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author | Kevin Wolf <kwolf@redhat.com> | 2013-03-28 15:29:24 +0100 |
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committer | Kevin Wolf <kwolf@redhat.com> | 2013-04-22 10:27:59 +0200 |
commit | 31ca6d077c24b7aaa322d8930e3e5debbdb4a047 (patch) | |
tree | 81974b0ff7bd37ca4493b0c4f95556adaab2f1f0 /block.c | |
parent | 2af5ef70af9fdc823407ddc4ae14766806d4837a (diff) | |
download | qemu-31ca6d077c24b7aaa322d8930e3e5debbdb4a047.zip qemu-31ca6d077c24b7aaa322d8930e3e5debbdb4a047.tar.gz qemu-31ca6d077c24b7aaa322d8930e3e5debbdb4a047.tar.bz2 |
block: Add driver-specific options for backing files
Options starting in "backing." are passed to the backing file now. If
you don't need to specify the filename for the backing file, you can add
it on the command line instead of in the image file:
$ qemu-nbd -t /tmp/test.img
$ qemu-img create -f qcow2 empty.qcow2 1G
$ qemu-system-x86_64 -drive file=empty.qcow2,backing.file.driver=nbd,\
backing.file.host=localhost
Note that this doesn't override the backing filename from the image. If
the image has one, this will fail because NBD doesn't want the options
and a filename at the same time.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r-- | block.c | 27 |
1 files changed, 23 insertions, 4 deletions
@@ -845,18 +845,33 @@ fail: return ret; } -int bdrv_open_backing_file(BlockDriverState *bs) +/* + * Opens the backing file for a BlockDriverState if not yet open + * + * options is a QDict of options to pass to the block drivers, or NULL for an + * empty set of options. The reference to the QDict is transferred to this + * function (even on failure), so if the caller intends to reuse the dictionary, + * it needs to use QINCREF() before calling bdrv_file_open. + */ +int bdrv_open_backing_file(BlockDriverState *bs, QDict *options) { char backing_filename[PATH_MAX]; int back_flags, ret; BlockDriver *back_drv = NULL; if (bs->backing_hd != NULL) { + QDECREF(options); return 0; } + /* NULL means an empty set of options */ + if (options == NULL) { + options = qdict_new(); + } + bs->open_flags &= ~BDRV_O_NO_BACKING; - if (bs->backing_file[0] == '\0') { + if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) { + QDECREF(options); return 0; } @@ -871,7 +886,8 @@ int bdrv_open_backing_file(BlockDriverState *bs) /* backing files always opened read-only */ back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT); - ret = bdrv_open(bs->backing_hd, backing_filename, NULL, + ret = bdrv_open(bs->backing_hd, + *backing_filename ? backing_filename : NULL, options, back_flags, back_drv); if (ret < 0) { bdrv_delete(bs->backing_hd); @@ -1027,7 +1043,10 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options, /* If there is a backing file, use it */ if ((flags & BDRV_O_NO_BACKING) == 0) { - ret = bdrv_open_backing_file(bs); + QDict *backing_options; + + extract_subqdict(options, &backing_options, "backing."); + ret = bdrv_open_backing_file(bs, backing_options); if (ret < 0) { goto close_and_fail; } |