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2008-04-07[SCSI] block: add sg buffer copy helper functionsFUJITA Tomonori
This patch adds new three helper functions to copy data between an SG list and a linear buffer. - sg_copy_from_buffer copies data from linear buffer to an SG list - sg_copy_to_buffer copies data from an SG list to a linear buffer When the APIs copy data from a linear buffer to an SG list, flush_kernel_dcache_page is called. It's not necessary for everyone but it's a no-op on most architectures and in general the API is not used in performance critical path. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Acked-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-01-28SG: work with the SCSI fixed maximum allocations.James Bottomley
SCSI sg table allocation has a maximum size (of SCSI_MAX_SG_SEGMENTS, currently 128) and this will cause a BUG_ON() in SCSI if something tries an allocation over it. This patch adds a size limit to the chaining allocator to allow the specification of the maximum allocation size for chaining, so we always chain in units of the maximum SCSI allocation size. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-01-28SG: Move functions to lib/scatterlist.c and add sg chaining allocator helpersJens Axboe
Manually doing chained sg lists is not trivial, so add some helpers to make sure that drivers get it right. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>