Mirrored writes are used by live block copy. Signed-off-by: Marcelo Tosatti Index: qemu-block-copy/block/blkmirror.c =================================================================== --- /dev/null +++ qemu-block-copy/block/blkmirror.c @@ -0,0 +1,239 @@ +/* + * Block driver for mirrored writes. + * + * Copyright (C) 2011 Red Hat, Inc. + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +#include +#include "block_int.h" + +typedef struct { + BlockDriverState *bs[2]; +} BdrvMirrorState; + +/* Valid blkmirror filenames look like blkmirror:path/to/image1:path/to/image2 */ +static int blkmirror_open(BlockDriverState *bs, const char *filename, int flags) +{ + BdrvMirrorState *m = bs->opaque; + int ret; + char *raw, *c; + + /* Parse the blkmirror: prefix */ + if (strncmp(filename, "blkmirror:", strlen("blkmirror:"))) { + return -EINVAL; + } + filename += strlen("blkmirror:"); + + /* Parse the raw image filename */ + c = strchr(filename, ':'); + if (c == NULL) { + return -EINVAL; + } + + raw = strdup(filename); + raw[c - filename] = '\0'; + ret = bdrv_file_open(&m->bs[0], raw, flags); + free(raw); + if (ret < 0) { + return ret; + } + filename = c + 1; + + ret = bdrv_file_open(&m->bs[1], filename, flags); + if (ret < 0) { + bdrv_delete(m->bs[0]); + return ret; + } + + return 0; +} + +static void blkmirror_close(BlockDriverState *bs) +{ + BdrvMirrorState *m = bs->opaque; + int i; + + for (i=0; i<2; i++) { + bdrv_delete(m->bs[i]); + m->bs[i] = NULL; + } +} + +static int blkmirror_flush(BlockDriverState *bs) +{ + BdrvMirrorState *m = bs->opaque; + + bdrv_flush(m->bs[0]); + bdrv_flush(m->bs[1]); + + return 0; +} + +static int64_t blkmirror_getlength(BlockDriverState *bs) +{ + BdrvMirrorState *m = bs->opaque; + + return bdrv_getlength(m->bs[0]); +} + +static BlockDriverAIOCB *blkmirror_aio_readv(BlockDriverState *bs, + int64_t sector_num, + QEMUIOVector *qiov, + int nb_sectors, + BlockDriverCompletionFunc *cb, + void *opaque) +{ + BdrvMirrorState *m = bs->opaque; + return bdrv_aio_readv(m->bs[0], sector_num, qiov, nb_sectors, cb, opaque); +} + +typedef struct DupAIOCB { + BlockDriverAIOCB common; + int count; + + BlockDriverCompletionFunc *cb; + void *opaque; + + BlockDriverAIOCB *src_aiocb; + BlockDriverAIOCB *dest_aiocb; + + int ret; +} DupAIOCB; + +static void dup_aio_cancel(BlockDriverAIOCB *blockacb) +{ + DupAIOCB *acb = container_of(blockacb, DupAIOCB, common); + + bdrv_aio_cancel(acb->src_aiocb); + bdrv_aio_cancel(acb->dest_aiocb); + qemu_aio_release(acb); +} + +static AIOPool dup_aio_pool = { + .aiocb_size = sizeof(DupAIOCB), + .cancel = dup_aio_cancel, +}; + +static void blkmirror_aio_cb(void *opaque, int ret) +{ + DupAIOCB *dcb = opaque; + + dcb->count--; + assert(dcb->count >= 0); + if (dcb->count == 0) { + if (dcb->ret < 0) { + ret = dcb->ret; + } + dcb->common.cb(dcb->opaque, ret); + qemu_aio_release(dcb); + } + dcb->ret = ret; +} + +static DupAIOCB *dup_aio_get(BlockDriverState *bs, + BlockDriverCompletionFunc *cb, + void *opaque) +{ + DupAIOCB *dcb; + + dcb = qemu_aio_get(&dup_aio_pool, bs, cb, opaque); + if (!dcb) + return NULL; + dcb->count = 2; + dcb->ret = 0; + dcb->opaque = opaque; + + return dcb; +} + +static BlockDriverAIOCB *blkmirror_aio_writev(BlockDriverState *bs, + int64_t sector_num, + QEMUIOVector *qiov, + int nb_sectors, + BlockDriverCompletionFunc *cb, + void *opaque) +{ + BdrvMirrorState *m = bs->opaque; + DupAIOCB *dcb = dup_aio_get(bs, cb, opaque); + + dcb->src_aiocb = bdrv_aio_writev(m->bs[0], sector_num, qiov, nb_sectors, + &blkmirror_aio_cb, dcb); + if (!dcb->src_aiocb) { + qemu_aio_release(dcb); + return NULL; + } + + dcb->dest_aiocb = bdrv_aio_writev(m->bs[1], sector_num, qiov, nb_sectors, + &blkmirror_aio_cb, dcb); + if (!dcb->dest_aiocb) { + bdrv_aio_cancel(dcb->src_aiocb); + qemu_aio_release(dcb); + return NULL; + } + + return &dcb->common; +} + +static BlockDriverAIOCB *blkmirror_aio_flush(BlockDriverState *bs, + BlockDriverCompletionFunc *cb, + void *opaque) +{ + BdrvMirrorState *m = bs->opaque; + DupAIOCB *dcb = dup_aio_get(bs, cb, opaque); + + dcb->src_aiocb = bdrv_aio_flush(m->bs[0], &blkmirror_aio_cb, dcb); + if (!dcb->src_aiocb) { + qemu_aio_release(dcb); + return NULL; + } + dcb->dest_aiocb = bdrv_aio_flush(m->bs[1], &blkmirror_aio_cb, dcb); + if (!dcb->dest_aiocb) { + bdrv_aio_cancel(dcb->src_aiocb); + qemu_aio_release(dcb); + return NULL; + } + + return &dcb->common; +} + +static int blkmirror_discard(BlockDriverState *bs, int64_t sector_num, + int nb_sectors) +{ + BdrvMirrorState *m = bs->opaque; + int ret; + + ret = bdrv_discard(m->bs[0], sector_num, nb_sectors); + if (ret < 0) { + return ret; + } + + return bdrv_discard(m->bs[1], sector_num, nb_sectors); +} + + +static BlockDriver bdrv_blkmirror = { + .format_name = "blkmirror", + .protocol_name = "blkmirror", + .instance_size = sizeof(BdrvMirrorState), + + .bdrv_getlength = blkmirror_getlength, + + .bdrv_file_open = blkmirror_open, + .bdrv_close = blkmirror_close, + .bdrv_flush = blkmirror_flush, + .bdrv_discard = blkmirror_discard, + + .bdrv_aio_readv = blkmirror_aio_readv, + .bdrv_aio_writev = blkmirror_aio_writev, + .bdrv_aio_flush = blkmirror_aio_flush, +}; + +static void bdrv_blkmirror_init(void) +{ + bdrv_register(&bdrv_blkmirror); +} + +block_init(bdrv_blkmirror_init); Index: qemu-block-copy/Makefile.objs =================================================================== --- qemu-block-copy.orig/Makefile.objs +++ qemu-block-copy/Makefile.objs @@ -22,7 +22,7 @@ block-nested-y += raw.o cow.o qcow.o vdi block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o block-nested-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o block-nested-y += qed-check.o -block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o +block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o blkmirror.o block-nested-$(CONFIG_WIN32) += raw-win32.o block-nested-$(CONFIG_POSIX) += raw-posix.o block-nested-$(CONFIG_CURL) += curl.o