text: /*
   * 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 "qemu/osdep.h"
  #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.
       */
      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;
      char *backing_file_str;
  } 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;
  }
  
  typedef struct {
      int ret;
  } CommitCompleteData;
  
  static void commit_complete(BlockJob *job, void *opaque)
  {
      CommitBlockJob *s = container_of(job, CommitBlockJob, common);
      CommitCompleteData *data = opaque;
      BlockDriverState *active = s->active;
      BlockDriverState *top = s->top;
      BlockDriverState *base = s->base;
      BlockDriverState *overlay_bs;
      int ret = data->ret;
  
      if (!block_job_is_cancelled(&s->common) && ret == 0) {
          /* success */
          ret = bdrv_drop_intermediate(active, top, base, s->backing_file_str);
      }
  
      /* 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);
      }
      overlay_bs = bdrv_find_overlay(active, top);
      if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
          bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL);
      }
      g_free(s->backing_file_str);
      block_job_completed(&s->common, ret);
      g_free(data);
  }
  
  static void coroutine_fn commit_run(void *opaque)
  {
      CommitBlockJob *s = opaque;
      CommitCompleteData *data;
      BlockDriverState *top = s->top;
      BlockDriverState *base = s->base;
      int64_t sector_num, end;
      int ret = 0;
      int n = 0;
      void *buf = NULL;
      int bytes_written = 0;
      int64_t base_len;
  
      ret = s->common.len = bdrv_getlength(top);
  
  
      if (s->common.len < 0) {
          goto out;
      }
  
      ret = base_len = bdrv_getlength(base);
      if (base_len < 0) {
          goto out;
      }
  
      if (base_len < s->common.len) {
          ret = bdrv_truncate(base, s->common.len);
          if (ret) {
              goto out;
          }
      }
  
      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 bdrv_drain_all() returns.
           */
          block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
          if (block_job_is_cancelled(&s->common)) {
              break;
          }
          /* Copy if allocated above the base */
          ret = bdrv_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 out;
              } else {
                  n = 0;
                  continue;
              }
          }
          /* Publish progress */
          s->common.offset += n * BDRV_SECTOR_SIZE;
      }
  
      ret = 0;
  
  out:
      qemu_vfree(buf);
  
      data = g_malloc(sizeof(*data));
      data->ret = ret;
      block_job_defer_to_main_loop(&s->common, commit_complete, data);
  }
  
  static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp)
  {
      CommitBlockJob *s = container_of(job, CommitBlockJob, 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 commit_job_driver = {
      .instance_size = sizeof(CommitBlockJob),
      .job_type      = BLOCK_JOB_TYPE_COMMIT,
      .set_speed     = commit_set_speed,
  };
  
  void commit_start(BlockDriverState *bs, BlockDriverState *base,
                    BlockDriverState *top, int64_t speed,
                    BlockdevOnError on_error, BlockCompletionFunc *cb,
                    void *opaque, const char *backing_file_str, 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) &&
          (!bs->blk || !blk_iostatus_is_enabled(bs->blk))) {
          error_setg(errp, "Invalid parameter combination");
          return;
      }
  
      assert(top != bs);
      if (top == base) {
          error_setg(errp, "Invalid files for merge: top and base are the same");
          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_overlay_flags & BDRV_O_RDWR)) {
          reopen_queue = bdrv_reopen_queue(reopen_queue, overlay_bs, NULL,
                                           orig_overlay_flags | BDRV_O_RDWR);
      }
      if (!(orig_base_flags & BDRV_O_RDWR)) {
          reopen_queue = bdrv_reopen_queue(reopen_queue, base, NULL,
                                           orig_base_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_driver, 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->backing_file_str = g_strdup(backing_file_str);
  
      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);
  }
  