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authorFUJITA Tomonori2008-04-11 05:56:52 -0500
committerJens Axboe2008-04-21 02:50:08 -0500
commitf18573abcc57844a7c3c12699d40eead8728cd8a (patch)
tree99d5dcfdfe29578bb23900e63f226022f5e87281 /block
parentafdc1a780ef84a54b613dae6f971407748aab61c (diff)
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block: move the padding adjustment to blk_rq_map_sg
blk_rq_map_user adjusts bi_size of the last bio. It breaks the rule that req->data_len (the true data length) is equal to sum(bio). It broke the scsi command completion code. commit e97a294ef6938512b655b1abf17656cf2b26f709 was introduced to fix the above issue. However, the partial completion code doesn't work with it. The commit is also a layer violation (scsi mid-layer should not know about the block layer's padding). This patch moves the padding adjustment to blk_rq_map_sg (suggested by James). The padding works like the drain buffer. This patch breaks the rule that req->data_len is equal to sum(sg), however, the drain buffer already broke it. So this patch just restores the rule that req->data_len is equal to sub(bio) without breaking anything new. Now when a low level driver needs padding, blk_rq_map_user and blk_rq_map_user_iov guarantee there's enough room for padding. blk_rq_map_sg can safely extend the last entry of a scatter list. blk_rq_map_sg must extend the last entry of a scatter list only for a request that got through bio_copy_user_iov. This patches introduces new REQ_COPY_USER flag. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Tejun Heo <htejun@gmail.com> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
-rw-r--r--block/blk-map.c24
-rw-r--r--block/blk-merge.c9
2 files changed, 14 insertions, 19 deletions
diff --git a/block/blk-map.c b/block/blk-map.c
index ab43533ba64..3c942bd6422 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -141,25 +141,8 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
141 ubuf += ret; 141 ubuf += ret;
142 } 142 }
143 143
144 /* 144 if (!bio_flagged(bio, BIO_USER_MAPPED))
145 * __blk_rq_map_user() copies the buffers if starting address 145 rq->cmd_flags |= REQ_COPY_USER;
146 * or length isn't aligned to dma_pad_mask. As the copied
147 * buffer is always page aligned, we know that there's enough
148 * room for padding. Extend the last bio and update
149 * rq->data_len accordingly.
150 *
151 * On unmap, bio_uncopy_user() will use unmodified
152 * bio_map_data pointed to by bio->bi_private.
153 */
154 if (len & q->dma_pad_mask) {
155 unsigned int pad_len = (q->dma_pad_mask & ~len) + 1;
156 struct bio *tail = rq->biotail;
157
158 tail->bi_io_vec[tail->bi_vcnt - 1].bv_len += pad_len;
159 tail->bi_size += pad_len;
160
161 rq->extra_len += pad_len;
162 }
163 146
164 rq->buffer = rq->data = NULL; 147 rq->buffer = rq->data = NULL;
165 return 0; 148 return 0;
@@ -224,6 +207,9 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
224 return -EINVAL; 207 return -EINVAL;
225 } 208 }
226 209
210 if (!bio_flagged(bio, BIO_USER_MAPPED))
211 rq->cmd_flags |= REQ_COPY_USER;
212
227 bio_get(bio); 213 bio_get(bio);
228 blk_rq_bio_prep(q, rq, bio); 214 blk_rq_bio_prep(q, rq, bio);
229 rq->buffer = rq->data = NULL; 215 rq->buffer = rq->data = NULL;
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 0f58616bcd7..b5c5c4a9e3f 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -220,6 +220,15 @@ new_segment:
220 bvprv = bvec; 220 bvprv = bvec;
221 } /* segments in rq */ 221 } /* segments in rq */
222 222
223
224 if (unlikely(rq->cmd_flags & REQ_COPY_USER) &&
225 (rq->data_len & q->dma_pad_mask)) {
226 unsigned int pad_len = (q->dma_pad_mask & ~rq->data_len) + 1;
227
228 sg->length += pad_len;
229 rq->extra_len += pad_len;
230 }
231
223 if (q->dma_drain_size && q->dma_drain_needed(rq)) { 232 if (q->dma_drain_size && q->dma_drain_needed(rq)) {
224 if (rq->cmd_flags & REQ_RW) 233 if (rq->cmd_flags & REQ_RW)
225 memset(q->dma_drain_buffer, 0, q->dma_drain_size); 234 memset(q->dma_drain_buffer, 0, q->dma_drain_size);