Messages in this thread | | | Date | Tue, 14 May 2002 02:36:50 +0100 (BST) | From | Anton Altaparmakov <> | Subject | Re: [PATCH] remove 2TB block device limit |
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On Tue, 14 May 2002, Peter Chubb wrote: > >>>>> "Christoph" == Christoph Hellwig <hch@infradead.org> 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: > >> > >> http://www.gelato.unsw.edu.au/patches/2.5.15-largefile-patch > >> bk://gelato.unsw.edu.au:2023/ > > Christoph> This looks really good, I'd like to see something like that > Christoph> merged soon! Some comments: [snip] > 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 -- Anton Altaparmakov <aia21 at cantab.net> (replace at with @) Linux NTFS maintainer / IRC: #ntfs on irc.openprojects.net WWW: http://linux-ntfs.sf.net/ & http://www-stu.christs.cam.ac.uk/~aia21/
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