Commit Graph

67 Commits

Author SHA1 Message Date
Philippe Mathieu-Daudé
a95921f171 qapi: Inline and remove QERR_DEVICE_HAS_NO_MEDIUM definition
Address the comment added in commit 4629ed1e98
("qerror: Finally unused, clean up"), from 2015:

  /*
   * These macros will go away, please don't use
   * in new code, and do not add new ones!
   */

Mechanical transformation using sed, and manual cleanup.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240312141343.3168265-4-armbru@redhat.com>
2024-04-24 09:50:58 +02:00
Zhao Liu
ce33d85d45 block/snapshot: Fix missing ERRP_GUARD() for error_prepend()
As the comment in qapi/error, passing @errp to error_prepend() requires
ERRP_GUARD():

* = Why, when and how to use ERRP_GUARD() =
*
* Without ERRP_GUARD(), use of the @errp parameter is restricted:
...
* - It should not be passed to error_prepend(), error_vprepend() or
*   error_append_hint(), because that doesn't work with &error_fatal.
* ERRP_GUARD() lifts these restrictions.
*
* To use ERRP_GUARD(), add it right at the beginning of the function.
* @errp can then be used without worrying about the argument being
* NULL or &error_fatal.

ERRP_GUARD() could avoid the case when @errp is &error_fatal, the user
can't see this additional information, because exit() happens in
error_setg earlier than information is added [1].

In block/snapshot.c, there are 2 functions passing @errp to
error_prepend() without ERRP_GUARD():
 - bdrv_all_delete_snapshot()
 - bdrv_all_goto_snapshot()

As the APIs exposed in include/block/snapshot.h, they could be called
by other modules.

To avoid potential issues as [1] said, add missing ERRP_GUARD() at the
beginning of these 2 functions.

[1]: Issue description in the commit message of commit ae7c80a7bd
     ("error: New macro ERRP_GUARD()").

Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Hanna Reitz <hreitz@redhat.com>
Cc: qemu-block@nongnu.org
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Message-ID: <20240311033822.3142585-11-zhao1.liu@linux.intel.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2024-03-12 11:45:34 +01:00
Stefan Hajnoczi
b49f4755c7 block: remove AioContext locking
This is the big patch that removes
aio_context_acquire()/aio_context_release() from the block layer and
affected block layer users.

There isn't a clean way to split this patch and the reviewers are likely
the same group of people, so I decided to do it in one patch.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Message-ID: <20231205182011.1976568-7-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-12-21 22:49:27 +01:00
Stefan Hajnoczi
6bc30f1949 graph-lock: remove AioContext locking
Stop acquiring/releasing the AioContext lock in
bdrv_graph_wrlock()/bdrv_graph_unlock() since the lock no longer has any
effect.

The distinction between bdrv_graph_wrunlock() and
bdrv_graph_wrunlock_ctx() becomes meaningless and they can be collapsed
into one function.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231205182011.1976568-6-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-12-21 22:49:27 +01:00
Kevin Wolf
d3007d348a block: Fix crash when loading snapshot on inactive node
bdrv_is_read_only() only checks if the node is configured to be
read-only eventually, but even if it returns false, writing to the node
may not be permitted at the moment (because it's inactive).

bdrv_is_writable() checks that the node can be written to right now, and
this is what the snapshot operations really need.

Change bdrv_can_snapshot() to use bdrv_is_writable() to fix crashes like
the following:

$ ./qemu-system-x86_64 -hda /tmp/test.qcow2 -loadvm foo -incoming defer
qemu-system-x86_64: ../block/io.c:1990: int bdrv_co_write_req_prepare(BdrvChild *, int64_t, int64_t, BdrvTrackedRequest *, int): Assertion `!(bs->open_flags & BDRV_O_INACTIVE)' failed.

