From patchwork Tue Nov 27 10:24:51 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dietmar Maurer X-Patchwork-Id: 202178 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 6AD732C008F for ; Tue, 27 Nov 2012 21:25:54 +1100 (EST) Received: from localhost ([::1]:42463 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TdIMS-0002x4-IS for incoming@patchwork.ozlabs.org; Tue, 27 Nov 2012 05:25:52 -0500 Received: from eggs.gnu.org ([208.118.235.92]:44038) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TdIMB-0002uW-7z for qemu-devel@nongnu.org; Tue, 27 Nov 2012 05:25:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TdIM3-0003xi-9R for qemu-devel@nongnu.org; Tue, 27 Nov 2012 05:25:35 -0500 Received: from www.maurer-it.com ([213.129.239.114]:44984 helo=proxmox.maurer-it.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TdIM2-0003xY-Qy for qemu-devel@nongnu.org; Tue, 27 Nov 2012 05:25:27 -0500 Received: from proxmox.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox.maurer-it.com (Proxmox) with ESMTP id 4179A26A0912; Tue, 27 Nov 2012 11:24:55 +0100 (CET) From: Dietmar Maurer To: Kevin Wolf Thread-Topic: [PATCH 1/5] RFC: Efficient VM backup for qemu (v1) Thread-Index: AQHNx8bEpbUrGWNU+0WIi8W6oOxKnpf0CzIAgAAR35CAAAxrAIAC3uyQgAALlYCAABN/UIAAAxhg////7oCABHj6YIAAWWgAgAFAoGCAAA9CsIAACr8AgAAnqrA= Date: Tue, 27 Nov 2012 10:24:51 +0000 Message-ID: <24E144B8C0207547AD09C467A8259F7557832A36@lisa.maurer-it.com> References: <1353488464-82756-1-git-send-email-dietmar@proxmox.com> <50ACB184.5080204@redhat.com> <24E144B8C0207547AD09C467A8259F755782D8A1@lisa.maurer-it.com> <50ACCAEC.2030001@redhat.com> <24E144B8C0207547AD09C467A8259F755782F79B@lisa.maurer-it.com> <50AF3D23.2010909@redhat.com> <24E144B8C0207547AD09C467A8259F755782FA23@lisa.maurer-it.com> <24E144B8C0207547AD09C467A8259F755782FA71@lisa.maurer-it.com> <50AF5007.4030505@redhat.com> <24E144B8C0207547AD09C467A8259F7557831181@lisa.maurer-it.com> <50B35B80.2010605@redhat.com> <24E144B8C0207547AD09C467A8259F755783274A@lisa.maurer-it.com> <24E144B8C0207547AD09C467A8259F75578327EC@lisa.maurer-it.com> <50B47E46.5020001@redhat.com> In-Reply-To: <50B47E46.5020001@redhat.com> Accept-Language: en-US, de-AT Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 213.129.239.114 Cc: Paolo Bonzini , "qemu-devel@nongnu.org" Subject: Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1) X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org > >>> The only solution I came up with is to add before/after hooks in the > >>> block job. I agree with the criticism, but I think it's general > >>> enough and at the same time easy enough to implement. Ok, here is another try - do you think that is better? Note: This code is not tested - I just want to ask if I am moving into the right direction. I tried to move BackupInfo into the block job. From 86c3ca6467e8d220369f5e7b235cdc0e88a79ff9 Mon Sep 17 00:00:00 2001 From: Dietmar Maurer Date: Tue, 27 Nov 2012 11:05:23 +0100 Subject: [PATCH] add basic backup support to block driver Function bdrv_backup_init() creates a block job to backup a block device. We call brdv_co_backup_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 --- Makefile.objs | 1 + backup.c | 302 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ backup.h | 30 ++++++ block.c | 71 ++++++++++++- block.h | 2 + blockjob.h | 10 ++ 6 files changed, 410 insertions(+), 6 deletions(-) create mode 100644 backup.c create mode 100644 backup.h diff --git a/Makefile.objs b/Makefile.objs index 3c7abca..cb46be5 100644 --- a/Makefile.objs +++ b/Makefile.objs @@ -48,6 +48,7 @@ coroutine-obj-$(CONFIG_WIN32) += coroutine-win32.o block-obj-y = iov.o cache-utils.o qemu-option.o module.o async.o block-obj-y += nbd.o block.o blockjob.o aes.o qemu-config.o block-obj-y += thread-pool.o qemu-progress.o qemu-sockets.o uri.o notify.o +block-obj-y += backup.o block-obj-y += $(coroutine-obj-y) $(qobject-obj-y) $(version-obj-y) block-obj-$(CONFIG_POSIX) += event_notifier-posix.o aio-posix.o block-obj-$(CONFIG_WIN32) += event_notifier-win32.o aio-win32.o diff --git a/backup.c b/backup.c new file mode 100644 index 0000000..e86b76e --- /dev/null +++ b/backup.c @@ -0,0 +1,302 @@ +/* + * QEMU backup + * + * Copyright (C) 2012 Proxmox Server Solutions + * + * Authors: + * Dietmar Maurer (dietmar@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 +#include +#include + +#include "block.h" +#include "block_int.h" +#include "blockjob.h" +#include "backup.h" + +#define DEBUG_BACKUP 0 + +#define DPRINTF(fmt, ...) \ + do { if (DEBUG_BACKUP) { printf("backup: " fmt, ## __VA_ARGS__); } } \ + while (0) + + +#define BITS_PER_LONG (sizeof(unsigned long) * 8) + +typedef struct BackupBlockJob { + BlockJob common; + unsigned long *bitmap; + int bitmap_size; + BackupDumpFunc *backup_dump_cb; + BlockDriverCompletionFunc *backup_complete_cb; + void *opaque; +} BackupBlockJob; + +static int backup_get_bitmap(BlockDriverState *bs, int64_t cluster_num) +{ + assert(bs); + BackupBlockJob *job = (BackupBlockJob *)bs->job; + 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(BlockDriverState *bs, int64_t cluster_num, + int dirty) +{ + assert(bs); + BackupBlockJob *job = (BackupBlockJob *)bs->job; + 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) { + if (!