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qemu-io: Add discard command 

discard [-Cq] off len -- discards a number of bytes at a specified
offset

 discards a range of bytes from the given offset

 Example:
 'discard 512 1k' - discards 1 kilobyte from 512 bytes into the file

 Discards a segment of the currently open file.
 -C, -- report statistics in a machine parsable format
 -q, -- quite mode, do not show I/O statistics

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2010-12-13 09:36:26 +00:00 committed by Kevin Wolf
parent ea3bd56f56
commit edff5db1f5
1 changed files with 88 additions and 0 deletions
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88
qemu-io.c
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@ -1394,6 +1394,93 @@ static const cmdinfo_t info_cmd = {
.oneline = "prints information about the current file",
};
static void
discard_help(void)
{
printf(
"\n"
" discards a range of bytes from the given offset\n"
"\n"
" Example:\n"
" 'discard 512 1k' - discards 1 kilobyte from 512 bytes into the file\n"
"\n"
" Discards a segment of the currently open file.\n"
" -C, -- report statistics in a machine parsable format\n"
" -q, -- quite mode, do not show I/O statistics\n"
"\n");
}
static int discard_f(int argc, char **argv);
static const cmdinfo_t discard_cmd = {
.name = "discard",
.altname = "d",
.cfunc = discard_f,
.argmin = 2,
.argmax = -1,
.args = "[-Cq] off len",
.oneline = "discards a number of bytes at a specified offset",
.help = discard_help,
};
static int
discard_f(int argc, char **argv)
{
struct timeval t1, t2;
int Cflag = 0, qflag = 0;
int c, ret;
int64_t offset;
int count;
while ((c = getopt(argc, argv, "Cq")) != EOF) {
switch (c) {
case 'C':
Cflag = 1;
break;
case 'q':
qflag = 1;
break;
default:
return command_usage(&discard_cmd);
}
}
if (optind != argc - 2) {
return command_usage(&discard_cmd);
}
offset = cvtnum(argv[optind]);
if (offset < 0) {
printf("non-numeric length argument -- %s\n", argv[optind]);
return 0;
}
optind++;
count = cvtnum(argv[optind]);
if (count < 0) {
printf("non-numeric length argument -- %s\n", argv[optind]);
return 0;
}
gettimeofday(&t1, NULL);
ret = bdrv_discard(bs, offset, count);
gettimeofday(&t2, NULL);
if (ret < 0) {
printf("discard failed: %s\n", strerror(-ret));
goto out;
}
/* Finally, report back -- -C gives a parsable format */
if (!qflag) {
t2 = tsub(t2, t1);
print_report("discard", &t2, offset, count, count, 1, Cflag);
}
out:
return 0;
}
static int
alloc_f(int argc, char **argv)
{
@ -1715,6 +1802,7 @@ int main(int argc, char **argv)
add_command(&truncate_cmd);
add_command(&length_cmd);
add_command(&info_cmd);
add_command(&discard_cmd);
add_command(&alloc_cmd);
add_command(&map_cmd);