/* * Image mirroring * * Copyright Red Hat, Inc. 2012 * * Authors: * Paolo Bonzini <pbonzini@redhat.com> * * This work is licensed under the terms of the GNU LGPL, version 2 or later. * See the COPYING.LIB file in the top-level directory. * */ #include "qemu/osdep.h" #include "qemu/cutils.h" #include "trace.h" #include "block/blockjob_int.h" #include "block/block_int.h" #include "sysemu/block-backend.h" #include "qapi/error.h" #include "qapi/qmp/qerror.h" #include "qemu/ratelimit.h" #include "qemu/bitmap.h" #define SLICE_TIME 100000000ULL /* ns */ #define MAX_IN_FLIGHT 16 #define MAX_IO_BYTES (1 << 20) /* 1 Mb */ #define DEFAULT_MIRROR_BUF_SIZE (MAX_IN_FLIGHT * MAX_IO_BYTES) /* The mirroring buffer is a list of granularity-sized chunks. * Free chunks are organized in a list. */ typedef struct MirrorBuffer { QSIMPLEQ_ENTRY(MirrorBuffer) next; } MirrorBuffer; typedef struct MirrorBlockJob { BlockJob common; RateLimit limit; BlockBackend *target; BlockDriverState *mirror_top_bs; BlockDriverState *source; BlockDriverState *base; /* The name of the graph node to replace */ char *replaces; /* The BDS to replace */ BlockDriverState *to_replace; /* Used to block operations on the drive-mirror-replace target */ Error *replace_blocker; bool is_none_mode; BlockMirrorBackingMode backing_mode; BlockdevOnError on_source_error, on_target_error; bool synced; bool should_complete; int64_t granularity; size_t buf_size; int64_t bdev_length; unsigned long *cow_bitmap; BdrvDirtyBitmap *dirty_bitmap; BdrvDirtyBitmapIter *dbi; uint8_t *buf; QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; int buf_free_count; uint64_t last_pause_ns; unsigned long *in_flight_bitmap; int in_flight; int64_t bytes_in_flight; int ret; bool unmap; bool waiting_for_io; int target_cluster_size; int max_iov; bool initial_zeroing_ongoing; } MirrorBlockJob; typedef struct MirrorOp { MirrorBlockJob *s; QEMUIOVector qiov; int64_t offset; uint64_t bytes; } MirrorOp; static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, int error) { s->synced = false; if (read) { return block_job_error_action(&s->common, s->on_source_error, true, error); } else { return block_job_error_action(&s->common, s->on_target_error, false, error); } } static void mirror_iteration_done(MirrorOp *op, int ret) { MirrorBlockJob *s = op->s; struct iovec *iov; int64_t chunk_num; int i, nb_chunks; trace_mirror_iteration_done(s, op->offset, op->bytes, ret); s->in_flight--; s->bytes_in_flight -= op->bytes; iov = op->qiov.iov; for (i = 0; i < op->qiov.niov; i++) { MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); s->buf_free_count++; } chunk_num = op->offset / s->granularity; nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); if (ret >= 0) { if (s->cow_bitmap) { bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); } if (!s->initial_zeroing_ongoing) { s->common.offset += op->bytes; } } qemu_iovec_destroy(&op->qiov); g_free(op); if (s->waiting_for_io) { qemu_coroutine_enter(s->common.co); } } static void mirror_write_complete(void *opaque, int ret) { MirrorOp *op = opaque; MirrorBlockJob *s = op->s; aio_context_acquire(blk_get_aio_context(s->common.blk)); if (ret < 0) { BlockErrorAction action; bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset >> BDRV_SECTOR_BITS, op->bytes >> BDRV_SECTOR_BITS); action = mirror_error_action(s, false, -ret); if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { s->ret = ret; } } mirror_iteration_done(op, ret); aio_context_release(blk_get_aio_context(s->common.blk)); } static void mirror_read_complete(void *opaque, int ret) { MirrorOp *op = opaque; MirrorBlockJob *s = op->s; aio_context_acquire(blk_get_aio_context(s->common.blk)); if (ret < 0) { BlockErrorAction action; bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset >> BDRV_SECTOR_BITS, op->bytes >> BDRV_SECTOR_BITS); action = mirror_error_action(s, true, -ret); if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { s->ret = ret; } mirror_iteration_done(op, ret); } else { blk_aio_pwritev(s->target, op->offset, &op->qiov, 0, mirror_write_complete, op); } aio_context_release(blk_get_aio_context(s->common.blk)); } /* Clip bytes relative to offset to not exceed end-of-file */ static inline int64_t mirror_clip_bytes(MirrorBlockJob *s, int64_t offset, int64_t bytes) { return MIN(bytes, s->bdev_length - offset); } /* Round offset and/or bytes to target cluster if COW is needed, and * return the offset of the adjusted tail against original. */ static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, uint64_t *bytes) { bool