(val & (1UL << bit))) { + val |= 1UL << bit; + } + } else { + if (val & (1UL << bit)) { + val &= ~(1UL << bit); + } + } + job->bitmap[idx] = val; +} + +static int backup_in_progress_count; + +static int coroutine_fn bdrv_co_backup_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; + + backup_in_progress_count++; + + 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%zd %zd %d\n", + bdrv_get_device_name(bs), start, sector_num, nb_sectors); + + for (; start < end; start++) { + if (backup_get_bitmap(bs, start)) { + DPRINTF("brdv_co_backup_cow skip C%zd\n", start); + continue; /* already copied */ + } + + /* immediately set bitmap (avoid coroutine race) */ + backup_set_bitmap(bs, start, 1); + + DPRINTF("brdv_co_backup_cow C%zd\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); + } + + 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%zd failed\n", start); + goto out; + } + + ret = job->backup_dump_cb(job->opaque, bs, start, bounce_buffer); + if (ret < 0) { + DPRINTF("brdv_co_backup_cow dump_cluster_cb C%zd failed\n", start); + goto out; + } + + DPRINTF("brdv_co_backup_cow done C%zd\n", start); + } + +out: + if (bounce_buffer) { + qemu_vfree(bounce_buffer); + } + + backup_in_progress_count--; + + return ret; +} + +static int coroutine_fn backup_before_read(BlockDriverState *bs, + int64_t sector_num, + int nb_sectors, QEMUIOVector *qiov) +{ + return bdrv_co_backup_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 bdrv_co_backup_cow(bs, sector_num, nb_sectors); +} + + +static BlockJobType backup_job_type = { + .instance_size = sizeof(BackupBlockJob), + .before_read = backup_before_read, + .before_write = backup_before_write, + .job_type = "backup", +}; + +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 %zd %zd\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; + } + + if (backup_get_bitmap(bs, start)) { + continue; /* already copied */ + } + + /* we need to yield so that qemu_aio_flush() returns. + * (without, VM does not reboot) + * todo: can we avoid that? + */ + co_sleep_ns(rt_clock, 0); + if (block_job_is_cancelled(&job->common)) { + ret = -1; + break; + } + DPRINTF("backup_run loop C%zd\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; + } + + while (backup_in_progress_count > 0) { + DPRINTF("backup_run backup_in_progress_count != 0 (%d)", + backup_in_progress_count); + co_sleep_ns(rt_clock, 10000); + } + + 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); +} + +int +bdrv_backup_init(BlockDriverState *bs, BackupDumpFunc *backup_dump_cb, + BlockDriverCompletionFunc *backup_complete_cb, + void *opaque) +{ + 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, 0, + backup_job_cleanup_cb, bs, &errp); + + 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; + job->common.co = qemu_coroutine_create(backup_run); + qemu_coroutine_enter(job->common.co, job); + + return 0; +} diff --git a/backup.h b/backup.h new file mode 100644 index 0000000..577ac19 --- /dev/null +++ b/backup.h @@ -0,0 +1,30 @@ +/* + * QEMU backup related definitions + * + * Copyright (C) Proxmox Server Solutions + * + * Authors: + * Dietmar Maurer (dietmar@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 + +#include "block.h" + +#define BACKUP_CLUSTER_BITS 16 +#define BACKUP_CLUSTER_SIZE (1<backing_hd) { return -ENOTSUP; } @@ -1679,6 +1680,22 @@ static void 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 */ @@ -1693,7 +1710,9 @@ 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; @@ -1709,6 +1728,11 @@ static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs, 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) { @@ -2278,12 +2302,24 @@ 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 (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; @@ -2327,6 +2363,17 @@ 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) { @@ -2384,12 +2431,23 @@ 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 { @@ -2408,6 +2466,7 @@ 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/block.h b/block.h index 722c620..94e5903 100644 --- a/block.h +++ b/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/blockjob.h b/blockjob.h index 3792b73..1d3f4fd 100644 --- a/blockjob.h +++ b/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;