| Message ID | fcdfe9c672ecdb179264187e0671b5432fced4c4.1491416061.git.jcody@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 04/05/2017 02:28 PM, Jeff Cody wrote: > 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 <jcody@redhat.com> > --- > 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", COW? > + 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); >
On Wed, Apr 05, 2017 at 03:16:38PM -0400, John Snow wrote: > > > On 04/05/2017 02:28 PM, Jeff Cody wrote: > > 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 <jcody@redhat.com> > > --- > > 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", > > COW? > Mooo! You are right, that should be COR (or better yet, I should just write it out - copy on read). > > + 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); > >
On Wed, Apr 05, 2017 at 02:28:44PM -0400, Jeff Cody wrote: Minor comments but: Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> > 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", Users might be puzzled by "COR". The -drive option is called "copy-on-read" so spelling it out is clearer than using an acronym. > @@ -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; > + } read_only = false by default. There's no need to set it now that you've moved the bdrv_set_read_only(bs, true) call.
On Wed, Apr 05, 2017 at 02:28:44PM -0400, Jeff Cody wrote: > @@ -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; > + } I realized later in the series why you are doing this. The error code path introduces a resource leak: enable_write_target() has already been called and isn't cleaned up by the fail label. It would be cleaner to check that bs is writable before calling enable_write_target(). Stefan
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);
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 <jcody@redhat.com> --- 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(-)