Manage BlockDriverState lifecycle with refcnt, so bdrv_delete() is no longer public and should be called by bdrv_unref() if refcnt is decreased to 0. This is an identical change because effectively, there's no multiple reference of BDS now: no caller of bdrv_ref() yet, only bdrv_new() sets bs->refcnt to 1, so all bdrv_unref() now actually delete the BDS. Signed-off-by: Fam Zheng <famz@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
585 lines
19 KiB
C
585 lines
19 KiB
C
/*
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* Image mirroring
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*
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* Copyright Red Hat, Inc. 2012
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*
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* Authors:
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* Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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#include "trace.h"
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#include "block/blockjob.h"
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#include "block/block_int.h"
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#include "qemu/ratelimit.h"
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#include "qemu/bitmap.h"
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#define SLICE_TIME 100000000ULL /* ns */
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#define MAX_IN_FLIGHT 16
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/* The mirroring buffer is a list of granularity-sized chunks.
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* Free chunks are organized in a list.
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*/
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typedef struct MirrorBuffer {
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QSIMPLEQ_ENTRY(MirrorBuffer) next;
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} MirrorBuffer;
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typedef struct MirrorBlockJob {
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BlockJob common;
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RateLimit limit;
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BlockDriverState *target;
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MirrorSyncMode mode;
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BlockdevOnError on_source_error, on_target_error;
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bool synced;
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bool should_complete;
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int64_t sector_num;
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int64_t granularity;
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size_t buf_size;
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unsigned long *cow_bitmap;
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HBitmapIter hbi;
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uint8_t *buf;
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QSIMPLEQ_HEAD(, MirrorBuffer) buf_free;
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int buf_free_count;
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unsigned long *in_flight_bitmap;
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int in_flight;
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int ret;
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} MirrorBlockJob;
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typedef struct MirrorOp {
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MirrorBlockJob *s;
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QEMUIOVector qiov;
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int64_t sector_num;
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int nb_sectors;
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} MirrorOp;
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static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read,
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int error)
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{
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s->synced = false;
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if (read) {
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return block_job_error_action(&s->common, s->common.bs,
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s->on_source_error, true, error);
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} else {
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return block_job_error_action(&s->common, s->target,
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s->on_target_error, false, error);
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}
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}
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static void mirror_iteration_done(MirrorOp *op, int ret)
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{
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MirrorBlockJob *s = op->s;
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struct iovec *iov;
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int64_t chunk_num;
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int i, nb_chunks, sectors_per_chunk;
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trace_mirror_iteration_done(s, op->sector_num, op->nb_sectors, ret);
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s->in_flight--;
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iov = op->qiov.iov;
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for (i = 0; i < op->qiov.niov; i++) {
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MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base;
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QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next);
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s->buf_free_count++;
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}
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sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS;
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chunk_num = op->sector_num / sectors_per_chunk;
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nb_chunks = op->nb_sectors / sectors_per_chunk;
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bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks);
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if (s->cow_bitmap && ret >= 0) {
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bitmap_set(s->cow_bitmap, chunk_num, nb_chunks);
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}
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g_slice_free(MirrorOp, op);
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qemu_coroutine_enter(s->common.co, NULL);
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}
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static void mirror_write_complete(void *opaque, int ret)
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{
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MirrorOp *op = opaque;
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MirrorBlockJob *s = op->s;
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if (ret < 0) {
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BlockDriverState *source = s->common.bs;
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BlockErrorAction action;
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bdrv_set_dirty(source, op->sector_num, op->nb_sectors);
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action = mirror_error_action(s, false, -ret);
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if (action == BDRV_ACTION_REPORT && s->ret >= 0) {
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s->ret = ret;
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}
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}
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mirror_iteration_done(op, ret);
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}
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static void mirror_read_complete(void *opaque, int ret)
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{
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MirrorOp *op = opaque;
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MirrorBlockJob *s = op->s;
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if (ret < 0) {
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BlockDriverState *source = s->common.bs;
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BlockErrorAction action;
