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xen-blkfront: handle bvecs with partial data
Currently blkfront fails to handle cases in blkif_completion like the following: 1st loop in rq_for_each_segment * bv_offset: 3584 * bv_len: 512 * offset += bv_len * i: 0 2nd loop: * bv_offset: 0 * bv_len: 512 * i: 0 In the second loop i should be 1, since we assume we only wanted to read a part of the previous page. This patches fixes this cases where only a part of the shared page is read, and blkif_completion assumes that if the bv_offset of a bvec is less than the previous bv_offset plus the bv_size we have to switch to the next shared page. Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Cc: linux-kernel@vger.kernel.org Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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ebb351cf78
commit
d62f691858
1 changed files with 4 additions and 3 deletions
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@ -836,7 +836,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
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static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
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struct blkif_response *bret)
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{
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int i;
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int i = 0;
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struct bio_vec *bvec;
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struct req_iterator iter;
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unsigned long flags;
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@ -853,7 +853,8 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
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*/
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rq_for_each_segment(bvec, s->request, iter) {
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BUG_ON((bvec->bv_offset + bvec->bv_len) > PAGE_SIZE);
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i = offset >> PAGE_SHIFT;
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if (bvec->bv_offset < offset)
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i++;
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BUG_ON(i >= s->req.u.rw.nr_segments);
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shared_data = kmap_atomic(
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pfn_to_page(s->grants_used[i]->pfn));
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@ -862,7 +863,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
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bvec->bv_len);
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bvec_kunmap_irq(bvec_data, &flags);
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kunmap_atomic(shared_data);
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offset += bvec->bv_len;
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offset = bvec->bv_offset + bvec->bv_len;
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}
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}
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/* Add the persistent grant into the list of free grants */
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