Merge remote-tracking branch 'stefanha/block' into staging

* stefanha/block:
  Revert "block/vpc: Fix size calculation"
  block/raw-posix: detect readonly Linux block devices using BLKROGET

block/raw-posix.c

@@ -1257,9 +1257,43 @@ static int hdev_probe_device(const char *filename)
     return 0;
 }
 
+static int check_hdev_writable(BDRVRawState *s)
+{
+#if defined(BLKROGET)
+    /* Linux block devices can be configured "read-only" using blockdev(8).
+     * This is independent of device node permissions and therefore open(2)
+     * with O_RDWR succeeds.  Actual writes fail with EPERM.
+     *
+     * bdrv_open() is supposed to fail if the disk is read-only.  Explicitly
+     * check for read-only block devices so that Linux block devices behave
+     * properly.
+     */
+    struct stat st;
+    int readonly = 0;
+
+    if (fstat(s->fd, &st)) {
+        return -errno;
+    }
+
+    if (!S_ISBLK(st.st_mode)) {
+        return 0;
+    }
+
+    if (ioctl(s->fd, BLKROGET, &readonly) < 0) {
+        return -errno;
+    }
+
+    if (readonly) {
+        return -EACCES;
+    }
+#endif /* defined(BLKROGET) */
+    return 0;
+}
+
 static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
 {
     BDRVRawState *s = bs->opaque;
+    int ret;
 
 #if defined(__APPLE__) && defined(__MACH__)
     if (strstart(filename, "/dev/cdrom", NULL)) {
@@ -1300,7 +1334,20 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
     }
 #endif
 
-    return raw_open_common(bs, filename, flags, 0);
+    ret = raw_open_common(bs, filename, flags, 0);
+    if (ret < 0) {
+        return ret;
+    }
+
+    if (flags & BDRV_O_RDWR) {
+        ret = check_hdev_writable(s);
+        if (ret < 0) {
+            raw_close(bs);
+            return ret;
+        }
+    }
+
+    return ret;
 }
 
 #if defined(__linux__)

block/vpc.c

@@ -34,8 +34,6 @@
 
 #define HEADER_SIZE 512
 
-#define VHD_SECTOR_SIZE 512
-
 //#define CACHE
 
 enum vhd_type {
@@ -206,13 +204,11 @@ static int vpc_open(BlockDriverState *bs, int flags)
     /* Write 'checksum' back to footer, or else will leave it with zero. */
     footer->checksum = be32_to_cpu(checksum);
 
-    /* The visible size of a image in Virtual PC depends on the guest:
+    // The visible size of a image in Virtual PC depends on the geometry
-     * QEMU and other emulators report the real size (here in sectors).
+    // rather than on the size stored in the footer (the size in the footer
-     * All modern operating systems use this real size.
+    // is too large usually)
-     * Very old operating systems use CHS values to calculate the total size.
+    bs->total_sectors = (int64_t)
-     * This calculated size is usually smaller than the real size.
+        be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
-     */
-    bs->total_sectors = be64_to_cpu(footer->size) / VHD_SECTOR_SIZE;
 
     /* Allow a maximum disk size of approximately 2 TB */
     if (bs->total_sectors >= 65535LL * 255 * 255) {