[Xen-devel] [PATCH 1/2] tools - fix and use ROUNDUP macro (bug 1430 part 1)

[Andre Przywara <andre.przywara@xxxxxxx>]

Hi,

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).
(This alone does not fix the bug, the next patch is still needed)
Please also apply to the bugfix trees.

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

Regards,
Andre.

--
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 488-3567-12
----to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Jochen Polster; Thomas M. McCoy; Giuliano Meroni
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

# HG changeset patch
# User Andre Przywara <andre.przywara@xxxxxxx>
# Date 1243981525 -7200
# Node ID 3c62e9afafc6a70cb897ea77a99d5da1f6b9652e
# Parent  f72d26c0000292889cfe3a85008d2c4482fee772
fix and use ROUNDUP macro in blktap/qcow

diff -r f72d26c00002 -r 3c62e9afafc6 tools/blktap/drivers/block-qcow.c
--- a/tools/blktap/drivers/block-qcow.c Tue Jun 02 11:50:16 2009 +0100
+++ b/tools/blktap/drivers/block-qcow.c Wed Jun 03 00:25:25 2009 +0200
@@ -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 @@
 
        /* 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 @@
 
        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 @@
        
        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",

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