]>
git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - block/blk-map.c
2 * Functions related to mapping data to requests
4 #include <linux/kernel.h>
5 #include <linux/module.h>
7 #include <linux/blkdev.h>
8 #include <scsi/sg.h> /* for struct sg_iovec */
12 int blk_rq_append_bio(struct request_queue
*q
, struct request
*rq
,
16 blk_rq_bio_prep(q
, rq
, bio
);
17 else if (!ll_back_merge_fn(q
, rq
, bio
))
20 rq
->biotail
->bi_next
= bio
;
23 rq
->data_len
+= bio
->bi_size
;
27 EXPORT_SYMBOL(blk_rq_append_bio
);
29 static int __blk_rq_unmap_user(struct bio
*bio
)
34 if (bio_flagged(bio
, BIO_USER_MAPPED
))
37 ret
= bio_uncopy_user(bio
);
43 static int __blk_rq_map_user(struct request_queue
*q
, struct request
*rq
,
44 struct rq_map_data
*map_data
, void __user
*ubuf
,
45 unsigned int len
, gfp_t gfp_mask
)
48 struct bio
*bio
, *orig_bio
;
51 reading
= rq_data_dir(rq
) == READ
;
54 * if alignment requirement is satisfied, map in user pages for
55 * direct dma. else, set up kernel bounce buffers
57 uaddr
= (unsigned long) ubuf
;
58 if (blk_rq_aligned(q
, ubuf
, len
) && !map_data
)
59 bio
= bio_map_user(q
, NULL
, uaddr
, len
, reading
, gfp_mask
);
61 bio
= bio_copy_user(q
, map_data
, uaddr
, len
, reading
, gfp_mask
);
66 if (map_data
&& map_data
->null_mapped
)
67 bio
->bi_flags
|= (1 << BIO_NULL_MAPPED
);
70 blk_queue_bounce(q
, &bio
);
73 * We link the bounce buffer in and could have to traverse it
74 * later so we have to get a ref to prevent it from being freed
78 ret
= blk_rq_append_bio(q
, rq
, bio
);
82 /* if it was boucned we must call the end io function */
84 __blk_rq_unmap_user(orig_bio
);
90 * blk_rq_map_user - map user data to a request, for REQ_TYPE_BLOCK_PC usage
91 * @q: request queue where request should be inserted
92 * @rq: request structure to fill
93 * @map_data: pointer to the rq_map_data holding pages (if necessary)
94 * @ubuf: the user buffer
95 * @len: length of user data
96 * @gfp_mask: memory allocation flags
99 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
100 * a kernel bounce buffer is used.
102 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
103 * still in process context.
105 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
106 * before being submitted to the device, as pages mapped may be out of
107 * reach. It's the callers responsibility to make sure this happens. The
108 * original bio must be passed back in to blk_rq_unmap_user() for proper
111 int blk_rq_map_user(struct request_queue
*q
, struct request
*rq
,
112 struct rq_map_data
*map_data
, void __user
*ubuf
,
113 unsigned long len
, gfp_t gfp_mask
)
115 unsigned long bytes_read
= 0;
116 struct bio
*bio
= NULL
;
119 if (len
> (q
->max_hw_sectors
<< 9))
124 if (!ubuf
&& (!map_data
|| !map_data
->null_mapped
))
127 while (bytes_read
!= len
) {
128 unsigned long map_len
, end
, start
;
130 map_len
= min_t(unsigned long, len
- bytes_read
, BIO_MAX_SIZE
);
131 end
= ((unsigned long)ubuf
+ map_len
+ PAGE_SIZE
- 1)
133 start
= (unsigned long)ubuf
>> PAGE_SHIFT
;
136 * A bad offset could cause us to require BIO_MAX_PAGES + 1
137 * pages. If this happens we just lower the requested
138 * mapping len by a page so that we can fit
140 if (end
- start
> BIO_MAX_PAGES
)
141 map_len
-= PAGE_SIZE
;
143 ret
= __blk_rq_map_user(q
, rq
, map_data
, ubuf
, map_len
,
153 map_data
->offset
+= ret
;
156 if (!bio_flagged(bio
, BIO_USER_MAPPED
))
157 rq
->cmd_flags
|= REQ_COPY_USER
;
159 rq
->buffer
= rq
->data
= NULL
;
162 blk_rq_unmap_user(bio
);
166 EXPORT_SYMBOL(blk_rq_map_user
);
169 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
170 * @q: request queue where request should be inserted
171 * @rq: request to map data to
172 * @map_data: pointer to the rq_map_data holding pages (if necessary)
173 * @iov: pointer to the iovec
174 * @iov_count: number of elements in the iovec
175 * @len: I/O byte count
176 * @gfp_mask: memory allocation flags
179 * Data will be mapped directly for zero copy I/O, if possible. Otherwise
180 * a kernel bounce buffer is used.
