qemu/include
Ian Main fc5d3f8432 Implement sync modes for drive-backup.
This patch adds sync-modes to the drive-backup interface and
implements the FULL, NONE and TOP modes of synchronization.

FULL performs as before copying the entire contents of the drive
while preserving the point-in-time using CoW.
NONE only copies new writes to the target drive.
TOP copies changes to the topmost drive image and preserves the
point-in-time using CoW.

For sync mode TOP are creating a new target image using the same backing
file as the original disk image.  Then any new data that has been laid
on top of it since creation is copied in the main backup_run() loop.
There is an extra check in the 'TOP' case so that we don't bother to copy
all the data of the backing file as it already exists in the target.
This is where the bdrv_co_is_allocated() is used to determine if the
data exists in the topmost layer or below.

Also any new data being written is intercepted via the write_notifier
hook which ends up calling backup_do_cow() to copy old data out before
it gets overwritten.

For mode 'NONE' we create the new target image and only copy in the
original data from the disk image starting from the time the call was
made.  This preserves the point in time data by only copying the parts
that are *going to change* to the target image.  This way we can
reconstruct the final image by checking to see if the given block exists
in the new target image first, and if it does not, you can get it from
the original image.  This is basically an optimization allowing you to
do point-in-time snapshots with low overhead vs the 'FULL' version.

Since there is no old data to copy out the loop in backup_run() for the
NONE case just calls qemu_coroutine_yield() which only wakes up after
an event (usually cancel in this case).  The rest is handled by the
before_write notifier which again calls backup_do_cow() to write out
the old data so it can be preserved.

Signed-off-by: Ian Main <imain@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-07-26 22:01:31 +02:00
..
block Implement sync modes for drive-backup. 2013-07-26 22:01:31 +02:00
disas Add moxie disassembler 2013-03-23 14:25:41 +00:00
exec Merge remote-tracking branch 'riku/linux-user-for-upstream' into staging 2013-07-25 15:56:06 -05:00
fpu softfloat: Implement uint64_to_float128 2013-01-05 10:12:50 +00:00
hw isa_mmio: delete 2013-07-25 08:12:27 -05:00
migration rdma: account for the time spent in MIG_STATE_SETUP through QMP 2013-07-23 13:06:37 +02:00
monitor net: add support of mac-programming over macvtap in QEMU side 2013-07-15 21:23:08 +03:00
net net: add support of mac-programming over macvtap in QEMU side 2013-07-15 21:23:08 +03:00
qapi Implement qdict_flatten() 2013-07-26 22:01:31 +02:00
qemu QemuOpts: Add qemu_opt_unset() 2013-07-26 21:10:11 +02:00
qom cpu: Move gdb_regs field from CPU_COMMON to CPUState 2013-07-23 02:41:33 +02:00
sysemu kvm: Change kvm_{insert,remove}_breakpoint() argument to CPUState 2013-07-23 02:41:32 +02:00
ui vnc: use booleans for vnc_connect, vnc_listen_read and vnc_display_add_client 2013-06-21 22:52:50 +04:00
config.h janitor: move remaining public headers to include/ 2012-12-19 08:32:46 +01:00
elf.h include/elf.h: add aarch64 ELF machine and relocs 2013-06-12 16:20:22 +01:00
glib-compat.h glib: add a compatibility interface for g_timeout_add_seconds 2013-03-25 13:10:40 -05:00
qemu-common.h Introduce async_run_on_cpu() 2013-07-12 19:36:01 +02:00
qemu-io.h qemu-io: Interface cleanup 2013-06-06 11:27:05 +02:00
trace.h build: some simplifications for "trace/Makefile.objs" 2013-01-12 18:42:51 +01:00