| /* | |
| * 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 "qemu/osdep.h" | |
| #include "trace.h" | |
| #include "block/block_int.h" | |
| #include "block/blockjob_int.h" | |
| #include "qapi/error.h" | |
| #include "qobject/qdict.h" | |
| #include "qemu/ratelimit.h" | |
| #include "system/block-backend.h" | |
| #include "block/copy-on-read.h" | |
| enum { | |
| /* | |
| * Maximum chunk size to feed to copy-on-read. This should be | |
| * large enough to process multiple clusters in a single call, so | |
| * that populating contiguous regions of the image is efficient. | |
| */ | |
| STREAM_CHUNK = 512 * 1024, /* in bytes */ | |
| }; | |
| typedef struct StreamBlockJob { | |
| BlockJob common; | |
| BlockBackend *blk; | |
| BlockDriverState *base_overlay; /* COW overlay (stream from this) */ | |
| BlockDriverState *above_base; /* Node directly above the base */ | |
| BlockDriverState *cor_filter_bs; | |
| BlockDriverState *target_bs; | |
| BlockdevOnError on_error; | |
| char *backing_file_str; | |
| bool backing_mask_protocol; | |
| bool bs_read_only; | |
| } StreamBlockJob; | |
| static int coroutine_fn stream_populate(BlockBackend *blk, | |
| int64_t offset, uint64_t bytes) | |
| { | |
| assert(bytes < SIZE_MAX); | |
| return blk_co_preadv(blk, offset, bytes, NULL, BDRV_REQ_PREFETCH); | |
| } | |
| static int GRAPH_UNLOCKED stream_prepare(Job *job) | |
| { | |
| StreamBlockJob *s = container_of(job, StreamBlockJob, common.job); | |
| BlockDriverState *unfiltered_bs; | |
| BlockDriverState *unfiltered_bs_cow; | |
| BlockDriverState *base; | |
| BlockDriverState *unfiltered_base; | |
| Error *local_err = NULL; | |
| int ret = 0; | |
| GLOBAL_STATE_CODE(); | |
| bdrv_graph_rdlock_main_loop(); | |
| unfiltered_bs = bdrv_skip_filters(s->target_bs); | |
| unfiltered_bs_cow = bdrv_cow_bs(unfiltered_bs); | |
| bdrv_graph_rdunlock_main_loop(); | |
| /* We should drop filter at this point, as filter hold the backing chain */ | |
| bdrv_cor_filter_drop(s->cor_filter_bs); | |
| s->cor_filter_bs = NULL; | |
| /* | |
| * bdrv_set_backing_hd() requires that all block nodes are drained. Drain | |
| * already here, because the polling during drained_begin() might change the | |
| * graph, and if we do this only later, we may end up working with the wrong | |
| * base node (or it might even have gone away by the time we want to use | |
| * it). | |
| */ | |
| if (unfiltered_bs_cow) { | |
| bdrv_ref(unfiltered_bs_cow); | |
| } | |
| bdrv_drain_all_begin(); | |
| bdrv_graph_rdlock_main_loop(); | |
| base = bdrv_filter_or_cow_bs(s->above_base); | |
| unfiltered_base = bdrv_skip_filters(base); | |
| bdrv_graph_rdunlock_main_loop(); | |
| if (unfiltered_bs_cow) { | |
| const char *base_id = NULL, *base_fmt = NULL; | |
| if (unfiltered_base) { | |
| base_id = s->backing_file_str ?: unfiltered_base->filename; | |
| if (unfiltered_base->drv) { | |
| if (s->backing_mask_protocol && | |
| unfiltered_base->drv->protocol_name) { | |
| base_fmt = "raw"; | |
| } else { | |
| base_fmt = unfiltered_base->drv->format_name; | |
| } | |
| } | |
| } | |
| bdrv_graph_wrlock(); | |
| bdrv_set_backing_hd(unfiltered_bs, base, &local_err); | |
| bdrv_graph_wrunlock(); | |
| /* | |
| * This call will do I/O, so the graph can change again from here on. | |
| * We have already completed the graph change, so we are not in danger | |
| * of operating on the wrong node any more if this happens. | |
| */ | |
| ret = bdrv_change_backing_file(unfiltered_bs, base_id, base_fmt, false); | |
| if (local_err) { | |
| error_report_err(local_err); | |
| ret = -EPERM; | |
| goto out; | |
| } | |
| } | |
| out: | |
| bdrv_drain_all_end(); | |
| if (unfiltered_bs_cow) { | |
| bdrv_unref(unfiltered_bs_cow); | |
| } | |
| return ret; | |
| } | |
| static void stream_clean(Job *job) | |
| { | |
| StreamBlockJob *s = container_of(job, StreamBlockJob, common.job); | |
| if (s->cor_filter_bs) { | |
| bdrv_cor_filter_drop(s->cor_filter_bs); | |
| s->cor_filter_bs = NULL; | |
| } | |
| blk_unref(s->blk); | |
| s->blk = NULL; | |
| /* Reopen the image back in read-only mode if necessary */ | |
| if (s->bs_read_only) { | |
