Function backup_job_create() creates a block job to backup a block device. The coroutine is started with backup_job_start().
We call backup_do_cow() for each write during backup. That function reads the original data and pass it to backup_dump_cb(). The tracked_request infrastructure is used to serialize access. Currently backup cluster size is hardcoded to 65536 bytes. Signed-off-by: Dietmar Maurer <diet...@proxmox.com> --- Makefile.objs | 1 + backup.c | 355 ++++++++++++++++++++++++++++++++++++++++++++++ backup.h | 30 ++++ block.c | 71 +++++++++- include/block/block.h | 2 + include/block/blockjob.h | 10 ++ 6 files changed, 463 insertions(+), 6 deletions(-) create mode 100644 backup.c create mode 100644 backup.h diff --git a/Makefile.objs b/Makefile.objs index a68cdac..df64f70 100644 --- a/Makefile.objs +++ b/Makefile.objs @@ -13,6 +13,7 @@ block-obj-$(CONFIG_POSIX) += aio-posix.o block-obj-$(CONFIG_WIN32) += aio-win32.o block-obj-y += block/ block-obj-y += qapi-types.o qapi-visit.o +block-obj-y += backup.o block-obj-y += qemu-coroutine.o qemu-coroutine-lock.o qemu-coroutine-io.o block-obj-y += qemu-coroutine-sleep.o diff --git a/backup.c b/backup.c new file mode 100644 index 0000000..8955e1a --- /dev/null +++ b/backup.c @@ -0,0 +1,355 @@ +/* + * QEMU backup + * + * Copyright (C) 2013 Proxmox Server Solutions + * + * Authors: + * Dietmar Maurer (diet...@proxmox.com) + * + * 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 <stdio.h> +#include <errno.h> +#include <unistd.h> + +#include "block/block.h" +#include "block/block_int.h" +#include "block/blockjob.h" +#include "qemu/ratelimit.h" +#include "backup.h" + +#define DEBUG_BACKUP 0 + +#define USE_ALLOCATION_CHECK 0 + +#define DPRINTF(fmt, ...) \ + do { if (DEBUG_BACKUP) { printf("backup: " fmt, ## __VA_ARGS__); } } \ + while (0) + + +#define SLICE_TIME 100000000ULL /* ns */ + +typedef struct BackupBlockJob { + BlockJob common; + RateLimit limit; + CoRwlock rwlock; + uint64_t sectors_read; + unsigned long *bitmap; + int bitmap_size; + BackupDumpFunc *backup_dump_cb; + BlockDriverCompletionFunc *backup_complete_cb; + void *opaque; +} BackupBlockJob; + +static bool backup_get_bitmap(BackupBlockJob *job, int64_t cluster_num) +{ + assert(job); + assert(job->bitmap); + + unsigned long val, idx, bit; + + idx = cluster_num / BITS_PER_LONG; + + assert(job->bitmap_size > idx); + + bit = cluster_num % BITS_PER_LONG; + val = job->bitmap[idx]; + + return !!(val & (1UL << bit)); +} + +static void backup_set_bitmap(BackupBlockJob *job, int64_t cluster_num, + bool dirty) +{ + assert(job); + assert(job->bitmap); + + unsigned long val, idx, bit; + + idx = cluster_num / BITS_PER_LONG; + + assert(job->bitmap_size > idx); + + bit = cluster_num % BITS_PER_LONG; + val = job->bitmap[idx]; + if (dirty) { + val |= 1UL << bit; + } else { + val &= ~(1UL << bit); + } + job->bitmap[idx] = val; +} + +static int coroutine_fn backup_do_cow(BlockDriverState *bs, + int64_t sector_num, int nb_sectors) +{ + assert(bs); + BackupBlockJob *job = (BackupBlockJob *)bs->job; + assert(job); + + BlockDriver *drv = bs->drv; + struct iovec iov; + QEMUIOVector bounce_qiov; + void *bounce_buffer = NULL; + int ret = 0; + + qemu_co_rwlock_rdlock(&job->rwlock); + + int64_t start, end; + + start = sector_num / BACKUP_BLOCKS_PER_CLUSTER; + end = (sector_num + nb_sectors + BACKUP_BLOCKS_PER_CLUSTER - 1) / + BACKUP_BLOCKS_PER_CLUSTER; + + DPRINTF("brdv_co_backup_cow enter %s C%" PRId64 " %" PRId64 " %d\n", + bdrv_get_device_name(bs), start, sector_num, nb_sectors); + + for (; start < end; start++) { + bool zero = 0; + + if (backup_get_bitmap(job, start)) { + DPRINTF("brdv_co_backup_cow skip C%" PRId64 "\n", start); + continue; /* already copied */ + } + + /* immediately set bitmap (avoid coroutine race) */ + backup_set_bitmap(job, start, 1); + + DPRINTF("brdv_co_backup_cow C%" PRId64 "\n", start); + + if (!bounce_buffer) { + iov.iov_len = BACKUP_CLUSTER_SIZE; + iov.iov_base = bounce_buffer = qemu_blockalign(bs, iov.iov_len); + qemu_iovec_init_external(&bounce_qiov, &iov, 1); + } + +#if USE_ALLOCATION_CHECK + int n = 0; + ret = bdrv_co_is_allocated_above(bs, NULL, + start * BACKUP_BLOCKS_PER_CLUSTER, + BACKUP_BLOCKS_PER_CLUSTER, &n); + if (ret < 0) { + DPRINTF("brdv_co_backup_cow is_allocated C%" PRId64 " failed\n", + start); + goto out; + } + + zero = (ret == 0) && (n == BACKUP_BLOCKS_PER_CLUSTER); + + if (!zero) { +#endif + ret = drv->bdrv_co_readv(bs, start * BACKUP_BLOCKS_PER_CLUSTER, + BACKUP_BLOCKS_PER_CLUSTER, + &bounce_qiov); + if (ret < 0) { + DPRINTF("brdv_co_backup_cow bdrv_read C%" PRId64 " failed\n", + start); + goto out; + } +#if USE_ALLOCATION_CHECK + } +#endif + job->sectors_read += BACKUP_BLOCKS_PER_CLUSTER; + + ret = job->backup_dump_cb(job->opaque, bs, start, + zero ? NULL : bounce_buffer); + if (ret < 0) { + DPRINTF("brdv_co_backup_cow dump_cluster_cb C%" PRId64 " failed\n", + start); + goto out; + } + + DPRINTF("brdv_co_backup_cow done C%" PRId64 "\n", start); + } + +out: + if (bounce_buffer) { + qemu_vfree(bounce_buffer); + } + + qemu_co_rwlock_unlock(&job->rwlock); + + return ret; +} + +static int coroutine_fn backup_before_read(BlockDriverState *bs, + int64_t sector_num, + int nb_sectors, QEMUIOVector *qiov) +{ + return backup_do_cow(bs, sector_num, nb_sectors); +} + +static int coroutine_fn backup_before_write(BlockDriverState *bs, + int64_t sector_num, + int nb_sectors, QEMUIOVector *qiov) +{ + return backup_do_cow(bs, sector_num, nb_sectors); +} + +static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp) +{ + BackupBlockJob *s = container_of(job, BackupBlockJob, common); + + if (speed < 0) { + error_set(errp, QERR_INVALID_PARAMETER, "speed"); + return; + } + ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); +} + +static BlockJobType backup_job_type = { + .instance_size = sizeof(BackupBlockJob), + .before_read = backup_before_read, + .before_write = backup_before_write, + .job_type = "backup", + .set_speed = backup_set_speed, +}; + +static void coroutine_fn backup_run(void *opaque) +{ + BackupBlockJob *job = opaque; + BlockDriverState *bs = job->common.bs; + assert(bs); + + int64_t start, end; + + start = 0; + end = (bs->total_sectors + BACKUP_BLOCKS_PER_CLUSTER - 1) / + BACKUP_BLOCKS_PER_CLUSTER; + + DPRINTF("backup_run start %s %" PRId64 " %" PRId64 "\n", + bdrv_get_device_name(bs), start, end); + + int ret = 0; + + for (; start < end; start++) { + if (block_job_is_cancelled(&job->common)) { + ret = -1; + break; + } + + /* we need to yield so that qemu_aio_flush() returns. + * (without, VM does not reboot) + * Note: use 1000 instead of 0 (0 prioritize this task too much) + */ + if (job->common.speed) { + uint64_t delay_ns = ratelimit_calculate_delay( + &job->limit, job->sectors_read); + job->sectors_read = 0; + block_job_sleep_ns(&job->common, rt_clock, delay_ns); + } else { + block_job_sleep_ns(&job->common, rt_clock, 1000); + } + + if (block_job_is_cancelled(&job->common)) { + ret = -1; + break; + } + + if (backup_get_bitmap(job, start)) { + continue; /* already copied */ + } + + DPRINTF("backup_run loop C%" PRId64 "\n", start); + + /** + * This triggers a cluster copy + * Note: avoid direct call to brdv_co_backup_cow, because + * this does not call tracked_request_begin() + */ + ret = bdrv_co_backup(bs, start*BACKUP_BLOCKS_PER_CLUSTER, 1); + if (ret < 0) { + break; + } + /* Publish progress */ + job->common.offset += BACKUP_CLUSTER_SIZE; + } + + /* wait until pending backup_do_cow()calls have completed */ + qemu_co_rwlock_wrlock(&job->rwlock); + qemu_co_rwlock_unlock(&job->rwlock); + + DPRINTF("backup_run complete %d\n", ret); + block_job_completed(&job->common, ret); +} + +static void backup_job_cleanup_cb(void *opaque, int ret) +{ + BlockDriverState *bs = opaque; + assert(bs); + BackupBlockJob *job = (BackupBlockJob *)bs->job; + assert(job); + + DPRINTF("backup_job_cleanup_cb start %d\n", ret); + + job->backup_complete_cb(job->opaque, ret); + + DPRINTF("backup_job_cleanup_cb end\n"); + + g_free(job->bitmap); +} + +void +backup_job_start(BlockDriverState *bs, bool cancel) +{ + assert(bs); + assert(bs->job); + assert(bs->job->co == NULL); + + if (cancel) { + block_job_cancel(bs->job); /* set cancel flag */ + } + + bs->job->co = qemu_coroutine_create(backup_run); + qemu_coroutine_enter(bs->job->co, bs->job); +} + +int +backup_job_create(BlockDriverState *bs, BackupDumpFunc *backup_dump_cb, + BlockDriverCompletionFunc *backup_complete_cb, + void *opaque, int64_t speed) +{ + assert(bs); + assert(backup_dump_cb); + assert(backup_complete_cb); + + if (bs->job) { + DPRINTF("bdrv_backup_init failed - running job on %s\n", + bdrv_get_device_name(bs)); + return -1; + } + + int64_t bitmap_size; + const char *devname = bdrv_get_device_name(bs); + + if (!devname || !devname[0]) { + return -1; + } + + DPRINTF("bdrv_backup_init %s\n", bdrv_get_device_name(bs)); + + Error *errp; + BackupBlockJob *job = block_job_create(&backup_job_type, bs, speed, + backup_job_cleanup_cb, bs, &errp); + + qemu_co_rwlock_init(&job->rwlock); + + job->common.cluster_size = BACKUP_CLUSTER_SIZE; + + bitmap_size = bs->total_sectors + + BACKUP_BLOCKS_PER_CLUSTER * BITS_PER_LONG - 1; + bitmap_size /= BACKUP_BLOCKS_PER_CLUSTER * BITS_PER_LONG; + + job->backup_dump_cb = backup_dump_cb; + job->backup_complete_cb = backup_complete_cb; + job->opaque = opaque; + job->bitmap_size = bitmap_size; + job->bitmap = g_new0(unsigned long, bitmap_size); + + job->common.len = bs->total_sectors*BDRV_SECTOR_SIZE; + + return 0; +} diff --git a/backup.h b/backup.h new file mode 100644 index 0000000..9b1ea1c --- /dev/null +++ b/backup.h @@ -0,0 +1,30 @@ +/* + * QEMU backup related definitions + * + * Copyright (C) 2013 Proxmox Server Solutions + * + * Authors: + * Dietmar Maurer (diet...@proxmox.com) + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + */ + +#ifndef QEMU_BACKUP_H +#define QEMU_BACKUP_H + +#define BACKUP_CLUSTER_BITS 16 +#define BACKUP_CLUSTER_SIZE (1<<BACKUP_CLUSTER_BITS) +#define BACKUP_BLOCKS_PER_CLUSTER (BACKUP_CLUSTER_SIZE/BDRV_SECTOR_SIZE) + +typedef int BackupDumpFunc(void *opaque, BlockDriverState *bs, + int64_t cluster_num, unsigned char *buf); + +void backup_job_start(BlockDriverState *bs, bool cancel); + +int backup_job_create(BlockDriverState *bs, BackupDumpFunc *backup_dump_cb, + BlockDriverCompletionFunc *backup_complete_cb, + void *opaque, int64_t speed); + +#endif /* QEMU_BACKUP_H */ diff --git a/block.c b/block.c index 50dab8e..6e6d08f 100644 --- a/block.c +++ b/block.c @@ -54,6 +54,7 @@ typedef enum { BDRV_REQ_COPY_ON_READ = 0x1, BDRV_REQ_ZERO_WRITE = 0x2, + BDRV_REQ_BACKUP_ONLY = 0x4, } BdrvRequestFlags; static void bdrv_dev_change_media_cb(BlockDriverState *bs, bool load); @@ -1554,7 +1555,7 @@ int bdrv_commit(BlockDriverState *bs) if (!drv) return -ENOMEDIUM; - + if (!bs->backing_hd) { return -ENOTSUP; } @@ -1691,6 +1692,22 @@ void bdrv_round_to_clusters(BlockDriverState *bs, } } +/** + * Round a region to job cluster boundaries + */ +static void round_to_job_clusters(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, + int job_cluster_size, + int64_t *cluster_sector_num, + int *cluster_nb_sectors) +{ + int64_t c = job_cluster_size/BDRV_SECTOR_SIZE; + + *cluster_sector_num = QEMU_ALIGN_DOWN(sector_num, c); + *cluster_nb_sectors = QEMU_ALIGN_UP(sector_num - *cluster_sector_num + + nb_sectors, c); +} + static bool tracked_request_overlaps(BdrvTrackedRequest *req, int64_t sector_num, int nb_sectors) { /* aaaa bbbb */ @@ -1705,7 +1722,9 @@ static bool tracked_request_overlaps(BdrvTrackedRequest *req, } static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs, - int64_t sector_num, int nb_sectors) + int64_t