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 <gzhao@xxxxxxxx>
---
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
--
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