kvm tools: Add a wrapper function to open disk images

The patch was suggested by Ingo to move the disk image subsystem code
from the kvm-run.c file. The code to open all of the specified disk
images is now moved to a wrapper function in disk/core.c.

Signed-off-by: Prasad Joshi <prasadjoshi124@gmail.com>
Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

disk/core.c

@@ -59,6 +59,37 @@ struct disk_image *disk_image__open(const char *filename, bool readonly)
 	return NULL;
 }
 
+struct disk_image **disk_image__open_all(const char **filenames, bool *readonly, int count)
+{
+	struct disk_image **disks;
+	int i;
+
+	if (!count || count > MAX_DISK_IMAGES)
+		return NULL;
+
+	disks = calloc(count, sizeof(*disks));
+	if (!disks)
+		return NULL;
+
+	for (i = 0; i < count; i++) {
+		if (!filenames[i])
+			continue;
+
+		disks[i] = disk_image__open(filenames[i], readonly[i]);
+		if (!disks[i]) {
+			pr_error("Loading disk image '%s' failed", filenames[i]);
+			goto error;
+		}
+	}
+	return disks;
+error:
+	for (i = 0; i < count; i++)
+		disk_image__close(disks[i]);
+
+	free(disks);
+	return NULL;
+}
+
 int disk_image__flush(struct disk_image *disk)
 {
 	if (disk->ops->flush)

include/kvm/disk-image.h

@@ -23,6 +23,7 @@
 
 #define DISK_IMAGE_MMAP		0
 #define DISK_IMAGE_NOMMAP	1
+#define MAX_DISK_IMAGES         4
 
 struct disk_image;
 
@@ -51,6 +52,7 @@ struct disk_image {
 };
 
 struct disk_image *disk_image__open(const char *filename, bool readonly);
+struct disk_image **disk_image__open_all(const char **filenames, bool *readonly, int count);
 struct disk_image *disk_image__new(int fd, u64 size, struct disk_image_operations *ops, int mmap);
 int disk_image__close(struct disk_image *disk);
 int disk_image__flush(struct disk_image *disk);

include/kvm/kvm.h

@@ -32,6 +32,7 @@ struct kvm {
 	struct interrupt_table	interrupt_table;
 
 	const char		*vmlinux;
+	struct disk_image       **disks;
 };
 
 struct kvm *kvm__init(const char *kvm_dev, unsigned long ram_size);

kvm-run.c

@@ -44,7 +44,6 @@
 #define MB_SHIFT		(20)
 #define MIN_RAM_SIZE_MB		(64ULL)
 #define MIN_RAM_SIZE_BYTE	(MIN_RAM_SIZE_MB << MB_SHIFT)
-#define MAX_DISK_IMAGES		4
 
 static struct kvm *kvm;
 static struct kvm_cpu *kvm_cpus[KVM_NR_CPUS];
@@ -530,15 +529,15 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix)
 	if (!strstr(real_cmdline, "root="))
 		strlcat(real_cmdline, " root=/dev/vda rw ", sizeof(real_cmdline));
 
-	for (i = 0; i < image_count; i++) {
-		if (image_filename[i]) {
-			struct disk_image *disk = disk_image__open(image_filename[i], readonly_image[i]);
-			if (!disk)
-				die("unable to load disk image %s", image_filename[i]);
+	if (image_count) {
+		kvm->disks = disk_image__open_all(image_filename, readonly_image, image_count);
+		if (!kvm->disks)
+			die("Unable to load all disk images.");
 
-			virtio_blk__init(kvm, disk);
-		}
+		for (i = 0; i < image_count; i++)
+			virtio_blk__init(kvm, kvm->disks[i]);
 	}
+
 	free(hi);
 
 	printf("  # kvm run -k %s -m %Lu -c %d\n", kernel_filename, ram_size / 1024 / 1024, nrcpus);