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rbd: encapsulate handling for a single request

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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>
This commit is contained in:
Alex Elder 2012-11-08 08:01:39 -06:00
parent 8986cb37b1
commit 8295cda7ce
1 changed files with 63 additions and 56 deletions
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119
drivers/block/rbd.c
View file

@ -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);
}
}