Fixes the partition size for FAT.

BLKGETSIZE is in units of 512 bytes rather than bytes or the sector size
returned by BLKSSZGET. Use BLKGETSIZE64 instead, to get the block size
in bytes.

Also rename block_size to make it clearer that it's actually the size
of the whole block device.

Change-Id: I9eb6cd4394722f8624c6ac6368b6da31583f026e
Test: Create an new filesystem by newfs_msdos

1 files changed, 8 insertions, 7 deletions

diff --git a/mkfs_msdos.c b/mkfs_msdos.c
index 0ef30f2..878ff8f 100644
--- a/mkfs_msdos.c
+++ b/mkfs_msdos.c
@@ -847,16 +847,17 @@ static int getdiskinfo(int fd, const char *fname, const char *dtype,
 
     if (ckgeom(fname, bpb->bpbBytesPerSec, "bytes/sector") == -1) return -1;
 
-    u_long block_size;
-    if (ioctl(fd, BLKGETSIZE, &block_size)) {
-        err(1, "ioctl(BLKGETSIZE) failed");
+    u_long device_size;
+    if (ioctl(fd, BLKGETSIZE64, &device_size)) {
+        err(1, "ioctl(BLKGETSIZE64) failed");
     }
 
-    if (block_size > UINT32_MAX) {
-        errx(1, "block size too large: %lu", block_size);
+    u_long sectors = device_size/bpb->bpbBytesPerSec;
+    if (sectors > UINT32_MAX) {
+        errx(1, "too many sectors: %lu (%lu byte device, %u bytes/sector)",
+             sectors, device_size, bpb->bpbBytesPerSec);
     }
-
-    bpb->bpbHugeSectors = (u_int)block_size;
+    bpb->bpbHugeSectors = sectors;
 
     bpb->bpbSecPerTrack = 63;
     if (ckgeom(fname, bpb->bpbSecPerTrack, "sectors/track") == -1) return -1;