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bdrv_set_dirty(source, op->sector_num, op->nb_sectors);
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action = mirror_error_action(s, true, -ret);
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if (action == BDRV_ACTION_REPORT && s->ret >= 0) {
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s->ret = ret;
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}
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mirror_iteration_done(op, ret);
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return;
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}
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bdrv_aio_writev(s->target, op->sector_num, &op->qiov, op->nb_sectors,
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mirror_write_complete, op);
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}
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static void coroutine_fn mirror_iteration(MirrorBlockJob *s)
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{
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BlockDriverState *source = s->common.bs;
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int nb_sectors, sectors_per_chunk, nb_chunks;
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int64_t end, sector_num, next_chunk, next_sector, hbitmap_next_sector;
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MirrorOp *op;
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s->sector_num = hbitmap_iter_next(&s->hbi);
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if (s->sector_num < 0) {
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bdrv_dirty_iter_init(source, &s->hbi);
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s->sector_num = hbitmap_iter_next(&s->hbi);
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trace_mirror_restart_iter(s, bdrv_get_dirty_count(source));
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assert(s->sector_num >= 0);
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}
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hbitmap_next_sector = s->sector_num;
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sector_num = s->sector_num;
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sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS;
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end = s->common.len >> BDRV_SECTOR_BITS;
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/* Extend the QEMUIOVector to include all adjacent blocks that will
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* be copied in this operation.
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*
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* We have to do this if we have no backing file yet in the destination,
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* and the cluster size is very large. Then we need to do COW ourselves.
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* The first time a cluster is copied, copy it entirely. Note that,
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* because both the granularity and the cluster size are powers of two,
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* the number of sectors to copy cannot exceed one cluster.
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*
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* We also want to extend the QEMUIOVector to include more adjacent
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* dirty blocks if possible, to limit the number of I/O operations and
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* run efficiently even with a small granularity.
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*/
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nb_chunks = 0;
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nb_sectors = 0;
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next_sector = sector_num;
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next_chunk = sector_num / sectors_per_chunk;
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/* Wait for I/O to this cluster (from a previous iteration) to be done. */
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while (test_bit(next_chunk, s->in_flight_bitmap)) {
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trace_mirror_yield_in_flight(s, sector_num, s->in_flight);
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qemu_coroutine_yield();
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}
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do {
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int added_sectors, added_chunks;
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if (!bdrv_get_dirty(source, next_sector) ||
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test_bit(next_chunk, s->in_flight_bitmap)) {
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assert(nb_sectors > 0);
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break;
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}
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added_sectors = sectors_per_chunk;
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if (s->cow_bitmap && !test_bit(next_chunk, s->cow_bitmap)) {
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bdrv_round_to_clusters(s->target,
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next_sector, added_sectors,
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&next_sector, &added_sectors);
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/* On the first iteration, the rounding may make us copy
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* sectors before the first dirty one.
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*/
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if (next_sector < sector_num) {
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assert(nb_sectors == 0);
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sector_num = next_sector;
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next_chunk = next_sector / sectors_per_chunk;
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}
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}
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added_sectors = MIN(added_sectors, end - (sector_num + nb_sectors));
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added_chunks = (added_sectors + sectors_per_chunk - 1) / sectors_per_chunk;
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/* When doing COW, it may happen that there is not enough space for
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* a full cluster. Wait if that is the case.
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*/
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while (nb_chunks == 0 && s->buf_free_count < added_chunks) {
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trace_mirror_yield_buf_busy(s, nb_chunks, s->in_flight);
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qemu_coroutine_yield();
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}
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if (s->buf_free_count < nb_chunks + added_chunks) {
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trace_mirror_break_buf_busy(s, nb_chunks, s->in_flight);
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break;
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}
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/* We have enough free space to copy these sectors. */
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bitmap_set(s->in_flight_bitmap, next_chunk, added_chunks);
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nb_sectors += added_sectors;
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nb_chunks += added_chunks;
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next_sector += added_sectors;
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next_chunk += added_chunks;
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} while (next_sector < end);
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/* Allocate a MirrorOp that is used as an AIO callback. */
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op = g_slice_new(MirrorOp);
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op->s = s;
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op->sector_num = sector_num;
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op->nb_sectors = nb_sectors;
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/* Now make a QEMUIOVector taking enough granularity-sized chunks
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* from s->buf_free.
