In bdrv_find_backing_image when looking for the base BDS of a backing chain and a BDS having a multiple children block driver is found return NULL and set an error message.
This will hopefully remove any unwanted interference between stream, commit and drivers like quorum. CC: Jeff Cody <jc...@redhat.com> Signed-off-by: Benoît Canet <benoit.ca...@nodalink.com> --- block.c | 17 +++++++++++++++-- blockdev.c | 18 ++++++++++++------ include/block/block.h | 3 ++- 3 files changed, 29 insertions(+), 9 deletions(-) diff --git a/block.c b/block.c index d06dd51..ea86252 100644 --- a/block.c +++ b/block.c @@ -4339,9 +4339,13 @@ int bdrv_is_snapshot(BlockDriverState *bs) /* backing_file can either be relative, or absolute, or a protocol. If it is * relative, it must be relative to the chain. So, passing in bs->filename * from a BDS as backing_file should not be done, as that may be relative to - * the CWD rather than the chain. */ + * the CWD rather than the chain. + * If a multiple children BDS driver is found down the backing chain path then + * return NULL and set an error message. + */ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, - const char *backing_file) + const char *backing_file, + Error **errp) { char *filename_full = NULL; char *backing_file_full = NULL; @@ -4362,6 +4366,15 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, for (curr_bs = bs; curr_bs->backing_hd; curr_bs = curr_bs->backing_hd) { + /* If a BDS having a multiple children block driver is found then the + * function should fail. + */ + if (curr_bs->drv && curr_bs->drv->supports_multiple_children) { + error_setg(errp, "multiple children block driver found down the " + "backing chain"); + break; + } + /* If either of the filename paths is actually a protocol, then * compare unmodified paths; otherwise make paths relative */ if (is_protocol || path_has_protocol(curr_bs->backing_file)) { diff --git a/blockdev.c b/blockdev.c index e919566..4c5c28e 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1894,9 +1894,11 @@ void qmp_block_stream(const char *device, } if (has_base) { - base_bs = bdrv_find_backing_image(bs, base); + base_bs = bdrv_find_backing_image(bs, base, errp); if (base_bs == NULL) { - error_set(errp, QERR_BASE_NOT_FOUND, base); + if (!*errp) { + error_set(errp, QERR_BASE_NOT_FOUND, base); + } return; } base_name = base; @@ -1965,23 +1967,27 @@ void qmp_block_commit(const char *device, if (has_top && top) { if (strcmp(bs->filename, top) != 0) { - top_bs = bdrv_find_backing_image(bs, top); + top_bs = bdrv_find_backing_image(bs, top, errp); } } if (top_bs == NULL) { - error_setg(errp, "Top image file %s not found", top ? top : "NULL"); + if (!*errp) { + error_setg(errp, "Top image file %s not found", top ? top : "NULL"); + } return; } if (has_base && base) { - base_bs = bdrv_find_backing_image(top_bs, base); + base_bs = bdrv_find_backing_image(top_bs, base, errp); } else { base_bs = bdrv_find_base(top_bs); } if (base_bs == NULL) { - error_set(errp, QERR_BASE_NOT_FOUND, base ? base : "NULL"); + if (!*errp) { + error_set(errp, QERR_BASE_NOT_FOUND, base ? base : "NULL"); + } return; } diff --git a/include/block/block.h b/include/block/block.h index 8f4ad16..65cde65 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -272,7 +272,8 @@ int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num, int coroutine_fn bdrv_co_write_zeroes(BlockDriverState *bs, int64_t sector_num, int nb_sectors, BdrvRequestFlags flags); BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, - const char *backing_file); + const char *backing_file, + Error **errp); int bdrv_get_backing_file_depth(BlockDriverState *bs); void bdrv_refresh_filename(BlockDriverState *bs); int bdrv_truncate(BlockDriverState *bs, int64_t offset); -- 2.1.0