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    SubjectRe: [PATCH] remove 2TB block device limit
    On Tue, 14 May 2002, Peter Chubb wrote:
    > >>>>> "Christoph" == Christoph Hellwig <> writes:
    > Christoph> On Mon, May 13, 2002 at 08:28:30PM +1000, Peter Chubb
    > Christoph> wrote:
    > >> There's now a patch available against 2.5.15, and the BK repository
    > >> has been updated to v2.5.15 as well:
    > >>
    > >>
    > >> bk://
    > Christoph> This looks really good, I'd like to see something like that
    > Christoph> merged soon! Some comments:
    > Christoph> - why is the get_block block argument
    > Christoph> a sector_t? It presents a logical filesystem block which
    > Christoph> usually is larger than the sector, not to mention that for
    > Christoph> the usual blocksize == PAGE_SIZE case a ulong is enough as
    > Christoph> that is the same size the pagecache limit triggers.
    > For filesystems that *can* handle logical filesystem blocks beyond the
    > 2^32 limit (i.e., that use >32bit offsets in their on-disc format),
    > the get_block() argument has to be > 32bits long. At the moment
    > that's only JFS and XFS, but reiserfs version 4 looks as if it might
    > go that way. We'll need this especially when the pagecache limit is
    > gone.

    NTFS uses signed 64 bits for all offsets on disk, too. And yes at the
    moment the pagecache limit is also a problem which we just ignore in the
    hope that the kernel will have gone to 64 bits by the time devices grow
    that large as to start using > 32 bits of blocks/pages...

    > Besides, blocksize is not usually pagesize. ext[23] uses 1k or 4k
    > blocks depending on the size and expected use of the filesystem; alpha
    > pagesize is usually 8k, for example. The arm uses 4k, 16k or 32k
    > pagesizes depending on the model.
    > So on 32-bit systems, ulong is not enough. (in fact if you look at
    > jfs, the first thing jfs_get_block does is convert the block number
    > arg to a 64-bit number).

    NTFS does that, too, but not quite immediately... (-;

    Best regards,

    Anton Altaparmakov <aia21 at> (replace at with @)
    Linux NTFS maintainer / IRC: #ntfs on
    WWW: &

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