1 files changed, 152 insertions, 79 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index c800047f5835..cc06c55875b9 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -826,77 +826,144 @@ static void zero_bio_chain(struct bio *chain, int start_ofs)
 }
 
 /*
- * bio_chain_clone - clone a chain of bios up to a certain length.
- * might return a bio_pair that will need to be released.
+ * Clone a portion of a bio, starting at the given byte offset
+ * and continuing for the number of bytes indicated.
  */
-static struct bio *bio_chain_clone(struct bio **old, struct bio **next,
-				   struct bio_pair **bp,
-				   int len, gfp_t gfpmask)
-{
-	struct bio *old_chain = *old;
-	struct bio *new_chain = NULL;
-	struct bio *tail;
-	int total = 0;
-
-	if (*bp) {
-		bio_pair_release(*bp);
-		*bp = NULL;
-	}
+static struct bio *bio_clone_range(struct bio *bio_src,
+					unsigned int offset,
+					unsigned int len,
+					gfp_t gfpmask)
+{
+	struct bio_vec *bv;
+	unsigned int resid;
+	unsigned short idx;
+	unsigned int voff;
+	unsigned short end_idx;
+	unsigned short vcnt;
+	struct bio *bio;
 
-	while (old_chain && (total < len)) {
-		struct bio *tmp;
+	/* Handle the easy case for the caller */
 
-		tmp = bio_kmalloc(gfpmask, old_chain->bi_max_vecs);
-		if (!tmp)
-			goto err_out;
-		gfpmask &= ~__GFP_WAIT;	/* can't wait after the first */
+	if (!offset && len == bio_src->bi_size)
+		return bio_clone(bio_src, gfpmask);
 
-		if (total + old_chain->bi_size > len) {
-			struct bio_pair *bp;
+	if (WARN_ON_ONCE(!len))
+		return NULL;
+	if (WARN_ON_ONCE(len > bio_src->bi_size))
+		return NULL;
+	if (WARN_ON_ONCE(offset > bio_src->bi_size - len))
+		return NULL;
 
-			/*
-			 * this split can only happen with a single paged bio,
-			 * split_bio will BUG_ON if this is not the case
-			 */
-			dout("bio_chain_clone split! total=%d remaining=%d"
-			     "bi_size=%u\n",
-			     total, len - total, old_chain->bi_size);
+	/* Find first affected segment... */
 
-			/* split the bio. We'll release it either in the next
-			   call, or it will have to be released outside */
-			bp = bio_split(old_chain, (len - total) / SECTOR_SIZE);
-			if (!bp)
-				goto err_out;
+	resid = offset;
+	__bio_for_each_segment(bv, bio_src, idx, 0) {
+		if (resid < bv->bv_len)
+			break;
+		resid -= bv->bv_len;
+	}
+	voff = resid;
 
-			__bio_clone(tmp, &bp->bio1);
+	/* ...and the last affected segment */
 
-			*next = &bp->bio2;
-		} else {
-			__bio_clone(tmp, old_chain);
-			*next = old_chain->bi_next;
-		}
+	resid += len;
+	__bio_for_each_segment(bv, bio_src, end_idx, idx) {
+		if (resid <= bv->bv_len)
+			break;
+		resid -= bv->bv_len;
+	}
+	vcnt = end_idx - idx + 1;
+
+	/* Build the clone */
+
+	bio = bio_alloc(gfpmask, (unsigned int) vcnt);
+	if (!bio)
+		return NULL;	/* ENOMEM */
 
-		tmp->bi_bdev = NULL;
-		tmp->bi_next = NULL;
-		if (new_chain)
-			tail->bi_next = tmp;
-		else
-			new_chain = tmp;
-		tail = tmp;
-		old_chain = old_chain->bi_next;
+	bio->bi_bdev = bio_src->bi_bdev;
+	bio->bi_sector = bio_src->bi_sector + (offset >> SECTOR_SHIFT);
+	bio->bi_rw = bio_src->bi_rw;
+	bio->bi_flags |= 1 << BIO_CLONED;
 
-		total += tmp->bi_size;
+	/*
+	 * Copy over our part of the bio_vec, then update the first
+	 * and last (or only) entries.
+	 */
+	memcpy(&bio->bi_io_vec[0], &bio_src->bi_io_vec[idx],
+			vcnt * sizeof (struct bio_vec));
+	bio->bi_io_vec[0].bv_offset += voff;
+	if (vcnt > 1) {
+		bio->bi_io_vec[0].bv_len -= voff;
+		bio->bi_io_vec[vcnt - 1].bv_len = resid;
+	} else {
+		bio->bi_io_vec[0].bv_len = len;
 	}
 
-	rbd_assert(total == len);
+	bio->bi_vcnt = vcnt;
+	bio->bi_size = len;
+	bio->bi_idx = 0;
+
+	return bio;
+}
+
+/*
+ * Clone a portion of a bio chain, starting at the given byte offset
+ * into the first bio in the source chain and continuing for the
+ * number of bytes indicated.  The result is another bio chain of
+ * exactly the given length, or a null pointer on error.
+ *
+ * The bio_src and offset parameters are both in-out.  On entry they
+ * refer to the first source bio and the offset into that bio where
+ * the start of data to be cloned is located.
+ *
+ * On return, bio_src is updated to refer to the bio in the source
+ * chain that contains first un-cloned byte, and *offset will
+ * contain the offset of that byte within that bio.
+ */
+static struct bio *bio_chain_clone_range(struct bio **bio_src,
+					unsigned int *offset,
+					unsigned int len,
+					gfp_t gfpmask)
+{
+	struct bio *bi = *bio_src;
+	unsigned int off = *offset;
+	struct bio *chain = NULL;
+	struct bio **end;
+
+	/* Build up a chain of clone bios up to the limit */
+
+	if (!bi || off >= bi->bi_size || !len)
+		return NULL;		/* Nothing to clone */
 
