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2016-07-05block: Move request_alignment into BlockLimitEric Blake1-1/+1
It makes more sense to have ALL block size limit constraints in the same struct. Improve the documentation while at it. Simplify a couple of conditionals, now that we have audited and documented that request_alignment is always non-zero. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-07-05block: Set default request_alignment during bdrv_refresh_limits()Eric Blake1-1/+0
We want to eventually stick request_alignment alongside other BlockLimits, but first, we must ensure it is populated at the same time as all other limits, rather than being a special case that is set only when a block is first opened. Now that all drivers have been updated to supply an override of request_alignment during their .bdrv_refresh_limits(), as needed, the block layer itself can defer setting the default alignment until part of the overall bdrv_refresh_limits(). Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-06-20Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2016-06-20' ↵Peter Maydell1-15/+5
into staging Error reporting patches for 2016-06-20 # gpg: Signature made Mon 20 Jun 2016 15:56:15 BST # gpg: using RSA key 0x3870B400EB918653 # gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" # gpg: aka "Markus Armbruster <armbru@pond.sub.org>" # Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867 4E5F 3870 B400 EB91 8653 * remotes/armbru/tags/pull-error-2016-06-20: log: Fix qemu_set_log_filename() error handling log: Fix qemu_set_dfilter_ranges() error reporting log: Plug memory leak on multiple -dfilter coccinelle: Remove unnecessary variables for function return value error: Remove unnecessary local_err variables error: Remove NULL checks on error_propagate() calls vl: Error messages need to go to stderr, fix some Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2016-06-20error: Remove NULL checks on error_propagate() callsEduardo Habkost1-15/+5
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>
2016-06-20block: use safe iteration over AioContext notifiersStefan Hajnoczi1-10/+36
It's possible that an AioContext notifier user was close to finishing when .detach_aio_context() or .attached_aio_context() is called. In that case they may call bdrv_remove_aio_context_notifier() during the callback. Use safe iteration to avoid crashing when the notifier list is modified during iteration. We must not only handle the case where the current aio notifier is removed during a callback but also the one where any other aio notifier is removed. The next patch adds an AioContext notifier for block jobs and they really could be terminating just as .detach_aio_context() is invoked. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 1466096189-6477-6-git-send-email-stefanha@redhat.com
2016-06-16block/mirror: Fix target backing BDSMax Reitz1-8/+0
Currently, we are trying to move the backing BDS from the source to the target in bdrv_replace_in_backing_chain() which is called from mirror_exit(). However, mirror_complete() already tries to open the target's backing chain with a call to bdrv_open_backing_file(). First, we should only set the target's backing BDS once. Second, the mirroring block job has a better idea of what to set it to than the generic code in bdrv_replace_in_backing_chain() (in fact, the latter's conditions on when to move the backing BDS from source to target are not really correct). Therefore, remove that code from bdrv_replace_in_backing_chain() and leave it to mirror_complete(). Depending on what kind of mirroring is performed, we furthermore want to use different strategies to open the target's backing chain: - If blockdev-mirror is used, we can assume the user made sure that the target already has the correct backing chain. In particular, we should not try to open a backing file if the target does not have any yet. - If drive-mirror with mode=absolute-paths is used, we can and should reuse the already existing chain of nodes that the source BDS is in. In case of sync=full, no backing BDS is required; with sync=top, we just link the source's backing BDS to the target, and with sync=none, we use the source BDS as the target's backing BDS. We should not try to open these backing files anew because this would lead to two BDSs existing per physical file in the backing chain, and we would like to avoid such concurrent access. - If drive-mirror with mode=existing is used, we have to use the information provided in the physical image file which means opening the target's backing chain completely anew, just as it has been done already. If the target's backing chain shares images with the source, this may lead to multiple BDSs per physical image file. But since we cannot reliably ascertain this case, there is nothing we can do about it. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20160610185750.30956-3-mreitz@redhat.com Reviewed-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2016-06-16block: Allow replacement of a BDS by its overlayMax Reitz1-1/+15
