/* * 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_of_bds, BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, 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, 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_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 int coroutine_fn cor_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov) { return bdrv_co_pwritev(bs->file, offset, bytes, qiov, BDRV_REQ_WRITE_COMPRESSED); } 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 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_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_co_pwritev_compressed = cor_co_pwritev_compressed, .bdrv_eject = cor_eject, .bdrv_lock_medium = cor_lock_medium, .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);