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*/
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qemu_iovec_init(&op->qiov, nb_chunks);
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next_sector = sector_num;
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while (nb_chunks-- > 0) {
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MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free);
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QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next);
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s->buf_free_count--;
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qemu_iovec_add(&op->qiov, buf, s->granularity);
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/* Advance the HBitmapIter in parallel, so that we do not examine
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* the same sector twice.
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*/
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if (next_sector > hbitmap_next_sector && bdrv_get_dirty(source, next_sector)) {
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hbitmap_next_sector = hbitmap_iter_next(&s->hbi);
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}
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next_sector += sectors_per_chunk;
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}
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bdrv_reset_dirty(source, sector_num, nb_sectors);
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/* Copy the dirty cluster. */
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s->in_flight++;
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trace_mirror_one_iteration(s, sector_num, nb_sectors);
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bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors,
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mirror_read_complete, op);
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}
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static void mirror_free_init(MirrorBlockJob *s)
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{
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int granularity = s->granularity;
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size_t buf_size = s->buf_size;
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uint8_t *buf = s->buf;
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assert(s->buf_free_count == 0);
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QSIMPLEQ_INIT(&s->buf_free);
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while (buf_size != 0) {
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MirrorBuffer *cur = (MirrorBuffer *)buf;
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QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next);
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s->buf_free_count++;
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buf_size -= granularity;
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buf += granularity;
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}
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}
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static void mirror_drain(MirrorBlockJob *s)
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{
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while (s->in_flight > 0) {
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qemu_coroutine_yield();
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}
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}
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static void coroutine_fn mirror_run(void *opaque)
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{
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MirrorBlockJob *s = opaque;
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BlockDriverState *bs = s->common.bs;
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int64_t sector_num, end, sectors_per_chunk, length;
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uint64_t last_pause_ns;
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BlockDriverInfo bdi;
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char backing_filename[1024];
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int ret = 0;
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int n;
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if (block_job_is_cancelled(&s->common)) {
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goto immediate_exit;
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}
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s->common.len = bdrv_getlength(bs);
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if (s->common.len <= 0) {
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block_job_completed(&s->common, s->common.len);
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return;
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}
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length = (bdrv_getlength(bs) + s->granularity - 1) / s->granularity;
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s->in_flight_bitmap = bitmap_new(length);
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/* If we have no backing file yet in the destination, we cannot let
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* the destination do COW. Instead, we copy sectors around the
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* dirty data if needed. We need a bitmap to do that.
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*/
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bdrv_get_backing_filename(s->target, backing_filename,
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sizeof(backing_filename));
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if (backing_filename[0] && !s->target->backing_hd) {
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bdrv_get_info(s->target, &bdi);
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if (s->granularity < bdi.cluster_size) {
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s->buf_size = MAX(s->buf_size, bdi.cluster_size);
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s->cow_bitmap = bitmap_new(length);
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}
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}
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end = s->common.len >> BDRV_SECTOR_BITS;
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s->buf = qemu_blockalign(bs, s->buf_size);
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sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS;
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mirror_free_init(s);
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if (s->mode != MIRROR_SYNC_MODE_NONE) {
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/* First part, loop on the sectors and initialize the dirty bitmap. */
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BlockDriverState *base;
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base = s->mode == MIRROR_SYNC_MODE_FULL ? NULL : bs->backing_hd;
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for (sector_num = 0; sector_num < end; ) {
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int64_t next = (sector_num | (sectors_per_chunk - 1)) + 1;
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ret = bdrv_co_is_allocated_above(bs, base,
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sector_num, next - sector_num, &n);
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if (ret < 0) {
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goto immediate_exit;
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}
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assert(n > 0);
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if (ret == 1) {
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bdrv_set_dirty(bs, sector_num, n);
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sector_num = next;
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} else {
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sector_num += n;
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}
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}
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}
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bdrv_dirty_iter_init(bs, &s->hbi);
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last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
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for (;;) {
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uint64_t delay_ns;
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int64_t cnt;
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bool should_complete;
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if (s->ret < 0) {
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ret = s->ret;
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goto immediate_exit;
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}
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cnt = bdrv_get_dirty_count(bs);
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/* Note that even when no rate limit is applied we need to yield
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* periodically with no pending I/O so that qemu_aio_flush() returns.