The resulting error message after this patch isn't perfect yet, but at
least it doesn't crash any more:

$ ./qemu-system-x86_64 -hda /tmp/test.qcow2 -loadvm foo -incoming defer
qemu-system-x86_64: Device 'ide0-hd0' is writable but does not support snapshots

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231201142520.32255-2-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-12-21 22:49:27 +01:00
Kevin Wolf
6bc0bcc89f block: Fix deadlocks in bdrv_graph_wrunlock()
bdrv_graph_wrunlock() calls aio_poll(), which may run callbacks that
have a nested event loop. Nested event loops can depend on other
iothreads making progress, so in order to allow them to make progress it
must not hold the AioContext lock of another thread while calling
aio_poll().

This introduces a @bs parameter to bdrv_graph_wrunlock() whose
AioContext is temporarily dropped (which matches bdrv_graph_wrlock()),
and a bdrv_graph_wrunlock_ctx() that can be used if the BlockDriverState
doesn't necessarily exist any more when unlocking.

This also requires a change to bdrv_schedule_unref(), which was relying
on the incorrectly taken lock. It needs to take the lock itself now.
While this is a separate bug, it can't be fixed a separate patch because
otherwise the intermediate state would either deadlock or try to release
a lock that we don't even hold.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231115172012.112727-3-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
[kwolf: Fixed up bdrv_schedule_unref()]
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-11-21 12:45:21 +01:00
Thomas Huth
6ab4f1c9e2 block/snapshot: Fix compiler warning with -Wshadow=local
No need to declare a new variable in the the inner code block
here, we can re-use the "ret" variable that has been declared
at the beginning of the function. With this change, the code
can now be successfully compiled with -Wshadow=local again.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20231023175038.111607-1-thuth@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2023-11-13 07:41:35 +01:00
Kevin Wolf
4026f1c4f3 block: Mark bdrv_get_parent_name() and callers GRAPH_RDLOCK
This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_get_parent_name() need to hold a reader lock for the graph
because it accesses the parents list of a node.

For some places, we know that they will hold the lock, but we don't have
the GRAPH_RDLOCK annotations yet. In this case, add assume_graph_lock()
with a FIXME comment. These places will be removed once everything is
properly annotated.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230929145157.45443-13-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-10-12 16:31:33 +02:00
Kevin Wolf
c0fc5123ad block: Mark bdrv_primary_child() and callers GRAPH_RDLOCK
This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_primary_child() need to hold a reader lock for the graph
because it accesses the children list of a node.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230929145157.45443-12-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-10-12 16:31:33 +02:00
Kevin Wolf
a32e781838 block: Mark bdrv_snapshot_fallback() and callers GRAPH_RDLOCK
This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_snapshot_fallback() need to hold a reader lock for the graph
because it accesses the children list of a node.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230929145157.45443-8-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-10-12 16:31:33 +02:00
Kevin Wolf
2b3912f135 block: Mark bdrv_first_blk() and bdrv_is_root_node() GRAPH_RDLOCK
This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_first_blk() and bdrv_is_root_node() need to hold a reader lock
for the graph. These functions are the only functions in block-backend.c
that access the parent list of a node.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230929145157.45443-5-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-10-12 16:31:33 +02:00
Kevin Wolf
32a8aba37e block: Mark bdrv_unref_child() GRAPH_WRLOCK
Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_unref_child(). These callers will typically
already hold the graph lock once the locking work is completed, which
means that they can't call functions that take it internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-21-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-09-20 17:46:01 +02:00
Vladimir Sementsov-Ogievskiy
c5c2174146 block/snapshot: drop indirection around bdrv_snapshot_fallback_ptr
Now the indirection is not actually used, we can safely reduce it to
simple pointer. For consistency do a bit of refactoring to get rid of
_ptr suffixes that become meaningless.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-15-vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-10-27 20:14:11 +02:00
Vladimir Sementsov-Ogievskiy
5bb0474778 block: Manipulate bs->file / bs->backing pointers in .attach/.detach
bs->file and bs->backing are a kind of duplication of part of
bs->children. But very useful diplication, so let's not drop them at
all:)

We should manage bs->file and bs->backing in same place, where we
manage bs->children, to keep them in sync.

