| /* |
| * 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 "qapi/qmp/qdict.h" |
| #include "qemu/ratelimit.h" |
| #include "sysemu/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 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 stream_prepare(Job *job) |
| { |
| StreamBlockJob *s = container_of(job, StreamBlockJob, common.job); |
| BlockDriverState *unfiltered_bs = bdrv_skip_filters(s->target_bs); |
| BlockDriverState *base; |
| BlockDriverState *unfiltered_base; |
| Error *local_err = NULL; |
| int ret = 0; |
| |
| /* 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 unfiltered_bs is drained. Drain |
| * already here and use bdrv_set_backing_hd_drained() instead 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). |
| */ |
| bdrv_drained_begin(unfiltered_bs); |
| |
| base = bdrv_filter_or_cow_bs(s->above_base); |
| unfiltered_base = bdrv_skip_filters(base); |
| |
| if (bdrv_cow_child(unfiltered_bs)) { |
| const char *base_id = NULL, *base_fmt = NULL; |
| if (unfiltered_base) { |
| base_id = s->backing_file_str ?: unfiltered_base->filename; |
| if (unfiltered_base->drv) { |
| base_fmt = unfiltered_base->drv->format_name; |
| } |
| } |
| |
| bdrv_set_backing_hd_drained(unfiltered_bs, base, &local_err); |
| |
| /* |
| * 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_drained_end(unfiltered_bs); |
| 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 = bdrv_skip_filters(s->target_bs); |
| int64_t len; |
| int64_t offset = 0; |
| int error = 0; |
| int64_t n = 0; /* bytes */ |
| |
| if (unfiltered_bs == s->base_overlay) { |
| /* Nothing to stream */ |
| return 0; |
| } |
| |
| WITH_GRAPH_RDLOCK_GUARD() { |
| 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; |
| |
| /* 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_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_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, |
| 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)); |
| |
| 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); |
| return; |
| } |
| |
| /* |
| * 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) { |
| int ret; |
| /* Hold the chain during reopen */ |
| if (bdrv_freeze_backing_chain(bs, above_base, errp) < 0) { |
| return; |
| } |
| |
| 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) { |
| return; |
| } |
| } |
| |
| 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. |
| */ |
| if (block_job_add_bdrv(&s->common, "active node", bs, 0, |
| basic_flags | BLK_PERM_WRITE, errp)) { |
| 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) { |
| goto fail; |
| } |
| } |
| |
| s->base_overlay = base_overlay; |
| s->above_base = above_base; |
| s->backing_file_str = g_strdup(backing_file_str); |
| 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); |
| } |
| } |