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* We do so every SLICE_TIME nanoseconds, or when there is an error,
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* or when the source is clean, whichever comes first.
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*/
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if (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - last_pause_ns < SLICE_TIME &&
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s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
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if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 ||
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(cnt == 0 && s->in_flight > 0)) {
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trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt);
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qemu_coroutine_yield();
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continue;
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} else if (cnt != 0) {
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mirror_iteration(s);
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continue;
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}
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}
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should_complete = false;
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if (s->in_flight == 0 && cnt == 0) {
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trace_mirror_before_flush(s);
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ret = bdrv_flush(s->target);
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if (ret < 0) {
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if (mirror_error_action(s, false, -ret) == BDRV_ACTION_REPORT) {
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goto immediate_exit;
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}
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} else {
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/* We're out of the streaming phase. From now on, if the job
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* is cancelled we will actually complete all pending I/O and
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* report completion. This way, block-job-cancel will leave
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* the target in a consistent state.
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*/
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s->common.offset = end * BDRV_SECTOR_SIZE;
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if (!s->synced) {
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block_job_ready(&s->common);
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s->synced = true;
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}
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should_complete = s->should_complete ||
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block_job_is_cancelled(&s->common);
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cnt = bdrv_get_dirty_count(bs);
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}
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}
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if (cnt == 0 && should_complete) {
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/* The dirty bitmap is not updated while operations are pending.
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* If we're about to exit, wait for pending operations before
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* calling bdrv_get_dirty_count(bs), or we may exit while the
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* source has dirty data to copy!
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*
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* Note that I/O can be submitted by the guest while
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* mirror_populate runs.
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*/
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trace_mirror_before_drain(s, cnt);
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bdrv_drain_all();
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cnt = bdrv_get_dirty_count(bs);
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}
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ret = 0;
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trace_mirror_before_sleep(s, cnt, s->synced);
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if (!s->synced) {
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/* Publish progress */
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s->common.offset = (end - cnt) * BDRV_SECTOR_SIZE;
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if (s->common.speed) {
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delay_ns = ratelimit_calculate_delay(&s->limit, sectors_per_chunk);
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} else {
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delay_ns = 0;
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}
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block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
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if (block_job_is_cancelled(&s->common)) {
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break;
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}
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} else if (!should_complete) {
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delay_ns = (s->in_flight == 0 && cnt == 0 ? SLICE_TIME : 0);
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block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
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} else if (cnt == 0) {
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/* The two disks are in sync. Exit and report successful
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* completion.
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*/
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assert(QLIST_EMPTY(&bs->tracked_requests));
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s->common.cancelled = false;
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break;
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}
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last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
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}
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immediate_exit:
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if (s->in_flight > 0) {
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/* We get here only if something went wrong. Either the job failed,
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* or it was cancelled prematurely so that we do not guarantee that
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* the target is a copy of the source.
