A few block drivers will set the BDS read_only flag from their .bdrv_open() function. This means the bs->read_only flag could be set after we enable copy_on_read, as the BDRV_O_COPY_ON_READ flag check occurs prior to the call to bdrv->bdrv_open().
This adds an error return to bdrv_set_read_only(), and an error will be return if we try to set the BDS to read_only while copy_on_read is enabled. Signed-off-by: Jeff Cody <[email protected]> --- block.c | 10 +++++++++- block/bochs.c | 5 ++++- block/cloop.c | 5 ++++- block/dmg.c | 6 +++++- block/rbd.c | 6 +++++- block/vvfat.c | 15 ++++++++++++--- include/block/block.h | 2 +- 7 files changed, 40 insertions(+), 9 deletions(-) diff --git a/block.c b/block.c index 7b4c7ef..f60d5ea 100644 --- a/block.c +++ b/block.c @@ -192,9 +192,17 @@ void path_combine(char *dest, int dest_size, } } -void bdrv_set_read_only(BlockDriverState *bs, bool read_only) +int bdrv_set_read_only(BlockDriverState *bs, bool read_only, Error **errp) { + /* Do not set read_only if copy_on_read is enabled */ + if (bs->copy_on_read && read_only) { + error_setg(errp, "Cannot set node '%s' to r/o while COW enabled", + bdrv_get_device_or_node_name(bs)); + return -EINVAL; + } + bs->read_only = read_only; + return 0; } void bdrv_get_full_backing_filename_from_filename(const char *backed, diff --git a/block/bochs.c b/block/bochs.c index bdc2831..a759b6e 100644 --- a/block/bochs.c +++ b/block/bochs.c @@ -110,7 +110,10 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags, return -EINVAL; } - bdrv_set_read_only(bs, true); /* no write support yet */ + ret = bdrv_set_read_only(bs, true, errp); /* no write support yet */ + if (ret < 0) { + return ret; + } ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs)); if (ret < 0) { diff --git a/block/cloop.c b/block/cloop.c index 11f17c8..d6597fc 100644 --- a/block/cloop.c +++ b/block/cloop.c @@ -72,7 +72,10 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags, return -EINVAL; } - bdrv_set_read_only(bs, true); + ret = bdrv_set_read_only(bs, true, errp); + if (ret < 0) { + return ret; + } /* read header */ ret = bdrv_pread(bs->file, 128, &s->block_size, 4); diff --git a/block/dmg.c b/block/dmg.c index 27ce4a6..900ae5a 100644 --- a/block/dmg.c +++ b/block/dmg.c @@ -419,8 +419,12 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags, return -EINVAL; } + ret = bdrv_set_read_only(bs, true, errp); + if (ret < 0) { + return ret; + } + block_module_load_one("dmg-bz2"); - bdrv_set_read_only(bs, true); s->n_chunks = 0; s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL; diff --git a/block/rbd.c b/block/rbd.c index 6ad2904..328e4a9 100644 --- a/block/rbd.c +++ b/block/rbd.c @@ -641,7 +641,11 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags, goto failed_open; } - bdrv_set_read_only(bs, (s->snap != NULL)); + r = bdrv_set_read_only(bs, (s->snap != NULL), &local_err); + if (r < 0) { + error_propagate(errp, local_err); + goto failed_open; + } qemu_opts_del(opts); return 0; diff --git a/block/vvfat.c b/block/vvfat.c index d4ce6d7..34a2854 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -1156,8 +1156,6 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags, s->current_cluster=0xffffffff; - /* read only is the default for safety */ - bdrv_set_read_only(bs, true); s->qcow = NULL; s->qcow_filename = NULL; s->fat2 = NULL; @@ -1173,7 +1171,18 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags, if (ret < 0) { goto fail; } - bdrv_set_read_only(bs, false); + ret = bdrv_set_read_only(bs, false, &local_err); + if (ret < 0) { + error_propagate(errp, local_err); + goto fail; + } + } else { + /* read only is the default for safety */ + ret = bdrv_set_read_only(bs, true, &local_err); + if (ret < 0) { + error_propagate(errp, local_err); + goto fail; + } } bs->total_sectors = cyls * heads * secs; diff --git a/include/block/block.h b/include/block/block.h index 06c9032..beb563a 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -426,7 +426,7 @@ int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *base, int64_t sector_num, int nb_sectors, int *pnum); bool bdrv_is_read_only(BlockDriverState *bs); -void bdrv_set_read_only(BlockDriverState *bs, bool read_only); +int bdrv_set_read_only(BlockDriverState *bs, bool read_only, Error **errp); bool bdrv_is_sg(BlockDriverState *bs); bool bdrv_is_inserted(BlockDriverState *bs); int bdrv_media_changed(BlockDriverState *bs); -- 2.9.3
