bd86fb990c
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>
149 lines
4.5 KiB
C
149 lines
4.5 KiB
C
/*
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* Copy-on-read filter block driver
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*
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* Copyright (c) 2018 Red Hat, Inc.
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*
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* Author:
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* Max Reitz <mreitz@redhat.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 or
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* (at your option) version 3 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "block/block_int.h"
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#include "qemu/module.h"
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static int cor_open(BlockDriverState *bs, QDict *options, int flags,
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Error **errp)
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{
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bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, false,
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errp);
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if (!bs->file) {
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return -EINVAL;
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}
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bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
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(BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
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bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
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((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
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bs->file->bs->supported_zero_flags);
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return 0;
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}
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#define PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \
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| BLK_PERM_WRITE \
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| BLK_PERM_RESIZE)
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#define PERM_UNCHANGED (BLK_PERM_ALL & ~PERM_PASSTHROUGH)
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static void cor_child_perm(BlockDriverState *bs, BdrvChild *c,
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const BdrvChildClass *child_class,
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BlockReopenQueue *reopen_queue,
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uint64_t perm, uint64_t shared,
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uint64_t *nperm, uint64_t *nshared)
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{
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*nperm = perm & PERM_PASSTHROUGH;
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*nshared = (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED;
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/* We must not request write permissions for an inactive node, the child
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* cannot provide it. */
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if (!(bs->open_flags & BDRV_O_INACTIVE)) {
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*nperm |= BLK_PERM_WRITE_UNCHANGED;
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}
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}
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static int64_t cor_getlength(BlockDriverState *bs)
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{
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return bdrv_getlength(bs->file->bs);
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}
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static int coroutine_fn cor_co_preadv(BlockDriverState *bs,
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uint64_t offset, uint64_t bytes,
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QEMUIOVector *qiov, int flags)
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{
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return bdrv_co_preadv(bs->file, offset, bytes, qiov,
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flags | BDRV_REQ_COPY_ON_READ);
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}
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static int coroutine_fn cor_co_pwritev(BlockDriverState *bs,
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uint64_t offset, uint64_t bytes,
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QEMUIOVector *qiov, int flags)
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{
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return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
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}
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static int coroutine_fn cor_co_pwrite_zeroes(BlockDriverState *bs,
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int64_t offset, int bytes,
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BdrvRequestFlags flags)
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{
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return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
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}
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static int coroutine_fn cor_co_pdiscard(BlockDriverState *bs,
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int64_t offset, int bytes)
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{
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return bdrv_co_pdiscard(bs->file, offset, bytes);
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}
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static void cor_eject(BlockDriverState *bs, bool eject_flag)
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{
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bdrv_eject(bs->file->bs, eject_flag);
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}
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static void cor_lock_medium(BlockDriverState *bs, bool locked)
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{
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bdrv_lock_medium(bs->file->bs, locked);
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}
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static BlockDriver bdrv_copy_on_read = {
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.format_name = "copy-on-read",
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.bdrv_open = cor_open,
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.bdrv_child_perm = cor_child_perm,
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.bdrv_getlength = cor_getlength,
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.bdrv_co_preadv = cor_co_preadv,
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.bdrv_co_pwritev = cor_co_pwritev,
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.bdrv_co_pwrite_zeroes = cor_co_pwrite_zeroes,
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.bdrv_co_pdiscard = cor_co_pdiscard,
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.bdrv_eject = cor_eject,
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.bdrv_lock_medium = cor_lock_medium,
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.bdrv_co_block_status = bdrv_co_block_status_from_file,
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.has_variable_length = true,
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.is_filter = true,
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};
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static void bdrv_copy_on_read_init(void)
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{
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bdrv_register(&bdrv_copy_on_read);
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}
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block_init(bdrv_copy_on_read_init);
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