need_cow; int ret = 0; int64_t align_offset = *offset; unsigned int align_bytes = *bytes; int max_bytes = s->granularity * s->max_iov; assert(*bytes < INT_MAX); need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap); need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, s->cow_bitmap); if (need_cow) { bdrv_round_to_clusters(blk_bs(s->target), *offset, *bytes, &align_offset, &align_bytes); } if (align_bytes > max_bytes) { align_bytes = max_bytes; if (need_cow) { align_bytes = QEMU_ALIGN_DOWN(align_bytes, s->target_cluster_size); } } /* Clipping may result in align_bytes unaligned to chunk boundary, but * that doesn't matter because it's already the end of source image. */ align_bytes = mirror_clip_bytes(s, align_offset, align_bytes); ret = align_offset + align_bytes - (*offset + *bytes); *offset = align_offset; *bytes = align_bytes; assert(ret >= 0); return ret; } static inline void mirror_wait_for_io(MirrorBlockJob *s) { assert(!s->waiting_for_io); s->waiting_for_io = true; qemu_coroutine_yield(); s->waiting_for_io = false; } /* Submit async read while handling COW. * Returns: The number of bytes copied after and including offset, * excluding any bytes copied prior to offset due to alignment. * This will be @bytes if no alignment is necessary, or * (new_end - offset) if tail is rounded up or down due to * alignment or buffer limit. */ static uint64_t mirror_do_read(MirrorBlockJob *s, int64_t offset, uint64_t bytes) { BlockBackend *source = s->common.blk; int nb_chunks; uint64_t ret; MirrorOp *op; uint64_t max_bytes; max_bytes = s->granularity * s->max_iov; /* We can only handle as much as buf_size at a time. */ bytes = MIN(s->buf_size, MIN(max_bytes, bytes)); assert(bytes); assert(bytes < BDRV_REQUEST_MAX_BYTES); ret = bytes; if (s->cow_bitmap) { ret += mirror_cow_align(s, &offset, &bytes); } assert(bytes <= s->buf_size); /* The offset is granularity-aligned because: * 1) Caller passes in aligned values; * 2) mirror_cow_align is used only when target cluster is larger. */ assert(QEMU_IS_ALIGNED(offset, s->granularity)); /* The range is sector-aligned, since bdrv_getlength() rounds up. */ assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE)); nb_chunks = DIV_ROUND_UP(bytes, s->granularity); while (s->buf_free_count < nb_chunks) { trace_mirror_yield_in_flight(s, offset, s->in_flight); mirror_wait_for_io(s); } /* Allocate a MirrorOp that is used as an AIO callback. */ op = g_new(MirrorOp, 1); op->s = s; op->offset = offset; op->bytes = bytes; /* Now make a QEMUIOVector taking enough granularity-sized chunks * from s->buf_free. */ qemu_iovec_init(&op->qiov, nb_chunks); while (nb_chunks-- > 0) { MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); size_t remaining = bytes - op->qiov.size; QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); s->buf_free_count--; qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining)); } /* Copy the dirty cluster. */ s->in_flight++; s->bytes_in_flight += bytes; trace_mirror_one_iteration(s, offset, bytes); blk_aio_preadv(source, offset, &op->qiov, 0, mirror_read_complete, op); return ret; } static void mirror_do_zero_or_discard(MirrorBlockJob *s, int64_t offset, uint64_t bytes, bool is_discard) { MirrorOp *op; /* Allocate a MirrorOp that is used as an AIO callback. The qiov is zeroed * so the freeing in mirror_iteration_done is nop. */ op = g_new0(MirrorOp, 1); op->s = s; op->offset = offset; op->bytes = bytes; s->in_flight++; s->bytes_in_flight += bytes; if (is_discard) { blk_aio_pdiscard(s->target, offset, op->bytes, mirror_write_complete, op); } else { blk_aio_pwrite_zeroes(s->target, offset, op->bytes, s->unmap ? BDRV_REQ_MAY_UNMAP : 0, mirror_write_complete, op); } } static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) { BlockDriverState *source = s->source; int64_t offset, first_chunk; uint64_t delay_ns = 0; /* At least the first dirty chunk is mirrored in one iteration. */ int nb_chunks = 1; int sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); int max_io_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES); bdrv_dirty_bitmap_lock(s->dirty_bitmap); offset = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE; if (offset < 0) { bdrv_set_dirty_iter(s->dbi, 0); offset = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE; trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap) * BDRV_SECTOR_SIZE); assert(offset >= 0); } bdrv_dirty_bitmap_unlock(s->dirty_bitmap); first_chunk = offset / s->granularity; while (test_bit(first_chunk, s->in_flight_bitmap)) { trace_mirror_yield_in_flight(s, offset, s->in_flight); mirror_wait_for_io(s); } block_job_pause_point(&s->common); /* Find the number of consective dirty chunks following the first dirty * one, and wait for in flight requests in them. */ bdrv_dirty_bitmap_lock(s->dirty_bitmap); while (nb_chunks * s->granularity < s->buf_size) { int64_t next_dirty; int64_t next_offset = offset + nb_chunks * s->granularity; int64_t next_chunk = next_offset / s->granularity; if (next_offset >= s->bdev_length || !bdrv_get_dirty_locked(source, s->dirty_bitmap, next_offset >> BDRV_SECTOR_BITS)) { break; } if (test_bit(next_chunk, s->in_flight_bitmap)) { break; } next_dirty = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE; if (next_dirty > next_offset || next_dirty < 0) { /* The bitmap iterator's cache is stale, refresh it */ bdrv_set_dirty_iter(s->dbi, next_offset >> BDRV_SECTOR_BITS); next_dirty = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE; } assert(next_dirty == next_offset); nb_chunks++; } /* Clear dirty bits before querying the block status, because * calling bdrv_get_block_status_above could yield - if some blocks are * marked dirty in this window, we need to know. */ bdrv_reset_dirty_bitmap_locked(s->dirty_bitmap, offset >> BDRV_SECTOR_BITS, nb_chunks * sectors_per_chunk); bdrv_dirty_bitmap_unlock(s->dirty_bitmap); bitmap_set(s->in_flight_bitmap, offset / s->granularity, nb_chunks); while (nb_chunks > 0 && offset < s->bdev_length) { int64_t ret; int io_sectors; unsigned int io_bytes; int64_t io_bytes_acct; BlockDriverState *file; enum MirrorMethod { MIRROR_METHOD_COPY, MIRROR_METHOD_ZERO, MIRROR_METHOD_DISCARD } mirror_method = MIRROR_METHOD_COPY; assert(!(offset % s->granularity)); ret = bdrv_get_block_status_above(source, NULL, offset >> BDRV_SECTOR_BITS, nb_chunks * sectors_per_chunk, &io_sectors, &file); io_bytes = io_sectors * BDRV_SECTOR_SIZE; if (ret < 0) { io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); } else if (ret & BDRV_BLOCK_DATA) { io_bytes = MIN(io_bytes, max_io_bytes); } io_bytes -= io_bytes % s->granularity; if (io_bytes < s->granularity) { io_bytes = s->granularity; } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { int64_t target_offset; unsigned int target_bytes; bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes, &target_offset, &target_bytes); if (target_offset == offset && target_bytes == io_bytes) { mirror_method = ret & BDRV_BLOCK_ZERO ? MIRROR_METHOD_ZERO : MIRROR_METHOD_DISCARD; } } while (s->in_flight >= MAX_IN_FLIGHT) { trace_mirror_yield_in_flight(s, offset, s->in_flight); mirror_wait_for_io(s); } if (s->ret < 0) { return 0; } io_bytes = mirror_clip_bytes(s, offset, io_bytes); switch (mirror_method) { case MIRROR_METHOD_COPY: io_bytes = io_bytes_acct = mirror_do_read(s, offset, io_bytes); break; case MIRROR_METHOD_ZERO: case MIRROR_METHOD_DISCARD: mirror_do_zero_or_discard(s, offset, io_bytes, mirror_method == MIRROR_METHOD_DISCARD); if (write_zeroes_ok) { io_bytes_acct = 0; } else { io_bytes_acct = io_bytes; } break; default: abort(); } assert(io_bytes); offset += io_bytes; nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity); if (s->common.speed) { delay_ns = ratelimit_calculate_delay(&s->limit, io_bytes_acct); } } return delay_ns; } static void mirror_free_init(MirrorBlockJob *s) { int granularity = s->granularity; size_t buf_size = s->buf_size; uint8_t *buf = s->buf; assert(s->buf_free_count == 0); QSIMPLEQ_INIT(&s->buf_free); while (buf_size != 0) { MirrorBuffer *cur = (MirrorBuffer *)buf; QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); s->buf_free_count++; buf_size -= granularity; buf += granularity; } } /* This is also used for the .pause callback. There is no matching * mirror_resume() because mirror_run() will begin iterating again * when the job is resumed. */ static void mirror_wait_for_all_io(MirrorBlockJob *s) { while (s->in_flight > 0) { mirror_wait_for_io(s); } } typedef struct { int ret; } MirrorExitData; static void mirror_exit(BlockJob *job, void *opaque) { MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); MirrorExitData *data = opaque; AioContext *replace_aio_context = NULL; BlockDriverState *src = s->source; BlockDriverState *target_bs = blk_bs(s->target); BlockDriverState *mirror_top_bs = s->mirror_top_bs; Error *local_err = NULL; bdrv_release_dirty_bitmap(src, s->dirty_bitmap); /* Make sure that the source BDS doesn't go away before we called * block_job_completed(). */ bdrv_ref(src); bdrv_ref(mirror_top_bs); bdrv_ref(target_bs); /* Remove target parent that still uses BLK_PERM_WRITE/RESIZE before * inserting target_bs at s->to_replace, where we might not be able to get * these permissions. * * Note that blk_unref() alone doesn't necessarily drop permissions because * we might be running nested inside mirror_drain(), which takes an extra * reference, so use an explicit blk_set_perm() first. */ blk_set_perm(s->target, 0, BLK_PERM_ALL, &error_abort); blk_unref(s->target); s->target = NULL; /* We don't access the source any more. Dropping any WRITE/RESIZE is * required before it could become a backing file of target_bs. */ bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL, &error_abort); if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { BlockDriverState *backing = s->is_none_mode ? src : s->base; if (backing_bs(target_bs) != backing) { bdrv_set_backing_hd(target_bs, backing, &local_err); if (local_err) { error_report_err(local_err); data->ret = -EPERM; } } } if (s->to_replace) { replace_aio_context = bdrv_get_aio_context(s->to_replace); aio_context_acquire(replace_aio_context); } if (s->should_complete && data->ret == 0) { BlockDriverState *to_replace = src; if (s->to_replace) { to_replace = s->to_replace; } if (bdrv_get_flags(target_bs) != bdrv_get_flags(to_replace)) { bdrv_reopen(target_bs, bdrv_get_flags(to_replace), NULL); } /* The mirror job has no requests in flight any more, but we need to * drain potential other users of the BDS before changing the graph. */ bdrv_drained_begin(target_bs); bdrv_replace_node(to_replace, target_bs, &local_err); bdrv_drained_end(target_bs); if (local_err) { error_report_err(local_err); data->ret = -EPERM; } } if (s->to_replace) { bdrv_op_unblock_all(s->to_replace, s->replace_blocker); error_free(s->replace_blocker); bdrv_unref(s->to_replace); } if (replace_aio_context) { aio_context_release(replace_aio_context); } g_free(s->replaces); bdrv_unref(target_bs); /* Remove the mirror filter driver from the graph. Before this, get rid of * the blockers on the intermediate nodes so that the resulting state is * valid. Also give up permissions on mirror_top_bs->backing, which might * block the removal. */ block_job_remove_all_bdrv(job); bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL, &error_abort); bdrv_replace_node(mirror_top_bs, backing_bs(mirror_top_bs), &error_abort); /* We just changed the BDS the job BB refers to (with either or both of the * bdrv_replace_node() calls), so switch the BB back so the cleanup does * the right thing. We don't need any permissions any more now. */ blk_remove_bs(job->blk); blk_set_perm(job->blk, 0, BLK_PERM_ALL, &error_abort); blk_insert_bs(job->blk, mirror_top_bs, &error_abort); block_job_completed(&s->common, data->ret); g_free(data); bdrv_drained_end(src); bdrv_unref(mirror_top_bs); bdrv_unref(src); } static void mirror_throttle(MirrorBlockJob *s) { int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); if (now - s->last_pause_ns > SLICE_TIME) { s->last_pause_ns = now; block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 0); } else { block_job_pause_point(&s->common); } } static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) { int64_t sector_num, end; BlockDriverState *base = s->base; BlockDriverState *bs = s->source; BlockDriverState *target_bs = blk_bs(s->target); int ret, n; int64_t count; end = s->bdev_length / BDRV_SECTOR_SIZE; if (base == NULL && !bdrv_has_zero_init(target_bs)) { if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end); return 0; } s->initial_zeroing_ongoing = true; for (sector_num = 0; sector_num < end; ) { int nb_sectors = MIN(end - sector_num, QEMU_ALIGN_DOWN(INT_MAX, s->granularity) >> BDRV_SECTOR_BITS); mirror_throttle(s); if (block_job_is_cancelled(&s->common)) { s->initial_zeroing_ongoing = false; return 0; } if (s->in_flight >= MAX_IN_FLIGHT) { trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, s->in_flight); mirror_wait_for_io(s); continue; } mirror_do_zero_or_discard(s, sector_num * BDRV_SECTOR_SIZE, nb_sectors * BDRV_SECTOR_SIZE, false); sector_num += nb_sectors; } mirror_wait_for_all_io(s); s->initial_zeroing_ongoing = false; } /* First part, loop on the sectors and initialize the dirty bitmap. */ for (sector_num = 0; sector_num < end; ) { /* Just to make sure we are not exceeding int limit. */ int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS, end - sector_num); mirror_throttle(s); if (block_job_is_cancelled(&s->common)) { return 0; } ret = bdrv_is_allocated_above(bs, base, sector_num * BDRV_SECTOR_SIZE, nb_sectors * BDRV_SECTOR_SIZE, &count); if (ret < 0) { return ret; } /* TODO: Relax this once bdrv_is_allocated_above