linux-toradex.git/include/linux/scatterlist.h, branch v2.6.36-rc5

lib/scatterlist: add a flags to signalize mapping direction

2009-07-31T10:28:45+00:00

sg_miter_start() is currently unaware of the direction of the copy
process (to or from the scatter list). It is important to know the
direction because the page has to be flushed in case the data written
is seen on a different mapping in user land on cache incoherent
architectures.

Signed-off-by: Sebastian Andrzej Siewior 
Acked-by: FUJITA Tomonori 
Acked-by: Tejun Heo 
Signed-off-by: Pierre Ossman

sg: reimplement sg mapping iterator

2008-07-23T12:42:09+00:00

This is alternative implementation of sg content iterator introduced
by commit 83e7d317... from Pierre Ossman in next-20080716.  As there's
already an sg iterator which iterates over sg entries themselves, name
this sg_mapping_iterator.

Slightly edited description from the original implementation follows.

Iteration over a sg list is not that trivial when you take into
account that memory pages might have to be mapped before being used.
Unfortunately, that means that some parts of the kernel restrict
themselves to directly accesible memory just to not have to deal with
the mess.

This patch adds a simple iterator system that allows any code to
easily traverse an sg list and not have to deal with all the details.
The user can decide to consume part of the iteration.  Also, iteration
can be stopped and resumed later if releasing the kmap between
iteration steps is necessary.  These features are useful to implement
piecemeal sg copying for interrupt drive PIO for example.

Signed-off-by: Tejun Heo 
Signed-off-by: Pierre Ossman

[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

Don't blatt first element of prv in sg_chain()

2008-01-11T09:12:55+00:00

I realize that sg chaining is a ploy to make the rest of the kernel
devs feel the pain of the SCSI subsystem.  But this was a little
unsubtle.

Signed-off-by: Rusty Russell 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe

scatterlist: add more safeguards

2007-11-27T08:30:39+00:00

Add more safeguards to protect against misinterpreting a chain entry
as a normal scatterlist and vice-versa.

* Make sure the entry isn't a chain when assigning and reading a
  normal sg.

* Clear offset and length when chaining.

Signed-off-by: Tejun Heo 
Signed-off-by: Jens Axboe

[SG] Get rid of __sg_mark_end()

2007-11-02T07:47:06+00:00

sg_mark_end() overwrites the page_link information, but all users want
__sg_mark_end() behaviour where we just set the end bit. That is the most
natural way to use the sg list, since you'll fill it in and then mark the
end point.

So change sg_mark_end() to only set the termination bit. Add a sg_magic
debug check as well, and clear a chain pointer if it is set.

Signed-off-by: Jens Axboe

SG: Make sg_init_one() use general table init functions

2007-11-02T07:47:06+00:00

Don't open code sg_init_one(), make it reuse sg_init_table().

Signed-off-by: Jens Axboe

sg_init_table() should use unsigned loop index variable

2007-10-29T08:18:04+00:00

Clean up: fix a mixed sign comparison in sg_init_table() accidentally
introduced by commit d6ec0842.  The sign of the loop index variable
should match the sign of the "nents" argument.

Signed-off-by: Chuck Lever 
Cc: Jens Axboe 
Signed-off-by: Jens Axboe