From afdc1a780ef84a54b613dae6f971407748aab61c Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Fri, 11 Apr 2008 12:56:51 +0200 Subject: [PATCH] block: add bio_copy_user_iov support to blk_rq_map_user_iov With this patch, blk_rq_map_user_iov uses bio_copy_user_iov when a low level driver needs padding or a buffer in sg_iovec isn't aligned. That is, it uses temporary kernel buffers instead of mapping user pages directly. When a LLD needs padding, later blk_rq_map_sg needs to extend the last entry of a scatter list. bio_copy_user_iov guarantees that there is enough space for padding by using temporary kernel buffers instead of user pages. blk_rq_map_user_iov needs buffers in sg_iovec to be aligned. The comment in blk_rq_map_user_iov indicates that drivers/scsi/sg.c also needs buffers in sg_iovec to be aligned. Actually, drivers/scsi/sg.c works with unaligned buffers in sg_iovec (it always uses temporary kernel buffers). Signed-off-by: FUJITA Tomonori Cc: Tejun Heo Cc: Mike Christie Cc: James Bottomley Signed-off-by: Jens Axboe --- block/blk-map.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/block/blk-map.c b/block/blk-map.c index c07d9c8317f..ab43533ba64 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -5,6 +5,7 @@ #include #include #include +#include /* for struct sg_iovec */ #include "blk.h" @@ -194,15 +195,26 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, struct sg_iovec *iov, int iov_count, unsigned int len) { struct bio *bio; + int i, read = rq_data_dir(rq) == READ; + int unaligned = 0; if (!iov || iov_count <= 0) return -EINVAL; - /* we don't allow misaligned data like bio_map_user() does. If the - * user is using sg, they're expected to know the alignment constraints - * and respect them accordingly */ - bio = bio_map_user_iov(q, NULL, iov, iov_count, - rq_data_dir(rq) == READ); + for (i = 0; i < iov_count; i++) { + unsigned long uaddr = (unsigned long)iov[i].iov_base; + + if (uaddr & queue_dma_alignment(q)) { + unaligned = 1; + break; + } + } + + if (unaligned || (q->dma_pad_mask & len)) + bio = bio_copy_user_iov(q, iov, iov_count, read); + else + bio = bio_map_user_iov(q, NULL, iov, iov_count, read); + if (IS_ERR(bio)) return PTR_ERR(bio); -- 2.20.1