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