![Harvey Harrison](/assets/img/avatar_default.png)
Introduced between 2.6.25-rc2 and -rc3 block/blk-map.c:154:14: warning: symbol 'bio' shadows an earlier one block/blk-map.c:110:13: originally declared here Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
284 lines
7.1 KiB
C
284 lines
7.1 KiB
C
/*
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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 "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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EXPORT_SYMBOL(blk_rq_append_bio);
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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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void __user *ubuf, unsigned int len)
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{
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unsigned long uaddr;
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unsigned int alignment;
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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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alignment = queue_dma_alignment(q) | q->dma_pad_mask;
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if (!(uaddr & alignment) && !(len & alignment))
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bio = bio_map_user(q, NULL, uaddr, len, reading);
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else
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bio = bio_copy_user(q, uaddr, len, reading);
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if (IS_ERR(bio))
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return PTR_ERR(bio);
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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_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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* @ubuf: the user buffer
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* @len: length of user data
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*
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* Description:
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* Data will be mapped directly for zero copy io, 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 io, 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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void __user *ubuf, unsigned long len)
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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 > (q->max_hw_sectors << 9))
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return -EINVAL;
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if (!len || !ubuf)
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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, ubuf, map_len);
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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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}
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/*
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* __blk_rq_map_user() copies the buffers if starting address
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* or length isn't aligned to dma_pad_mask. As the copied
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* buffer is always page aligned, we know that there's enough
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* room for padding. Extend the last bio and update
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* rq->data_len accordingly.
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*
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* On unmap, bio_uncopy_user() will use unmodified
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* bio_map_data pointed to by bio->bi_private.
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*/
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if (len & q->dma_pad_mask) {
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unsigned int pad_len = (q->dma_pad_mask & ~len) + 1;
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struct bio *tail = rq->biotail;
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tail->bi_io_vec[tail->bi_vcnt - 1].bv_len += pad_len;
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tail->bi_size += pad_len;
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rq->extra_len += pad_len;
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}
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rq->buffer = rq->data = 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_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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* @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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*
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* Description:
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* Data will be mapped directly for zero copy io, 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 io, 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 sg_iovec *iov, int iov_count, unsigned int len)
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{
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struct bio *bio;
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if (!iov || iov_count <= 0)
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return -EINVAL;
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/* we don't allow misaligned data like bio_map_user() does. If the
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* user is using sg, they're expected to know the alignment constraints
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* and respect them accordingly */
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bio = bio_map_user_iov(q, NULL, iov, iov_count,
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rq_data_dir(rq) == READ);
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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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bio_endio(bio, 0);
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bio_unmap_user(bio);
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return -EINVAL;
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}
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bio_get(bio);
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blk_rq_bio_prep(q, rq, bio);
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rq->buffer = rq->data = NULL;
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return 0;
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}
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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 io 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_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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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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struct bio *bio;
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if (len > (q->max_hw_sectors << 9))
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return -EINVAL;
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if (!len || !kbuf)
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return -EINVAL;
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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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blk_rq_bio_prep(q, rq, bio);
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blk_queue_bounce(q, &rq->bio);
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rq->buffer = rq->data = 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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