and dirty * bitmaps no longer require sector alignment. */ assert(QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE)); n = count >> BDRV_SECTOR_BITS; assert(n > 0); if (ret == 1) { bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n); } sector_num += n; } return 0; } /* Called when going out of the streaming phase to flush the bulk of the * data to the medium, or just before completing. */ static int mirror_flush(MirrorBlockJob *s) { int ret = blk_flush(s->target); if (ret < 0) { if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { s->ret = ret; } } return ret; } static void coroutine_fn mirror_run(void *opaque) { MirrorBlockJob *s = opaque; MirrorExitData *data; BlockDriverState *bs = s->source; BlockDriverState *target_bs = blk_bs(s->target); bool need_drain = true; int64_t length; BlockDriverInfo bdi; char backing_filename[2]; /* we only need 2 characters because we are only checking for a NULL string */ int ret = 0; if (block_job_is_cancelled(&s->common)) { goto immediate_exit; } s->bdev_length = bdrv_getlength(bs); if (s->bdev_length < 0) { ret = s->bdev_length; goto immediate_exit; } /* Active commit must resize the base image if its size differs from the * active layer. */ if (s->base == blk_bs(s->target)) { int64_t base_length; base_length = blk_getlength(s->target); if (base_length < 0) { ret = base_length; goto immediate_exit; } if (s->bdev_length > base_length) { ret = blk_truncate(s->target, s->bdev_length, PREALLOC_MODE_OFF, NULL); if (ret < 0) { goto immediate_exit; } } } if (s->bdev_length == 0) { /* Report BLOCK_JOB_READY and wait for complete. */ block_job_event_ready(&s->common); s->synced = true; while (!block_job_is_cancelled(&s->common) && !s->should_complete) { block_job_yield(&s->common); } s->common.cancelled = false; goto immediate_exit; } length = DIV_ROUND_UP(s->bdev_length, s->granularity); s->in_flight_bitmap = bitmap_new(length); /* If we have no backing file yet in the destination, we cannot let * the destination do COW. Instead, we copy sectors around the * dirty data if needed. We need a bitmap to do that. */ bdrv_get_backing_filename(target_bs, backing_filename, sizeof(backing_filename)); if (!bdrv_get_info(target_bs, &bdi) && bdi.cluster_size) { s->target_cluster_size = bdi.cluster_size; } else { s->target_cluster_size = BDRV_SECTOR_SIZE; } if (backing_filename[0] && !target_bs->backing && s->granularity < s->target_cluster_size) { s->buf_size = MAX(s->buf_size, s->target_cluster_size); s->cow_bitmap = bitmap_new(length); } s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); s->buf = qemu_try_blockalign(bs, s->buf_size); if (s->buf == NULL) { ret = -ENOMEM; goto immediate_exit; } mirror_free_init(s); s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); if (!s->is_none_mode) { ret = mirror_dirty_init(s); if (ret < 0 || block_job_is_cancelled(&s->common)) { goto immediate_exit; } } assert(!s->dbi); s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap, 0); for (;;) { uint64_t delay_ns = 0; int64_t cnt, delta; bool should_complete; if (s->ret < 0) { ret = s->ret; goto immediate_exit; } block_job_pause_point(&s->common); cnt = bdrv_get_dirty_count(s->dirty_bitmap); /* s->common.offset contains the number of bytes already processed so * far, cnt is the number of dirty sectors remaining and * s->bytes_in_flight is the number of bytes currently being * processed; together those are the current total operation length */ s->common.len = s->common.offset + s->bytes_in_flight + cnt * BDRV_SECTOR_SIZE; /* Note that even when no rate limit is applied we need to yield * periodically with no pending I/O so that bdrv_drain_all() returns. * We do so every SLICE_TIME nanoseconds, or when there is an error, * or when the source is clean, whichever comes first. */ delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; if (delta < SLICE_TIME && s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || (cnt == 0 && s->in_flight > 0)) { trace_mirror_yield(s, cnt * BDRV_SECTOR_SIZE, s->buf_free_count, s->in_flight); mirror_wait_for_io(s); continue; } else if (cnt != 0) { delay_ns = mirror_iteration(s); } } should_complete = false; if (s->in_flight == 0 && cnt == 0) { trace_mirror_before_flush(s); if (!s->synced) { if (mirror_flush(s) < 0) { /* Go check s->ret. */ continue; } /* We're out of the streaming phase. From now on, if the job * is cancelled we will actually complete all pending I/O and * report completion. This way, block-job-cancel will leave * the target in a consistent state. */ block_job_event_ready(&s->common); s->synced = true; } should_complete = s->should_complete || block_job_is_cancelled(&s->common); cnt = bdrv_get_dirty_count(s->dirty_bitmap); } if (cnt == 0 && should_complete) { /* The dirty bitmap is not updated while operations are pending. * If we're about to exit, wait for pending operations before * calling bdrv_get_dirty_count(bs), or we may exit while the * source has dirty data to copy! * * Note that I/O can be submitted by the guest while * mirror_populate runs, so pause it now. Before deciding * whether to switch to target check one last time if I/O has * come in the meanwhile, and if not flush the data to disk. */ trace_mirror_before_drain(s, cnt * BDRV_SECTOR_SIZE); bdrv_drained_begin(bs); cnt = bdrv_get_dirty_count(s->dirty_bitmap); if (cnt > 0 || mirror_flush(s) < 0) { bdrv_drained_end(bs); continue; } /* The two disks are in sync. Exit and report successful * completion. */ assert(QLIST_EMPTY(&bs->tracked_requests)); s->common.cancelled = false; need_drain = false; break; } ret = 0; trace_mirror_before_sleep(s, cnt * BDRV_SECTOR_SIZE, s->synced, delay_ns); if (!s->synced) { block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); if (block_job_is_cancelled(&s->common)) { break; } } else if (!should_complete) { delay_ns = (s->in_flight == 0 && cnt == 0 ? SLICE_TIME : 0); block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); } s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); } immediate_exit: if (s->in_flight > 0) { /* We get here only if something went wrong. Either the job failed, * or it was cancelled prematurely so that we do not guarantee that * the target is a copy of the source. */ assert(ret < 0 || (!s->synced && block_job_is_cancelled(&s->common))); assert(need_drain); mirror_wait_for_all_io(s); } assert(s->in_flight == 0); qemu_vfree(s->buf); g_free(s->cow_bitmap); g_free(s->in_flight_bitmap); bdrv_dirty_iter_free(s->dbi); data = g_malloc(sizeof(*data)); data->ret = ret; if (need_drain) { bdrv_drained_begin(bs); } block_job_defer_to_main_loop(&s->common, mirror_exit, data); } static void mirror_set_speed(BlockJob *job, int64_t speed, Error **errp) { MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); if (speed < 0) { error_setg(errp, QERR_INVALID_PARAMETER, "speed"); return; } ratelimit_set_speed(&s->limit, speed, SLICE_TIME); } static void mirror_complete(BlockJob *job, Error **errp) { MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); BlockDriverState *target; target = blk_bs(s->target); if (!s->synced) { error_setg(errp, "The active block job '%s' cannot be completed", job->id); return; } if (s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { int ret; assert(!target->backing); ret = bdrv_open_backing_file(target, NULL, "backing", errp); if (ret < 0) { return; } } /* block all operations on to_replace bs */ if (s->replaces) { AioContext *replace_aio_context; s->to_replace = bdrv_find_node(s->replaces); if (!s->to_replace) { error_setg(errp, "Node name '%s' not found", s->replaces); return; } replace_aio_context = bdrv_get_aio_context(s->to_replace); aio_context_acquire(replace_aio_context); /* TODO Translate this into permission system. Current definition of * GRAPH_MOD would require to request it for the parents; they might * not even be BlockDriverStates, however, so a BdrvChild can't address * them. May need redefinition of GRAPH_MOD. */ error_setg(&s->replace_blocker, "block device is in use by block-job-complete"); bdrv_op_block_all(s->to_replace, s->replace_blocker); bdrv_ref(s->to_replace); aio_context_release(replace_aio_context); } s->should_complete = true; block_job_enter(&s->common); } static void mirror_pause(BlockJob *job) { MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); mirror_wait_for_all_io(s); } static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context) { MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); blk_set_aio_context(s->target, new_context); } static void mirror_drain(BlockJob *job) { MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); /* Need to keep a reference in case blk_drain triggers execution * of mirror_complete... */ if (s->target) { BlockBackend *target = s->target; blk_ref(target); blk_drain(target); blk_unref(target); } } static const BlockJobDriver mirror_job_driver = { .instance_size = sizeof(MirrorBlockJob), .job_type = BLOCK_JOB_TYPE_MIRROR, .set_speed = mirror_set_speed, .start = mirror_run, .complete = mirror_complete, .pause = mirror_pause, .attached_aio_context = mirror_attached_aio_context, .drain = mirror_drain, }; static const