182 * A matching blk_rq_unmap_user() must be issued at the end of I/O, while
183 * still in process context.
185 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
186 * before being submitted to the device, as pages mapped may be out of
187 * reach. It's the callers responsibility to make sure this happens. The
188 * original bio must be passed back in to blk_rq_unmap_user() for proper
191 int blk_rq_map_user_iov(struct request_queue
*q
, struct request
*rq
,
192 struct rq_map_data
*map_data
, struct sg_iovec
*iov
,
193 int iov_count
, unsigned int len
, gfp_t gfp_mask
)
196 int i
, read
= rq_data_dir(rq
) == READ
;
199 if (!iov
|| iov_count
<= 0)
202 for (i
= 0; i
< iov_count
; i
++) {
203 unsigned long uaddr
= (unsigned long)iov
[i
].iov_base
;
205 if (uaddr
& queue_dma_alignment(q
)) {
211 if (unaligned
|| (q
->dma_pad_mask
& len
) || map_data
)
212 bio
= bio_copy_user_iov(q
, map_data
, iov
, iov_count
, read
,
215 bio
= bio_map_user_iov(q
, NULL
, iov
, iov_count
, read
, gfp_mask
);
220 if (bio
->bi_size
!= len
) {
222 * Grab an extra reference to this bio, as bio_unmap_user()
223 * expects to be able to drop it twice as it happens on the
224 * normal IO completion path
228 __blk_rq_unmap_user(bio
);
232 if (!bio_flagged(bio
, BIO_USER_MAPPED
))
233 rq
->cmd_flags
|= REQ_COPY_USER
;
235 blk_queue_bounce(q
, &bio
);
237 blk_rq_bio_prep(q
, rq
, bio
);
238 rq
->buffer
= rq
->data
= NULL
;
241 EXPORT_SYMBOL(blk_rq_map_user_iov
);
244 * blk_rq_unmap_user - unmap a request with user data
245 * @bio: start of bio list
248 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
249 * supply the original rq->bio from the blk_rq_map_user() return, since
250 * the I/O completion may have changed rq->bio.
252 int blk_rq_unmap_user(struct bio
*bio
)
254 struct bio
*mapped_bio
;
259 if (unlikely(bio_flagged(bio
, BIO_BOUNCED
)))
260 mapped_bio
= bio
->bi_private
;
262 ret2
= __blk_rq_unmap_user(mapped_bio
);
273 EXPORT_SYMBOL(blk_rq_unmap_user
);
276 * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
277 * @q: request queue where request should be inserted
278 * @rq: request to fill
279 * @kbuf: the kernel buffer
280 * @len: length of user data
281 * @gfp_mask: memory allocation flags
284 * Data will be mapped directly if possible. Otherwise a bounce
287 int blk_rq_map_kern(struct request_queue
*q
, struct request
*rq
, void *kbuf
,
288 unsigned int len
, gfp_t gfp_mask
)
290 int reading
= rq_data_dir(rq
) == READ
;
294 if (len
> (q
->max_hw_sectors
<< 9))
299 do_copy
= !blk_rq_aligned(q
, kbuf
, len
) || object_is_on_stack(kbuf
);
301 bio
= bio_copy_kern(q
, kbuf
, len
, gfp_mask
, reading
);
303 bio
= bio_map_kern(q
, kbuf
, len
, gfp_mask
);
308 if (rq_data_dir(rq
) == WRITE
)
309 bio
->bi_rw
|= (1 << BIO_RW
);
312 rq
->cmd_flags
|= REQ_COPY_USER
;
314 blk_rq_bio_prep(q
, rq
, bio
);
315 blk_queue_bounce(q
, &rq
->bio
);
316 rq
->buffer
= rq
->data
= NULL
;
319 EXPORT_SYMBOL(blk_rq_map_kern
);