rbd: encapsulate handling for a single request

In rbd_rq_fn(), requests are fetched from the block layer and each
request is processed, looping through the request's list of bio's
until they've all been consumed.

Separate the handling for a single request into its own function to
make it a bit easier to see what's going on.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 8d93b6a..738d1e4 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1583,6 +1583,64 @@ static struct rbd_req_coll *rbd_alloc_coll(int num_reqs)
        return coll;
 }
 
+static int rbd_dev_do_request(struct request *rq,
+                               struct rbd_device *rbd_dev,
+                               struct ceph_snap_context *snapc,
+                               u64 ofs, unsigned int size,
+                               struct bio *bio_chain)
+{
+       int num_segs;
+       struct rbd_req_coll *coll;
+       unsigned int bio_offset;
+       int cur_seg = 0;
+
+       dout("%s 0x%x bytes at 0x%llx\n",
+               rq_data_dir(rq) == WRITE ? "write" : "read",
+               size, (unsigned long long) blk_rq_pos(rq) * SECTOR_SIZE);
+
+       num_segs = rbd_get_num_segments(&rbd_dev->header, ofs, size);
+       if (num_segs <= 0)
+               return num_segs;
+
+       coll = rbd_alloc_coll(num_segs);
+       if (!coll)
+               return -ENOMEM;
+
+       bio_offset = 0;
+       do {
+               u64 limit = rbd_segment_length(rbd_dev, ofs, size);
+               unsigned int clone_size;
+               struct bio *bio_clone;
+
+               BUG_ON(limit > (u64)UINT_MAX);
+               clone_size = (unsigned int)limit;
+               dout("bio_chain->bi_vcnt=%hu\n", bio_chain->bi_vcnt);
+
+               kref_get(&coll->kref);
+
+               /* Pass a cloned bio chain via an osd request */
+
+               bio_clone = bio_chain_clone_range(&bio_chain,
+                                       &bio_offset, clone_size,
+                                       GFP_ATOMIC);
+               if (bio_clone)
+                       (void)rbd_do_op(rq, rbd_dev, snapc,
+                                       ofs, clone_size,
+                                       bio_clone, coll, cur_seg);
+               else
+                       rbd_coll_end_req_index(rq, coll, cur_seg,
+                                               (s32)-ENOMEM,
+                                               clone_size);
+               size -= clone_size;
+               ofs += clone_size;
+
+               cur_seg++;
+       } while (size > 0);
+       kref_put(&coll->kref, rbd_coll_release);
+
+       return 0;
+}
+
 /*
  * block device queue callback
  */
@@ -1596,10 +1654,8 @@ static void rbd_rq_fn(struct request_queue *q)
                bool do_write;
                unsigned int size;
                u64 ofs;
-               int num_segs, cur_seg = 0;
-               struct rbd_req_coll *coll;
                struct ceph_snap_context *snapc;
-               unsigned int bio_offset;
+               int result;
 
                dout("fetched request\n");
 
@@ -1637,60 +1693,11 @@ static void rbd_rq_fn(struct request_queue *q)
                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);
-
-               num_segs = rbd_get_num_segments(&rbd_dev->header, ofs, size);
-               if (num_segs <= 0) {
-                       spin_lock_irq(q->queue_lock);
-                       __blk_end_request_all(rq, num_segs);
-                       ceph_put_snap_context(snapc);
-                       continue;
-               }
-               coll = rbd_alloc_coll(num_segs);
-               if (!coll) {
-                       spin_lock_irq(q->queue_lock);
-                       __blk_end_request_all(rq, -ENOMEM);
-                       ceph_put_snap_context(snapc);
-                       continue;
-               }
-
-               bio_offset = 0;
-               do {
-                       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);
-
-                       kref_get(&coll->kref);
-
-                       /* 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, chain_size,
-                                               bio_chain, coll, cur_seg);
-                       else
-                               rbd_coll_end_req_index(rq, coll, cur_seg,
-                                                      (s32)-ENOMEM,
-                                                      chain_size);
-                       size -= chain_size;
-                       ofs += chain_size;
-
-                       cur_seg++;
-               } while (size > 0);
-               kref_put(&coll->kref, rbd_coll_release);
-
-               spin_lock_irq(q->queue_lock);
-
+               result = rbd_dev_do_request(rq, rbd_dev, snapc, ofs, size, bio);
                ceph_put_snap_context(snapc);
+               spin_lock_irq(q->queue_lock);
+               if (!size || result < 0)
+                       __blk_end_request_all(rq, result);
        }
 }