Moreover, generic io paths are unprepared to BdrvChild without a bs, so
it's double good to clear bs->file / bs->backing when we detach the
child.

Detach is simple: if we detach bs->file or bs->backing child, just
set corresponding field to NULL.

Attach is a bit more complicated. But we still can precisely detect
should we set one of bs->file / bs->backing or not:

- if role is BDRV_CHILD_COW, we definitely deal with bs->backing
- else, if role is BDRV_CHILD_FILTERED (it must be also
  BDRV_CHILD_PRIMARY), it's a filtered child. Use
  bs->drv->filtered_child_is_backing to chose the pointer field to
  modify.
- else, if role is BDRV_CHILD_PRIMARY, we deal with bs->file
- in all other cases, it's neither bs->backing nor bs->file. It's some
  other child and we shouldn't care

OK. This change brings one more good thing: we can (and should) get rid
of all indirect pointers in the block-graph-change transactions:

bdrv_attach_child_common() stores BdrvChild** into transaction to clear
it on abort.

bdrv_attach_child_common() has two callers: bdrv_attach_child_noperm()
just pass-through this feature, bdrv_root_attach_child() doesn't need
the feature.

Look at bdrv_attach_child_noperm() callers:
  - bdrv_attach_child() doesn't need the feature
  - bdrv_set_file_or_backing_noperm() uses the feature to manage
    bs->file and bs->backing, we don't want it anymore
  - bdrv_append() uses the feature to manage bs->backing, again we
    don't want it anymore

So, we should drop this stuff! Great!

We could probably keep BdrvChild** argument to keep the int return
value, but it seems not worth the complexity.

Finally, we now set .file / .backing automatically in generic code and
want to restring setting them by hand outside of .attach/.detach.
So, this patch cleanups all remaining places where they were set.
To find such places I use:

  git grep '\->file ='
  git grep '\->backing ='
  git grep '&.*\<backing\>'
  git grep '&.*\<file\>'

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-14-vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-10-27 20:14:11 +02:00
Vladimir Sementsov-Ogievskiy
0c6100a7ff block/snapshot: stress that we fallback to primary child
Actually what we chose is a primary child. Let's stress it in the code.

We are going to drop indirect pointer logic here in future. Actually
this commit simplifies the future work: we drop use of indirection in
the assertion now.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220726201134.924743-9-vsementsov@yandex-team.ru>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-10-27 20:14:11 +02:00
Emanuele Giuseppe Esposito
6b573efec8 include/block/snapshot: global state API + assertions
Snapshots run also under the BQL, so they all are
in the global state API. The aiocontext lock that they hold
is currently an overkill and in future could be removed.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-23-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-03-04 18:18:25 +01:00
Max Reitz
32a9a245d7 block/snapshot: Clarify goto fallback behavior
In the bdrv_snapshot_goto() fallback code, we work with a pointer to
either bs->file or bs->backing.  We detach that child, close the node
(with .bdrv_close()), apply the snapshot on the child node, and then
re-open the node (with .bdrv_open()).

In order for .bdrv_open() to attach the same child node that we had
before, we pass "file={child-node}" or "backing={child-node}" to it.
Therefore, when .bdrv_open() has returned success, we can assume that
bs->file or bs->backing (respectively) points to our original child
again.  This is verified by an assertion.

All of this is not immediately clear from a quick glance at the code,
so add a comment to the assertion what it is for, and why it is valid.
It certainly confused Coverity.

Reported-by: Coverity (CID 1452774)
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210503095418.31521-1-mreitz@redhat.com>
[mreitz: s/close/detach/]
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2021-06-24 09:49:04 +02:00
Vladimir Sementsov-Ogievskiy
307261b243 block: consistently use bdrv_is_read_only()
It's better to use accessor function instead of bs->read_only directly.
In some places use bdrv_is_writable() instead of
checking both BDRV_O_RDWR set and BDRV_O_INACTIVE not set.