change_parent_backing_link() asserts that the BDS to be replaced is not used as a backing file. However, we may want to replace a BDS by its overlay in which case that very link should not be redirected. For instance, when doing a sync=none drive-mirror operation, we may have the following BDS/BB forest before block job completion: target base <- source <- BlockBackend During job completion, we want to establish the source BDS as the target's backing node: target | v base <- source <- BlockBackend This makes the target a valid replacement for the source: target <- BlockBackend | v base <- source Without this modification to change_parent_backing_link() we have to inject the target into the graph before the source is its backing node, thus temporarily creating a wrong graph: target <- BlockBackend base <- source Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20160610185750.30956-2-mreitz@redhat.com Reviewed-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2016-06-16block: Fix snapshot=on with aio=nativeKevin Wolf1-0/+4
snapshot=on creates a temporary overlay that is always opened with cache=unsafe (the cache mode specified by the user is only for the actual image file and its children). This means that we must not inherit the BDRV_O_NATIVE_AIO flag for the temporary overlay because trying to use Linux AIO with cache=unsafe results in an error. Reproducer without this patch: $ x86_64-softmmu/qemu-system-x86_64 -drive file=/tmp/test.qcow2,cache=none,aio=native,snapshot=on qemu-system-x86_64: -drive file=/tmp/test.qcow2,cache=none,aio=native,snapshot=on: aio=native was specified, but it requires cache.direct=on, which was not specified. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-06-16block: Remove bs->zero_beyond_eofKevin Wolf1-2/+0
It is always true for open images now. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-06-16block: Don't enforce 512 byte minimum alignmentKevin Wolf1-1/+1
If block drivers say that they can do an alignment < 512 bytes, let's just suppose they mean it. raw-posix used to be an offender with respect to this, but it can actually deal with byte-aligned requests now. The default is still 512 bytes for any drivers that only implement sector-based interfaces, but it is 1 now for drivers that implement .bdrv_co_preadv. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-06-08block: assert that bs->request_alignment is a power of 2Peter Lieven1-1/+1
at least bdrv_co_preadv/pwritev expect this. Signed-off-by: Peter Lieven <pl@kamp.de> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-25block: Cancel jobs first in bdrv_close_all()Kevin Wolf1-21/+2
So far, bdrv_close_all() first removed all root BlockDriverStates of BlockBackends and monitor owned BDSes, and then assumed that the remaining BDSes must be related to jobs and cancelled these jobs. This order doesn't work that well any more when block jobs use BlockBackends internally because then they will lose their BDS before being cancelled. This patch changes bdrv_close_all() to first cancel all jobs and then remove all root BDSes from the remaining BBs. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-05-25block: Propagate .drained_begin/end callbacksKevin Wolf1-1/+19
When draining intermediate nodes (i.e. nodes that aren't the root node for at least one of their parents; with node references, the user can always configure the graph to create this situation), we need to propagate the .drained_begin/end callbacks all the way up to the root for the drain to be effective. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com>
2016-05-25block: Fix reconfiguring graph with drained nodesKevin Wolf1-4/+14
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: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com>
2016-05-25block: Introduce bdrv_replace_child()Kevin Wolf1-6/+20
This adds a common function that is called when attaching a new child to a parent, removing a child from a parent and when reconfiguring the graph so that an existing child points to a different node now. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com>
2016-05-25block: Drop bdrv_parent_cb_...() from bdrv_close()Max Reitz1-2/+0
bdrv_close() now asserts that the BDS's refcount is 0, therefore it cannot have any parents and the bdrv_parent_cb_change_media() call is a no-op. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-25block: Assert !bs->refcnt in bdrv_close()Max Reitz1-2/+1
The only caller of bdrv_close() left is bdrv_delete(). We may as well assert that, in a way (there are some things in bdrv_close() that make more sense under that assumption, such as the call to bdrv_release_all_dirty_bitmaps() which in turn assumes that no frozen bitmaps are attached to the BDS). In addition, being called only in bdrv_delete() means that we can drop bdrv_close()'s forward declaration at the top of block.c. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-25block: Make bdrv_open() return a BDSMax Reitz1-94/+44
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: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-25block: Drop bdrv_new_root()Max Reitz1-5/+0
