264Reported-by: NPeter Krempa <pkrempa@redhat.com>
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Message-id: 1478553214-497-2-git-send-email-jsnow@redhat.com
Signed-off-by: NJohn Snow <jsnow@redhat.com>

We want the BDS event loop to run exclusively in the iothread that
owns the BDS's AioContext.  This macro will provide the synchronization
between the two event loops; for now it just wraps the common idiom
of a while loop around aio_poll.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Message-Id: <1477565348-5458-8-git-send-email-pbonzini@redhat.com>
Signed-off-by: NFam Zheng <famz@redhat.com>

Unlike tracked_requests, this field also counts throttled requests,
and remains non-zero if an AIO operation needs a BH to be "really"
completed.

With this change, it is no longer necessary to have a dummy
BdrvTrackedRequest for requests that are never serialising, and
it is no longer necessary to poll the AioContext once after
bdrv_requests_pending(bs) returns false.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Message-Id: <1477565348-5458-5-git-send-email-pbonzini@redhat.com>
Signed-off-by: NFam Zheng <famz@redhat.com>

All read/write functions already have a single coroutine-based function
on the BlockBackend level through which all requests go (no matter what
API style the external caller used) and which passes the requests down
to the block node level.

This patch exports a bdrv_co_ioctl() function and uses it to extend this
mode of operation to ioctls.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

All read/write functions already have a single coroutine-based function
on the BlockBackend level through which all requests go (no matter what
API style the external caller used) and which passes the requests down
to the block node level.

This patch extends this mode of operation to discards.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

All read/write functions already have a single coroutine-based function
on the BlockBackend level through which all requests go (no matter what
API style the external caller used) and which passes the requests down
to the block node level.

This patch extends this mode of operation to flushes.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

The event currently only contains the BlockBackend name. However, with
anonymous BlockBackends, this is always the empty string. Add the qdev
ID (or if none was given, the QOM path) so that the user can still see
which device caused the event.

Event generation has to be moved from bdrv_eject() to the BlockBackend
because the BDS doesn't know the attached device, but that's easy
because blk_eject() is the only user of it.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

Almost all block devices are qdevified by now. This allows us to go back
from the BlockBackend to the DeviceState. xen_disk is the last device
that is missing. We'll remember in the BlockBackend if a xen_disk is
attached and can then disable any features that require going from a BB
to the DeviceState.

While at it, clearly mark the function used by xen_disk as legacy even
in its name, not just in TODO comments.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

The event currently only contains the BlockBackend name. However, with
anonymous BlockBackends, this is always the empty string. Add the node
name so that the user can still see which block device caused the event.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

This simplifies bottom half handlers by removing calls to qemu_bh_delete and
thus removing the need to stash the bottom half pointer in the opaque
datum.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Instead of modifying the new BDS after it has been opened, use the newly
supported 'detect-zeroes' option in bdrv_open_common() so that all
requirements are checked (detect-zeroes=unmap requires discard=unmap).
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

We can teach Xen to drain and flush each device as it needs to, instead
of trying to flush ALL devices. This removes the last user of
blk_flush_all.

The function is therefore removed under the premise that any new uses
of blk_flush_all would be the wrong paradigm: either flush the single
device that requires flushing, or use an appropriate flush_all mechanism
from outside of the BlkBackend layer.
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Acked-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This finds a BlockBackend given the device model that is attached to it.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

There are no block drivers left that implement the old
.bdrv_write_compressed interface, so it can be removed. Also now we have
no need to use the bdrv_pwrite_compressed function and we can remove it
entirely.
Signed-off-by: NPavel Butsykin <pbutsykin@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NDenis V. Lunev <den@openvz.org>
CC: Jeff Cody <jcody@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: John Snow <jsnow@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NPavel Butsykin <pbutsykin@virtuozzo.com>
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
CC: Jeff Cody <jcody@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: John Snow <jsnow@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This is a preparatory patch, which continues the general trend of the
transition to the byte-based interfaces. bdrv_check_request() and
blk_check_request() are no longer used, thus we can remove them.
Signed-off-by: NPavel Butsykin <pbutsykin@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NDenis V. Lunev <den@openvz.org>
CC: Jeff Cody <jcody@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: John Snow <jsnow@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

In order to remove the necessity to use BlockBackend names in the
external API, we want to allow node-names everywhere. This converts
block-stream to accept a node-name without lifting the restriction that
we're operating at a root node.

