Re: [Qemu-devel] [PATCH v2 02/12] block: update error reporting for bdrv_snapshot_delete() and related functions

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

  bdrv_snapshot_delete() do not return error number now, and I checked
original caller code, they used it only for error reporting, so it is
safe to change.

Reviewed-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>


> Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
> ---
>   block.c                   | 21 +++++++++++++--------
>   block/qcow2-snapshot.c    | 19 +++++++++++++------
>   block/qcow2.h             |  4 +++-
>   block/rbd.c               | 10 +++++++---
>   block/sheepdog.c          |  6 ++++--
>   include/block/block.h     |  4 +++-
>   include/block/block_int.h |  4 +++-
>   qemu-img.c                |  8 +++-----
>   savevm.c                  | 32 ++++++++++++++++----------------
>   9 files changed, 65 insertions(+), 43 deletions(-)
> 
> diff --git a/block.c b/block.c
> index aa9a533..3f7ee38 100644
> --- a/block.c
> +++ b/block.c
> @@ -3438,16 +3438,21 @@ int bdrv_snapshot_goto(BlockDriverState *bs,
>       return -ENOTSUP;
>   }
> 
> -int bdrv_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
> +void bdrv_snapshot_delete(BlockDriverState *bs,
> +                          const char *snapshot_id,
> +                          Error **errp)
>   {
>       BlockDriver *drv = bs->drv;
> -    if (!drv)
> -        return -ENOMEDIUM;
> -    if (drv->bdrv_snapshot_delete)
> -        return drv->bdrv_snapshot_delete(bs, snapshot_id);
> -    if (bs->file)
> -        return bdrv_snapshot_delete(bs->file, snapshot_id);
> -    return -ENOTSUP;
> +
> +    if (!drv) {
> +        error_setg(errp, "Device has no medium");
> +    } else if (drv->bdrv_snapshot_delete) {
> +        drv->bdrv_snapshot_delete(bs, snapshot_id, errp);
> +    } else if (bs->file) {
> +        bdrv_snapshot_delete(bs->file, snapshot_id, errp);
> +    } else {
> +        error_setg(errp, "Snapshots are not supported");
> +    }
>   }
> 
>   int bdrv_snapshot_list(BlockDriverState *bs,
> diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
> index 992a5c8..fd0e231 100644
> --- a/block/qcow2-snapshot.c
> +++ b/block/qcow2-snapshot.c
> @@ -530,7 +530,9 @@ fail:
>       return ret;
>   }
> 
> -int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
> +void qcow2_snapshot_delete(BlockDriverState *bs,
> +                           const char *snapshot_id,
> +                           Error **errp)
>   {
>       BDRVQcowState *s = bs->opaque;
>       QCowSnapshot sn;
> @@ -539,7 +541,9 @@ int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
>       /* Search the snapshot */
>       snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
>       if (snapshot_index < 0) {
> -        return -ENOENT;
> +        error_setg(errp, "Failed to find snapshot '%s' by id or name",
> +                   snapshot_id);
> +        return;
>       }
>       sn = s->snapshots[snapshot_index];
> 
> @@ -550,7 +554,9 @@ int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
>       s->nb_snapshots--;
>       ret = qcow2_write_snapshots(bs);
>       if (ret < 0) {
> -        return ret;
> +        error_setg_errno(errp, -ret, "Failed to remove snapshot '%s' from "
> +                         "snapshot list", sn.name);
> +        return;
>       }
> 
>       /*
> @@ -567,14 +573,16 @@ int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
>       ret = qcow2_update_snapshot_refcount(bs, sn.l1_table_offset,
>                                            sn.l1_size, -1);
>       if (ret < 0) {
> -        return ret;
> +        error_setg_errno(errp, -ret, "Failed to update refcounts");
> +        return;
>       }
>       qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t));
> 
>       /* must update the copied flag on the current cluster offsets */
>       ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
