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    SubjectRe: [PATCH] remove 2TB block device limit
    Peter Chubb wrote:
    > Hi,
    > At present, linux is limited to 2TB filesystems even on 64-bit
    > systems, because there are various places where the block offset on
    > disc are assigned to unsigned or int 32-bit variables.
    > There's a type, sector_t, that's meant to hold offsets in sectors and
    > blocks. It's not used consistently (yet).
    > The patch at
    > ...
    > As this touches lots of places -- the generic block layer (Andrew?)
    > the IDE code (Martin?) and RAID (Neil?) and minor changes to the scsi
    > I've CCd a few people directly.

    That would be more Jens and aviro than I.

    My vote would be: just merge the sucker while it still (almost)
    applies. 2TB is a showstopper for some people in 2.4 today. Obviously
    2.6 will need 64-bit block numbers.

    The next obstacle will be page cache indices into the blockdev mapping.
    That's either an 8TB or 16TB limit, depending on signedness correctness.

    One minor point - it is currently not possible to print sector_t's.
    This code:

    printk("%lu%s", some_sector, some_string);

    will work fine with 32-bit sector_t. But with 64-bit sector_t it
    will generate a warning at compile-time and an oops at runtime.

    The same problem applies to dma_addr_t. Jeff, davem and I kicked
    that around a while back and ended up deciding that although there
    are a number of high-tech solutions, the dumb one was best:

    --- 2.5.14/include/linux/types.h~sector_t-printing Thu May 9 17:08:13 2002
    +++ 2.5.14-akpm/include/linux/types.h Thu May 9 17:08:13 2002
    @@ -120,8 +120,10 @@ typedef __s64 int64_t;

    #ifdef BLK_64BIT_SECTOR
    typedef u64 sector_t;
    +#define FMT_SECTOR_T "%Lu"
    typedef unsigned long sector_t;
    +#define FMT_SECTOR_T "%lu"

    #endif /* __KERNEL_STRICT_NAMES */
    --- 2.5.14/fs/buffer.c~sector_t-printing Thu May 9 17:08:13 2002
    +++ 2.5.14-akpm/fs/buffer.c Thu May 9 17:09:35 2002
    @@ -179,7 +179,8 @@ __clear_page_buffers(struct page *page)

    static void buffer_io_error(struct buffer_head *bh)
    - printk(KERN_ERR "Buffer I/O error on device %s, logical block %ld\n",
    + printk(KERN_ERR "Buffer I/O error on device %s,"
    + " logical block " FMT_SECTOR_T "\n",
    bdevname(bh->b_bdev), bh->b_blocknr);
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      Last update: 2005-03-22 13:26    [W:0.024 / U:1.944 seconds]
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