Commit Graph

3 Commits

Author SHA1 Message Date
FUJITA Tomonori b1adaf65ba [SCSI] block: add sg buffer copy helper functions
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>
2008-04-07 12:15:45 -05:00
James Bottomley 7cedb1f17f SG: work with the SCSI fixed maximum allocations.
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>
2008-01-28 10:54:49 +01:00
Jens Axboe 0db9299f48 SG: Move functions to lib/scatterlist.c and add sg chaining allocator helpers
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>
2008-01-28 10:05:27 +01:00