| /* Give up write permissions before making it read-only */ | |
| bdrv_reopen_set_read_only(s->target_bs, true, NULL); | |
| } | |
| g_free(s->backing_file_str); | |
| } | |
| static int coroutine_fn stream_run(Job *job, Error **errp) | |
| { | |
| StreamBlockJob *s = container_of(job, StreamBlockJob, common.job); | |
| BlockDriverState *unfiltered_bs = NULL; | |
| int64_t len = -1; | |
| int64_t offset = 0; | |
| int error = 0; | |
| int64_t n = 0; /* bytes */ | |
| WITH_GRAPH_RDLOCK_GUARD() { | |
| unfiltered_bs = bdrv_skip_filters(s->target_bs); | |
| if (unfiltered_bs == s->base_overlay) { | |
| /* Nothing to stream */ | |
| return 0; | |
| } | |
| len = bdrv_co_getlength(s->target_bs); | |
| if (len < 0) { | |
| return len; | |
| } | |
| } | |
| job_progress_set_remaining(&s->common.job, len); | |
| for ( ; offset < len; offset += n) { | |
| bool copy; | |
| int ret = -1; | |
| /* 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_ratelimit_sleep(&s->common); | |
| if (job_is_cancelled(&s->common.job)) { | |
| break; | |
| } | |
| copy = false; | |
| WITH_GRAPH_RDLOCK_GUARD() { | |
| ret = bdrv_co_is_allocated(unfiltered_bs, offset, STREAM_CHUNK, &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 [offset, offset+n*BDRV_SECTOR_SIZE). | |
| */ | |
| ret = bdrv_co_is_allocated_above(bdrv_cow_bs(unfiltered_bs), | |
| s->base_overlay, true, | |
| offset, n, &n); | |
| /* Finish early if end of backing file has been reached */ | |
| if (ret == 0 && n == 0) { | |
| n = len - offset; | |
| } | |
| copy = (ret > 0); | |
| } | |
| } | |
| trace_stream_one_iteration(s, offset, n, ret); | |
| if (copy) { | |
| ret = stream_populate(s->blk, offset, n); | |
| } | |
| if (ret < 0) { | |
| BlockErrorAction action = | |
| block_job_error_action(&s->common, 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; | |
| } | |
| } | |
| /* Publish progress */ | |
| job_progress_update(&s->common.job, n); | |
| if (copy) { | |
| block_job_ratelimit_processed_bytes(&s->common, n); | |
| } | |
| } | |
| /* Do not remove the backing file if an error was there but ignored. */ | |
| return error; | |
| } | |
| static const BlockJobDriver stream_job_driver = { | |
| .job_driver = { | |
| .instance_size = sizeof(StreamBlockJob), | |
| .job_type = JOB_TYPE_STREAM, | |
| .free = block_job_free, | |
| .run = stream_run, | |
| .prepare = stream_prepare, | |
| .clean = stream_clean, | |
| .user_resume = block_job_user_resume, | |
| }, | |
| }; | |
| void stream_start(const char *job_id, BlockDriverState *bs, | |
| BlockDriverState *base, const char *backing_file_str, | |
| bool backing_mask_protocol, | |
| BlockDriverState *bottom, | |
| int creation_flags, int64_t speed, | |
| BlockdevOnError on_error, | |
| const char *filter_node_name, | |
| Error **errp) | |
| { | |
| StreamBlockJob *s = NULL; | |
| BlockDriverState *iter; | |
| bool bs_read_only; | |
| int basic_flags = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED; | |
| BlockDriverState *base_overlay; | |
| BlockDriverState *cor_filter_bs = NULL; | |
| BlockDriverState *above_base; | |
| QDict *opts; | |
| int ret; | |
| GLOBAL_STATE_CODE(); | |
| assert(!(base && bottom)); | |
| assert(!(backing_file_str && bottom)); | |
| bdrv_graph_rdlock_main_loop(); | |
| if (bottom) { | |
| /* | |
| * New simple interface. The code is written in terms of old interface | |
| * with @base parameter (still, it doesn't freeze link to base, so in | |
| * this mean old code is correct for new interface). So, for now, just | |
| * emulate base_overlay and above_base. Still, when old interface | |
| * finally removed, we should refactor code to use only "bottom", but | |
| * not "*base*" things. | |
| */ | |
| assert(!bottom->drv->is_filter); | |
| base_overlay = above_base = bottom; | |
| } else { | |
| base_overlay = bdrv_find_overlay(bs, base); | |
| if (!base_overlay) { | |
| error_setg(errp, "'%s' is not in the backing chain of '%s'", | |
| base->node_name, bs->node_name); | |
| goto out_rdlock; | |
| } | |
| /* | |
| * Find the node directly above @base. @base_overlay is a COW overlay, | |
| * so it must have a bdrv_cow_child(), but it is the immediate overlay | |