It is unused now, so we may just as well drop it. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-25block: Let bdrv_open_inherit() return the snapshotMax Reitz1-7/+40
If bdrv_open_inherit() creates a snapshot BDS and *pbs is NULL, that snapshot BDS should be returned instead of the BDS under it. This has worked so far because (nearly) all users of BDRV_O_SNAPSHOT use blk_new_open() to create the BDS tree. bdrv_append() (which is called by bdrv_append_temp_snapshot()) redirects pointers from parents (i.e. the BB in this case) to the newly appended child (i.e. the overlay), therefore, while bdrv_open_inherit() did not return the root BDS, the BB still pointed to it. The only instance where BDRV_O_SNAPSHOT is used but blk_new_open() is not is in blockdev_init() if no BDS tree is created, and instead blk_new() is used and the flags are stored in the BB root state. However, qmp_blockdev_change_medium() filters the BDRV_O_SNAPSHOT flag before invoking bdrv_open(), so it will not have any effect. In any case, it would be nicer if bdrv_open_inherit() could just always return the root of the BDS tree that has been created. To this end, bdrv_append_temp_snapshot() now returns the snapshot BDS instead of just appending it on top of the snapshotted BDS. Also, it calls bdrv_ref() before bdrv_append() (which bdrv_open_inherit() has to undo if not returning the overlay). Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-25block: Drop useless bdrv_new() callMax Reitz1-2/+1
bdrv_append_temp_snapshot() uses bdrv_new() to create an empty BDS before invoking bdrv_open() on that BDS. This is probably a relict from when it used to do some modifications on that empty BDS, but now that is unnecessary, so we can just set bs_snapshot to NULL and let bdrv_open() do the rest. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-25block: Fix bdrv_next() memory leakKevin Wolf1-10/+8
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>
2016-05-19block: Propagate AioContext change to all childrenMax Reitz1-10/+6
Instead of propagating any change of a BDS's AioContext only to its file and backing children and letting driver-specific code do the rest, just propagate it to all and drop the thus superfluous implementations of bdrv_{at,de}tach_aio_context() in Quorum, blkverify and VMDK. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-19block: Remove BlockDriverState.blkKevin Wolf1-9/+1
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: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-05-19block: Avoid bs->blk in bdrv_next()Kevin Wolf1-28/+12
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>
2016-05-19block: User BdrvChild callback for device nameKevin Wolf1-2/+20
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: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-05-19block: Use BdrvChild callbacks for change_media/resizeKevin Wolf1-13/+26
We want to get rid of BlockDriverState.blk in order to allow multiple BlockBackends per BDS. Converting the device callbacks in block.c (which assume a single BlockBackend) to per-child callbacks gets us rid of the first few instances. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-05-19Revert "block: Forbid I/O throttling on nodes with multiple parents for 2.6"Kevin Wolf1-6/+0
This reverts commit 76b223200ef4fb09dd87f0e213159795eb68e7a5. Now that I/O throttling is fully done on the BlockBackend level, there is no reason any more to block I/O throttling for nodes with multiple parents as the parents don't influence each other any more. Conflicts: block.c Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-05-19block: Remove bdrv_move_feature_fields()Kevin Wolf1-30/+0
bdrv_move_feature_fields() and swap_feature_fields() are empty now, they can be removed. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-05-19block: Decouple throttling from BlockDriverStateKevin Wolf1-34/+0
This moves the throttling related part of the BDS life cycle management to BlockBackend. The throttling group reference is now kept even when no medium is inserted. With this commit, throttling isn't disabled and then re-enabled any more during graph reconfiguration. This fixes the temporary breakage of I/O throttling when used with live snapshots or block jobs that manipulate the graph. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-05-19block: Move I/O throttling configuration functions to BlockBackendKevin Wolf1-1/+1
Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-05-19block: Move throttling fields from BDS to BBKevin Wolf1-11/+11
This patch changes where the throttling state is stored (used to be the BlockDriverState, now it is the BlockBackend), but it doesn't actually make it a BB level feature yet. For example, throttling is still disabled when the BDS is detached from the BB. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-05-19block: Make sure throttled BDSes always have a BBKevin Wolf1-0/+14
