Commit edff5db1 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi Committed by Kevin Wolf
Browse files

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: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent ea3bd56f

qemu-io.c

+88 −0
Original line number Diff line number Diff line
@@ -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);