| * of @base, so between the two there can only be filters. | |
| */ | |
| above_base = base_overlay; | |
| if (bdrv_cow_bs(above_base) != base) { | |
| above_base = bdrv_cow_bs(above_base); | |
| while (bdrv_filter_bs(above_base) != base) { | |
| above_base = bdrv_filter_bs(above_base); | |
| } | |
| } | |
| } | |
| /* Make sure that the image is opened in read-write mode */ | |
| bs_read_only = bdrv_is_read_only(bs); | |
| if (bs_read_only) { | |
| /* Hold the chain during reopen */ | |
| if (bdrv_freeze_backing_chain(bs, above_base, errp) < 0) { | |
| goto out_rdlock; | |
| } | |
| ret = bdrv_reopen_set_read_only(bs, false, errp); | |
| /* failure, or cor-filter will hold the chain */ | |
| bdrv_unfreeze_backing_chain(bs, above_base); | |
| if (ret < 0) { | |
| goto out_rdlock; | |
| } | |
| } | |
| bdrv_graph_rdunlock_main_loop(); | |
| opts = qdict_new(); | |
| qdict_put_str(opts, "driver", "copy-on-read"); | |
| qdict_put_str(opts, "file", bdrv_get_node_name(bs)); | |
| /* Pass the base_overlay node name as 'bottom' to COR driver */ | |
| qdict_put_str(opts, "bottom", base_overlay->node_name); | |
| if (filter_node_name) { | |
| qdict_put_str(opts, "node-name", filter_node_name); | |
| } | |
| cor_filter_bs = bdrv_insert_node(bs, opts, BDRV_O_RDWR, errp); | |
| if (!cor_filter_bs) { | |
| goto fail; | |
| } | |
| if (!filter_node_name) { | |
| cor_filter_bs->implicit = true; | |
| } | |
| s = block_job_create(job_id, &stream_job_driver, NULL, cor_filter_bs, | |
| 0, BLK_PERM_ALL, | |
| speed, creation_flags, NULL, NULL, errp); | |
| if (!s) { | |
| goto fail; | |
| } | |
| s->blk = blk_new_with_bs(cor_filter_bs, BLK_PERM_CONSISTENT_READ, | |
| basic_flags | BLK_PERM_WRITE, errp); | |
| if (!s->blk) { | |
| goto fail; | |
| } | |
| /* | |
| * Disable request queuing in the BlockBackend to avoid deadlocks on drain: | |
| * The job reports that it's busy until it reaches a pause point. | |
| */ | |
| blk_set_disable_request_queuing(s->blk, true); | |
| blk_set_allow_aio_context_change(s->blk, true); | |
| /* | |
| * Prevent concurrent jobs trying to modify the graph structure here, we | |
| * already have our own plans. Also don't allow resize as the image size is | |
| * queried only at the job start and then cached. | |
| */ | |
| bdrv_graph_wrlock_drained(); | |
| if (block_job_add_bdrv(&s->common, "active node", bs, 0, | |
| basic_flags | BLK_PERM_WRITE, errp)) { | |
| bdrv_graph_wrunlock(); | |
| goto fail; | |
| } | |
| /* Block all intermediate nodes between bs and base, because they will | |
| * disappear from the chain after this operation. The streaming job reads | |
| * every block only once, assuming that it doesn't change, so forbid writes | |
| * and resizes. Reassign the base node pointer because the backing BS of the | |
| * bottom node might change after the call to bdrv_reopen_set_read_only() | |
| * due to parallel block jobs running. | |
| * above_base node might change after the call to | |
| * bdrv_reopen_set_read_only() due to parallel block jobs running. | |
| */ | |
| base = bdrv_filter_or_cow_bs(above_base); | |
| for (iter = bdrv_filter_or_cow_bs(bs); iter != base; | |
| iter = bdrv_filter_or_cow_bs(iter)) | |
| { | |
| ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, | |
| basic_flags, errp); | |
| if (ret < 0) { | |
| bdrv_graph_wrunlock(); | |
| goto fail; | |
| } | |
| } | |
| bdrv_graph_wrunlock(); | |
| s->base_overlay = base_overlay; | |
| s->above_base = above_base; | |
| s->backing_file_str = g_strdup(backing_file_str); | |
| s->backing_mask_protocol = backing_mask_protocol; | |
| s->cor_filter_bs = cor_filter_bs; | |
| s->target_bs = bs; | |
| s->bs_read_only = bs_read_only; | |
| s->on_error = on_error; | |
| trace_stream_start(bs, base, s); | |
| job_start(&s->common.job); | |
| return; | |
| fail: | |
| if (s) { | |
| job_early_fail(&s->common.job); | |
| } | |
| if (cor_filter_bs) { | |
| bdrv_cor_filter_drop(cor_filter_bs); | |
| } | |
| if (bs_read_only) { | |
| bdrv_reopen_set_read_only(bs, true, NULL); | |
| } | |
| return; | |
| out_rdlock: | |
| bdrv_graph_rdunlock_main_loop(); | |
| } |