From 60ec20815201e613c2cd49d58ea41c48271e550e Mon Sep 17 00:00:00 2001 From: Stefan Weil Date: Mon, 10 May 2010 21:46:26 +0200 Subject: [PATCH] block/vpc: Fix conversion from size to disk geometry The VHD algorithm calculates a disk geometry which is usually smaller than the requested size. QEMU tried to round up but failed for certain sizes: qemu-img create -f vpc disk.vpc 9437184 would create an image with 9435136 bytes (which is too small for qemu-img convert). Instead of hacking the geometry algorithm, the patch increases the number of sectors until we get enough sectors. Cc: Kevin Wolf Signed-off-by: Stefan Weil Signed-off-by: Kevin Wolf --- block/vpc.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/block/vpc.c b/block/vpc.c index f94e469..214e9d1 100644 --- a/block/vpc.c +++ b/block/vpc.c @@ -463,9 +463,7 @@ static int calculate_geometry(int64_t total_sectors, uint16_t* cyls, } } - // Note: Rounding up deviates from the Virtual PC behaviour - // However, we need this to avoid truncating images in qemu-img convert - *cyls = (cyls_times_heads + *heads - 1) / *heads; + *cyls = cyls_times_heads / *heads; return 0; } @@ -477,9 +475,9 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options) struct vhd_dyndisk_header* dyndisk_header = (struct vhd_dyndisk_header*) buf; int fd, i; - uint16_t cyls; - uint8_t heads; - uint8_t secs_per_cyl; + uint16_t cyls = 0; + uint8_t heads = 0; + uint8_t secs_per_cyl = 0; size_t block_size, num_bat_entries; int64_t total_sectors = 0; @@ -496,9 +494,14 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options) if (fd < 0) return -EIO; - // Calculate matching total_size and geometry - if (calculate_geometry(total_sectors, &cyls, &heads, &secs_per_cyl)) - return -EFBIG; + /* Calculate matching total_size and geometry. Increase the number of + sectors requested until we get enough (or fail). */ + for (i = 0; total_sectors > (int64_t)cyls * heads * secs_per_cyl; i++) { + if (calculate_geometry(total_sectors + i, + &cyls, &heads, &secs_per_cyl)) { + return -EFBIG; + } + } total_sectors = (int64_t) cyls * heads * secs_per_cyl; // Prepare the Hard Disk Footer -- 2.7.4