| Message ID | 1342010053-9306-1-git-send-email-gzhao@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jul 11, 2012 at 5:34 AM, Guangliang Zhao <gzhao@suse.com> wrote: > > 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@suse.com> > --- > drivers/block/rbd.c | 66 > ++++++++++++++++++++------------------------------- > 1 files changed, 26 insertions(+), 40 deletions(-) > > diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c > index 013c7a5..6a12040 100644 > --- a/drivers/block/rbd.c > +++ b/drivers/block/rbd.c > @@ -712,51 +712,43 @@ 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; > - > + __bio_clone(tmp, old_chain); > + if (total + (tmp->bi_size - *offset) > len) { can change this to: if (tmp->bi_size - *offset > need) I think it'll be slightly more readable > + tmp->bi_sector += *offset >> SECTOR_SHIFT; > + tmp->bi_io_vec->bv_offset += *offset >> > SECTOR_SHIFT; Shouldn't these two lines be outside this if? > /* > - * this split can only happen with a single paged > bio, > - * split_bio will BUG_ON if this is not the case > + * This can only happen with a single paged bio, > + * rbd_merge_bvec would guarantee it. > */ > - 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; > + 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; > + *offset = 0; > } > > tmp->bi_bdev = NULL; > @@ -769,7 +761,6 @@ 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 +1438,12 @@ 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 +1493,7 @@ 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 +1521,8 @@ 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); > } > } Yeah, looks cleaner. Thanks, Yehuda -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jul 17, 2012 at 01:18:50PM -0700, Yehuda Sadeh wrote: > On Wed, Jul 11, 2012 at 5:34 AM, Guangliang Zhao <gzhao@suse.com> wrote: > > > > 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@suse.com> > > --- > > drivers/block/rbd.c | 66 > > ++++++++++++++++++++------------------------------- > > 1 files changed, 26 insertions(+), 40 deletions(-) > > > > diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c > > index 013c7a5..6a12040 100644 > > --- a/drivers/block/rbd.c > > +++ b/drivers/block/rbd.c > > @@ -712,51 +712,43 @@ 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; > > - > > + __bio_clone(tmp, old_chain); > > + if (total + (tmp->bi_size - *offset) > len) { > > can change this to: > if (tmp->bi_size - *offset > need) > > I think it'll be slightly more readable Yes, I will modify it in the next version. > > > + tmp->bi_sector += *offset >> SECTOR_SHIFT; > > + tmp->bi_io_vec->bv_offset += *offset >> > > SECTOR_SHIFT; > > Shouldn't these two lines be outside this if? Excellent, the else branch need it too. > > > > > /* > > - * this split can only happen with a single paged > > bio, > > - * split_bio will BUG_ON if this is not the case > > + * This can only happen with a single paged bio, > > + * rbd_merge_bvec would guarantee it. > > */ > > - 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; > > + 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; > > + *offset = 0; We also need adjust the length of tmp bios in the else branch, so the following two lines should be added. tmp->bi_size -= *offset; tmp->bi_io_vec->bv_offset -= *offset; > > } > > > > tmp->bi_bdev = NULL; > > @@ -769,7 +761,6 @@ 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 +1438,12 @@ 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 +1493,7 @@ 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 +1521,8 @@ 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); > > } > > } > > Yeah, looks cleaner. > > Thanks, > Yehuda > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html I will send patch v2 if everything above mentioned is OK. Thanks for your review.
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 013c7a5..6a12040 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -712,51 +712,43 @@ 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; - + __bio_clone(tmp, old_chain); + if (total + (tmp->bi_size - *offset) > len) { + tmp->bi_sector += *offset >> SECTOR_SHIFT; + tmp->bi_io_vec->bv_offset += *offset >> SECTOR_SHIFT; /* - * this split can only happen with a single paged bio, - * split_bio will BUG_ON if this is not the case + * This can only happen with a single paged bio, + * rbd_merge_bvec would guarantee it. */ - 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; + 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; + *offset = 0; } tmp->bi_bdev = NULL; @@ -769,7 +761,6 @@ 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 +1438,12 @@ 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 +1493,7 @@ 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 +1521,8 @@ 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); } }
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@suse.com> --- drivers/block/rbd.c | 66 ++++++++++++++++++++------------------------------- 1 files changed, 26 insertions(+), 40 deletions(-)