kvm tools: Consolidate disk_image__{new, new_readonly}

This patch simplifies the disk image API.

Signed-off-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --git a/tools/kvm/disk/core.c b/tools/kvm/disk/core.c
index 3b12fff841f59cb6f94c160c4432cdfa10430a1b..2990caaed49eb98c12e55ad6479dc9a0ae2aa9f3 100644 (file)
--- a/tools/kvm/disk/core.c
+++ b/tools/kvm/disk/core.c
@@ -1,7 +1,7 @@
 #include "kvm/disk-image.h"
 #include "kvm/qcow.h"
 
-struct disk_image *disk_image__new(int fd, u64 size, struct disk_image_operations *ops)
+struct disk_image *disk_image__new(int fd, u64 size, struct disk_image_operations *ops, int use_mmap)
 {
        struct disk_image *disk;
 
@@ -12,20 +12,16 @@ struct disk_image *disk_image__new(int fd, u64 size, struct disk_image_operation
        disk->fd        = fd;
        disk->size      = size;
        disk->ops       = ops;
-       return disk;
-}
-
-struct disk_image *disk_image__new_readonly(int fd, u64 size, struct disk_image_operations *ops)
-{
-       struct disk_image *disk;
 
-       disk = disk_image__new(fd, size, ops);
-       if (!disk)
-               return NULL;
+       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)
+                       die("mmap() failed");
+       }
 
-       disk->priv = mmap(NULL, size, PROT_RW, MAP_PRIVATE | MAP_NORESERVE, fd, 0);
-       if (disk->priv == MAP_FAILED)
-               die("mmap() failed");
        return disk;
 }
 

diff --git a/tools/kvm/disk/qcow.c b/tools/kvm/disk/qcow.c
index bb2345ced5ce9a768511d9d346cf298f7b11fb53..b29efb4f63cf521dc80f67c5a924b567251ebc08 100644 (file)
--- a/tools/kvm/disk/qcow.c
+++ b/tools/kvm/disk/qcow.c
@@ -433,10 +433,13 @@ static struct disk_image *qcow2_probe(int fd, bool readonly)
        if (qcow_read_l1_table(q) < 0)
                goto error;
 
+       /*
+        * Do not use mmap use read/write instead
+        */
        if (readonly)
-               disk_image = disk_image__new(fd, h->size, &qcow1_disk_readonly_ops);
+               disk_image = disk_image__new(fd, h->size, &qcow1_disk_readonly_ops, DISK_IMAGE_NOMMAP);
        else
-               disk_image = disk_image__new(fd, h->size, &qcow1_disk_ops);
+               disk_image = disk_image__new(fd, h->size, &qcow1_disk_ops, DISK_IMAGE_NOMMAP);
 
        if (!disk_image)
                goto error;
@@ -527,10 +530,13 @@ static struct disk_image *qcow1_probe(int fd, bool readonly)
        if (qcow_read_l1_table(q) < 0)
                goto error;
 
+       /*
+        * Do not use mmap use read/write instead
+        */
        if (readonly)
-               disk_image = disk_image__new(fd, h->size, &qcow1_disk_readonly_ops);
+               disk_image = disk_image__new(fd, h->size, &qcow1_disk_readonly_ops, DISK_IMAGE_NOMMAP);
        else
-               disk_image = disk_image__new(fd, h->size, &qcow1_disk_ops);
+               disk_image = disk_image__new(fd, h->size, &qcow1_disk_ops, DISK_IMAGE_NOMMAP);
 
        if (!disk_image)
                goto error;

diff --git a/tools/kvm/disk/raw.c b/tools/kvm/disk/raw.c
index b1a484d43342dc6a869aa3dcac048a8ba877051c..a419c32ce24a3ec2e27b89e19950ade362c40537 100644 (file)
--- a/tools/kvm/disk/raw.c
+++ b/tools/kvm/disk/raw.c
@@ -57,10 +57,18 @@ static struct disk_image_operations raw_image_ro_mmap_ops = {
 
 struct disk_image *raw_image__probe(int fd, struct stat *st, bool readonly)
 {
+
        if (readonly)
-               return disk_image__new_readonly(fd, st->st_size, &raw_image_ro_mmap_ops);
+               /*
+                * Use mmap's MAP_PRIVATE to implement non-persistent write
+                * FIXME: This does not work on 32-bit host.
+                */
+               return disk_image__new(fd, st->st_size, &raw_image_ro_mmap_ops, DISK_IMAGE_MMAP);
        else
-               return disk_image__new(fd, st->st_size, &raw_image_ops);
+               /*
+                * Use read/write instead of mmap
+                */
+               return disk_image__new(fd, st->st_size, &raw_image_ops, DISK_IMAGE_NOMMAP);
 }
 
 struct disk_image *blkdev__probe(const char *filename, struct stat *st)
@@ -80,5 +88,5 @@ struct disk_image *blkdev__probe(const char *filename, struct stat *st)
                return NULL;
        }
 
-       return disk_image__new_readonly(fd, size, &raw_image_ro_mmap_ops);
+       return disk_image__new(fd, size, &raw_image_ro_mmap_ops, DISK_IMAGE_MMAP);
 }

diff --git a/tools/kvm/include/kvm/disk-image.h b/tools/kvm/include/kvm/disk-image.h
index e6d9e8ef7df7918c2e5c5699a276f85602e39afe..efa3e428afd18d6129a5835ed99c6a8378000e37 100644 (file)
--- a/tools/kvm/include/kvm/disk-image.h
+++ b/tools/kvm/include/kvm/disk-image.h
@@ -21,6 +21,9 @@
 #define SECTOR_SHIFT           9
 #define SECTOR_SIZE            (1UL << SECTOR_SHIFT)
 
+#define DISK_IMAGE_MMAP                0
+#define DISK_IMAGE_NOMMAP      1
+
 struct disk_image;
 
 struct disk_image_operations {
@@ -40,8 +43,7 @@ struct disk_image {
 };
 
 struct disk_image *disk_image__open(const char *filename, bool readonly);
-struct disk_image *disk_image__new(int fd, u64 size, struct disk_image_operations *ops);
-struct disk_image *disk_image__new_readonly(int fd, u64 size, struct disk_image_operations *ops);
+struct disk_image *disk_image__new(int fd, u64 size, struct disk_image_operations *ops, int mmap);
 void disk_image__close(struct disk_image *disk);
 
 ssize_t disk_image__read(struct disk_image *disk, u64 sector, const struct iovec *iov, int iovcount);