Commit 4e4bf5c4 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

block: Attach bs->file only during .bdrv_open() 



The way that attaching bs->file worked was a bit unusual in that it was
the only child that would be attached to a node which is not opened yet.
Because of this, the block layer couldn't know yet which permissions the
driver would eventually need.

This patch moves the point where bs->file is attached to the beginning
of the individual .bdrv_open() implementations, so drivers already know
what they are going to do with the child. This is also more consistent
with how driver-specific children work.

For a moment, bdrv_open() gets its own BdrvChild to perform image
probing, but instead of directly assigning this BdrvChild to the BDS, it
becomes a temporary one and the node name is passed as an option to the
drivers, so that they can simply use bdrv_open_child() to create another
reference for their own use.

This duplicated child for (the not opened yet) bs is not the final
state, a follow-up patch will change the image probing code to use a
BlockBackend, which is completely independent of bs.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarMax Reitz <mreitz@redhat.com>
parent 52cdbc58

block.c

+24 −11
Original line number Diff line number Diff line
@@ -1103,13 +1103,6 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file, 
        assert(!drv->bdrv_needs_filename || filename != NULL);

        ret = drv->bdrv_file_open(bs, options, open_flags, &local_err);

    } else {

        if (file == NULL) {

            error_setg(errp, "Can't use '%s' as a block driver for the "

                       "protocol level", drv->format_name);

            ret = -EINVAL;

            goto free_and_fail;

        }

        bs->file = file;

        ret = drv->bdrv_open(bs, options, open_flags, &local_err);

    }
@@ -1145,7 +1138,6 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file, 
    return 0;



free_and_fail:

    bs->file = NULL;

    g_free(bs->opaque);

    bs->opaque = NULL;

    bs->drv = NULL;
@@ -1368,8 +1360,19 @@ void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child) 
    }



    if (child->bs->inherits_from == parent) {

        BdrvChild *c;



        /* Remove inherits_from only when the last reference between parent and

         * child->bs goes away. */

        QLIST_FOREACH(c, &parent->children, next) {

            if (c != child && c->bs == child->bs) {

                break;

            }

        }

        if (c == NULL) {

            child->bs->inherits_from = NULL;

        }

    }



    bdrv_root_unref_child(child);

}
@@ -1789,13 +1792,20 @@ static BlockDriverState *bdrv_open_inherit(const char *filename, 
        qdict_del(options, "backing");

    }



    /* Open image file without format layer */

    /* Open image file without format layer. This BdrvChild is only used for

     * probing, the block drivers will do their own bdrv_open_child() for the

     * same BDS, which is why we put the node name back into options. */

    if ((flags & BDRV_O_PROTOCOL) == 0) {

        /* FIXME Shouldn't attach a child to a node that isn't opened yet. */

        file = bdrv_open_child(filename, options, "file", bs,

                               &child_file, true, &local_err);

        if (local_err) {

            goto fail;

        }

        if (file != NULL) {

            qdict_put(options, "file",

                      qstring_from_str(bdrv_get_node_name(file->bs)));

        }

    }



    /* Image format probing */
@@ -1835,7 +1845,7 @@ static BlockDriverState *bdrv_open_inherit(const char *filename, 
        goto fail;

    }



    if (file && (bs->file != file)) {

    if (file) {

        bdrv_unref_child(bs, file);

        file = NULL;

    }
@@ -1901,6 +1911,9 @@ fail: 
    if (file != NULL) {

        bdrv_unref_child(bs, file);

    }

    if (bs->file != NULL) {

        bdrv_unref_child(bs, bs->file);

    }

    QDECREF(snapshot_options);

    QDECREF(bs->explicit_options);

    QDECREF(bs->options);

block/bochs.c

+6 −0
Original line number Diff line number Diff line
@@ -104,6 +104,12 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags, 
    struct bochs_header bochs;

    int ret;



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

                               false, errp);

    if (!bs->file) {

        return -EINVAL;

    }



    bs->read_only = true; /* no write support yet */



    ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));

block/cloop.c

+6 −0
Original line number Diff line number Diff line
@@ -66,6 +66,12 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags, 
    uint32_t offsets_size, max_compressed_block_size = 1, i;

    int ret;



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

                               false, errp);

    if (!bs->file) {

        return -EINVAL;

    }



    bs->read_only = true;



    /* read header */

block/crypto.c

+6 −0
Original line number Diff line number Diff line
@@ -300,6 +300,12 @@ static int block_crypto_open_generic(QCryptoBlockFormat format, 
    QCryptoBlockOpenOptions *open_opts = NULL;

    unsigned int cflags = 0;



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

                               false, errp);

    if (!bs->file) {

        return -EINVAL;

    }



    opts = qemu_opts_create(opts_spec, NULL, 0, &error_abort);

    qemu_opts_absorb_qdict(opts, options, &local_err);

    if (local_err) {

block/dmg.c

+6 −0
Original line number Diff line number Diff line
@@ -413,6 +413,12 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags, 
    int64_t offset;

    int ret;



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

                               false, errp);

    if (!bs->file) {

        return -EINVAL;

    }



    block_module_load_one("dmg-bz2");

    bs->read_only = true;