/* * Image streaming * * Copyright IBM, Corp. 2011 * * Authors: * Stefan Hajnoczi <stefanha@linux.vnet.ibm.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 "trace.h" #include "block/block_int.h" #include "block/blockjob.h" #include "qapi/qmp/qerror.h" #include "qemu/ratelimit.h" #include "sysemu/block-backend.h" enum { /* * Size of data buffer for populating the image file. This should be large * enough to process multiple clusters in a single call, so that populating * contiguous regions of the image is efficient. */ STREAM_BUFFER_SIZE = 512 * 1024, /* in bytes */ }; #define SLICE_TIME 100000000ULL /* ns */ typedef struct StreamBlockJob { BlockJob common; RateLimit limit; BlockDriverState *base; BlockdevOnError on_error; char *backing_file_str; } StreamBlockJob; static int coroutine_fn stream_populate(BlockDriverState *bs, int64_t sector_num, int nb_sectors, void *buf) { struct iovec iov = { .iov_base = buf, .iov_len = nb_sectors * BDRV_SECTOR_SIZE, }; QEMUIOVector qiov; qemu_iovec_init_external(&qiov, &iov, 1); /* Copy-on-read the unallocated clusters */ return bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, &qiov); } typedef struct { int ret; bool reached_end; } StreamCompleteData; static void stream_complete(BlockJob *job, void *opaque) { StreamBlockJob *s = container_of(job, StreamBlockJob, common); StreamCompleteData *data = opaque; BlockDriverState *base = s->base; if (!block_job_is_cancelled(&s->common) && data->reached_end && data->ret == 0) { const char *base_id = NULL, *base_fmt = NULL; if (base) { base_id = s->backing_file_str; if (base->drv) { base_fmt = base->drv->format_name; } } data->ret = bdrv_change_backing_file(job->bs, base_id, base_fmt); bdrv_set_backing_hd(job->bs, base); } g_free(s->backing_file_str); block_job_completed(&s->common, data->ret); g_free(data); } static void coroutine_fn stream_run(void *opaque) { StreamBlockJob *s = opaque; StreamCompleteData *data; BlockDriverState *bs = s->common.bs; BlockDriverState *base = s->base; int64_t sector_num, end; int error = 0; int ret = 0; int n = 0; void *buf; if (!bs->backing) { block_job_completed(&s->common, 0); return; } s->common.len = bdrv_getlength(bs); if (s->common.len < 0) { block_job_completed(&s->common, s->common.len); return; } end = s->common.len >> BDRV_SECTOR_BITS; buf = qemu_blockalign(bs, STREAM_BUFFER_SIZE); /* Turn on copy-on-read for the whole block device so that guest read * requests help us make progress. Only do this when copying the entire * backing chain since the copy-on-read operation does not take base into * account. */ if (!base) { bdrv_enable_copy_on_read(bs); } for (sector_num = 0; sector_num < end; sector_num += n) { uint64_t delay_ns = 0; bool copy; wait: /* Note that even when no rate limit is applied we need to yield * with no pending I/O here so that bdrv_drain_all() returns. */ block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); if (block_job_is_cancelled(&s->common)) { break; } copy = false; ret = bdrv_is_allocated(bs, sector_num, STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n); if (ret == 1) { /* Allocated in the top, no need to copy. */ } else if (ret >= 0) { /* Copy if allocated in the intermediate images. Limit to the * known-unallocated area [sector_num, sector_num+n). */ ret = bdrv_is_allocated_above(backing_bs(bs), base, sector_num, n, &n); /* Finish early if end of backing file has been reached */ if (ret == 0 && n == 0) { n = end - sector_num; } copy = (ret == 1); } trace_stream_one_iteration(s, sector_num, n, ret); if (copy) { if (s->common.speed) { delay_ns = ratelimit_calculate_delay(&s->limit, n); if (delay_ns > 0) { goto wait; } } ret = stream_populate(bs, sector_num, n, buf); } if (ret < 0) { BlockErrorAction action = block_job_error_action(&s->common, s->common.bs, s->on_error, true, -ret); if (action == BLOCK_ERROR_ACTION_STOP) { n = 0; continue; } if (error == 0) { error = ret; } if (action == BLOCK_ERROR_ACTION_REPORT) { break; } } ret = 0; /* Publish progress */ s->common.offset += n * BDRV_SECTOR_SIZE; } if (!base) { bdrv_disable_copy_on_read(bs); } /* Do not remove the backing file if an error was there but ignored. */ ret = error; qemu_vfree(buf); /* Modify backing chain and close BDSes in main loop */ data = g_malloc(sizeof(*data)); data->ret = ret; data->reached_end = sector_num == end; block_job_defer_to_main_loop(&s->common, stream_complete, data); } static void stream_set_speed(BlockJob *job, int64_t speed, Error **errp) { StreamBlockJob *s = container_of(job, StreamBlockJob, common); if (speed < 0) { error_setg(errp, QERR_INVALID_PARAMETER, "speed"); return; } ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); } static const BlockJobDriver stream_job_driver = { .instance_size = sizeof(StreamBlockJob), .job_type = BLOCK_JOB_TYPE_STREAM, .set_speed = stream_set_speed, }; void stream_start(BlockDriverState *bs, BlockDriverState *base, const char *backing_file_str, int64_t speed, BlockdevOnError on_error, BlockCompletionFunc *cb, void *opaque, Error **errp) { StreamBlockJob *s; if ((on_error == BLOCKDEV_ON_ERROR_STOP || on_error == BLOCKDEV_ON_ERROR_ENOSPC) && (!bs->blk || !blk_iostatus_is_enabled(bs->blk))) { error_setg(errp, QERR_INVALID_PARAMETER, "on-error"); return; } s = block_job_create(&stream_job_driver, bs, speed, cb, opaque, errp); if (!s) { return; } s->base = base; s->backing_file_str = g_strdup(backing_file_str); s->on_error = on_error; s->common.co = qemu_coroutine_create(stream_run); trace_stream_start(bs, base, s, s->common.co, opaque); qemu_coroutine_enter(s->common.co, s); }