linux-stable.git/lib/scatterlist.c, branch linux-2.6.26.y

sg: disable interrupts inside sg_copy_buffer

2008-10-09T03:22:58+00:00

This is the backport of the upstream commit 50bed2e2862a8f3a4f7d683d0d27292e71ef18b9

The callers of sg_copy_buffer must disable interrupts before calling
it (since it uses kmap_atomic). Some callers use it on
interrupt-disabled code but some need to take the trouble to disable
interrupts just for this. No wonder they forget about it and we hit a
bug like:

http://bugzilla.kernel.org/show_bug.cgi?id=11529

James said that it might be better to disable interrupts inside the
function rather than risk the callers getting it wrong.

Signed-off-by: FUJITA Tomonori 
Signed-off-by: Jens Axboe 
Signed-off-by: James Bottomley 
Signed-off-by: Greg Kroah-Hartman

[SCSI] block: add sg buffer copy helper functions

2008-04-07T17:15:45+00:00

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 
Acked-by: Jens Axboe 
Signed-off-by: James Bottomley

SG: work with the SCSI fixed maximum allocations.

2008-01-28T09:54:49+00:00

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 
Signed-off-by: Jens Axboe

SG: Move functions to lib/scatterlist.c and add sg chaining allocator helpers

2008-01-28T09:05:27+00:00

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