Message ID | 1291743586-3518-1-git-send-email-Jes.Sorensen@redhat.com |
---|---|
State | New |
Headers | show |
On Tue, Dec 7, 2010 at 5:39 PM, <Jes.Sorensen@redhat.com> wrote: > // The size for the image must always be specified, with one exception: > // If we are using a backing file, we can obtain the size from there > - if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n == -1) { > - > + if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n == 0) { > QEMUOptionParameter *backing_file = > get_option_parameter(param, BLOCK_OPT_BACKING_FILE); > QEMUOptionParameter *backing_fmt = Today it is possible to create 0 byte sized images. Your patch will change that: If there is a backing file, then the size will be taken from the backing file. If there is no backing file, then an error about missing size will be printed, even though a size of 0 has been given. I don't think 0 sized images are very useful, but I'm not sure we should make this change. Stefan
On 12/07/10 21:36, Stefan Hajnoczi wrote: > On Tue, Dec 7, 2010 at 5:39 PM, <Jes.Sorensen@redhat.com> wrote: >> // The size for the image must always be specified, with one exception: >> // If we are using a backing file, we can obtain the size from there >> - if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n == -1) { >> - >> + if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n == 0) { >> QEMUOptionParameter *backing_file = >> get_option_parameter(param, BLOCK_OPT_BACKING_FILE); >> QEMUOptionParameter *backing_fmt = > > Today it is possible to create 0 byte sized images. Your patch will > change that: > If there is a backing file, then the size will be taken from the backing file. > If there is no backing file, then an error about missing size will be > printed, even though a size of 0 has been given. > > I don't think 0 sized images are very useful, but I'm not sure we > should make this change. The old code also fails if there is no size, except for when a backing file is present. I hadn't thought of the zero sized file, but on the other hand, I don't see it being useful. I would like to make this change to get the option handling cleaned up as it allows me to refactor the code in img_create(). Cheers, Jes
Am 07.12.2010 21:36, schrieb Stefan Hajnoczi: > On Tue, Dec 7, 2010 at 5:39 PM, <Jes.Sorensen@redhat.com> wrote: >> // The size for the image must always be specified, with one exception: >> // If we are using a backing file, we can obtain the size from there >> - if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n == -1) { >> - >> + if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n == 0) { >> QEMUOptionParameter *backing_file = >> get_option_parameter(param, BLOCK_OPT_BACKING_FILE); >> QEMUOptionParameter *backing_fmt = > > Today it is possible to create 0 byte sized images. Your patch will > change that: > If there is a backing file, then the size will be taken from the backing file. > If there is no backing file, then an error about missing size will be > printed, even though a size of 0 has been given. I can think of one use case for it: You can store the VM state on a zero-sized qcow2 image for internal snapshots. Otherwise it's probably rather useless, but we have supported it for a long time, so I wouldn't remove it. People have actually noticed in the past when something was broken with it. Kevin
On 12/08/10 09:54, Kevin Wolf wrote: > Am 07.12.2010 21:36, schrieb Stefan Hajnoczi: >> Today it is possible to create 0 byte sized images. Your patch will >> change that: >> If there is a backing file, then the size will be taken from the backing file. >> If there is no backing file, then an error about missing size will be >> printed, even though a size of 0 has been given. > > I can think of one use case for it: You can store the VM state on a > zero-sized qcow2 image for internal snapshots. > > Otherwise it's probably rather useless, but we have supported it for a > long time, so I wouldn't remove it. People have actually noticed in the > past when something was broken with it. Ok that is fair, I have just posted an updated version which should do the right thing. Shows up it made the patch even simpler :) Cheers, Jes
diff --git a/qemu-img.c b/qemu-img.c index d146d8c..eaec725 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -282,6 +282,7 @@ static int add_old_style_options(const char *fmt, QEMUOptionParameter *list, static int img_create(int argc, char **argv) { int c, ret = 0; + uint64_t img_size = 0; const char *fmt = "raw"; const char *base_fmt = NULL; const char *filename; @@ -329,6 +330,11 @@ static int img_create(int argc, char **argv) } filename = argv[optind++]; + /* Get image size, if specified */ + if (optind < argc) { + img_size = strtosz(argv[optind++], NULL); + } + if (options && !strcmp(options, "?")) { ret = print_block_option_help(filename, fmt); goto out; @@ -356,7 +362,6 @@ static int img_create(int argc, char **argv) /* Create parameter list with default values */ param = parse_option_parameters("", create_options, param); - set_option_parameter_int(param, BLOCK_OPT_SIZE, -1); /* Parse -o options */ if (options) { @@ -368,21 +373,19 @@ static int img_create(int argc, char **argv) } } - /* Add size to parameters */ - if (optind < argc) { - set_option_parameter(param, BLOCK_OPT_SIZE, argv[optind++]); - } - /* Add old-style options to parameters */ ret = add_old_style_options(fmt, param, base_filename, base_fmt); if (ret < 0) { goto out; } + if (img_size) { + set_option_parameter_int(param, BLOCK_OPT_SIZE, img_size); + } + // The size for the image must always be specified, with one exception: // If we are using a backing file, we can obtain the size from there - if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n == -1) { - + if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n == 0) { QEMUOptionParameter *backing_file = get_option_parameter(param, BLOCK_OPT_BACKING_FILE); QEMUOptionParameter *backing_fmt =