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authorJeff Cody <jcody@redhat.com>2017-04-07 16:55:26 -0400
committerJeff Cody <jcody@redhat.com>2017-04-24 15:09:33 -0400
commite2b8247a322cd92945785edf25f09e6b3e8285f9 (patch)
treee63597037c31624af5aefaa18551b000d52dc912 /block/vvfat.c
parentfe5241bfe3fb61ec3f589ceacd91c1469bfd400f (diff)
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block: do not set BDS read_only if copy_on_read enabled
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 <jcody@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Message-id: 0c5b4c1cc2c651471b131f21376dfd5ea24d2196.1491597120.git.jcody@redhat.com
Diffstat (limited to 'block/vvfat.c')
-rw-r--r--block/vvfat.c19
1 files changed, 15 insertions, 4 deletions
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;