-	*old = old_chain;
+	end = &chain;
+	while (len) {
+		unsigned int bi_size;
+		struct bio *bio;
+
+		if (!bi)
+			goto out_err;	/* EINVAL; ran out of bio's */
+		bi_size = min_t(unsigned int, bi->bi_size - off, len);
+		bio = bio_clone_range(bi, off, bi_size, gfpmask);
+		if (!bio)
+			goto out_err;	/* ENOMEM */
+
+		*end = bio;
+		end = &bio->bi_next;
+
+		off += bi_size;
+		if (off == bi->bi_size) {
+			bi = bi->bi_next;
+			off = 0;
+		}
+		len -= bi_size;
+	}
+	*bio_src = bi;
+	*offset = off;
 
-	return new_chain;
+	return chain;
+out_err:
+	bio_chain_put(chain);
 
-err_out:
-	dout("bio_chain_clone with err\n");
-	bio_chain_put(new_chain);
 	return NULL;
 }
 
@@ -1014,8 +1081,9 @@ static int rbd_do_request(struct request *rq,
 		req_data->coll_index = coll_index;
 	}
 
-	dout("rbd_do_request object_name=%s ofs=%llu len=%llu\n", object_name,
-		(unsigned long long) ofs, (unsigned long long) len);
+	dout("rbd_do_request object_name=%s ofs=%llu len=%llu coll=%p[%d]\n",
+		object_name, (unsigned long long) ofs,
+		(unsigned long long) len, coll, coll_index);
 
 	osdc = &rbd_dev->rbd_client->client->osdc;
 	req = ceph_osdc_alloc_request(osdc, flags, snapc, ops,
@@ -1463,18 +1531,16 @@ static void rbd_rq_fn(struct request_queue *q)
 {
 	struct rbd_device *rbd_dev = q->queuedata;
 	struct request *rq;
-	struct bio_pair *bp = NULL;
 
 	while ((rq = blk_fetch_request(q))) {
 		struct bio *bio;
-		struct bio *rq_bio, *next_bio = NULL;
 		bool do_write;
 		unsigned int size;
-		u64 op_size = 0;
 		u64 ofs;
 		int num_segs, cur_seg = 0;
 		struct rbd_req_coll *coll;
 		struct ceph_snap_context *snapc;
+		unsigned int bio_offset;
 
 		dout("fetched request\n");
 
@@ -1486,10 +1552,6 @@ static void rbd_rq_fn(struct request_queue *q)
 
 		/* deduce our operation (read, write) */
 		do_write = (rq_data_dir(rq) == WRITE);
-
-		size = blk_rq_bytes(rq);
-		ofs = blk_rq_pos(rq) * SECTOR_SIZE;
-		rq_bio = rq->bio;
 		if (do_write && rbd_dev->mapping.read_only) {
 			__blk_end_request_all(rq, -EROFS);
 			continue;
@@ -1512,6 +1574,10 @@ static void rbd_rq_fn(struct request_queue *q)
 
 		up_read(&rbd_dev->header_rwsem);
 
+		size = blk_rq_bytes(rq);
+		ofs = blk_rq_pos(rq) * SECTOR_SIZE;
+		bio = rq->bio;
+
 		dout("%s 0x%x bytes at 0x%llx\n",
 		     do_write ? "write" : "read",
 		     size, (unsigned long long) blk_rq_pos(rq) * SECTOR_SIZE);
@@ -1531,30 +1597,37 @@ static void rbd_rq_fn(struct request_queue *q)
 			continue;
 		}
 
+		bio_offset = 0;
 		do {
-			/* a bio clone to be passed down to OSD req */
+			u64 limit = rbd_segment_length(rbd_dev, ofs, size);
+			unsigned int chain_size;
+			struct bio *bio_chain;
+
+			BUG_ON(limit > (u64) UINT_MAX);
+			chain_size = (unsigned int) limit;
 			dout("rq->bio->bi_vcnt=%hu\n", rq->bio->bi_vcnt);
-			op_size = rbd_segment_length(rbd_dev, ofs, size);
+
 			kref_get(&coll->kref);
-			bio = bio_chain_clone(&rq_bio, &next_bio, &bp,
-					      op_size, GFP_ATOMIC);
-			if (bio)
+
+			/* Pass a cloned bio chain via an osd request */
+
+			bio_chain = bio_chain_clone_range(&bio,
+						&bio_offset, chain_size,
+						GFP_ATOMIC);
+			if (bio_chain)
 				(void) rbd_do_op(rq, rbd_dev, snapc,
-						ofs, op_size,
-						bio, coll, cur_seg);
+						ofs, chain_size,
+						bio_chain, coll, cur_seg);
 			else
 				rbd_coll_end_req_index(rq, coll, cur_seg,
-						       -ENOMEM, op_size);
-			size -= op_size;
-			ofs += op_size;
+						       -ENOMEM, chain_size);
+			size -= chain_size;
+			ofs += chain_size;
 
 			cur_seg++;
-			rq_bio = next_bio;
 		} while (size > 0);
 		kref_put(&coll->kref, rbd_coll_release);
 
-		if (bp)
-			bio_pair_release(bp);
 		spin_lock_irq(q->queue_lock);
 
 		ceph_put_snap_context(snapc);
@@ -1564,7 +1637,7 @@ static void rbd_rq_fn(struct request_queue *q)
 /*
  * a queue callback. Makes sure that we don't create a bio that spans across
  * multiple osd objects. One exception would be with a single page bios,
- * which we handle later at bio_chain_clone
+ * which we handle later at bio_chain_clone_range()
  */
 static int rbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
 			  struct bio_vec *bvec)