sector_num, + int nb_sectors, + int job_cluster_size) { BdrvTrackedRequest *req; int64_t cluster_sector_num; @@ -1721,6 +1740,11 @@ static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs, bdrv_round_to_clusters(bs, sector_num, nb_sectors, &cluster_sector_num, &cluster_nb_sectors); + if (job_cluster_size) { + round_to_job_clusters(bs, sector_num, nb_sectors, job_cluster_size, + &cluster_sector_num, &cluster_nb_sectors); + } + do { retry = false; QLIST_FOREACH(req, &bs->tracked_requests, list) { @@ -2260,12 +2284,24 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, bs->copy_on_read_in_flight++; } - if (bs->copy_on_read_in_flight) { - wait_for_overlapping_requests(bs, sector_num, nb_sectors); + int job_cluster_size = bs->job && bs->job->cluster_size ? + bs->job->cluster_size : 0; + + if (bs->copy_on_read_in_flight || job_cluster_size) { + wait_for_overlapping_requests(bs, sector_num, nb_sectors, + job_cluster_size); } tracked_request_begin(&req, bs, sector_num, nb_sectors, false); + if (bs->job && bs->job->job_type->before_read) { + ret = bs->job->job_type->before_read(bs, sector_num, nb_sectors, qiov); + if ((ret < 0) || (flags & BDRV_REQ_BACKUP_ONLY)) { + /* Note: We do not return any data to the caller */ + goto out; + } + } + if (flags & BDRV_REQ_COPY_ON_READ) { int pnum; @@ -2309,6 +2345,17 @@ int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, BDRV_REQ_COPY_ON_READ); } +int coroutine_fn bdrv_co_backup(BlockDriverState *bs, + int64_t sector_num, int nb_sectors) +{ + if (!bs->job) { + return -ENOTSUP; + } + + return bdrv_co_do_readv(bs, sector_num, nb_sectors, NULL, + BDRV_REQ_BACKUP_ONLY); +} + static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs, int64_t sector_num, int nb_sectors) { @@ -2366,12 +2413,23 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs, bdrv_io_limits_intercept(bs, true, nb_sectors); } - if (bs->copy_on_read_in_flight) { - wait_for_overlapping_requests(bs, sector_num, nb_sectors); + int job_cluster_size = bs->job && bs->job->cluster_size ? + bs->job->cluster_size : 0; + + if (bs->copy_on_read_in_flight || job_cluster_size) { + wait_for_overlapping_requests(bs, sector_num, nb_sectors, + job_cluster_size); } tracked_request_begin(&req, bs, sector_num, nb_sectors, true); + if (bs->job && bs->job->job_type->before_write) { + ret = bs->job->job_type->before_write(bs, sector_num, nb_sectors, qiov); + if (ret < 0) { + goto out; + } + } + if (flags & BDRV_REQ_ZERO_WRITE) { ret = bdrv_co_do_write_zeroes(bs, sector_num, nb_sectors); } else { @@ -2390,6 +2448,7 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs, bs->wr_highest_sector = sector_num + nb_sectors - 1; } +out: tracked_request_end(&req); return ret; diff --git a/include/block/block.h b/include/block/block.h index 5c3b911..b6144be 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -172,6 +172,8 @@ int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); +int coroutine_fn bdrv_co_backup(BlockDriverState *bs, + int64_t sector_num, int nb_sectors); int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); /* diff --git a/include/block/blockjob.h b/include/block/blockjob.h index c290d07..6f42495 100644 --- a/include/block/blockjob.h +++ b/include/block/blockjob.h @@ -50,6 +50,13 @@ typedef struct BlockJobType { * manually. */ void (*complete)(BlockJob *job, Error **errp); + + /** tracked requests */ + int coroutine_fn (*before_read)(BlockDriverState *bs, int64_t sector_num, + int nb_sectors, QEMUIOVector *qiov); + int coroutine_fn (*before_write)(BlockDriverState *bs, int64_t sector_num, + int nb_sectors, QEMUIOVector *qiov); + } BlockJobType; /** @@ -103,6 +110,9 @@ struct BlockJob { /** Speed that was set with @block_job_set_speed. */ int64_t speed; + /** tracked requests */ + int cluster_size; + /** The completion function that will be called when the job completes. */ BlockDriverCompletionFunc *cb; -- 1.7.2.5