Commit 95b98f34 authored by Max Reitz's avatar Max Reitz
Browse files

block/qcow2: Metadata preallocation for truncate 



We can support PREALLOC_MODE_METADATA by invoking preallocate() in
qcow2_truncate().

Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
Message-id: 20170613202107.10125-12-mreitz@redhat.com
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
parent 652fecd0

block/qcow2.c

+31 −2
Original line number Diff line number Diff line
@@ -3077,10 +3077,11 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset, 
                          PreallocMode prealloc, Error **errp)

{

    BDRVQcow2State *s = bs->opaque;

    uint64_t old_length;

    int64_t new_l1_size;

    int ret;



    if (prealloc != PREALLOC_MODE_OFF) {

    if (prealloc != PREALLOC_MODE_OFF && prealloc != PREALLOC_MODE_METADATA) {

        error_setg(errp, "Unsupported preallocation mode '%s'",

                   PreallocMode_lookup[prealloc]);

        return -ENOTSUP;
@@ -3104,8 +3105,10 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset, 
        return -ENOTSUP;

    }



    old_length = bs->total_sectors * 512;



    /* shrinking is currently not supported */

    if (offset < bs->total_sectors * 512) {

    if (offset < old_length) {

        error_setg(errp, "qcow2 doesn't support shrinking images yet");

        return -ENOTSUP;

    }
@@ -3117,6 +3120,32 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset, 
        return ret;

    }



    switch (prealloc) {

    case PREALLOC_MODE_OFF:

        break;



    case PREALLOC_MODE_METADATA:

        ret = preallocate(bs, old_length, offset);

        if (ret < 0) {

            error_setg_errno(errp, -ret, "Preallocation failed");

            return ret;

        }

        break;



    default:

        g_assert_not_reached();

    }



    if (prealloc != PREALLOC_MODE_OFF) {

        /* Flush metadata before actually changing the image size */

        ret = bdrv_flush(bs);

        if (ret < 0) {

            error_setg_errno(errp, -ret,

                             "Failed to flush the preallocated area to disk");

            return ret;

        }

    }



    /* write updated header.size */

    offset = cpu_to_be64(offset);

    ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, size),