Re: [libvirt] [PATCH] Compressed save image format for Qemu.

Implement a compressed save image format for qemu. While ideally we would have the choice between compressed/non-compressed available to the libvirt API, unfortunately there is no "flags" parameter to the virDomainSave() API. Therefore, implement this as a qemu.conf option. Both gzip and bzip2 are implemented, and it should be very easy to implement additional compression methods. One open question is if/how we should detect the gzip and bzip2 binaries. One way to do it is to do compile-time setting of the paths (via configure.in), but that doesn't seem like a great thing to do. Another solution (my preferred solution) is not to detect at all; when we go to run the commands that need them, if they aren't available, or aren't available in one of the standard paths, then we'll fail. Maybe somebody else has another option or opinion, though. In the future, we'll have a more robust (managed) save/restore API, at which time we can expose this functionality properly in the API. V2: get rid of redundant dd command and just use >> to append data. V3: Add back the missing pieces for the enum and bumping the save version.

diff --git a/src/qemu_driver.c b/src/qemu_driver.c index 20906ef..8d700bf 100644 --- a/src/qemu_driver.c +++ b/src/qemu_driver.c @@ -3411,18 +3411,26 @@ static char *qemudEscapeShellArg(const char *in) } #define QEMUD_SAVE_MAGIC "LibvirtQemudSave" -#define QEMUD_SAVE_VERSION 1 +#define QEMUD_SAVE_VERSION 2 + +enum qemud_save_formats { + QEMUD_SAVE_FORMAT_RAW, + QEMUD_SAVE_FORMAT_GZIP, + QEMUD_SAVE_FORMAT_BZIP2, +}; struct qemud_save_header { char magic[sizeof(QEMUD_SAVE_MAGIC)-1]; int version; int xml_len; int was_running; - int unused[16]; + char compressed; + int unused[15]; };