Messages in this thread | | | Date | Wed, 22 Feb 2006 08:39:47 +1100 | From | Nathan Scott <> | Subject | Re: [PATCH 0/3] map multiple blocks in get_block() and mpage_readpages() |
| |
On Tue, Feb 21, 2006 at 08:03:54AM -0800, Badari Pulavarty wrote: > ... > Thinking more about it, currently (without my patches) only DIO > code can request for large chunks of mapping through get_blocks(). > Since b_size is only u32, you can only map 4GB max. Isn't it ? > With my patches, now mpage_readpages() also can request large > chunks. (through readahead). So, my patches are not adding any > extra limitation. Its carrying the same existing limitation.
The DIO get_blocks is super-freaky at the moment, in that it passes in an unsigned long max_blocks (units of blocks) but it expects the filesystem to fill in a u32 b_size (in bytes). This does at least give the filesystem the hint that this was a monster write and it gets the chance to allocate contiguously, but that was probably unintentional, who knows? I guess that subtlety would be dropped with this change if b_size isn't made a 64 bit entity.
> In order to handle larger chunks of disk mapping, changing b_size > to u64 is required and we should request for it irrespective of my > patches.
*shrug*... its all very closely inter-related, I'd keep it together. I'd also thought that size_t was the right type here, not u64? 32 bit platforms aren't capable of submitting IOs this large, so they needn't be doing any 64 bit manipulation here, no?
cheers.
-- Nathan - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |