327 lines
8.1 KiB
C
327 lines
8.1 KiB
C
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/*
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* Functions related to mapping data to requests
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <scsi/sg.h> /* for struct sg_iovec */
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#include "blk.h"
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int blk_rq_append_bio(struct request_queue *q, struct request *rq,
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struct bio *bio)
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{
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if (!rq->bio)
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blk_rq_bio_prep(q, rq, bio);
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else if (!ll_back_merge_fn(q, rq, bio))
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return -EINVAL;
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else {
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rq->biotail->bi_next = bio;
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rq->biotail = bio;
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rq->__data_len += bio->bi_size;
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}
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return 0;
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}
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static int __blk_rq_unmap_user(struct bio *bio)
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{
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int ret = 0;
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if (bio) {
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if (bio_flagged(bio, BIO_USER_MAPPED))
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bio_unmap_user(bio);
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else
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ret = bio_uncopy_user(bio);
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}
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return ret;
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}
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static int __blk_rq_map_user(struct request_queue *q, struct request *rq,
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struct rq_map_data *map_data, void __user *ubuf,
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unsigned int len, gfp_t gfp_mask)
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{
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unsigned long uaddr;
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struct bio *bio, *orig_bio;
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int reading, ret;
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reading = rq_data_dir(rq) == READ;
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/*
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* if alignment requirement is satisfied, map in user pages for
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* direct dma. else, set up kernel bounce buffers
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*/
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uaddr = (unsigned long) ubuf;
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if (blk_rq_aligned(q, ubuf, len) && !map_data)
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bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask);
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else
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bio = bio_copy_user(q, map_data, uaddr, len, reading, gfp_mask);
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if (IS_ERR(bio))
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return PTR_ERR(bio);
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if (map_data && map_data->null_mapped)
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bio->bi_flags |= (1 << BIO_NULL_MAPPED);
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orig_bio = bio;
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blk_queue_bounce(q, &bio);
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/*
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* We link the bounce buffer in and could have to traverse it
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* later so we have to get a ref to prevent it from being freed
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*/
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bio_get(bio);
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ret = blk_rq_append_bio(q, rq, bio);
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if (!ret)
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return bio->bi_size;
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/* if it was boucned we must call the end io function */
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bio_endio(bio, 0);
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__blk_rq_unmap_user(orig_bio);
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bio_put(bio);
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return ret;
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}
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/**
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* blk_rq_map_user - map user data to a request, for REQ_TYPE_BLOCK_PC usage
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* @q: request queue where request should be inserted
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* @rq: request structure to fill
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* @map_data: pointer to the rq_map_data holding pages (if necessary)
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* @ubuf: the user buffer
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* @len: length of user data
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* @gfp_mask: memory allocation flags
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*
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* Description:
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* Data will be mapped directly for zero copy I/O, if possible. Otherwise
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* a kernel bounce buffer is used.
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*
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* A matching blk_rq_unmap_user() must be issued at the end of I/O, while
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* still in process context.
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*
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* Note: The mapped bio may need to be bounced through blk_queue_bounce()
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* before being submitted to the device, as pages mapped may be out of
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* reach. It's the callers responsibility to make sure this happens. The
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* original bio must be passed back in to blk_rq_unmap_user() for proper
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* unmapping.
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*/
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int blk_rq_map_user(struct request_queue *q, struct request *rq,
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struct rq_map_data *map_data, void __user *ubuf,
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unsigned long len, gfp_t gfp_mask)
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{
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unsigned long bytes_read = 0;
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struct bio *bio = NULL;
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int ret;
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if (len > (queue_max_hw_sectors(q) << 9))
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return -EINVAL;
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if (!len)
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return -EINVAL;
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if (!ubuf && (!map_data || !map_data->null_mapped))
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return -EINVAL;
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while (bytes_read != len) {
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unsigned long map_len, end, start;
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map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
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end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
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>> PAGE_SHIFT;
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start = (unsigned long)ubuf >> PAGE_SHIFT;
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/*
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* A bad offset could cause us to require BIO_MAX_PAGES + 1
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* pages. If this happens we just lower the requested
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* mapping len by a page so that we can fit
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*/
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if (end - start > BIO_MAX_PAGES)
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map_len -= PAGE_SIZE;
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ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len,
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gfp_mask);
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if (ret < 0)
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goto unmap_rq;
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if (!bio)
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bio = rq->bio;
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bytes_read += ret;
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ubuf += ret;
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if (map_data)
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map_data->offset += ret;
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}
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if (!bio_flagged(bio, BIO_USER_MAPPED))
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rq->cmd_flags |= REQ_COPY_USER;
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rq->buffer = NULL;
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return 0;
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unmap_rq:
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blk_rq_unmap_user(bio);
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rq->bio = NULL;
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return ret;
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}
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EXPORT_SYMBOL(blk_rq_map_user);
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/**
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* blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
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* @q: request queue where request should be inserted
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* @rq: request to map data to
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* @map_data: pointer to the rq_map_data holding pages (if necessary)
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* @iov: pointer to the iovec
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* @iov_count: number of elements in the iovec
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* @len: I/O byte count
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* @gfp_mask: memory allocation flags
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*
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* Description:
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* Data will be mapped directly for zero copy I/O, if possible. Otherwise
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* a kernel bounce buffer is used.
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*
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* A matching blk_rq_unmap_user() must be issued at the end of I/O, while
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* still in process context.
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*
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* Note: The mapped bio may need to be bounced through blk_queue_bounce()
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* before being submitted to the device, as pages mapped may be out of
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* reach. It's the callers responsibility to make sure this happens. The
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* original bio must be passed back in to blk_rq_unmap_user() for proper
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* unmapping.
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*/
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int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
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struct rq_map_data *map_data, struct sg_iovec *iov,
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int iov_count, unsigned int len, gfp_t gfp_mask)
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{
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struct bio *bio;
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int i, read = rq_data_dir(rq) == READ;
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int unaligned = 0;
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if (!iov || iov_count <= 0)
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return -EINVAL;
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for (i = 0; i < iov_count; i++) {
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unsigned long uaddr = (unsigned long)iov[i].iov_base;
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if (uaddr & queue_dma_alignment(q)) {
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unaligned = 1;
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break;
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}
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}
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if (unaligned || (q->dma_pad_mask & len) || map_data)
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bio = bio_copy_user_iov(q, map_data, iov, iov_count, read,
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gfp_mask);
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else
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bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask);
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if (IS_ERR(bio))
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return PTR_ERR(bio);
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if (bio->bi_size != len) {
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/*
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* Grab an extra reference to this bio, as bio_unmap_user()
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* expects to be able to drop it twice as it happens on the
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* normal IO completion path
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*/
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bio_get(bio);
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bio_endio(bio, 0);
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__blk_rq_unmap_user(bio);
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return -EINVAL;
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}
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if (!bio_flagged(bio, BIO_USER_MAPPED))
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rq->cmd_flags |= REQ_COPY_USER;
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blk_queue_bounce(q, &bio);
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bio_get(bio);
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blk_rq_bio_prep(q, rq, bio);
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rq->buffer = NULL;
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return 0;
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}
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EXPORT_SYMBOL(blk_rq_map_user_iov);
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/**
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* blk_rq_unmap_user - unmap a request with user data
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* @bio: start of bio list
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*
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* Description:
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* Unmap a rq previously mapped by blk_rq_map_user(). The caller must
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* supply the original rq->bio from the blk_rq_map_user() return, since
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* the I/O completion may have changed rq->bio.
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*/
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int blk_rq_unmap_user(struct bio *bio)
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{
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struct bio *mapped_bio;
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int ret = 0, ret2;
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while (bio) {
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mapped_bio = bio;
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if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
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mapped_bio = bio->bi_private;
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ret2 = __blk_rq_unmap_user(mapped_bio);
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if (ret2 && !ret)
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ret = ret2;
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mapped_bio = bio;
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bio = bio->bi_next;
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bio_put(mapped_bio);
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}
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return ret;
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}
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EXPORT_SYMBOL(blk_rq_unmap_user);
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/**
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* blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
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* @q: request queue where request should be inserted
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* @rq: request to fill
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* @kbuf: the kernel buffer
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* @len: length of user data
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* @gfp_mask: memory allocation flags
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*
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* Description:
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* Data will be mapped directly if possible. Otherwise a bounce
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* buffer is used. Can be called multple times to append multple
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* buffers.
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*/
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int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
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unsigned int len, gfp_t gfp_mask)
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{
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int reading = rq_data_dir(rq) == READ;
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int do_copy = 0;
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struct bio *bio;
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int ret;
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if (len > (queue_max_hw_sectors(q) << 9))
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return -EINVAL;
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if (!len || !kbuf)
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return -EINVAL;
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do_copy = !blk_rq_aligned(q, kbuf, len) || object_is_on_stack(kbuf);
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if (do_copy)
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bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
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else
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bio = bio_map_kern(q, kbuf, len, gfp_mask);
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if (IS_ERR(bio))
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return PTR_ERR(bio);
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if (rq_data_dir(rq) == WRITE)
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bio->bi_rw |= (1 << BIO_RW);
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if (do_copy)
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rq->cmd_flags |= REQ_COPY_USER;
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ret = blk_rq_append_bio(q, rq, bio);
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if (unlikely(ret)) {
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/* request is too big */
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bio_put(bio);
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return ret;
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}
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blk_queue_bounce(q, &rq->bio);
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rq->buffer = NULL;
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return 0;
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}
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EXPORT_SYMBOL(blk_rq_map_kern);
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