Commit 54a32bfe authored by Kevin Wolf's avatar Kevin Wolf
Browse files

block: Allow reopen rw without BDRV_O_ALLOW_RDWR 



BDRV_O_ALLOW_RDWR is a flag that tells whether qemu can internally
reopen a node read-write temporarily because the user requested
read-write for the top-level image, but qemu decided that read-only is
enough for this node (a backing file).

bdrv_reopen() is different, it is also used for cases where the user
changed their mind and wants to update the options. There is no reason
to forbid making a node read-write in that case.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarJeff Cody <jcody@redhat.com>
Reviewed-by: default avatarJohn Snow <jsnow@redhat.com>
parent 8aecf1d1

block.c

+7 −4
Original line number Diff line number Diff line
@@ -246,7 +246,8 @@ bool bdrv_is_writable(BlockDriverState *bs) 
    return !bdrv_is_read_only(bs) && !(bs->open_flags & BDRV_O_INACTIVE);

}



int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, Error **errp)

int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,

                           bool ignore_allow_rdw, Error **errp)

{

    /* Do not set read_only if copy_on_read is enabled */

    if (bs->copy_on_read && read_only) {
@@ -256,7 +257,9 @@ int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, Error **errp) 
    }



    /* Do not clear read_only if it is prohibited */

    if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR)) {

    if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&

        !ignore_allow_rdw)

    {

        error_setg(errp, "Node '%s' is read only",

                   bdrv_get_device_or_node_name(bs));

        return -EPERM;
@@ -269,7 +272,7 @@ int bdrv_set_read_only(BlockDriverState *bs, bool read_only, Error **errp) 
{

    int ret = 0;



    ret = bdrv_can_set_read_only(bs, read_only, errp);

    ret = bdrv_can_set_read_only(bs, read_only, false, errp);

    if (ret < 0) {

        return ret;

    }
@@ -2907,7 +2910,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, 
     * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is

     * not set, or if the BDS still has copy_on_read enabled */

    read_only = !(reopen_state->flags & BDRV_O_RDWR);

    ret = bdrv_can_set_read_only(reopen_state->bs, read_only, &local_err);

    ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err);

    if (local_err) {

        error_propagate(errp, local_err);

        goto error;

include/block/block.h

+2 −1
Original line number Diff line number Diff line
@@ -436,7 +436,8 @@ int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *base, 


bool bdrv_is_read_only(BlockDriverState *bs);

bool bdrv_is_writable(BlockDriverState *bs);

int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, Error **errp);

int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,

                           bool ignore_allow_rdw, Error **errp);

int bdrv_set_read_only(BlockDriverState *bs, bool read_only, Error **errp);

bool bdrv_is_sg(BlockDriverState *bs);

bool bdrv_is_inserted(BlockDriverState *bs);