In bdrv_open_common() it's a bit strange to add one more variable, but
we are going to drop bs->read_only in the next patch, so new ro local
variable substitutes it here.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210527154056.70294-2-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2021-06-02 14:23:20 +02:00
Daniel P. Berrangé
3d3e9b1f66 block: rename and alter bdrv_all_find_snapshot semantics
Currently bdrv_all_find_snapshot() will return 0 if it finds
a snapshot, -1 if an error occurs, or if it fails to find a
snapshot. New callers to be added want to distinguish between
the error scenario and failing to find a snapshot.

Rename it to bdrv_all_has_snapshot and make it return -1 on
error, 0 if no snapshot is found and 1 if snapshot is found.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-7-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2021-02-08 11:19:51 +00:00
Daniel P. Berrangé
c22d644ca7 block: allow specifying name of block device for vmstate storage
Currently the vmstate will be stored in the first block device that
supports snapshots. Historically this would have usually been the
root device, but with UEFI it might be the variable store. There
needs to be a way to override the choice of block device to store
the state in.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-6-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2021-02-08 11:19:51 +00:00
Daniel P. Berrangé
cf3a74c94f block: add ability to specify list of blockdevs during snapshot
When running snapshot operations, there are various rules for which
blockdevs are included/excluded. While this provides reasonable default
behaviour, there are scenarios that are not well handled by the default
logic. Some of the conditions do not have a single correct answer.

Thus there needs to be a way for the mgmt app to provide an explicit
list of blockdevs to perform snapshots across. This can be achieved
by passing a list of node names that should be used.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-5-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2021-02-08 11:19:51 +00:00
Daniel P. Berrangé
e26f98e209 block: push error reporting into bdrv_all_*_snapshot functions
The bdrv_all_*_snapshot functions return a BlockDriverState pointer
for the invalid backend, which the callers then use to report an
error message. In some cases multiple callers are reporting the
same error message, but with slightly different text. In the future
there will be more error scenarios for some of these methods, which
will benefit from fine grained error message reporting. So it is
helpful to push error reporting down a level.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
[PMD: Initialize variables]
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210204124834.774401-2-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2021-02-08 11:19:51 +00:00
Max Reitz
c8af87573f block/snapshot: Fix fallback
If the top node's driver does not provide snapshot functionality and we
want to fall back to a node down the chain, we need to snapshot all
non-COW children.  For simplicity's sake, just do not fall back if there
is more than one such child.  Furthermore, we really only can fall back
to bs->file and bs->backing, because bdrv_snapshot_goto() has to modify
the child link (notably, set it to NULL).

Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
2020-09-07 12:31:31 +02:00
Vladimir Sementsov-Ogievskiy
e53a578a8b block/snapshot: rename Error ** parameter to more common errp
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@Redhat.com>
Message-Id: <20191205174635.18758-11-vsementsov@virtuozzo.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2019-12-18 08:43:19 +01:00
Kevin Wolf
05f4aced65 block/snapshot: Restrict set of snapshot nodes
Nodes involved in internal snapshots were those that were returned by
bdrv_next(), inserted and not read-only. bdrv_next() in turn returns all
nodes that are either the root node of a BlockBackend or monitor-owned
nodes.

With the typical -drive use, this worked well enough. However, in the
typical -blockdev case, the user defines one node per option, making all
nodes monitor-owned nodes. This includes protocol nodes etc. which often
are not snapshottable, so "savevm" only returns an error.

Change the conditions so that internal snapshot still include all nodes
that have a BlockBackend attached (we definitely want to snapshot
anything attached to a guest device and probably also the built-in NBD
server; snapshotting block job BlockBackends is more of an accident, but
a preexisting one), but other monitor-owned nodes are only included if
they have no parents.

This makes internal snapshots usable again with typical -blockdev
configurations.

Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>
2019-10-04 11:52:40 +02:00
Daniel Henrique Barboza
8c04093c8c block/snapshot: remove bdrv_snapshot_delete_by_id_or_name
After the previous patch, the only instance of this function left
is inside qemu-img.c.

qemu-img is using it inside the 'img_snapshot' function to delete
snapshots in the SNAPSHOT_DELETE case, based on a "snapshot_name"
string that refers to the tag, not ID, of the QEMUSnapshotInfo struct.
This can be verified by checking the SNAPSHOT_CREATE case that
comes shortly before SNAPSHOT_DELETE. In that case, the same
"snapshot_name" variable is being strcpy to the 'name' field
of the QEMUSnapshotInfo struct sn:

pstrcpy(sn.name, sizeof(sn.name), snapshot_name);

Based on that, it is unlikely that "snapshot_name" might contain
an "id" in SNAPSHOT_DELETE.

This patch changes SNAPSHOT_DELETE to use snapshot_find() and
snapshot_delete() instead of bdrv_snapshot_delete_by_id_or_name.
After that, there is no instances left of bdrv_snapshot_delete_by_id_or_name
in the code, so it is safe to remove it entirely.

Suggested-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-02-25 15:03:18 +01:00
Daniel Henrique Barboza
6ca080453e block/snapshot.c: eliminate use of ID input in snapshot operations
At this moment, QEMU attempts to create/load/delete snapshots
by using either an ID (id_str) or a name. The problem is that the code
isn't consistent of whether the entered argument is an ID or a name,
causing unexpected behaviors.

For example, when creating snapshots via savevm <arg>, what happens is that
"arg" is treated as both name and id_str. In a guest without snapshots, create
a single snapshot via savevm:

(qemu) savevm 0
(qemu) info snapshots
List of snapshots present on all disks:
ID        TAG                 VM SIZE                DATE       VM CLOCK
--        0                      741M 2018-07-31 13:39:56   00:41:25.313

A snapshot with name "0" is created. ID is hidden from the user, but the
ID is a non-zero integer that starts at "1". Thus, this snapshot has
id_str=1, TAG="0". Creating a second snapshot with arg = 1, the first one
is deleted:

(qemu) savevm 1
(qemu) info snapshots
List of snapshots present on all disks:
ID        TAG                 VM SIZE                DATE       VM CLOCK
--        1                      741M 2018-07-31 13:42:14   00:41:55.252

What happened?

- when creating the second snapshot, a verification is done inside
bdrv_all_delete_snapshot to delete any existing snapshots that matches an
string argument. Here, the code calls bdrv_all_delete_snapshot("1", ...);

- bdrv_all_delete_snapshot calls bdrv_snapshot_find(..., "1") for each
BlockDriverState of the guest. And this is where things goes tilting:
bdrv_snapshot_find does a search by both id_str and name. It finds
out that there is a snapshot that has id_str = 1, stores a reference
to the snapshot in the sn_info pointer and then returns match found;

- since a match was found, a call to bdrv_snapshot_delete_by_id_or_name() is
made. This function ignores the pointer written by bdrv_snapshot_find. Instead,
it deletes the snapshot using bdrv_snapshot_delete() calling it first with
id_str = 1. If it fails to delete, then it calls it again with name = 1.

- after all that, QEMU creates the new snapshot, that has id_str = 1 and
name = 1. The user is left wondering that happened with the first snapshot
created. Similar bugs can be triggered when using loadvm and delvm.

Before contemplating discarding the use of ID input in these operations,
I've searched the code of what would be the implications. My findings
are:

- the RBD and Sheepdog drivers don't care. Both uses the 'name' field as
key in their logic, making id_str = name when appropriate.
replay-snapshot.c does not make any special use of id_str;

- qcow2 uses id_str as an unique identifier but it is automatically
calculated, not being influenced by user input. Other than that, there are
no distinguish operations made only with id_str;

- in blockdev.c, the delete operation uses a match of both id_str AND
name. Given that id_str is either a copy of 'name' or auto-generated,
we're fine here.

