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Re: [Qemu-devel] [PATCH] qemu-io: add flag to mark files growable
From: |
Christoph Hellwig |
Subject: |
Re: [Qemu-devel] [PATCH] qemu-io: add flag to mark files growable |
Date: |
Mon, 6 Jul 2009 13:14:08 +0200 |
User-agent: |
Mutt/1.3.28i |
On Mon, Jul 06, 2009 at 01:04:55PM +0200, Kevin Wolf wrote:
> > Well, the primary use of qemu-iotests is to try out the I/O patterns,
> > and the -g option is to check out we do the correct thing for growable
> > files, so I'd really prefer it to fail if we're not allow to actually
> > make it growable.
>
> Perfectly reasonable. But then make it really fail.
Oh, now I see your complaint. The lack of a return 1 after the error
message was not intentional - I've added it now.
> > Now one think I could do is to just add a growable flag to the
> > BlockDriver to make it explicit. Currently only raw files (in the posix
> > and win32 flavours) would set it.
>
> Good point actually, your current logic is wrong: raw-win32 doesn't have
> the file protocol. I'm not sure though if introducing a new flag just
> for qemu-io is right. After all qemu-io should test what the drivers
> provide to qemu and not extend them to work with qemu-io. Currently the
> drivers don't have the concept of non-growable images.
True. I'll stick to the current one with the added error return.
win32 raw should probably grow a protocol name, but I'll leave that to
people who can actually test win32.
> > That would also fix the bug what we
> > currenly allow to grow host devices even if we can't.
>
> How that? The host device drivers don't have a protocol name, do they?
They don't, I was confused.
Updated patch below:
Index: qemu/qemu-io.c
===================================================================
--- qemu.orig/qemu-io.c 2009-07-06 13:09:45.223364426 +0200
+++ qemu/qemu-io.c 2009-07-06 13:11:41.347269140 +0200
@@ -1172,7 +1172,7 @@ static const cmdinfo_t close_cmd = {
.oneline = "close the current open file",
};
-static int openfile(char *name, int flags)
+static int openfile(char *name, int flags, int growable)
{
if (bs) {
fprintf(stderr, "file open already, try 'help close'\n");
@@ -1189,6 +1189,17 @@ static int openfile(char *name, int flag
return 1;
}
+
+ if (growable) {
+ if (!bs->drv || !bs->drv->protocol_name) {
+ fprintf(stderr,
+ "%s: only protocols can be opened growable\n",
+ progname);
+ return 1;
+ }
+ bs->growable = 1;
+ }
+
return 0;
}
@@ -1207,6 +1218,7 @@ open_help(void)
" -r, -- open file read-only\n"
" -s, -- use snapshot file\n"
" -n, -- disable host cache\n"
+" -g, -- allow file to grow (only applies to protocols)"
"\n");
}
@@ -1217,9 +1229,10 @@ open_f(int argc, char **argv)
{
int flags = 0;
int readonly = 0;
+ int growable = 0;
int c;
- while ((c = getopt(argc, argv, "snCr")) != EOF) {
+ while ((c = getopt(argc, argv, "snCrg")) != EOF) {
switch (c) {
case 's':
flags |= BDRV_O_SNAPSHOT;
@@ -1233,6 +1246,9 @@ open_f(int argc, char **argv)
case 'r':
readonly = 1;
break;
+ case 'g':
+ growable = 1;
+ break;
default:
return command_usage(&open_cmd);
}
@@ -1246,7 +1262,7 @@ open_f(int argc, char **argv)
if (optind != argc - 1)
return command_usage(&open_cmd);
- return openfile(argv[optind], flags);
+ return openfile(argv[optind], flags, growable);
}
static const cmdinfo_t open_cmd = {
@@ -1306,7 +1322,8 @@ static void usage(const char *name)
int main(int argc, char **argv)
{
int readonly = 0;
- const char *sopt = "hVc:Crsnm";
+ int growable = 0;
+ const char *sopt = "hVc:Crsnmg";
struct option lopt[] = {
{ "help", 0, 0, 'h' },
{ "version", 0, 0, 'V' },
@@ -1317,6 +1334,7 @@ int main(int argc, char **argv)
{ "snapshot", 0, 0, 's' },
{ "nocache", 0, 0, 'n' },
{ "misalign", 0, 0, 'm' },
+ { "growable", 0, 0, 'g' },
{ NULL, 0, 0, 0 }
};
int c;
@@ -1345,6 +1363,9 @@ int main(int argc, char **argv)
case 'm':
misalign = 1;
break;
+ case 'g':
+ growable = 1;
+ break;
case 'V':
printf("%s version %s\n", progname, VERSION);
exit(0);
@@ -1392,7 +1413,7 @@ int main(int argc, char **argv)
flags |= BDRV_O_RDWR;
if ((argc - optind) == 1)
- openfile(argv[optind], flags);
+ openfile(argv[optind], flags, growable);
command_loop();
/*