blktap: fix and use ROUNDUP macro (bug 1430 part 1)

As pointed out in Xen Bugzilla 1430 in the blktap QCOW driver the
rounding function is wrong in line 824 of block-qcow.c.
This patch replaces this (and other roundings) with the already
existing ROUNDUP macro (and fixes the usual macro pitfall).

Signed-off-by: Andre Przywara <andre.przywara@amd.com>

diff --git a/tools/blktap/drivers/block-qcow.c b/tools/blktap/drivers/block-qcow.c
index c6d32a40776815f4fd3b192675eb9eec866e68e4..dd65cd01bbf950ea115bb07484d277493b2afc21 100644 (file)
--- a/tools/blktap/drivers/block-qcow.c
+++ b/tools/blktap/drivers/block-qcow.c
@@ -55,7 +55,7 @@
 #define ROUNDUP(l, s) \
 ({ \
     (uint64_t)( \
-        (l + (s - 1)) - ((l + (s - 1)) % s)); \
+        ((l) + ((s) - 1)) - (((l) + ((s) - 1)) % (s))); \
 })
 
 #undef IOCB_IDX
@@ -800,14 +800,14 @@ static int tdqcow_open (struct disk_driver *dd, const char *name, td_flag_t flag
 
        /* read the level 1 table */
        shift = s->cluster_bits + s->l2_bits;
-       s->l1_size = (header->size + (1LL << shift) - 1) >> shift;
+       s->l1_size = ROUNDUP(header->size, 1LL << shift);
        
        s->l1_table_offset = header->l1_table_offset;
 
        /*allocate a 4Kbyte multiple of memory*/
        l1_table_size = s->l1_size * sizeof(uint64_t);
        if (l1_table_size % 4096 > 0) {
-               l1_table_size = ((l1_table_size >> 12) + 1) << 12;
+               l1_table_size = ROUNDUP(l1_table_size, 4096);
        }
        ret = posix_memalign((void **)&s->l1_table, 4096, l1_table_size);
        if (ret != 0) goto fail;
@@ -821,7 +821,7 @@ static int tdqcow_open (struct disk_driver *dd, const char *name, td_flag_t flag
 
        lseek(fd, 0, SEEK_SET);
        l1_table_block = l1_table_size + s->l1_table_offset;
-       l1_table_block = l1_table_block + 512 - (l1_table_block % 512); 
+       l1_table_block = ROUNDUP(l1_table_block, 512);
        ret = posix_memalign((void **)&buf2, 4096, l1_table_block);
        if (ret != 0) goto fail;
        if (read(fd, buf2, l1_table_block) != l1_table_block)
@@ -1226,11 +1226,11 @@ int qcow_create(const char *filename, uint64_t total_size,
        
        header_size = (header_size + 7) & ~7;
        if (header_size % 4096 > 0) {
-               header_size = ((header_size >> 12) + 1) << 12;
+               header_size = ROUNDUP(header_size, 4096);
        }
 
        shift = header.cluster_bits + header.l2_bits;
-       l1_size = ((size * 512) + (1LL << shift) - 1) >> shift;
+       l1_size = ROUNDUP(size * 512, 1LL << shift);
 
        header.l1_table_offset = cpu_to_be64(header_size);
        DPRINTF("L1 Table offset: %d, size %d\n",