diff options
Diffstat (limited to 'block/commit.c')
| -rw-r--r-- | block/commit.c | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/block/commit.c b/block/commit.c new file mode 100644 index 000000000..733c91403 --- /dev/null +++ b/block/commit.c @@ -0,0 +1,268 @@ +/* + * Live block commit + * + * Copyright Red Hat, Inc. 2012 + * + * Authors: + * Jeff Cody <jcody@redhat.com> + * Based on stream.c by Stefan Hajnoczi + * + * 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_int.h" +#include "blockjob.h" +#include "qemu/ratelimit.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. + */ + COMMIT_BUFFER_SIZE = 512 * 1024, /* in bytes */ +}; + +#define SLICE_TIME 100000000ULL /* ns */ + +typedef struct CommitBlockJob { + BlockJob common; + RateLimit limit; + BlockDriverState *active; + BlockDriverState *top; + BlockDriverState *base; + BlockdevOnError on_error; + int base_flags; + int orig_overlay_flags; +} CommitBlockJob; + +static int coroutine_fn commit_populate(BlockDriverState *bs, + BlockDriverState *base, + int64_t sector_num, int nb_sectors, + void *buf) +{ + int ret = 0; + + ret = bdrv_read(bs, sector_num, buf, nb_sectors); + if (ret) { + return ret; + } + + ret = bdrv_write(base, sector_num, buf, nb_sectors); + if (ret) { + return ret; + } + + return 0; +} + +static void coroutine_fn commit_run(void *opaque) +{ + CommitBlockJob *s = opaque; + BlockDriverState *active = s->active; + BlockDriverState *top = s->top; + BlockDriverState *base = s->base; + BlockDriverState *overlay_bs = NULL; + int64_t sector_num, end; + int ret = 0; + int n = 0; + void *buf; + int bytes_written = 0; + int64_t base_len; + + ret = s->common.len = bdrv_getlength(top); + + + if (s->common.len < 0) { + goto exit_restore_reopen; + } + + ret = base_len = bdrv_getlength(base); + if (base_len < 0) { + goto exit_restore_reopen; + } + + if (base_len < s->common.len) { + ret = bdrv_truncate(base, s->common.len); + if (ret) { + goto exit_restore_reopen; + } + } + + overlay_bs = bdrv_find_overlay(active, top); + + end = s->common.len >> BDRV_SECTOR_BITS; + buf = qemu_blockalign(top, COMMIT_BUFFER_SIZE); + + 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 qemu_aio_flush() returns. + */ + block_job_sleep_ns(&s->common, rt_clock, delay_ns); + if (block_job_is_cancelled(&s->common)) { + break; + } + /* Copy if allocated above the base */ + ret = bdrv_co_is_allocated_above(top, base, sector_num, + COMMIT_BUFFER_SIZE / BDRV_SECTOR_SIZE, + &n); + copy = (ret == 1); + trace_commit_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 = commit_populate(top, base, sector_num, n, buf); + bytes_written += n * BDRV_SECTOR_SIZE; + } + if (ret < 0) { + if (s->on_error == BLOCKDEV_ON_ERROR_STOP || + s->on_error == BLOCKDEV_ON_ERROR_REPORT|| + (s->on_error == BLOCKDEV_ON_ERROR_ENOSPC && ret == -ENOSPC)) { + goto exit_free_buf; + } else { + n = 0; + continue; + } + } + /* Publish progress */ + s->common.offset += n * BDRV_SECTOR_SIZE; + } + + ret = 0; + + if (!block_job_is_cancelled(&s->common) && sector_num == end) { + /* success */ + ret = bdrv_drop_intermediate(active, top, base); + } + +exit_free_buf: + qemu_vfree(buf); + +exit_restore_reopen: + /* restore base open flags here if appropriate (e.g., change the base back + * to r/o). These reopens do not need to be atomic, since we won't abort + * even on failure here */ + if (s->base_flags != bdrv_get_flags(base)) { + bdrv_reopen(base, s->base_flags, NULL); + } + if (s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) { + bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL); + } + + block_job_complete(&s->common, ret); +} + +static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp) +{ + CommitBlockJob *s = container_of(job, CommitBlockJob, common); + + if (speed < 0) { + error_set(errp, QERR_INVALID_PARAMETER, "speed"); + return; + } + ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); +} + +static BlockJobType commit_job_type = { + .instance_size = sizeof(CommitBlockJob), + .job_type = "commit", + .set_speed = commit_set_speed, +}; + +void commit_start(BlockDriverState *bs, BlockDriverState *base, + BlockDriverState *top, int64_t speed, + BlockdevOnError on_error, BlockDriverCompletionFunc *cb, + void *opaque, Error **errp) +{ + CommitBlockJob *s; + BlockReopenQueue *reopen_queue = NULL; + int orig_overlay_flags; + int orig_base_flags; + BlockDriverState *overlay_bs; + Error *local_err = NULL; + + if ((on_error == BLOCKDEV_ON_ERROR_STOP || + on_error == BLOCKDEV_ON_ERROR_ENOSPC) && + !bdrv_iostatus_is_enabled(bs)) { + error_set(errp, QERR_INVALID_PARAMETER_COMBINATION); + return; + } + + /* Once we support top == active layer, remove this check */ + if (top == bs) { + error_setg(errp, + "Top image as the active layer is currently unsupported"); + return; + } + + if (top == base) { + error_setg(errp, "Invalid files for merge: top and base are the same"); + return; + } + + /* top and base may be valid, but let's make sure that base is reachable + * from top */ + if (bdrv_find_backing_image(top, base->filename) != base) { + error_setg(errp, + "Base (%s) is not reachable from top (%s)", + base->filename, top->filename); + return; + } + + overlay_bs = bdrv_find_overlay(bs, top); + + if (overlay_bs == NULL) { + error_setg(errp, "Could not find overlay image for %s:", top->filename); + return; + } + + orig_base_flags = bdrv_get_flags(base); + orig_overlay_flags = bdrv_get_flags(overlay_bs); + + /* convert base & overlay_bs to r/w, if necessary */ + if (!(orig_base_flags & BDRV_O_RDWR)) { + reopen_queue = bdrv_reopen_queue(reopen_queue, base, + orig_base_flags | BDRV_O_RDWR); + } + if (!(orig_overlay_flags & BDRV_O_RDWR)) { + reopen_queue = bdrv_reopen_queue(reopen_queue, overlay_bs, + orig_overlay_flags | BDRV_O_RDWR); + } + if (reopen_queue) { + bdrv_reopen_multiple(reopen_queue, &local_err); + if (local_err != NULL) { + error_propagate(errp, local_err); + return; + } + } + + + s = block_job_create(&commit_job_type, bs, speed, cb, opaque, errp); + if (!s) { + return; + } + + s->base = base; + s->top = top; + s->active = bs; + + s->base_flags = orig_base_flags; + s->orig_overlay_flags = orig_overlay_flags; + + s->on_error = on_error; + s->common.co = qemu_coroutine_create(commit_run); + + trace_commit_start(bs, base, top, s, s->common.co, opaque); + qemu_coroutine_enter(s->common.co, s); +} |