>       if (ret < 0) {
> -        return ret;
> +        error_setg_errno(errp, -ret, "Failed to update cluster flags");
> +        return;
>       }
> 
>   #ifdef DEBUG_ALLOC
> @@ -583,7 +591,6 @@ int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
>           qcow2_check_refcounts(bs, &result, 0);
>       }
>   #endif
> -    return 0;
>   }
> 
>   int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
> diff --git a/block/qcow2.h b/block/qcow2.h
> index 9421843..dbd332d 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -384,7 +384,9 @@ int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors);
>   /* qcow2-snapshot.c functions */
>   int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info);
>   int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id);
> -int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id);
> +void qcow2_snapshot_delete(BlockDriverState *bs,
> +                           const char *snapshot_id,
> +                           Error **errp);
>   int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab);
>   int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name);
> 
> diff --git a/block/rbd.c b/block/rbd.c
> index 1826411..1e54c55 100644
> --- a/block/rbd.c
> +++ b/block/rbd.c
> @@ -899,14 +899,18 @@ static int qemu_rbd_snap_create(BlockDriverState *bs,
>       return 0;
>   }
> 
> -static int qemu_rbd_snap_remove(BlockDriverState *bs,
> -                                const char *snapshot_name)
> +static void qemu_rbd_snap_remove(BlockDriverState *bs,
> +                                 const char *snapshot_name,
> +                                 Error **errp)
>   {
>       BDRVRBDState *s = bs->opaque;
>       int r;
> 
>       r = rbd_snap_remove(s->image, snapshot_name);
> -    return r;
> +    if (r < 0) {
> +        error_setg_errno(errp, -r, "Failed to remove snapshot '%s'",
> +                         snapshot_name);
> +    }
>   }
> 
>   static int qemu_rbd_snap_rollback(BlockDriverState *bs,
> diff --git a/block/sheepdog.c b/block/sheepdog.c
> index 20b5d06..7e0610f 100644
> --- a/block/sheepdog.c
> +++ b/block/sheepdog.c
> @@ -1937,10 +1937,12 @@ out:
>       return ret;
>   }
> 
> -static int sd_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
> +static void sd_snapshot_delete(BlockDriverState *bs,
> +                               const char *snapshot_id,
> +                               Error **errp)
>   {
>       /* FIXME: Delete specified snapshot id.  */
> -    return 0;
> +    error_setg(errp, "Deleting snapshot is not supported");
>   }
> 
>   static int sd_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
> diff --git a/include/block/block.h b/include/block/block.h
> index 1251c5c..abb636d 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -337,7 +337,9 @@ int bdrv_snapshot_create(BlockDriverState *bs,
>                            QEMUSnapshotInfo *sn_info);
>   int bdrv_snapshot_goto(BlockDriverState *bs,
>                          const char *snapshot_id);
> -int bdrv_snapshot_delete(BlockDriverState *bs, const char *snapshot_id);
> +void bdrv_snapshot_delete(BlockDriverState *bs,
> +                          const char *snapshot_id,
> +                          Error **errp);
>   int bdrv_snapshot_list(BlockDriverState *bs,
>                          QEMUSnapshotInfo **psn_info);
>   int bdrv_snapshot_load_tmp(BlockDriverState *bs,
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 6078dd3..c3f67c3 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -156,7 +156,9 @@ struct BlockDriver {
>                                   QEMUSnapshotInfo *sn_info);
>       int (*bdrv_snapshot_goto)(BlockDriverState *bs,
>                                 const char *snapshot_id);
> -    int (*bdrv_snapshot_delete)(BlockDriverState *bs, const char *snapshot_id);
> +    void (*bdrv_snapshot_delete)(BlockDriverState *bs,
