[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] 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@xxxxxxxxxx> Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx> Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> --- drivers/block/xen-blkfront.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index df21b05..860f76d 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -843,7 +843,7 @@ static void blkif_free(struct blkfront_info *info, int suspend) static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, struct blkif_response *bret) { - int i; + int i = 0; struct bio_vec *bvec; struct req_iterator iter; unsigned long flags; @@ -860,7 +860,8 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, */ rq_for_each_segment(bvec, s->request, iter) { BUG_ON((bvec->bv_offset + bvec->bv_len) > PAGE_SIZE); - i = offset >> PAGE_SHIFT; + if (bvec->bv_offset < offset) + i++; BUG_ON(i >= s->req.u.rw.nr_segments); shared_data = kmap_atomic( pfn_to_page(s->grants_used[i]->pfn)); @@ -869,7 +870,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, bvec->bv_len); bvec_kunmap_irq(bvec_data, &flags); kunmap_atomic(shared_data); - offset += bvec->bv_len; + offset = bvec->bv_offset + bvec->bv_len; } } /* Add the persistent grant into the list of free grants */ -- 1.7.7.5 (Apple Git-26) _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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