David Chinner wrote:
> On Mon, Nov 12, 2007 at 11:33:30AM +1100, Timothy Shimmin wrote:
>> Where the attachment was supposed to look like...
>>
>> ===========================================================================
>> Index: fs/xfs/linux-2.6/xfs_linux.h
>> ===========================================================================
>>
>> --- a/fs/xfs/linux-2.6/xfs_linux.h 2007-11-12 11:24:05.000000000 +1100
>> +++ b/fs/xfs/linux-2.6/xfs_linux.h 2007-11-12 11:14:22.818831666 +1100
>> @@ -159,12 +159,6 @@
>> /* number of BB's per block device block */
>> #define BLKDEV_BB BTOBB(BLKDEV_IOSIZE)
>>
>> -/* bytes to clicks */
>> -#define btoc(x) (((__psunsigned_t)(x)+(NBPC-1))>>BPCSHIFT)
>> -#define btoct(x) ((__psunsigned_t)(x)>>BPCSHIFT)
>> -#define btoc64(x) (((__uint64_t)(x)+(NBPC-1))>>BPCSHIFT)
>> -#define btoct64(x) ((__uint64_t)(x)>>BPCSHIFT)
>> -
>> /* off_t bytes to clicks */
>> #define offtoc(x) (((__uint64_t)(x)+(NBPC-1))>>BPCSHIFT)
>> #define offtoct(x) ((xfs_off_t)(x)>>BPCSHIFT)
>> @@ -172,14 +166,6 @@
>> /* clicks to off_t bytes */
>> #define ctooff(x) ((xfs_off_t)(x)<<BPCSHIFT)
>>
>> -/* clicks to bytes */
>> -#define ctob(x) ((__psunsigned_t)(x)<<BPCSHIFT)
>> -#define btoct(x) ((__psunsigned_t)(x)>>BPCSHIFT)
>> -#define ctob64(x) ((__uint64_t)(x)<<BPCSHIFT)
>> -
>> -/* bytes to clicks */
>> -#define btoc(x) (((__psunsigned_t)(x)+(NBPC-1))>>BPCSHIFT)
>> -
>> #define ENOATTR ENODATA /* Attribute not found */
>> #define EWRONGFS EINVAL /* Mount with wrong filesystem type */
>> #define EFSCORRUPTED EUCLEAN /* Filesystem is corrupted */
>
> Perhaps we should look at cleaning up the cusers of offtoc, offtoct, etc
> and killing BPCSHIFT altogether....
>
Yeah, I had a quick look before, but I will look closer again ;-)
> egrep -Ir 'offtoc|ctoooff' . | egrep -v "anot|tag"
./linux-2.6/xfs_lrw.c:
ctooff(offtoct(*offset)),
./linux-2.6/xfs_lrw.c: ctooff(offtoct(pos)),
-1);
./linux-2.6/xfs_lrw.c: ctooff(offtoct(pos)),
./linux-2.6/xfs_linux.h:#define offtoc(x)
(((__uint64_t)(x)+(NBPC-1))>>BPCSHIFT)
./linux-2.6/xfs_linux.h:#define offtoct(x) ((xfs_off_t)(x)>>BPCSHIFT)
./xfs_vnodeops.c: ctooff(offtoct(ioffset)), -1);
./xfs_vnodeops.c: ctooff(offtoct(ioffset)),
So we basically just use:
ctooff(offtoct(pos))
where
#define ctooff(x) ((xfs_off_t)(x)<<BPCSHIFT)
#define offtoct(x) ((xfs_off_t)(x)>>BPCSHIFT)
#define BPCSHIFT PAGE_SHIFT /* LOG2(NBPC) if exact */
seems basically to be a:
#define round_down_page(x) ((x) & ~(PAGE_SIZE - 1))
or just use a
round_down(x, PAGE_SIZE)
and
define the round_down for size which is power of 2.
Like in asm-x86_64/proto.h
#define round_up(x,y) (((x) + (y) - 1) & ~((y)-1))
#define round_down(x,y) ((x) & ~((y)-1))
What way do you reckon?
--Tim
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