In case of an invalid device name, the command returns the GenericError
error class now instead of DeviceNotFound, because this is what
qmp_get_root_bs() returns.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>

Change sector-based blk_discard(), blk_co_discard(), and
blk_aio_discard() to instead be byte-based blk_pdiscard(),
blk_co_pdiscard(), and blk_aio_pdiscard().  NBD gets a lot
simpler now that ignoring the unaligned portion of a
byte-based discard request is handled under the hood by
the block layer.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-6-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Another step towards byte-based interfaces everywhere.  Replace
the sector-based bdrv_aio_discard() with a new byte-based
bdrv_aio_pdiscard(), which silently ignores any unaligned head
or tail.  Driver callbacks will be converted in followup patches.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-id: 1468624988-423-5-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Another step towards byte-based interfaces everywhere.  Replace
the sector-based bdrv_discard() with a new byte-based
bdrv_pdiscard(), which silently ignores any unaligned head
or tail.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-3-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Another step towards byte-based interfaces everywhere.  Replace
the sector-based bdrv_co_discard() with a new byte-based
bdrv_co_pdiscard(), which silently ignores any unaligned head
or tail.  Driver callbacks will be converted in followup patches.

By calculating the alignment outside of the loop, and clamping
the max discard to an aligned value, we can simplify the actions
done within the loop.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-2-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

The rerror/werror policies are implemented in the devices, so that's
where they should be configured. In comparison to the old options in
-drive, the qdev properties are only added to those devices that
actually support them.

If the option isn't given (or "auto" is specified), the setting of the
BlockBackend is used for compatibility with the old options. For block
jobs, "auto" is the same as "enospc".
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

In practice the entry argument is always known at creation time, and
it is confusing that sometimes qemu_coroutine_enter is used with a
non-NULL argument to re-enter a coroutine (this happens in
block/sheepdog.c and tests/test-coroutine.c).  So pass the opaque value
at creation time, for consistency with e.g. aio_bh_new.

Mostly done with the following semantic patch:

@ entry1 @
expression entry, arg, co;
@@
- co = qemu_coroutine_create(entry);
+ co = qemu_coroutine_create(entry, arg);
  ...
- qemu_coroutine_enter(co, arg);
+ qemu_coroutine_enter(co);

@ entry2 @
expression entry, arg;
identifier co;
@@
- Coroutine *co = qemu_coroutine_create(entry);
+ Coroutine *co = qemu_coroutine_create(entry, arg);
  ...
- qemu_coroutine_enter(co, arg);
+ qemu_coroutine_enter(co);

@ entry3 @
expression entry, arg;
@@
- qemu_coroutine_enter(qemu_coroutine_create(entry), arg);
+ qemu_coroutine_enter(qemu_coroutine_create(entry, arg));

@ reentry @
expression co;
@@
- qemu_coroutine_enter(co, NULL);
+ qemu_coroutine_enter(co);

except for the aforementioned few places where the semantic patch
stumbled (as expected) and for test_co_queue, which would otherwise
produce an uninitialized variable warning.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This is the final patch for converting the common I/O path to take
a BdrvChild parameter instead of BlockDriverState.

The completion of this conversion means that all users that perform I/O
on an image need to actually hold a reference (in the form of BdrvChild,
possible as part of a BlockBackend) to that image. This also protects
against inconsistent use of BlockBackend vs. BlockDriverState functions
because direct use of a BlockDriverState isn't possible any more and
blk->root is private for block-backends.c.

In addition, we can now distinguish different users in the I/O path,
and the future op blockers work is going to add assertions based on
permissions stored in BdrvChild.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>

Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>

Sector-based limits are awkward to think about; in our on-going
quest to move to byte-based interfaces, convert max_transfer_length
and opt_transfer_length.  Rename them (dropping the _length suffix)
so that the compiler will help us catch the change in semantics
across any rebased code, and improve the documentation.  Use unsigned
values, so that we don't have to worry about negative values and
so that bit-twiddling is easier; however, we are still constrained
by 2^31 of signed int in most APIs.

