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path: root/include/linux/scatterlist.h
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2009-07-31lib/scatterlist: add a flags to signalize mapping directionSebastian Andrzej Siewior1-0/+2
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 <sebastian@breakpoint.cc> Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Pierre Ossman <pierre@ossman.eu>
2008-07-23sg: reimplement sg mapping iteratorTejun Heo1-0/+38
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 <tj@kernel.org> Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
2008-04-07[SCSI] block: add sg buffer copy helper functionsFUJITA Tomonori1-0/+5
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 Bottomley1-2/+3
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 Axboe1-100/+25
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>
2008-01-11Don't blatt first element of prv in sg_chain()Rusty Russell1-2/+2
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 <rusty@rustcorp.com.au> Acked-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-11-27scatterlist: add more safeguardsTejun Heo1-11/+26
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 <htejun@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-11-02[SG] Get rid of __sg_mark_end()Jens Axboe1-10/+12
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 <jens.axboe@oracle.com>
2007-11-02SG: Make sg_init_one() use general table init functionsJens Axboe1-22/+18
Don't open code sg_init_one(), make it reuse sg_init_table(). Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-29sg_init_table() should use unsigned loop index variableChuck Lever1-1/+1
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 <chuck.lever@oracle.com> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Jens Axboe <axboe@carl.home.kernel.dk>
2007-10-29sg_last() should use unsigned loop index variableChuck Lever1-1/+1
Clean up: fix a mixed sign comparison in sg_last() accidentally introduced by commit 70eb8040. The sign of the loop index variable should match the sign of the "nents" argument. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Jens Axboe <axboe@carl.home.kernel.dk>
2007-10-29SG: clear termination bit in sg_chain()Jens Axboe1-1/+5
Since we are using the last entry in the list, clear any possible termination bit that may have already been set. Pointed out by Rusty. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-25fix sg_phys to use dma_addr_tHugh Dickins1-1/+2
x86_32 CONFIG_HIGHMEM64G with 5GB RAM hung when booting, after issuing some "request_module: runaway loop modprobe binfmt-0000" messages in trying to exec /sbin/init. The binprm buf doesn't see the right ".ELF" header because sg_phys() is providing the wrong physical addresses for high pages: a 32-bit unsigned long is too small in this case, we need to use dma_addr_t. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-24SG: Change sg_set_page() to take length and offset argumentJens Axboe1-11/+29
Most drivers need to set length and offset as well, so may as well fold those three lines into one. Add sg_assign_page() for those two locations that only needed to set the page, where the offset/length is set outside of the function context. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-23[SG] Add debug check for page alignmentJens Axboe1-0/+5
Suggested by Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-22Add CONFIG_DEBUG_SG sg validationJens Axboe1-0/+22
Add a Kconfig entry which will toggle some sanity checks on the sg entry and tables. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-22Change table chaining layoutJens Axboe1-24/+54
Change the page member of the scatterlist structure to be an unsigned long, and encode more stuff in the lower bits: - Bits 0 and 1 zero: this is a normal sg entry. Next sg entry is located at sg + 1. - Bit 0 set: this is a chain entry, the next real entry is at ->page_link with the two low bits masked off. - Bit 1 set: this is the final entry in the sg entry. sg_next() will return NULL when passed such an entry. It's thus important that sg table users use the proper accessors to get and set the page member. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-22[SG] Add helpers for manipulating SG entriesJens Axboe1-8/+104
We can then transition drivers without changing the generated code. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-16Add chained sg support to linux/scatterlist.hJens Axboe1-2/+77
The core of the patch - allow the last sg element in a scatterlist table to point to the start of a new table. We overload the LSB of the page pointer to indicate whether this is a valid sg entry, or merely a link to the next list. Includes a fix from Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> correcting the ifdef ARCH_HAS_SG_CHAIN guarding sg_last(). Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-16Add sg helpers for iterating over a scatterlist tableJens Axboe1-0/+9
First step to being able to change the scatterlist setup without having to modify drivers (a lot :-) Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-09-21[PATCH] scatterlist: Add const to sg_set_buf/sg_init_one pointer argumentHerbert Xu1-2/+2
This patch adds a const modifier to the buf argument of sg_set_buf and sg_init_one. This lets people call it with pointers that are const. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2005-10-30[PATCH] Introduce sg_set_bufHerbert Xu1-4/+13
sg_init_one is a nice tool for the block layer. However, users of struct scatterlist in other subsystems don't usually need the DMA attributes. For them it's a waste of time and space to initialise the whole struct scatterlist structure. Therefore this patch adds a new function sg_set_buf to initialise a scatterlist without zeroing the DMA attributes. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2005-04-16Linux-2.6.12-rc2Linus Torvalds1-0/+14
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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