It was already true in principle that a throttled BDS always has a BB attached, except that the order of operations while attaching or detaching a BDS to/from a BB wasn't careful enough. This commit breaks graph manipulations while I/O throttling is enabled. It would have been possible to keep things working with some temporary hacks, but quite cumbersome, so it's not worth the hassle. We'll fix things again in a minute. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-05-12quorum: implement bdrv_add_child() and bdrv_del_child()Wen Congyang1-4/+4
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com> Signed-off-by: Gonglei <arei.gonglei@huawei.com> Signed-off-by: Changlong Xie <xiecl.fnst@cn.fujitsu.com> Message-id: 1462865799-19402-3-git-send-email-xiecl.fnst@cn.fujitsu.com Reviewed-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2016-05-12Add new block driver interface to add/delete a BDS's childWen Congyang1-0/+49
In some cases, we want to take a quorum child offline, and take another child online. Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com> Signed-off-by: Gonglei <arei.gonglei@huawei.com> Signed-off-by: Changlong Xie <xiecl.fnst@cn.fujitsu.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Message-id: 1462865799-19402-2-git-send-email-xiecl.fnst@cn.fujitsu.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2016-05-12block: Inactivate all childrenFam Zheng1-11/+36
Currently we only inactivate the top BDS. Actually bdrv_inactivate should be the opposite of bdrv_invalidate_cache. Recurse into the whole subtree instead. Because a node may have multiple parents, and because once BDRV_O_INACTIVE is set for a node, further writes are not allowed, we cannot interleave flag settings and .bdrv_inactivate calls (that may submit write to other nodes in a graph) within a single pass. Therefore two passes are used here. Signed-off-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-12block: Invalidate all childrenFam Zheng1-6/+14
Currently we only recurse to bs->file, which will miss the children in quorum and VMDK. Recurse into the whole subtree to avoid that. Signed-off-by: Fam Zheng <famz@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-05-12block: Remove BlockDriver.bdrv_read/writeKevin Wolf1-2/+0
There are no block drivers left that implement the old .bdrv_read/write interface, so it can be removed now. This gets us rid of the corresponding emulation functions, too. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com>
2016-05-12block: introduce bdrv_no_throttling_begin/endPaolo Bonzini1-1/+0
Extract the handling of throttling from bdrv_flush_io_queue. These new functions will soon become BdrvChildRole callbacks, as they can be generalized to "beginning of drain" and "end of drain". Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-04-05block: Forbid I/O throttling on nodes with multiple parents for 2.6Kevin Wolf1-0/+7
As the patches to move I/O throttling to BlockBackend didn't make it in time for the 2.6 release, but the release adds new ways of configuring VMs whose behaviour would change once the move is done, we need to outlaw such configurations temporarily. The problem exists whenever a BDS has more users than just its BB, for example it is used as a backing file for another node. (This wasn't possible in 2.5 yet as we introduced node references to specify a backing file only recently.) In these cases, the throttling would apply to these other users now, but after moving throttling to the BlockBackend the other users wouldn't be throttled any more. This patch prevents making new references to a throttled node as well as using monitor commands to throttle a node with multiple parents. Compared to 2.5 this changes behaviour in some corner cases where references were allowed before, like bs->file or Quorum children. It seems reasonable to assume that users didn't use I/O throttling on such low level nodes. With the upcoming move of throttling into BlockBackend, such configurations won't be possible anyway. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2016-03-30block: Remove bdrv_(set_)enable_write_cache()Kevin Wolf1-16/+0
The only remaining users were block jobs (mirror and backup) which unconditionally enabled WCE on the BlockBackend of the target image. As these block jobs don't go through BlockBackend for their I/O requests, they aren't affected by this setting anyway but always get a writeback mode, so that call can be removed. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-03-30block: Remove BDRV_O_CACHE_WBKevin Wolf1-46/+2
The previous patches have successively made blk->enable_write_cache the true source for the information whether a writethrough mode must be implemented. The corresponding BDRV_O_CACHE_WB is only useless baggage we're carrying around, so now's the time to remove it. At the same time, we remove the 'cache.writeback' option parsing on the BDS level as the only effect was setting the BDRV_O_CACHE_WB flag. This change requires test cases that explicitly enabled the option to drop it. Other than that and the change of the error message when writethrough is enabled on the BDS level (from "Can't set writethrough mode" to "doesn't support the option"), there should be no change in behaviour. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-03-30block: Remove bdrv_parse_cache_flags()Kevin Wolf1-22/+7
