diff options
Diffstat (limited to 'block/copy-on-read.c')
| -rw-r--r-- | block/copy-on-read.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/block/copy-on-read.c b/block/copy-on-read.c new file mode 100644 index 0000000000..6a97208888 --- /dev/null +++ b/block/copy-on-read.c @@ -0,0 +1,173 @@ +/* + * 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" + + +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) & + bs->file->bs->supported_zero_flags); + + return 0; +} + + +static void cor_close(BlockDriverState *bs) +{ +} + + +#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) +{ + if (c == NULL) { + *nperm = (perm & PERM_PASSTHROUGH) | BLK_PERM_WRITE_UNCHANGED; + *nshared = (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED; + return; + } + + *nperm = (perm & PERM_PASSTHROUGH) | + (c->perm & PERM_UNCHANGED); + *nshared = (shared & PERM_PASSTHROUGH) | + (c->shared_perm & PERM_UNCHANGED); +} + + +static int64_t cor_getlength(BlockDriverState *bs) +{ + return bdrv_getlength(bs->file->bs); +} + + +static int cor_truncate(BlockDriverState *bs, int64_t offset, + PreallocMode prealloc, Error **errp) +{ + return bdrv_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->bs, 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); +} + + +BlockDriver bdrv_copy_on_read = { + .format_name = "copy-on-read", + + .bdrv_open = cor_open, + .bdrv_close = cor_close, + .bdrv_child_perm = cor_child_perm, + + .bdrv_getlength = cor_getlength, + .bdrv_truncate = cor_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); |