This gives motivation to not consider ID as a valid user input in HMP
commands - sticking with 'name' input only is more consistent. To
accomplish that, the following changes were made in this patch:

- bdrv_snapshot_find() does not match for id_str anymore, only 'name'. The
function is called in save_snapshot(), load_snapshot(), bdrv_all_delete_snapshot()
and bdrv_all_find_snapshot(). This change makes the search function more
predictable and does not change the behavior of any underlying code that uses
these affected functions, which are related to HMP (which is fine) and the
main loop inside vl.c (which doesn't care about it anyways);

- bdrv_all_delete_snapshot() does not call bdrv_snapshot_delete_by_id_or_name
anymore. Instead, it uses the pointer returned by bdrv_snapshot_find to
erase the snapshot with the exact match of id_str an name. This function
is called in save_snapshot and hmp_delvm, thus this change  produces the
intended effect;

- documentation changes to reflect the new behavior. I consider this to
be an API fix instead of an API change - the user was already creating
snapshots using 'name', but now he/she will also enjoy a consistent
behavior.

Ideally we would get rid of the id_str field entirely, but this would have
repercussions on existing snapshots. Another day perhaps.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-02-25 15:03:18 +01:00
Vladimir Sementsov-Ogievskiy
3c005293c2 block: make .bdrv_close optional
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-08-15 12:50:39 +02:00
Max Reitz
609f45ea95 block: Add block-specific QDict header
There are numerous QDict functions that have been introduced for and are
used only by the block layer.  Move their declarations into an own
header file to reflect that.

While qdict_extract_subqdict() is in fact used outside of the block
layer (in util/qemu-config.c), it is still a function related very
closely to how the block layer works with nested QDicts, namely by
sometimes flattening them.  Therefore, its declaration is put into this
header as well and util/qemu-config.c includes it with a comment stating
exactly which function it needs.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20180509165530.29561-7-mreitz@redhat.com>
[Copyright note tweaked, superfluous includes dropped]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-06-15 14:49:44 +02:00
Marc-André Lureau
cb3e7f08ae qobject: Replace qobject_incref/QINCREF qobject_decref/QDECREF
Now that we can safely call QOBJECT() on QObject * as well as its
subtypes, we can have macros qobject_ref() / qobject_unref() that work
everywhere instead of having to use QINCREF() / QDECREF() for QObject
and qobject_incref() / qobject_decref() for its subtypes.

The replacement is mechanical, except I broke a long line, and added a
cast in monitor_qmp_cleanup_req_queue_locked().  Unlike
qobject_decref(), qobject_unref() doesn't accept void *.

Note that the new macros evaluate their argument exactly once, thus no
need to shout them.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180419150145.24795-4-marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Rebased, semantic conflict resolved, commit message improved]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2018-05-04 08:27:53 +02:00
Markus Armbruster
922a01a013 Move include qemu/option.h from qemu-common.h to actual users
qemu-common.h includes qemu/option.h, but most places that include the
former don't actually need the latter.  Drop the include, and add it
to the places that actually need it.

While there, drop superfluous includes of both headers, and
separate #include from file comment with a blank line.

This cleanup makes the number of objects depending on qemu/option.h
drop from 4545 (out of 4743) to 284 in my "build everything" tree.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20180201111846.21846-20-armbru@redhat.com>
[Semantic conflict with commit bdd6a90a9e in block/nvme.c resolved]
2018-02-09 13:52:16 +01:00
Markus Armbruster
452fcdbc49 Include qapi/qmp/qdict.h exactly where needed
This cleanup makes the number of objects depending on qapi/qmp/qdict.h
drop from 4550 (out of 4743) to 368 in my "build everything" tree.
For qapi/qmp/qobject.h, the number drops from 4552 to 390.