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*/
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assert(ret < 0 || (!s->synced && block_job_is_cancelled(&s->common)));
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mirror_drain(s);
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}
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assert(s->in_flight == 0);
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qemu_vfree(s->buf);
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g_free(s->cow_bitmap);
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g_free(s->in_flight_bitmap);
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bdrv_set_dirty_tracking(bs, 0);
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bdrv_iostatus_disable(s->target);
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if (s->should_complete && ret == 0) {
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if (bdrv_get_flags(s->target) != bdrv_get_flags(s->common.bs)) {
|
|
bdrv_reopen(s->target, bdrv_get_flags(s->common.bs), NULL);
|
|
}
|
|
bdrv_swap(s->target, s->common.bs);
|
|
}
|
|
bdrv_close(s->target);
|
|
bdrv_unref(s->target);
|
|
block_job_completed(&s->common, ret);
|
|
}
|
|
|
|
static void mirror_set_speed(BlockJob *job, int64_t speed, Error **errp)
|
|
{
|
|
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
|
|
|
|
if (speed < 0) {
|
|
error_set(errp, QERR_INVALID_PARAMETER, "speed");
|
|
return;
|
|
}
|
|
ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
|
|
}
|
|
|
|
static void mirror_iostatus_reset(BlockJob *job)
|
|
{
|
|
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
|
|
|
|
bdrv_iostatus_reset(s->target);
|
|
}
|
|
|
|
static void mirror_complete(BlockJob *job, Error **errp)
|
|
{
|
|
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
|
|
int ret;
|
|
|
|
ret = bdrv_open_backing_file(s->target, NULL);
|
|
if (ret < 0) {
|
|
char backing_filename[PATH_MAX];
|
|
bdrv_get_full_backing_filename(s->target, backing_filename,
|
|
sizeof(backing_filename));
|
|
error_setg_file_open(errp, -ret, backing_filename);
|
|
return;
|
|
}
|
|
if (!s->synced) {
|
|
error_set(errp, QERR_BLOCK_JOB_NOT_READY, job->bs->device_name);
|
|
return;
|
|
}
|
|
|
|
s->should_complete = true;
|
|
block_job_resume(job);
|
|
}
|
|
|
|
static const BlockJobType mirror_job_type = {
|
|
.instance_size = sizeof(MirrorBlockJob),
|
|
.job_type = "mirror",
|
|
.set_speed = mirror_set_speed,
|
|
.iostatus_reset= mirror_iostatus_reset,
|
|
.complete = mirror_complete,
|
|
};
|
|
|
|
void mirror_start(BlockDriverState *bs, BlockDriverState *target,
|
|
int64_t speed, int64_t granularity, int64_t buf_size,
|
|
MirrorSyncMode mode, BlockdevOnError on_source_error,
|
|
BlockdevOnError on_target_error,
|
|
BlockDriverCompletionFunc *cb,
|
|
void *opaque, Error **errp)
|
|
{
|
|
MirrorBlockJob *s;
|
|
|
|
if (granularity == 0) {
|
|
/* Choose the default granularity based on the target file's cluster
|
|
* size, clamped between 4k and 64k. */
|
|
BlockDriverInfo bdi;
|
|
if (bdrv_get_info(target, &bdi) >= 0 && bdi.cluster_size != 0) {
|
|
granularity = MAX(4096, bdi.cluster_size);
|
|
granularity = MIN(65536, granularity);
|
|
} else {
|
|
granularity = 65536;
|
|
}
|
|
}
|
|
|
|
assert ((granularity & (granularity - 1)) == 0);
|
|
|
|
if ((on_source_error == BLOCKDEV_ON_ERROR_STOP ||
|
|
on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
|
|
!bdrv_iostatus_is_enabled(bs)) {
|
|
error_set(errp, QERR_INVALID_PARAMETER, "on-source-error");
|
|
return;
|
|
}
|
|
|
|
s = block_job_create(&mirror_job_type, bs, speed, cb, opaque, errp);
|
|
if (!s) {
|
|
return;
|
|
}
|
|
|
|
s->on_source_error = on_source_error;
|
|
s->on_target_error = on_target_error;
|
|
s->target = target;
|
|
s->mode = mode;
|
|
s->granularity = granularity;
|
|
s->buf_size = MAX(buf_size, granularity);
|
|
|
|
bdrv_set_dirty_tracking(bs, granularity);
|
|
bdrv_set_enable_write_cache(s->target, true);
|
|
bdrv_set_on_error(s->target, on_target_error, on_target_error);
|
|
bdrv_iostatus_enable(s->target);
|
|
s->common.co = qemu_coroutine_create(mirror_run);
|
|
trace_mirror_start(bs, s, s->common.co, opaque);
|
|
qemu_coroutine_enter(s->common.co, s);
|
|
}
|