Commit eaa2410f authored by Kevin Wolf's avatar Kevin Wolf
Browse files

block: Require auto-read-only for existing fallbacks 



Some block drivers have traditionally changed their node to read-only
mode without asking the user. This behaviour has been marked deprecated
since 2.11, expecting users to provide an explicit read-only=on option.

Now that we have auto-read-only=on, enable these drivers to make use of
the option.

This is the only use of bdrv_set_read_only(), so we can make it a bit
more specific and turn it into a bdrv_apply_auto_read_only() that is
more convenient for drivers to use.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
parent a51b9c48

block.c

+27 −15
Original line number Diff line number Diff line
@@ -266,29 +266,41 @@ int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, 
    return 0;

}



/* TODO Remove (deprecated since 2.11)

 * Block drivers are not supposed to automatically change bs->read_only.

 * Instead, they should just check whether they can provide what the user

 * explicitly requested and error out if read-write is requested, but they can

 * only provide read-only access. */

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

/*

 * Called by a driver that can only provide a read-only image.

 *

 * Returns 0 if the node is already read-only or it could switch the node to

 * read-only because BDRV_O_AUTO_RDONLY is set.

 *

 * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set

 * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg

 * is not NULL, it is used as the error message for the Error object.

 */

int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,

                              Error **errp)

{

    int ret = 0;



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

    if (ret < 0) {

        return ret;

    if (!(bs->open_flags & BDRV_O_RDWR)) {

        return 0;

    }

    if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {

        goto fail;

    }



    bs->read_only = read_only;

    ret = bdrv_can_set_read_only(bs, true, false, NULL);

    if (ret < 0) {

        goto fail;

    }



    if (read_only) {

    bs->read_only = true;

    bs->open_flags &= ~BDRV_O_RDWR;

    } else {

        bs->open_flags |= BDRV_O_RDWR;

    }



    return 0;



fail:

    error_setg(errp, "%s", errmsg ?: "Image is read-only");

    return -EACCES;

}



void bdrv_get_full_backing_filename_from_filename(const char *backed,

block/bochs.c

+6 −11
Original line number Diff line number Diff line
@@ -105,23 +105,18 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags, 
    struct bochs_header bochs;

    int ret;



    /* No write support yet */

    ret = bdrv_apply_auto_read_only(bs, NULL, errp);

    if (ret < 0) {

        return ret;

    }



    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,

                               false, errp);

    if (!bs->file) {

        return -EINVAL;

    }



    if (!bdrv_is_read_only(bs)) {

        error_report("Opening bochs images without an explicit read-only=on "

                     "option is deprecated. Future versions will refuse to "

                     "open the image instead of automatically marking the "

                     "image read-only.");

        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) {

        return ret;

block/cloop.c

+5 −11
Original line number Diff line number Diff line
@@ -67,23 +67,17 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags, 
    uint32_t offsets_size, max_compressed_block_size = 1, i;

    int ret;



    ret = bdrv_apply_auto_read_only(bs, NULL, errp);

    if (ret < 0) {

        return ret;

    }



    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,

                               false, errp);

    if (!bs->file) {

        return -EINVAL;

    }



    if (!bdrv_is_read_only(bs)) {

        error_report("Opening cloop images without an explicit read-only=on "

                     "option is deprecated. Future versions will refuse to "

                     "open the image instead of automatically marking the "

                     "image read-only.");

        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);

    if (ret < 0) {

block/dmg.c

+5 −11
Original line number Diff line number Diff line
@@ -413,23 +413,17 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags, 
    int64_t offset;

    int ret;



    ret = bdrv_apply_auto_read_only(bs, NULL, errp);

    if (ret < 0) {

        return ret;

    }



    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,

                               false, errp);

    if (!bs->file) {

        return -EINVAL;

    }



    if (!bdrv_is_read_only(bs)) {

        error_report("Opening dmg images without an explicit read-only=on "

                     "option is deprecated. Future versions will refuse to "

                     "open the image instead of automatically marking the "

                     "image read-only.");

        ret = bdrv_set_read_only(bs, true, errp);

        if (ret < 0) {

            return ret;

        }

    }



    block_module_load_one("dmg-bz2");



    s->n_chunks = 0;

block/rbd.c

+4 −11
Original line number Diff line number Diff line
@@ -780,19 +780,12 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags, 
    /* If we are using an rbd snapshot, we must be r/o, otherwise

     * leave as-is */

    if (s->snap != NULL) {

        if (!bdrv_is_read_only(bs)) {

            error_report("Opening rbd snapshots without an explicit "

                         "read-only=on option is deprecated. Future versions "

                         "will refuse to open the image instead of "

                         "automatically marking the image read-only.");

            r = bdrv_set_read_only(bs, true, &local_err);

        r = bdrv_apply_auto_read_only(bs, "rbd snapshots are read-only", errp);

        if (r < 0) {

            rbd_close(s->image);

                error_propagate(errp, local_err);

            goto failed_open;

        }

    }

    }



    r = 0;

    goto out;