BlockJobDriver commit_active_job_driver = { .instance_size = sizeof(MirrorBlockJob), .job_type = BLOCK_JOB_TYPE_COMMIT, .set_speed = mirror_set_speed, .start = mirror_run, .complete = mirror_complete, .pause = mirror_pause, .attached_aio_context = mirror_attached_aio_context, .drain = mirror_drain, }; static int coroutine_fn bdrv_mirror_top_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) { return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); } static int coroutine_fn bdrv_mirror_top_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) { return bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); } static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs) { return bdrv_co_flush(bs->backing->bs); } static int coroutine_fn bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int bytes, BdrvRequestFlags flags) { return bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); } static int coroutine_fn bdrv_mirror_top_pdiscard(BlockDriverState *bs, int64_t offset, int bytes) { return bdrv_co_pdiscard(bs->backing->bs, offset, bytes); } static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs, QDict *opts) { bdrv_refresh_filename(bs->backing->bs); pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->backing->bs->filename); } static void bdrv_mirror_top_close(BlockDriverState *bs) { } static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, const BdrvChildRole *role, uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared) { /* Must be able to forward guest writes to the real image */ *nperm = 0; if (perm & BLK_PERM_WRITE) { *nperm |= BLK_PERM_WRITE; } *nshared = BLK_PERM_ALL; } /* Dummy node that provides consistent read to its users without requiring it * from its backing file and that allows writes on the backing file chain. */ static BlockDriver bdrv_mirror_top = { .format_name = "mirror_top", .bdrv_co_preadv = bdrv_mirror_top_preadv, .bdrv_co_pwritev = bdrv_mirror_top_pwritev, .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, .bdrv_co_flush = bdrv_mirror_top_flush, .bdrv_co_get_block_status = bdrv_co_get_block_status_from_backing, .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, .bdrv_close = bdrv_mirror_top_close, .bdrv_child_perm = bdrv_mirror_top_child_perm, }; static void mirror_start_job(const char *job_id, BlockDriverState *bs, int creation_flags, BlockDriverState *target, const char *replaces, int64_t speed, uint32_t granularity, int64_t buf_size, BlockMirrorBackingMode backing_mode, BlockdevOnError on_source_error, BlockdevOnError on_target_error, bool unmap, BlockCompletionFunc *cb, void *opaque, const BlockJobDriver *driver, bool is_none_mode, BlockDriverState *base, bool auto_complete, const char *filter_node_name, bool is_mirror, Error **errp) { MirrorBlockJob *s; BlockDriverState *mirror_top_bs; bool target_graph_mod; bool target_is_backing; Error *local_err = NULL; int ret; if (granularity == 0) { granularity = bdrv_get_default_bitmap_granularity(target); } assert ((granularity & (granularity - 1)) == 0); /* Granularity must be large enough for sector-based dirty bitmap */ assert(granularity >= BDRV_SECTOR_SIZE); if (buf_size < 0) { error_setg(errp, "Invalid parameter 'buf-size'"); return; } if (buf_size == 0) { buf_size = DEFAULT_MIRROR_BUF_SIZE; } /* In the case of active commit, add dummy driver to provide consistent * reads on the top, while disabling it in the intermediate nodes, and make * the backing chain writable. */ mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, BDRV_O_RDWR, errp); if (mirror_top_bs == NULL) { return; } if (!filter_node_name) { mirror_top_bs->implicit = true; } mirror_top_bs->total_sectors = bs->total_sectors; bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs)); /* bdrv_append takes ownership of the mirror_top_bs reference, need to keep * it alive until block_job_create() succeeds even if bs has no parent. */ bdrv_ref(mirror_top_bs); bdrv_drained_begin(bs); bdrv_append(mirror_top_bs, bs, &local_err); bdrv_drained_end(bs); if (local_err) { bdrv_unref(mirror_top_bs); error_propagate(errp, local_err); return; } /* Make sure that the source is not resized while the job is running */ s = block_job_create(job_id, driver, mirror_top_bs, BLK_PERM_CONSISTENT_READ, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD, speed, creation_flags, cb, opaque, errp); if (!s) { goto fail; } /* The block job now has a reference to this node */ bdrv_unref(mirror_top_bs); s->source = bs; s->mirror_top_bs = mirror_top_bs; /* No resize for the target either; while the mirror is still running, a * consistent read isn't necessarily possible. We could possibly allow * writes and graph modifications, though it would likely defeat the * purpose of a mirror, so leave them blocked for now. * * In the case of active commit, things look a bit different, though, * because the target is an already populated backing file in active use. * We can allow anything except resize there.