The bio_pair alloced in bio_chain_clone would not be freed, this will cause a memory leak. It could be freed actually only after 3 times release, because the reference count of bio_pair is initialized to 3 when bio_split and bio_pair_release only drops the reference count.
The function bio_pair_release must be called three times for releasing bio_pair, and the callback functions of bios on the requests will be called when the last release time in bio_pair_release, however, these functions will also be called in rbd_req_cb. In other words, they will be called twice, and it may cause serious consequences. This patch clones bio chian from the origin directly, doesn't use bio_split(without bio_pair). The new bio chain can be release whenever we don't need it. Signed-off-by: Guangliang Zhao <[email protected]> --- drivers/block/rbd.c | 73 +++++++++++++++++++++----------------------------- 1 files changed, 31 insertions(+), 42 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 013c7a5..356657d 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -712,51 +712,46 @@ 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. +/** + * bio_chain_clone - clone a chain of bios up to a certain length. + * @old: bio to clone + * @offset: start point for bio clone + * @len: length of bio chain + * @gfp_mask: allocation priority + * + * RETURNS: + * Pointer to new bio chain on success, NULL on failure. */ -static struct bio *bio_chain_clone(struct bio **old, struct bio **next, - struct bio_pair **bp, +static struct bio *bio_chain_clone(struct bio **old, int *offset, int len, gfp_t gfpmask) { struct bio *tmp, *old_chain = *old, *new_chain = NULL, *tail = NULL; int total = 0; - if (*bp) { - bio_pair_release(*bp); - *bp = NULL; - } - while (old_chain && (total < len)) { + int need = len - total; + tmp = bio_kmalloc(gfpmask, old_chain->bi_max_vecs); if (!tmp) goto err_out; - if (total + old_chain->bi_size > len) { - struct bio_pair *bp; - - /* - * 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=%d\n", - (int)total, (int)len-total, - (int)old_chain->bi_size); - - /* 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; - - __bio_clone(tmp, &bp->bio1); - - *next = &bp->bio2; + __bio_clone(tmp, old_chain); + tmp->bi_sector += *offset >> SECTOR_SHIFT; + tmp->bi_io_vec->bv_offset += *offset >> SECTOR_SHIFT; + /* + * The bios span across multiple osd objects must be + * single paged, rbd_merge_bvec would guarantee it. + * So we needn't worry about other things. + */ + if (tmp->bi_size - *offset > need) { + tmp->bi_size = need; + tmp->bi_io_vec->bv_len = need; + *offset += need; } else { - __bio_clone(tmp, old_chain); - *next = old_chain->bi_next; + old_chain = old_chain->bi_next; + tmp->bi_size -= *offset; + tmp->bi_io_vec->bv_len -= *offset; + *offset = 0; } tmp->bi_bdev = NULL; @@ -769,7 +764,6 @@ static struct bio *bio_chain_clone(struct bio **old, struct bio **next, tail->bi_next = tmp; tail = tmp; } - old_chain = old_chain->bi_next; total += tmp->bi_size; } @@ -1447,13 +1441,12 @@ 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; + struct bio *rq_bio; bool do_write; - int size, op_size = 0; + int size, op_size = 0, offset = 0; u64 ofs; int num_segs, cur_seg = 0; struct rbd_req_coll *coll; @@ -1503,7 +1496,7 @@ static void rbd_rq_fn(struct request_queue *q) ofs, size, NULL, NULL); kref_get(&coll->kref); - bio = bio_chain_clone(&rq_bio, &next_bio, &bp, + bio = bio_chain_clone(&rq_bio, &offset, op_size, GFP_ATOMIC); if (!bio) { rbd_coll_end_req_index(rq, coll, cur_seg, @@ -1531,12 +1524,8 @@ next_seg: ofs += op_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); } } -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