All users are converted to bdrv_parse_cache_mode() now. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-03-30qemu-io: Use bdrv_parse_cache_mode() in reopen_f()Kevin Wolf1-12/+6
We must forbid changing the WCE flag in bdrv_reopen() in the same patch, as otherwise the behaviour would change so that the flag takes precedence over the explicitly specified option. The correct value of the WCE flag depends on the BlockBackend user (e.g. guest device) and isn't a decision that the QMP client makes, so this change is what we want. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-03-30block/qapi: Use blk_enable_write_cache()Kevin Wolf1-1/+1
Now that WCE is handled on the BlockBackend level, the flag is meaningless for BDSes. As the schema requires us to fill the field, we return an enabled write cache for them. Note that this means that querying the BlockBackend name may return writethrough as the cache information, whereas querying the node-name of the root of that same BlockBackend will return writeback. This may appear odd at first, but it actually makes sense because it correctly repesents the layer that implements the WCE handling. This becomes more apparent when you consider nodes that are the root node of multiple BlockBackends, where each BB can have its own WCE setting. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-03-30block: Move enable_write_cache to BB levelKevin Wolf1-9/+17
Whether a write cache is used or not is a decision that concerns the user (e.g. the guest device) rather than the backend. It was already logically part of the BB level as bdrv_move_feature_fields() always kept it on top of the BDS tree; with this patch, the core of it (the actual flag and the additional flushes) is also implemented there. Direct callers of bdrv_open() must pass BDRV_O_CACHE_WB now if bs doesn't have a BlockBackend attached. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-03-30block: Add bdrv_parse_cache_mode()Kevin Wolf1-0/+17
It's like bdrv_parse_cache_flags(), except that writethrough mode isn't included in the flags, but returned as a separate bool. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2016-03-30block: move encryption deprecation warning into qcow codeDaniel P. Berrange1-7/+5
For a couple of releases we have been warning Encrypted images are deprecated Support for them will be removed in a future release. You can use 'qemu-img convert' to convert your image to an unencrypted one. This warning was issued by system emulators, qemu-img, qemu-nbd and qemu-io. Such a broad warning was issued because the original intention was to rip out all the code for dealing with encryption inside the QEMU block layer APIs. The new block encryption framework used for the LUKS driver does not rely on the unloved block layer API for encryption keys, instead using the QOM 'secret' object type. It is thus no longer appropriate to warn about encryption unconditionally. When the qcow/qcow2 drivers are converted to use the new encryption framework too, it will be practical to keep AES-CBC support present for use in qemu-img, qemu-io & qemu-nbd to allow for interoperability with older QEMU versions and liberation of data from existing encrypted qcow2 files. This change moves the warning out of the generic block code and into the qcow/qcow2 drivers. Further, the warning is set to only appear when running the system emulators, since qemu-img, qemu-io, qemu-nbd are expected to support qcow2 encryption long term now that the maint burden has been eliminated. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-03-30block: add flag to indicate that no I/O will be performedDaniel P. Berrange1-2/+3
When opening an image it is useful to know whether the caller intends to perform I/O on the image or not. In the case of encrypted images this will allow the block driver to avoid having to prompt for decryption keys when we merely want to query header metadata about the image. eg qemu-img info This flag is enforced at the top level only, since even if we don't want todo I/O on the 'qcow2' file payload, the underlying 'file' driver will still need todo I/O to read the qcow2 header, for example. Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-03-30block: Reject writethrough mode except at the rootKevin Wolf1-0/+7
Writethrough mode is going to become a BlockBackend feature rather than a BDS one, so forbid it in places where we won't be able to support it when the code finally matches the envisioned design. We only allowed setting the cache mode of non-root nodes after the 2.5 release, so we're still free to make this change. The target of block jobs is now always opened in a writeback mode because it doesn't have a BlockBackend attached. This makes more sense anyway because block jobs know when to flush. If the graph is modified on job completion, the original cache mode moves to the new root, so for the guest device writethough always stays enabled if it was configured this way. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>