> +                                 const char *snapshot_id,
> +                                 Error **errp);
>       int (*bdrv_snapshot_list)(BlockDriverState *bs,
>                                 QEMUSnapshotInfo **psn_info);
>       int (*bdrv_snapshot_load_tmp)(BlockDriverState *bs,
> diff --git a/qemu-img.c b/qemu-img.c
> index ab83fbe..9cf3467 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -1932,6 +1932,7 @@ static int img_snapshot(int argc, char **argv)
>   {
>       BlockDriverState *bs;
>       QEMUSnapshotInfo sn;
> +    Error *local_err = NULL;
>       char *filename, *snapshot_name = NULL;
>       int c, ret = 0, bdrv_oflags;
>       int action = 0;
> @@ -2029,11 +2030,8 @@ static int img_snapshot(int argc, char **argv)
>           break;
> 
>       case SNAPSHOT_DELETE:
> -        ret = bdrv_snapshot_delete(bs, snapshot_name);
> -        if (ret) {
> -            error_report("Could not delete snapshot '%s': %d (%s)",
> -                snapshot_name, ret, strerror(-ret));
> -        }
> +        bdrv_snapshot_delete(bs, snapshot_name, &local_err);
> +        ret = qemu_img_handle_error(local_err);
>           break;
>       }
> 
> diff --git a/savevm.c b/savevm.c
> index 31dcce9..ba97c41 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -2291,18 +2291,20 @@ static int del_existing_snapshots(Monitor *mon, const char *name)
>   {
>       BlockDriverState *bs;
>       QEMUSnapshotInfo sn1, *snapshot = &sn1;
> -    int ret;
> +    Error *local_err = NULL;
> 
>       bs = NULL;
>       while ((bs = bdrv_next(bs))) {
>           if (bdrv_can_snapshot(bs) &&
>               bdrv_snapshot_find(bs, snapshot, name) >= 0)
>           {
> -            ret = bdrv_snapshot_delete(bs, name);
> -            if (ret < 0) {
> -                monitor_printf(mon,
> -                               "Error while deleting snapshot on '%s'\n",
> -                               bdrv_get_device_name(bs));
> +            bdrv_snapshot_delete(bs, name, &local_err);
> +            if (error_is_set(&local_err)) {
> +                qerror_report(ERROR_CLASS_GENERIC_ERROR, "Failed to delete "
> +                              "old snapshot on device '%s': %s",
> +                              bdrv_get_device_name(bs),
> +                              error_get_pretty(local_err));
> +                error_free(local_err);
>                   return -1;
>               }
>           }
> @@ -2516,7 +2518,7 @@ int load_vmstate(const char *name)
>   void do_delvm(Monitor *mon, const QDict *qdict)
>   {
>       BlockDriverState *bs, *bs1;
> -    int ret;
> +    Error *local_err = NULL;
>       const char *name = qdict_get_str(qdict, "name");
> 
>       bs = bdrv_snapshots();
> @@ -2528,15 +2530,13 @@ void do_delvm(Monitor *mon, const QDict *qdict)
>       bs1 = NULL;
>       while ((bs1 = bdrv_next(bs1))) {
>           if (bdrv_can_snapshot(bs1)) {
> -            ret = bdrv_snapshot_delete(bs1, name);
> -            if (ret < 0) {
> -                if (ret == -ENOTSUP)
> -                    monitor_printf(mon,
> -                                   "Snapshots not supported on device '%s'\n",
> -                                   bdrv_get_device_name(bs1));
> -                else
> -                    monitor_printf(mon, "Error %d while deleting snapshot on "
> -                                   "'%s'\n", ret, bdrv_get_device_name(bs1));
> +            bdrv_snapshot_delete(bs1, name, &local_err);
> +            if (error_is_set(&local_err)) {
> +                qerror_report(ERROR_CLASS_GENERIC_ERROR, "Failed to delete "
> +                              "old snapshot on device '%s': %s",
> +                              bdrv_get_device_name(bs),
> +                              error_get_pretty(local_err));
> +                error_free(local_err);
>               }
>           }
>       }
> 


-- 
Best Regards

Wenchao Xia