While there, separate #include from file comment with a blank line.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20180201111846.21846-13-armbru@redhat.com>
2018-02-09 13:52:15 +01:00
Kevin Wolf
70a5afedd6 block: Error out on load_vm with active dirty bitmaps
Loading a snapshot invalidates the bitmap. Just marking all blocks dirty
is not a useful response in practice, instead the user needs to be aware
that we switch to a completely different state. If they are okay with
losing the dirty bitmap, they can just explicitly delete it.

This effectively reverts commit 04dec3c3ae.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
2017-11-21 14:48:23 +01:00
Kevin Wolf
2b624fe079 block: Add errp to bdrv_all_goto_snapshot()
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
2017-11-21 14:48:22 +01:00
Kevin Wolf
0b62bcbc61 block: Add errp to bdrv_snapshot_goto()
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
2017-11-21 14:48:22 +01:00
Max Reitz
5e003f17ec block: Make bdrv_next() keep strong references
On one hand, it is a good idea for bdrv_next() to return a strong
reference because ideally nearly every pointer should be refcounted.
This fixes intermittent failure of iotest 194.

On the other, it is absolutely necessary for bdrv_next() itself to keep
a strong reference to both the BB (in its first phase) and the BDS (at
least in the second phase) because when called the next time, it will
dereference those objects to get a link to the next one.  Therefore, it
needs these objects to stay around until then.  Just storing the pointer
to the next in the iterator is not really viable because that pointer
might become invalid as well.

Both arguments taken together means we should probably just invoke
bdrv_ref() and blk_ref() in bdrv_next().  This means we have to assert
that bdrv_next() is always called from the main loop, but that was
probably necessary already before this patch and judging from the
callers, it also looks to actually be the case.

Keeping these strong references means however that callers need to give
them up if they decide to abort the iteration early.  They can do so
through the new bdrv_next_cleanup() function.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20171110172545.32609-1-mreitz@redhat.com
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-11-17 18:21:31 +01:00
Vladimir Sementsov-Ogievskiy
04dec3c3ae block/snapshot: dirty all dirty bitmaps on snapshot-switch
Snapshot-switch actually changes active state of disk so it should
reflect on dirty bitmaps. Otherwise next incremental backup using
these bitmaps will be invalid.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20171023092945.54532-1-vsementsov@virtuozzo.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-11-14 18:06:25 +01:00
Eric Blake
46f5ac205a qobject: Use simpler QDict/QList scalar insertion macros
We now have macros in place to make it less verbose to add a scalar
to QDict and QList, so use them.

Patch created mechanically via:
  spatch --sp-file scripts/coccinelle/qobject.cocci \
    --macro-file scripts/cocci-macro-file.h --dir . --in-place
then touched up manually to fix a couple of '?:' back to original
spacing, as well as avoiding a long line in monitor.c.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20170427215821.19397-7-eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2017-05-09 09:13:51 +02:00
Dong Jia Shi
7a9e51198c block: pass the right options for BlockDriver.bdrv_open()
raw_open() expects the caller always passing in the right actual
@options parameter. But when trying to applying snapshot on a RBD
image, bdrv_snapshot_goto() calls raw_open() (by calling the
bdrv_open callback on the BlockDriver) with a NULL @options, and
that will result in a Segmentation fault.

For the other non-raw format drivers, it also makes sense to passing
in the actual options, althought they don't trigger the problem so
far.

Let's prepare a @options by adding the "file" key-value pair to a
copy of the actual options that were given for the node (i.e.
bs->options), and pass it to the callback.

BlockDriver.bdrv_open() expects bs->file to be NULL and just
overwrites it with the result from bdrv_open_child(). That means we
should actually make sure it's NULL because otherwise the child BDS
will have a reference count that is 1 too high. So we unconditionally
invoke bdrv_unref_child() before calling BlockDriver.bdrv_open(), and
we wrap everything in bdrv_ref()/bdrv_unref() so the BDS isn't
deleted in the meantime.

