kvmtool/disk/core.c

#include "kvm/disk-image.h"
#include "kvm/qcow.h"
#include "kvm/virtio-blk.h"

#include <linux/err.h>
#include <sys/eventfd.h>
#include <sys/poll.h>

#define AIO_MAX 32

int debug_iodelay;

#ifdef CONFIG_HAS_AIO
static void *disk_image__thread(void *param)
{
	struct disk_image *disk = param;
	struct io_event event[AIO_MAX];
	struct timespec notime = {0};
	int nr, i;
	u64 dummy;

	while (read(disk->evt, &dummy, sizeof(dummy)) > 0) {
		nr = io_getevents(disk->ctx, 1, ARRAY_SIZE(event), event, &notime);
		for (i = 0; i < nr; i++)
			disk->disk_req_cb(event[i].data, event[i].res);
	}

	return NULL;
}
#endif

struct disk_image *disk_image__new(int fd, u64 size, struct disk_image_operations *ops, int use_mmap)
{
	struct disk_image *disk;
	int r;

	disk = malloc(sizeof *disk);
	if (!disk)
		return ERR_PTR(-ENOMEM);

	*disk = (struct disk_image) {
		.fd	= fd,
		.size	= size,
		.ops	= ops,
	};

	if (use_mmap == DISK_IMAGE_MMAP) {
		/*
		 * The write to disk image will be discarded
		 */
		disk->priv = mmap(NULL, size, PROT_RW, MAP_PRIVATE | MAP_NORESERVE, fd, 0);
		if (disk->priv == MAP_FAILED) {
			r = -errno;
			free(disk);
			return ERR_PTR(r);
		}
	}

#ifdef CONFIG_HAS_AIO
	if (disk) {
		pthread_t thread;

		disk->evt = eventfd(0, 0);
		io_setup(AIO_MAX, &disk->ctx);
		r = pthread_create(&thread, NULL, disk_image__thread, disk);
		if (r) {
			r = -errno;
			free(disk);
			return ERR_PTR(r);
		}
	}
#endif
	return disk;
}

struct disk_image *disk_image__open(const char *filename, bool readonly)
{
	struct disk_image *disk;
	struct stat st;
	int fd;

	if (stat(filename, &st) < 0)
		return ERR_PTR(-errno);

	/* blk device ?*/
	disk = blkdev__probe(filename, &st);
	if (!IS_ERR_OR_NULL(disk))
		return disk;

	fd = open(filename, readonly ? O_RDONLY : O_RDWR);
	if (fd < 0)
		return ERR_PTR(fd);

	/* qcow image ?*/
	disk = qcow_probe(fd, true);
	if (!IS_ERR_OR_NULL(disk)) {
		pr_warning("Forcing read-only support for QCOW");
		return disk;
	}

	/* raw image ?*/
	disk = raw_image__probe(fd, &st, readonly);
	if (!IS_ERR_OR_NULL(disk))
		return disk;

	if (close(fd) < 0)
		pr_warning("close() failed");

	return ERR_PTR(-ENOSYS);
}

struct disk_image **disk_image__open_all(const char **filenames, bool *readonly, int count)
{
	struct disk_image **disks;
	int i;
	void *err;

	if (!count)
		return ERR_PTR(-EINVAL);
	if (count > MAX_DISK_IMAGES)
		return ERR_PTR(-ENOSPC);

	disks = calloc(count, sizeof(*disks));
	if (!disks)
		return ERR_PTR(-ENOMEM);

	for (i = 0; i < count; i++) {
		if (!filenames[i])
			continue;

		disks[i] = disk_image__open(filenames[i], readonly[i]);
		if (IS_ERR_OR_NULL(disks[i])) {
			pr_err("Loading disk image '%s' failed", filenames[i]);
			err = disks[i];
			goto error;
		}
	}

	return disks;
error:
	for (i = 0; i < count; i++)
		if (!IS_ERR_OR_NULL(disks[i]))
			disk_image__close(disks[i]);

	free(disks);
	return err;
}

int disk_image__flush(struct disk_image *disk)
{
	if (disk->ops->flush)
		return disk->ops->flush(disk);

	return fsync(disk->fd);
}

int disk_image__close(struct disk_image *disk)
{
	/* If there was no disk image then there's nothing to do: */
	if (!disk)
		return 0;

	if (disk->ops->close)
		return disk->ops->close(disk);

	if (close(disk->fd) < 0)
		pr_warning("close() failed");

	free(disk);

	return 0;
}

int disk_image__close_all(struct disk_image **disks, int count)
{
	while (count)
		disk_image__close(disks[--count]);

	free(disks);

	return 0;
}

/*
 * Fill iov with disk data, starting from sector 'sector'.
 * Return amount of bytes read.
 */
ssize_t disk_image__read(struct disk_image *disk, u64 sector, const struct iovec *iov,
				int iovcount, void *param)
{
	ssize_t total = 0;

	if (debug_iodelay)
		msleep(debug_iodelay);

	if (disk->ops->read) {
		total = disk->ops->read(disk, sector, iov, iovcount, param);
		if (total < 0) {
			pr_info("disk_image__read error: total=%ld\n", (long)total);
			return total;
		}
	} else {
		/* Do nothing */
	}

	if (!disk->async && disk->disk_req_cb)
		disk->disk_req_cb(param, total);

	return total;
}

/*
 * Write iov to disk, starting from sector 'sector'.
 * Return amount of bytes written.
 */
ssize_t disk_image__write(struct disk_image *disk, u64 sector, const struct iovec *iov,
				int iovcount, void *param)
{
	ssize_t total = 0;

	if (debug_iodelay)
		msleep(debug_iodelay);

	if (disk->ops->write) {
		/*
		 * Try writev based operation first
		 */

		total = disk->ops->write(disk, sector, iov, iovcount, param);
		if (total < 0) {
			pr_info("disk_image__write error: total=%ld\n", (long)total);
			return total;
		}
	} else {
		/* Do nothing */
	}

	if (!disk->async && disk->disk_req_cb)
		disk->disk_req_cb(param, total);

	return total;
}

ssize_t disk_image__get_serial(struct disk_image *disk, void *buffer, ssize_t *len)
{
	struct stat st;
	int r;

	r = fstat(disk->fd, &st);
	if (r)
		return r;

	*len = snprintf(buffer, *len, "%llu%llu%llu", (u64)st.st_dev, (u64)st.st_rdev, (u64)st.st_ino);
	return *len;
}

void disk_image__set_callback(struct disk_image *disk, void (*disk_req_cb)(void *param, long len))
{
	disk->disk_req_cb = disk_req_cb;
}