From 04ecb169e46d027d3c5ac0ec2277e10065fa8c9c Mon Sep 17 00:00:00 2001 From: Jeffrey Cody Date: Wed, 26 Apr 2017 20:08:49 +0200 Subject: [PATCH 03/11] block: do not set BDS read_only if copy_on_read enabled RH-Author: Jeffrey Cody Message-id: Patchwork-id: 74897 O-Subject: [RHEV-7.4 qemu-kvm-rhev 2/8] block: do not set BDS read_only if copy_on_read enabled Bugzilla: 1189998 RH-Acked-by: John Snow RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Max Reitz 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. This patch also changes the behavior of vvfat. Before, vvfat could override the drive 'readonly' flag with its own, internal 'rw' flag. For instance, this -drive parameter would result in a writable image: "-drive format=vvfat,dir=/tmp/vvfat,rw,if=virtio,readonly=on" This is not correct. Now, attempting to use the above -drive parameter will result in an error (i.e., 'rw' is incompatible with 'readonly=on'). Signed-off-by: Jeff Cody Reviewed-by: Stefan Hajnoczi Reviewed-by: John Snow Message-id: 0c5b4c1cc2c651471b131f21376dfd5ea24d2196.1491597120.git.jcody@redhat.com (cherry picked from commit e2b8247a322cd92945785edf25f09e6b3e8285f9) Signed-off-by: Miroslav Rezanina --- block.c | 10 +++++++++- block/bochs.c | 5 ++++- block/cloop.c | 5 ++++- block/dmg.c | 6 +++++- block/rbd.c | 11 ++++++++++- block/vvfat.c | 19 +++++++++++++++---- include/block/block.h | 2 +- 7 files changed, 48 insertions(+), 10 deletions(-) diff --git a/block.c b/block.c index 25a4cfd..4766b8a 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, "Can't set node '%s' to r/o with copy-on-read 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..1c43171 100644 --- a/block/rbd.c +++ b/block/rbd.c @@ -635,13 +635,22 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags, goto failed_shutdown; } + /* rbd_open is always r/w */ r = rbd_open(s->io_ctx, s->name, &s->image, s->snap); if (r < 0) { error_setg_errno(errp, -r, "error reading header from %s", s->name); goto failed_open; } - bdrv_set_read_only(bs, (s->snap != NULL)); + /* If we are using an rbd snapshot, we must be r/o, otherwise + * leave as-is */ + if (s->snap != NULL) { + r = bdrv_set_read_only(bs, true, &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..b509d55 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; @@ -1169,11 +1167,24 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags, s->sector_count = cyls * heads * secs - (s->first_sectors_number - 1); if (qemu_opt_get_bool(opts, "rw", false)) { - ret = enable_write_target(bs, errp); + if (!bdrv_is_read_only(bs)) { + ret = enable_write_target(bs, errp); + if (ret < 0) { + goto fail; + } + } else { + ret = -EPERM; + error_setg(errp, + "Unable to set VVFAT to 'rw' when drive is read-only"); + 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; } - bdrv_set_read_only(bs, false); } bs->total_sectors = cyls * heads * secs; diff --git a/include/block/block.h b/include/block/block.h index 16eb909..3525590 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -434,7 +434,7 @@ 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); -- 1.8.3.1