From: George Dunlap Date: Thu, 24 Mar 2016 17:18:34 +0000 (+0000) Subject: libxl: Share logic for finding path between qemuu and pygrub X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~1392 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=ba09d5fcaa7d02645e9e78a66d3f1da8cef49008;p=xen.git libxl: Share logic for finding path between qemuu and pygrub qemu can also access disks which will be provided with a qdisk backend directly; add a flag to libxl__device_disk_find_local_path to indicate whether to check for qdisk direct access. Call libxl__device_disk_find_local_path() for most paths. If we can't find a local path, print an error and skip the disk, rather than using a bogus path. Now if there is no local access to the disk (i.e., because the disk has a non-local backend, or relies on a custom hotplug script), libxl will now print a warning and not provide the emulated disk, rather than providing bogus parameters to qemu which cause it to error out. (Such disks will still be available via the PV backend.) I left the libxl__blktap_devpath in the qemuu-specific code rather than sharing it with the pyrgub code because: 1) When the pygrub path runs the guest disks have not yet been set up 2) libxl__blktap_devpath() will give you the existing devpath if it already exists, but will set one up for you if you don't. So on the pygrub path, this would end up setting up a new tap device. 3) There is no tap-specific teardown code on the pygrub path, and I don't want to add any (particularly since I'm hoping to remove tapdisk altogether soon). Signed-off-by: George Dunlap Acked-by: Ian Jackson Tested-by: George Dunlap --- diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c index 805c06de4a..c46c2ec1fd 100644 --- a/tools/libxl/libxl.c +++ b/tools/libxl/libxl.c @@ -3069,8 +3069,9 @@ static char * libxl__alloc_vdev(libxl__gc *gc, void *get_vdev_user, /* Callbacks */ -static char *libxl__device_disk_find_local_path(libxl__gc *gc, - const libxl_device_disk *disk) +char *libxl__device_disk_find_local_path(libxl__gc *gc, + const libxl_device_disk *disk, + bool qdisk_direct) { char *path = NULL; @@ -3091,6 +3092,16 @@ static char *libxl__device_disk_find_local_path(libxl__gc *gc, goto out; } + /* + * If we're being called for a qemu path, we can pass the target + * string directly as well + */ + if (qdisk_direct && disk->backend == LIBXL_DISK_BACKEND_QDISK) { + path = libxl__strdup(gc, disk->pdev_path); + LOG(DEBUG, "Directly accessing local QDISK target %s", path); + goto out; + } + out: return path; } @@ -3115,7 +3126,7 @@ void libxl__device_disk_local_initiate_attach(libxl__egc *egc, LOG(DEBUG, "Trying to find local path"); - dls->diskpath = libxl__device_disk_find_local_path(gc, in_disk); + dls->diskpath = libxl__device_disk_find_local_path(gc, in_disk, false); if (dls->diskpath) { LOG(DEBUG, "Local path found, executing callback."); dls->callback(egc, dls, 0); diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c index c11e9b811e..2a3d0326b7 100644 --- a/tools/libxl/libxl_dm.c +++ b/tools/libxl/libxl_dm.c @@ -1327,23 +1327,42 @@ static int libxl__build_device_model_args_new(libxl__gc *gc, if (disks[i].format == LIBXL_DISK_FORMAT_EMPTY) { if (!disks[i].is_cdrom) { - LOG(WARN, "cannot support"" empty disk format for %s", + LOG(WARN, "Cannot support empty disk format for %s", disks[i].vdev); continue; } } else { if (format == NULL) { LOG(WARN, - "unable to determine"" disk image format %s", + "Unable to determine disk image format: %s\n" + "Disk will be available via PV drivers but not as an" + "emulated disk.", disks[i].vdev); continue; } + /* + * We can't call libxl__blktap_devpath from + * libxl__device_disk_find_local_path for now because + * the bootloader is called before the disks are set + * up, so this function would set up a blktap node, + * but there's no TAP tear-down on error conditions in + * the bootloader path. + */ if (disks[i].backend == LIBXL_DISK_BACKEND_TAP) target_path = libxl__blktap_devpath(gc, disks[i].pdev_path, disks[i].format); - else - target_path = disks[i].pdev_path; + else + target_path = libxl__device_disk_find_local_path(gc, + &disks[i], true); + + if (!target_path) { + LOG(WARN, "No way to get local access disk to image: %s\n" + "Disk will be available via PV drivers but not as an" + "emulated disk.", + disks[i].vdev); + continue; + } } if (disks[i].is_cdrom) { diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h index e3c919dfe6..c87c42ae6e 100644 --- a/tools/libxl/libxl_internal.h +++ b/tools/libxl/libxl_internal.h @@ -2716,6 +2716,14 @@ static inline void libxl__device_disk_local_init(libxl__disk_local_state *dls) dls->rc = 0; } +/* + * See if we can find a way to access a disk locally + */ +_hidden char * libxl__device_disk_find_local_path(libxl__gc *gc, + const libxl_device_disk *disk, + bool qdisk_direct); + + /* Make a disk available in this (the control) domain. Always calls * dls->callback when finished. * State Idle -> Attaching