| /* |
| * 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/qerror.h" |
| #include "qemu/ratelimit.h" |
| #include "sysemu/block-backend.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; |
| BlockDriverState *bottom; |
| BlockdevOnError on_error; |
| char *backing_file_str; |
| bool bs_read_only; |
| bool chain_frozen; |
| } 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_COPY_ON_READ | BDRV_REQ_PREFETCH); |
| } |
| |
| static void stream_abort(Job *job) |
| { |
| StreamBlockJob *s = container_of(job, StreamBlockJob, common.job); |
| |
| if (s->chain_frozen) { |
| BlockJob *bjob = &s->common; |
| bdrv_unfreeze_backing_chain(blk_bs(bjob->blk), s->bottom); |
| } |
| } |
| |
| static int stream_prepare(Job *job) |
| { |
| StreamBlockJob *s = container_of(job, StreamBlockJob, common.job); |
| BlockJob *bjob = &s->common; |
| BlockDriverState *bs = blk_bs(bjob->blk); |
| BlockDriverState *base = backing_bs(s->bottom); |
| Error *local_err = NULL; |
| int ret = 0; |
| |
| bdrv_unfreeze_backing_chain(bs, s->bottom); |
| s->chain_frozen = false; |
| |
| if (bs->backing) { |
| 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; |
| } |
| } |
| bdrv_set_backing_hd(bs, base, &local_err); |
| ret = bdrv_change_backing_file(bs, base_id, base_fmt); |
| if (local_err) { |
| error_report_err(local_err); |
| return -EPERM; |
| } |
| } |
| |
| return ret; |
| } |
| |
| static void stream_clean(Job *job) |
| { |
| StreamBlockJob *s = container_of(job, StreamBlockJob, common.job); |
| BlockJob *bjob = &s->common; |
| BlockDriverState *bs = blk_bs(bjob->blk); |
| |
| /* Reopen the image back in read-only mode if necessary */ |
| if (s->bs_read_only) { |
| /* Give up write permissions before making it read-only */ |
| blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort); |
| bdrv_reopen_set_read_only(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); |
| BlockBackend *blk = s->common.blk; |
| BlockDriverState *bs = blk_bs(blk); |
| bool enable_cor = !backing_bs(s->bottom); |
| int64_t len; |
| int64_t offset = 0; |
| uint64_t delay_ns = 0; |
| int error = 0; |
| int ret = 0; |
| int64_t n = 0; /* bytes */ |
| |
| if (bs == s->bottom) { |
| /* Nothing to stream */ |
| return 0; |
| } |
| |
| len = bdrv_getlength(bs); |
| if (len < 0) { |
| return len; |
| } |
| job_progress_set_remaining(&s->common.job, len); |
| |
| /* 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 (enable_cor) { |
| bdrv_enable_copy_on_read(bs); |
| } |
| |
| for ( ; offset < len; offset += n) { |
| bool copy; |
| |
| /* 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. |
| */ |
| job_sleep_ns(&s->common.job, delay_ns); |
| if (job_is_cancelled(&s->common.job)) { |
| break; |
| } |
| |
| copy = false; |
| |
| ret = bdrv_is_allocated(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(backing_bs(bs), s->bottom, true, |
| offset, n, &n); |
| /* Finish early if end of backing file has been reached */ |
| if (ret == 0 && n == 0) { |
| n = len - offset; |
| } |
| |
| copy = (ret == 1); |
| } |
| trace_stream_one_iteration(s, offset, n, ret); |
| if (copy) { |
| ret = stream_populate(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; |
| } |
| } |
| ret = 0; |
| |
| /* Publish progress */ |
| job_progress_update(&s->common.job, n); |
| if (copy) { |
| delay_ns = block_job_ratelimit_get_delay(&s->common, n); |
| } else { |
| delay_ns = 0; |
| } |
| } |
| |
| if (enable_cor) { |
| bdrv_disable_copy_on_read(bs); |
| } |
| |
| /* 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, |
| .abort = stream_abort, |
| .clean = stream_clean, |
| .user_resume = block_job_user_resume, |
| .drain = block_job_drain, |
| }, |
| }; |
| |
| void stream_start(const char *job_id, BlockDriverState *bs, |
| BlockDriverState *base, const char *backing_file_str, |
| int creation_flags, int64_t speed, |
| BlockdevOnError on_error, Error **errp) |
| { |
| StreamBlockJob *s; |
| BlockDriverState *iter; |
| bool bs_read_only; |
| int basic_flags = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED; |
| BlockDriverState *bottom = bdrv_find_overlay(bs, base); |
| |
| if (bdrv_freeze_backing_chain(bs, bottom, errp) < 0) { |
| return; |
| } |
| |
| /* Make sure that the image is opened in read-write mode */ |
| bs_read_only = bdrv_is_read_only(bs); |
| if (bs_read_only) { |
| if (bdrv_reopen_set_read_only(bs, false, errp) != 0) { |
| bs_read_only = false; |
| goto fail; |
| } |
| } |
| |
| /* 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. */ |
| s = block_job_create(job_id, &stream_job_driver, NULL, bs, |
| basic_flags | BLK_PERM_GRAPH_MOD, |
| basic_flags | BLK_PERM_WRITE, |
| speed, creation_flags, NULL, NULL, errp); |
| if (!s) { |
| 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. |
| */ |
| base = backing_bs(bottom); |
| for (iter = backing_bs(bs); iter && iter != base; iter = backing_bs(iter)) { |
| block_job_add_bdrv(&s->common, "intermediate node", iter, 0, |
| basic_flags, &error_abort); |
| } |
| |
| s->bottom = bottom; |
| s->backing_file_str = g_strdup(backing_file_str); |
| s->bs_read_only = bs_read_only; |
| s->chain_frozen = true; |
| |
| s->on_error = on_error; |
| trace_stream_start(bs, base, s); |
| job_start(&s->common.job); |
| return; |
| |
| fail: |
| if (bs_read_only) { |
| bdrv_reopen_set_read_only(bs, true, NULL); |
| } |
| bdrv_unfreeze_backing_chain(bs, bottom); |
| } |