When a value comes from an external source (iscsi and raw-posix),
sanitize the results to ensure that opt_transfer is a power of 2.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Making all callers special-case 0 as unlimited is awkward,
and we DO have a hard maximum of BDRV_REQUEST_MAX_SECTORS given
our current block layer API limits.

In the case of scsi, this means that we now always advertise a
limit to the guest, even in cases where the underlying layers
previously use 0 for no inherent limit beyond the block layer.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Also add trace points now that the function can be directly called.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>

The existing users of the function are:

1. blk_new_open(), which already enabled the write cache
2. Some test cases that don't care about the setting
3. blockdev_init() for empty drives, where the cache mode is overridden
   with the value from the options when a medium is inserted

Therefore, this patch doesn't change the current behaviour. It will be
convenient, however, for additional users of blk_new() (like block
jobs) if the most sensible WCE setting is the default.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NAlberto Garcia <berto@igalia.com>

Commit 983a1600 changed the semantics of blk_write_zeroes() to
be byte-based rather than sector-based, but did not change the
name, which is an open invitation for other code to misuse the
function.  Renaming to pwrite_zeroes() makes it more in line
with other byte-based interfaces, and will help make it easier
to track which remaining write_zeroes interfaces still need
conversion.
Reported-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

When changing the BlockDriverState that a BdrvChild points to while the
node is currently drained, we must call the .drained_end() parent
callback. Conversely, when this means attaching a new node that is
already drained, we need to call .drained_begin().

bdrv_root_attach_child() takes now an opaque parameter, which is needed
because the callbacks must also be called if we're attaching a new child
to the BlockBackend when the root node is already drained, and they need
a way to identify the BlockBackend. Previously, child->opaque was set
too late and the callbacks would still see it as NULL.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>

blk_new() cannot fail so its Error ** parameter has become superfluous.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

There are no callers to bdrv_open() or bdrv_open_inherit() left that
pass a pointer to a non-NULL BDS pointer as the first argument of these
functions, so we can finally drop that parameter and just make them
return the new BDS.

Generally, the following pattern is applied:

    bs = NULL;
    ret = bdrv_open(&bs, ..., &local_err);
    if (ret < 0) {
        error_propagate(errp, local_err);
        ...
    }

by

    bs = bdrv_open(..., errp);
    if (!bs) {
        ret = -EINVAL;
        ...
    }

Of course, there are only a few instances where the pattern is really
pure.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Its only caller is blk_new_open(), so we can just inline it there.

The bdrv_new_root() call is dropped in the process because we can just
let bdrv_open() create the BDS.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The bdrv_next() users all leaked the BdrvNextIterator after completing
the iteration. Simply changing bdrv_next() to free the iterator before
returning NULL at the end of list doesn't work because some callers exit
the loop before looking at all BDSes.

This patch moves the BdrvNextIterator from the heap to the stack of
the caller and switches to a bdrv_first()/bdrv_next() interface for
initialising the iterator.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>

This patch removes the remaining users of bs->blk, which will allow us
to have multiple BBs on top of a single BDS. In the meantime, all checks
that are currently in place to prevent the user from creating such
setups can be switched to bdrv_has_blk() instead of accessing BDS.blk.

Future patches can allow them and e.g. enable users to mirror to a block
device that already has a BlockBackend on it.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

We need to introduce a separate BdrvNextIterator struct that can keep
more state than just the current BDS in order to avoid using the bs->blk
pointer.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

In many cases we just want to know whether a BDS has at least one BB
attached, without needing to know the exact BB that is attached. In
contrast to bs->blk, this is still a valid question when more than one
BB can be attached, so just answer it by checking the parents list.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

Since virtio-blk implements request merging itself these days, the only
remaining users are test cases for the function. That doesn't make the
function exactly useful any more.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

In order to get rid of bs->blk for bdrv_get_device_name() and
bdrv_get_device_or_node_name(), ask all parents for their name and
simply pick the first one.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>