From 791b5bfb47b0e6182f6268bd58a6f65beb7ca80e Mon Sep 17 00:00:00 2001 From: Mike Christie Date: Wed, 28 Feb 2007 14:22:39 -0600 Subject: [PATCH] Add sg io mmap helper sg.c supports mmap, so this patch just move the code to the block layer for others to share and converts it to the bio reserved buffer. The helpers are: - blk_rq_mmap - does some checks to makre sure the reserved buf is large enough. - blk_rq_vma_nopage - traverses the reserved buffer and does get_page() To setup and teardown the request and bio reserved buffer mappings for the sg mmap operation you call blk_rq_setup_buffer() and blk_rq_destroy_buffer(). Signed-off-by: Mike Christie --- block/ll_rw_blk.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/blkdev.h | 4 +++ 2 files changed, 72 insertions(+), 0 deletions(-) diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index 4d6c2bd..35b66ed 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -2431,6 +2431,74 @@ unmap_rq: EXPORT_SYMBOL(blk_rq_setup_buffer); /** + * blk_rq_mmap - alloc and setup buffers for REQ_BLOCK_PC mmap + * @rbuf: reserve buffer + * @vma: vm struct + * + * Description: + * A the caller must also call blk_rq_setup_buffer on the request and + * blk_rq_destroy_buffer() must be issued at the end of io. + * It's the callers responsibility to make sure this happens. The + * original bio must be passed back in to blk_rq_destroy_buffer() for + * proper unmapping. + * + * The block layer mmap functions implement the old sg.c behavior + * where they can be only one sg mmap command outstanding. + */ +int blk_rq_mmap(struct bio_reserve_buf *rbuf, struct vm_area_struct *vma) +{ + unsigned long len; + + if (vma->vm_pgoff) + return -EINVAL; /* want no offset */ + + if (!rbuf) + return -ENOMEM; + + len = vma->vm_end - vma->vm_start; + if (len > rbuf->buf_size) + return -ENOMEM; + + vma->vm_flags |= VM_RESERVED; + return 0; +} +EXPORT_SYMBOL(blk_rq_mmap); + +struct page *blk_rq_vma_nopage(struct bio_reserve_buf *rbuf, + struct vm_area_struct *vma, unsigned long addr, + int *type) +{ + struct page *pg = NOPAGE_SIGBUS; + unsigned long offset, bytes = 0, sg_offset; + struct scatterlist *sg; + int i; + + if (!rbuf) + return pg; + + offset = addr - vma->vm_start; + if (offset >= rbuf->buf_size) + return pg; + + for (i = 0; i < rbuf->sg_count; i++) { + sg = &rbuf->sg[i]; + + bytes += sg->length; + if (bytes > offset) { + sg_offset = sg->length - (bytes - offset); + pg = &sg->page[sg_offset >> PAGE_SHIFT]; + get_page(pg); + break; + } + } + + if (type) + *type = VM_FAULT_MINOR; + return pg; +} +EXPORT_SYMBOL(blk_rq_vma_nopage); + +/** * blk_rq_map_user - map user data to a request. * @q: request queue where request should be inserted * @rq: request structure to fill diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 755f0b4..04c1b09 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -670,6 +670,10 @@ extern void blk_sync_queue(struct reques extern void __blk_stop_queue(request_queue_t *q); extern void blk_run_queue(request_queue_t *); extern void blk_start_queueing(request_queue_t *); +extern struct page *blk_rq_vma_nopage(struct bio_reserve_buf *, + struct vm_area_struct *, unsigned long, + int *); +extern int blk_rq_mmap(struct bio_reserve_buf *, struct vm_area_struct *); extern int blk_rq_init_transfer(request_queue_t *, struct request *, void __user *, unsigned long); extern int blk_rq_map_user(request_queue_t *, struct request *, void __user *, unsigned long); -- 1.4.1.1