From: Dietmar Maurer <diet...@proxmox.com>
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>
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.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 0128e27..fbb51e9 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);
@@ -1574,7 +1575,7 @@ int bdrv_commit(BlockDriverState *bs)
if (!drv)
return -ENOMEDIUM;
-
+
if (!bs->backing_hd) {
return -ENOTSUP;
}
@@ -1713,6 +1714,22 @@ 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 */
@@ -1727,7 +1744,9 @@ 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;
@@ -1743,6 +1762,11 @@ 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) {
@@ -2282,12 +2306,24 @@ 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;
@@ -2331,6 +2367,17 @@ 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)
{
@@ -2388,12 +2435,23 @@ 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 {
@@ -2412,6 +2470,7 @@ 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 0f750d7..7095aeb 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -175,6 +175,8 @@ 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;
--
1.8.1.4
