motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-04 00:03:54 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

block: Fix snapshot=on cache modes

Browse source 
Since commit 91a097e, we end up with a somewhat weird cache mode
configuration with snapshot=on: The commit broke the cache mode
inheritance for the snapshot overlay so that it is opened as
writethrough instead of unsafe now. The following bdrv_append() call to
put it on top of the tree swaps the WCE flag with the snapshot's backing
file (i.e. the originally given file), so what we eventually get is
cache=writeback on the temporary overlay and
cache=writethrough,cache.no-flush=on on the real image file.

This patch changes things so that the temporary overlay gets
cache=unsafe again like it used to, and the real images get whatever the
user specified. This means that cache.direct is now respected even with
snapshot=on, and in the case of committing changes, the final flush is
no longer ignored except explicitly requested by the user.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Kevin Wolf 2016-03-07 13:02:15 +01:00
parent f86b8b584b
commit 73176bee99
3 changed files with 25 additions and 19 deletions
Download patch file Download diff file Expand all files Collapse all files

7
blockdev.c
View file

@ -593,13 +593,6 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_DIRECT, "off");
qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_NO_FLUSH, "off");
if (snapshot) {
/* always use cache=unsafe with snapshot */
qdict_put(bs_opts, BDRV_OPT_CACHE_WB, qstring_from_str("on"));
qdict_put(bs_opts, BDRV_OPT_CACHE_DIRECT, qstring_from_str("off"));
qdict_put(bs_opts, BDRV_OPT_CACHE_NO_FLUSH, qstring_from_str("on"));
}
if (runstate_check(RUN_STATE_INMIGRATE)) {
bdrv_flags |= BDRV_O_INACTIVE;
}