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disk/part.c: 'usb storage' avoiding overflow when output capacity 

Before:
    Marvell>> usb storage
      Device 0: Vendor: StoreJet Rev:  Prod:  Transcend
                Type: Hard Disk
                Capacity: 28759.9 MB = 28.0 GB (488397168 x 512)
After:
    Marvell>> usb storage
      Device 0: Vendor: StoreJet Rev:  Prod:  Transcend
                Type: Hard Disk
                Capacity: 238475.1 MB = 232.8 GB (488397168 x 512)

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
This commit is contained in:
Sergei Trofimovich 2010-08-08 15:05:39 +03:00 committed by Wolfgang Denk
parent b9d51fbb18
commit 69a2a4d9a5
1 changed files with 24 additions and 6 deletions
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30
disk/part.c
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@ -109,13 +109,30 @@ block_dev_desc_t *get_dev(char* ifname, int dev)
/*
* reports device info to the user
*/
#ifdef CONFIG_LBA48
typedef uint64_t lba512_t;
#else
typedef lbaint_t lba512_t;
#endif
/*
* Overflowless variant of (block_count * mul_by / div_by)
* when div_by > mul_by
*/
static lba512_t lba512_muldiv (lba512_t block_count, lba512_t mul_by, lba512_t div_by)
{
lba512_t bc_quot, bc_rem;
/* x * m / d == x / d * m + (x % d) * m / d */
bc_quot = block_count / div_by;
bc_rem = block_count - div_by * bc_quot;
return bc_quot * mul_by + (bc_rem * mul_by) / div_by;
}
void dev_print (block_dev_desc_t *dev_desc)
{
#ifdef CONFIG_LBA48
uint64_t lba512; /* number of blocks if 512bytes block size */
#else
lbaint_t lba512;
#endif
lba512_t lba512; /* number of blocks if 512bytes block size */
if (dev_desc->type == DEV_TYPE_UNKNOWN) {
puts ("not available\n");
@ -184,8 +201,9 @@ void dev_print (block_dev_desc_t *dev_desc)
lba = dev_desc->lba;
lba512 = (lba * (dev_desc->blksz/512));
mb = (10 * lba512) / 2048; /* 2048 = (1024 * 1024) / 512 MB */
/* round to 1 digit */
mb = lba512_muldiv(lba512, 10, 2048); /* 2048 = (1024 * 1024) / 512 MB */
mb_quot = mb / 10;
mb_rem = mb - (10 * mb_quot);