Suggested-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-id: 20170405091909.36357-2-bjsdjshi@linux.vnet.ibm.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-04-11 15:33:00 +02:00
Eduardo Habkost
621ff94d50 error: Remove NULL checks on error_propagate() calls
error_propagate() already ignores local_err==NULL, so there's no
need to check it before calling.

Coccinelle patch used to perform the changes added to
scripts/coccinelle/error_propagate_null.cocci.

Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <1465855078-19435-2-git-send-email-ehabkost@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2016-06-20 16:38:13 +02:00
Kevin Wolf
2a9170bcd4 block: Fix bdrv_all_delete_snapshot() error handling
The code to exit the loop after bdrv_snapshot_delete_by_id_or_name()
returned failure was duplicated. The first copy of it was too early so
that the AioContext lock would not be freed. This patch removes it so
that only the second, correct copy remains.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-06-08 10:21:09 +02:00
Kevin Wolf
88be7b4be4 block: Fix bdrv_next() memory leak
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: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
2016-05-25 19:04:10 +02:00
Kevin Wolf
7c8eece45b block: Avoid bs->blk in bdrv_next()
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: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-05-19 16:45:31 +02:00
Markus Armbruster
da34e65cb4 include/qemu/osdep.h: Don't include qapi/error.h
Commit 57cb38b included qapi/error.h into qemu/osdep.h to get the
Error typedef.  Since then, we've moved to include qemu/osdep.h
everywhere.  Its file comment explains: "To avoid getting into
possible circular include dependencies, this file should not include
any other QEMU headers, with the exceptions of config-host.h,
compiler.h, os-posix.h and os-win32.h, all of which are doing a
similar job to this file and are under similar constraints."
qapi/error.h doesn't do a similar job, and it doesn't adhere to
similar constraints: it includes qapi-types.h.  That's in excess of
100KiB of crap most .c files don't actually need.

Add the typedef to qemu/typedefs.h, and include that instead of
qapi/error.h.  Include qapi/error.h in .c files that need it and don't
get it now.  Include qapi-types.h in qom/object.h for uint16List.

Update scripts/clean-includes accordingly.  Update it further to match
reality: replace config.h by config-target.h, add sysemu/os-posix.h,
sysemu/os-win32.h.  Update the list of includes in the qemu/osdep.h
comment quoted above similarly.

This reduces the number of objects depending on qapi/error.h from "all
of them" to less than a third.  Unfortunately, the number depending on
qapi-types.h shrinks only a little.  More work is needed for that one.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
[Fix compilation without the spice devel packages. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-22 22:20:15 +01:00
Peter Maydell
80c71a241a block: Clean up includes
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-01-20 13:36:23 +01:00
Paolo Bonzini
27a7649a48 block: use drained section around bdrv_snapshot_delete
Do not use bdrv_drain, since by itself it does not guarantee
anything.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-12-18 14:34:44 +01:00
Denis V. Lunev
7cb1448149 migration: implement bdrv_all_find_vmstate_bs helper
The patch also ensures proper locking for the operation.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Tested-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2015-11-19 11:50:00 +01:00
Denis V. Lunev
a9085f9b55 snapshot: create bdrv_all_create_snapshot helper
to create snapshot for all loaded block drivers.

The patch also ensures proper locking.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Tested-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2015-11-19 11:50:00 +01:00
Denis V. Lunev
723ccda1a0 snapshot: create bdrv_all_find_snapshot helper
to check that snapshot is available for all loaded block drivers.
The check bs != bs1 in hmp_info_snapshots is an optimization. The check
for availability of this snapshot will return always true as the list
of snapshots was collected from that image.

The patch also ensures proper locking.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Tested-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2015-11-19 11:50:00 +01:00
Denis V. Lunev
4c1cdbaad0 snapshot: create bdrv_all_goto_snapshot helper
to switch to snapshot on all loaded block drivers.

The patch also ensures proper locking.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Tested-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2015-11-19 11:50:00 +01:00