*/ target_is_backing = bdrv_chain_contains(bs, target); target_graph_mod = (backing_mode != MIRROR_LEAVE_BACKING_CHAIN); s->target = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE | (target_graph_mod ? BLK_PERM_GRAPH_MOD : 0), BLK_PERM_WRITE_UNCHANGED | (target_is_backing ? BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD : 0)); ret = blk_insert_bs(s->target, target, errp); if (ret < 0) { goto fail; } if (is_mirror) { /* XXX: Mirror target could be a NBD server of target QEMU in the case * of non-shared block migration. To allow migration completion, we * have to allow "inactivate" of the target BB. When that happens, we * know the job is drained, and the vcpus are stopped, so no write * operation will be performed. Block layer already has assertions to * ensure that. */ blk_set_force_allow_inactivate(s->target); } s->replaces = g_strdup(replaces); s->on_source_error = on_source_error; s->on_target_error = on_target_error; s->is_none_mode = is_none_mode; s->backing_mode = backing_mode; s->base = base; s->granularity = granularity; s->buf_size = ROUND_UP(buf_size, granularity); s->unmap = unmap; if (auto_complete) { s->should_complete = true; } s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); if (!s->dirty_bitmap) { goto fail; } /* Required permissions are already taken with blk_new() */ block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, &error_abort); /* In commit_active_start() all intermediate nodes disappear, so * any jobs in them must be blocked */ if (target_is_backing) { BlockDriverState *iter; for (iter = backing_bs(bs); iter != target; iter = backing_bs(iter)) { /* XXX BLK_PERM_WRITE needs to be allowed so we don't block * ourselves at s->base (if writes are blocked for a node, they are * also blocked for its backing file). The other options would be a * second filter driver above s->base (== target). */ ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, errp); if (ret < 0) { goto fail; } } } trace_mirror_start(bs, s, opaque); block_job_start(&s->common); return; fail: if (s) { /* Make sure this BDS does not go away until we have completed the graph * changes below */ bdrv_ref(mirror_top_bs); g_free(s->replaces); blk_unref(s->target); block_job_early_fail(&s->common); } bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL, &error_abort); bdrv_replace_node(mirror_top_bs, backing_bs(mirror_top_bs), &error_abort); bdrv_unref(mirror_top_bs); } void mirror_start(const char *job_id, BlockDriverState *bs, BlockDriverState *target, const char *replaces, int64_t speed, uint32_t granularity, int64_t buf_size, MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, BlockdevOnError on_source_error, BlockdevOnError on_target_error, bool unmap, const char *filter_node_name, Error **errp) { bool is_none_mode; BlockDriverState *base; if (mode == MIRROR_SYNC_MODE_INCREMENTAL) { error_setg(errp, "Sync mode 'incremental' not supported"); return; } is_none_mode = mode == MIRROR_SYNC_MODE_NONE; base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL; mirror_start_job(job_id, bs, BLOCK_JOB_DEFAULT, target, replaces, speed, granularity, buf_size, backing_mode, on_source_error, on_target_error, unmap, NULL, NULL, &mirror_job_driver, is_none_mode, base, false, filter_node_name, true, errp); } void commit_active_start(const char *job_id, BlockDriverState *bs, BlockDriverState *base, int creation_flags, int64_t speed, BlockdevOnError on_error, const char *filter_node_name, BlockCompletionFunc *cb, void *opaque, bool auto_complete, Error **errp) { int orig_base_flags; Error *local_err = NULL; orig_base_flags = bdrv_get_flags(base); if (bdrv_reopen(base, bs->open_flags, errp)) { return; } mirror_start_job(job_id, bs, creation_flags, base, NULL, speed, 0, 0, MIRROR_LEAVE_BACKING_CHAIN, on_error, on_error, true, cb, opaque, &commit_active_job_driver, false, base, auto_complete, filter_node_name, false, &local_err); if (local_err) { error_propagate(errp, local_err); goto error_restore_flags; } return; error_restore_flags: /* ignore error and errp for bdrv_reopen, because we want to propagate * the original error */ bdrv_reopen(base, orig_base_flags, NULL); return; }