diff options
Diffstat (limited to 'src/block/stream.c')
| -rw-r--r-- | src/block/stream.c | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/src/block/stream.c b/src/block/stream.c new file mode 100644 index 0000000..25af7ef --- /dev/null +++ b/src/block/stream.c @@ -0,0 +1,243 @@ +/* + * 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); +} |
