Andy Warner wrote:

Jeff Garzik wrote:

quoted

[...]

quoted

In libata-core.c:ata_sg_init_one() there is:

WARN_ON(buflen > PAGE_SIZE);

[...]
A non-scatter-gather transfer is assumed to be one page in length, using 
only a single 'struct scatterlist' element.  You could probably "cheat" 
and indicate the scatterlist element is longer than PAGE_SIZE, but make 
sure to review all code paths...

Bear with me, if I'm being dense, but why is that a valid
assumption ? Is it because in most instances, such requests
are made by filesystem code, as opposed to arbitrary user
initiated I/O ?

A struct scatterlist is a list of page/offset/length triplets, so it 
breaks the model if a triplet extends past a page boundary.

	Jeff