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2021-01-26copy-on-read: skip non-guest reads if no copy neededAndrey Shinkevich
If the flag BDRV_REQ_PREFETCH was set, skip idling read/write operations in COR-driver. It can be taken into account for the COR-algorithms optimization. That check is being made during the block stream job by the moment. Add the BDRV_REQ_PREFETCH flag to the supported_read_flags of the COR-filter. block: Modify the comment for the flag BDRV_REQ_PREFETCH as we are going to use it alone and pass it to the COR-filter driver for further processing. Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-Id: <20201216061703.70908-9-vsementsov@virtuozzo.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2021-01-26qapi: copy-on-read filter: add 'bottom' optionAndrey Shinkevich
Add an option to limit copy-on-read operations to specified sub-chain of backing-chain, to make copy-on-read filter useful for block-stream job. Suggested-by: Max Reitz <mreitz@redhat.com> Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> [vsementsov: change subject, modified to freeze the chain, do some fixes] Message-Id: <20201216061703.70908-6-vsementsov@virtuozzo.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2021-01-26copy-on-read: add filter drop functionAndrey Shinkevich
Provide API for the COR-filter removal. Also, drop the filter child permissions for an inactive state when the filter node is being removed. To insert the filter, the block generic layer function bdrv_insert_node() can be used. The new function bdrv_cor_filter_drop() may be considered as an intermediate solution before the QEMU permission update system has overhauled. Then we are able to implement the API function bdrv_remove_node() on the block generic layer. Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-Id: <20201216061703.70908-4-vsementsov@virtuozzo.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2021-01-26copy-on-read: support preadv/pwritev_part functionsAndrey Shinkevich
Add support for the recently introduced functions bdrv_co_preadv_part() and bdrv_co_pwritev_part() to the COR-filter driver. Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20201216061703.70908-2-vsementsov@virtuozzo.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-09-07block: Inline bdrv_co_block_status_from_*()Max Reitz
With bdrv_filter_bs(), we can easily handle this default filter behavior in bdrv_co_block_status(). blkdebug wants to have an additional assertion, so it keeps its own implementation, except bdrv_co_block_status_from_file() needs to be inlined there. Suggested-by: Eric Blake <eblake@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
2020-09-07copy-on-read: Support compressed writesMax Reitz
Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Drop @child_class from bdrv_child_perm()Max Reitz
Implementations should decide the necessary permissions based on @role. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200513110544.176672-35-mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Make filter drivers use child_of_bdsMax Reitz
Note that some filters have secondary children, namely blkverify (the image to be verified) and blklogwrites (the log). This patch does not touch those children. Note that for blkverify, the filtered child should not be format-probed. While there is nothing enforcing this here, in practice, it will not be: blkverify implements .bdrv_file_open. The block layer ensures (and in fact, asserts) that BDRV_O_PROTOCOL is set for every BDS whose driver implements .bdrv_file_open. This flag will then be bequeathed to blkverify's children, and they will thus (by default) not be probed either. ("By default" refers to the fact that blkverify's other child (the non-filtered one) will have BDRV_O_PROTOCOL force-unset, because that is what happens for all non-filtered children of non-format drivers.) Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200513110544.176672-27-mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Pass BdrvChildRole to bdrv_child_perm()Max Reitz
For now, all callers pass 0 and no callee evaluates this value. Later patches will change both. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200513110544.176672-7-mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Add BdrvChildRole to BdrvChildMax Reitz
For now, it is always set to 0. Later patches in this series will ensure that all callers pass an appropriate combination of flags. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200513110544.176672-6-mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-18block: Rename BdrvChildRole to BdrvChildClassMax Reitz
This structure nearly only contains parent callbacks for child state changes. It cannot really reflect a child's role, because different roles may overlap (as we will see when real roles are introduced), and because parents can have custom callbacks even when the child fulfills a standard role. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Message-Id: <20200513110544.176672-4-mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-02-18block: Remove bdrv_recurse_is_first_non_filter()Max Reitz
It no longer has any users. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20200218103454.296704-11-mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-10-28block/cor: Drop cor_co_truncate()Max Reitz
No other filter driver has a .bdrv_co_truncate() implementation, and there is no need to because the general block layer code can handle it just as well. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20190918095144.955-3-mreitz@redhat.com Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-07-30block/copy-on-read: Fix permissions for inactive nodeKevin Wolf
The copy-on-read drive must not request the WRITE_UNCHANGED permission for its child if the node is inactive, otherwise starting a migration destination with -incoming will fail because the child cannot provide write access yet: qemu-system-x86_64: -blockdev copy-on-read,file=img,node-name=cor: Block node is read-only Earlier QEMU versions additionally ran into an abort() on the migration source side: bdrv_inactivate_recurse() failed to update permissions. This is silently ignored today because it was only supposed to loosen restrictions. This is the symptom that was originally reported here: https://bugzilla.redhat.com/show_bug.cgi?id=1733022 Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2019-06-12Include qemu/module.h where needed, drop it from qemu-common.hMarkus Armbruster
Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20190523143508.25387-4-armbru@redhat.com> [Rebased with conflicts resolved automatically, except for hw/usb/dev-hub.c hw/misc/exynos4210_rng.c hw/misc/bcm2835_rng.c hw/misc/aspeed_scu.c hw/display/virtio-vga.c hw/arm/stm32f205_soc.c; ui/cocoa.m fixed up]
2019-03-26block: Advertise BDRV_REQ_NO_FALLBACK in filter driversKevin Wolf
Filter drivers that support .bdrv_co_pwrite_zeroes can safely advertise BDRV_REQ_NO_FALLBACK because they just forward the request flags to their child node. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Acked-by: Eric Blake <eblake@redhat.com>
2019-03-19block: Make bdrv_{copy_on_read,crypto_luks,replication} staticAlberto Garcia
Signed-off-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-08-15block: drop empty .bdrv_close handlersVladimir Sementsov-Ogievskiy
.bdrv_close handler is optional after previous commit, no needs to keep empty functions more. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-07-10block: Use BdrvChild to discardFam Zheng
Other I/O functions are already using a BdrvChild pointer in the API, so make discard do the same. It makes it possible to initiate the same permission checks before doing I/O, and much easier to share the helper functions for this, which will be added and used by write, truncate and copy range paths. Signed-off-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-06-29block: Convert .bdrv_truncate callback to coroutine_fnKevin Wolf
bdrv_truncate() is an operation that can block (even for a quite long time, depending on the PreallocMode) in I/O paths that shouldn't block. Convert it to a coroutine_fn so that we have the infrastructure for drivers to make their .bdrv_co_truncate implementation asynchronous. This change could potentially introduce new race conditions because bdrv_truncate() isn't necessarily executed atomically any more. Whether this is a problem needs to be evaluated for each block driver that supports truncate: * file-posix/win32, gluster, iscsi, nfs, rbd, ssh, sheepdog: The protocol drivers are trivially safe because they don't actually yield yet, so there is no change in behaviour. * copy-on-read, crypto, raw-format: Essentially just filter drivers that pass the request to a child node, no problem. * qcow2: The implementation modifies metadata, so it needs to hold s->lock to be safe with concurrent I/O requests. In order to avoid double locking, this requires pulling the locking out into preallocate_co() and using qcow2_write_caches() instead of bdrv_flush(). * qed: Does a single header update, this is fine without locking. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2018-05-15block: Support BDRV_REQ_WRITE_UNCHANGED in filtersMax Reitz
Update the rest of the filter drivers to support BDRV_REQ_WRITE_UNCHANGED. They already forward write request flags to their children, so we just have to announce support for it. This patch does not cover the replication driver because that currently does not support flags at all, and because it just grabs the WRITE permission for its children when it can, so we should be fine just submitting the incoming WRITE_UNCHANGED requests as normal writes. It also does not cover format drivers for similar reasons. They all use bdrv_format_default_perms() as their .bdrv_child_perm() implementation so they just always grab the WRITE permission for their file children whenever possible. In addition, it often would be difficult to ascertain whether incoming unchanging writes end up as unchanging writes in their files. So we just leave them as normal potentially changing writes. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Message-id: 20180421132929.21610-7-mreitz@redhat.com Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-05-15block: Add COR filter driverMax Reitz
This adds a simple copy-on-read filter driver. It relies on the already existing COR functionality in the central block layer code, which may be moved here once we no longer need it there. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20180421132929.21610-2-mreitz@redhat.com Reviewed-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>