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    SubjectRe: [PATCH v4 04/12] pktcdvd: Switch to bio_kmalloc()
    On 07/24/2012 11:11 PM, Kent Overstreet wrote:

    > This is prep work for killing bi_destructor - previously, pktcdvd had
    > its own pkt_bio_alloc which was basically duplication bio_kmalloc(),
    > necessitating its own bi_destructor implementation.
    >
    > Signed-off-by: Kent Overstreet <koverstreet@google.com>
    > ---
    > drivers/block/pktcdvd.c | 115 ++++++++++++++++-------------------------------
    > 1 files changed, 39 insertions(+), 76 deletions(-)
    >
    > diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
    > index ba66e44..6fe693a 100644
    > --- a/drivers/block/pktcdvd.c
    > +++ b/drivers/block/pktcdvd.c
    > @@ -522,36 +522,38 @@ static void pkt_bio_finished(struct pktcdvd_device *pd)
    > }
    > }
    >
    > -static void pkt_bio_destructor(struct bio *bio)
    > +static void pkt_end_io_read(struct bio *bio, int err)
    > {
    > - kfree(bio->bi_io_vec);
    > - kfree(bio);
    > -}


    Again here, you decided to move the pkt_end_io_read && pkt_end_io_packet_write
    functions from below, to above here. Which makes it impossible to find
    any bugs by just reviewing the patch.

    So I have not reviewed it.

    I know that you wanted so you can reference them at pkt_alloc_packet_data.
    I'd use a forward reference, in this case. And a move in a next patch. But
    this is just me. Perhaps the owner of this code can review it?

    Cheers
    Boaz

    > + struct packet_data *pkt = bio->bi_private;
    > + struct pktcdvd_device *pd = pkt->pd;
    > + BUG_ON(!pd);
    >
    > -static struct bio *pkt_bio_alloc(int nr_iovecs)
    > -{
    > - struct bio_vec *bvl = NULL;
    > - struct bio *bio;
    > + VPRINTK("pkt_end_io_read: bio=%p sec0=%llx sec=%llx err=%d\n", bio,
    > + (unsigned long long)pkt->sector, (unsigned long long)bio->bi_sector, err);
    >
    > - bio = kmalloc(sizeof(struct bio), GFP_KERNEL);
    > - if (!bio)
    > - goto no_bio;
    > - bio_init(bio);
    > + if (err)
    > + atomic_inc(&pkt->io_errors);
    > + if (atomic_dec_and_test(&pkt->io_wait)) {
    > + atomic_inc(&pkt->run_sm);
    > + wake_up(&pd->wqueue);
    > + }
    > + pkt_bio_finished(pd);
    > +}
    >
    > - bvl = kcalloc(nr_iovecs, sizeof(struct bio_vec), GFP_KERNEL);
    > - if (!bvl)
    > - goto no_bvl;
    > +static void pkt_end_io_packet_write(struct bio *bio, int err)
    > +{
    > + struct packet_data *pkt = bio->bi_private;
    > + struct pktcdvd_device *pd = pkt->pd;
    > + BUG_ON(!pd);
    >
    > - bio->bi_max_vecs = nr_iovecs;
    > - bio->bi_io_vec = bvl;
    > - bio->bi_destructor = pkt_bio_destructor;
    > + VPRINTK("pkt_end_io_packet_write: id=%d, err=%d\n", pkt->id, err);
    >
    > - return bio;
    > + pd->stats.pkt_ended++;
    >
    > - no_bvl:
    > - kfree(bio);
    > - no_bio:
    > - return NULL;
    > + pkt_bio_finished(pd);
    > + atomic_dec(&pkt->io_wait);
    > + atomic_inc(&pkt->run_sm);
    > + wake_up(&pd->wqueue);
    > }
    >
    > /*
    > @@ -567,10 +569,13 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
    > goto no_pkt;
    >
    > pkt->frames = frames;
    > - pkt->w_bio = pkt_bio_alloc(frames);
    > + pkt->w_bio = bio_kmalloc(GFP_KERNEL, frames);
    > if (!pkt->w_bio)
    > goto no_bio;
    >
    > + pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
    > + pkt->w_bio->bi_private = pkt;
    > +
    > for (i = 0; i < frames / FRAMES_PER_PAGE; i++) {
    > pkt->pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
    > if (!pkt->pages[i])
    > @@ -581,9 +586,12 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
    > bio_list_init(&pkt->orig_bios);
    >
    > for (i = 0; i < frames; i++) {
    > - struct bio *bio = pkt_bio_alloc(1);
    > + struct bio *bio = bio_kmalloc(GFP_KERNEL, 1);
    > if (!bio)
    > goto no_rd_bio;
    > +
    > + bio->bi_end_io = pkt_end_io_read;
    > + bio->bi_private = pkt;
    > pkt->r_bios[i] = bio;
    > }
    >
    > @@ -1036,40 +1044,6 @@ static void pkt_make_local_copy(struct packet_data *pkt, struct bio_vec *bvec)
    > }
    > }
    >
    > -static void pkt_end_io_read(struct bio *bio, int err)
    > -{
    > - struct packet_data *pkt = bio->bi_private;
    > - struct pktcdvd_device *pd = pkt->pd;
    > - BUG_ON(!pd);
    > -
    > - VPRINTK("pkt_end_io_read: bio=%p sec0=%llx sec=%llx err=%d\n", bio,
    > - (unsigned long long)pkt->sector, (unsigned long long)bio->bi_sector, err);
    > -
    > - if (err)
    > - atomic_inc(&pkt->io_errors);
    > - if (atomic_dec_and_test(&pkt->io_wait)) {
    > - atomic_inc(&pkt->run_sm);
    > - wake_up(&pd->wqueue);
    > - }
    > - pkt_bio_finished(pd);
    > -}
    > -
    > -static void pkt_end_io_packet_write(struct bio *bio, int err)
    > -{
    > - struct packet_data *pkt = bio->bi_private;
    > - struct pktcdvd_device *pd = pkt->pd;
    > - BUG_ON(!pd);
    > -
    > - VPRINTK("pkt_end_io_packet_write: id=%d, err=%d\n", pkt->id, err);
    > -
    > - pd->stats.pkt_ended++;
    > -
    > - pkt_bio_finished(pd);
    > - atomic_dec(&pkt->io_wait);
    > - atomic_inc(&pkt->run_sm);
    > - wake_up(&pd->wqueue);
    > -}
    > -
    > /*
    > * Schedule reads for the holes in a packet
    > */
    > @@ -1111,21 +1085,15 @@ static void pkt_gather_data(struct pktcdvd_device *pd, struct packet_data *pkt)
    > * Schedule reads for missing parts of the packet.
    > */
    > for (f = 0; f < pkt->frames; f++) {
    > - struct bio_vec *vec;
    > -
    > int p, offset;
    > +
    > if (written[f])
    > continue;
    > +
    > bio = pkt->r_bios[f];
    > - vec = bio->bi_io_vec;
    > - bio_init(bio);
    > - bio->bi_max_vecs = 1;
    > - bio->bi_sector = pkt->sector + f * (CD_FRAMESIZE >> 9);
    > - bio->bi_bdev = pd->bdev;
    > - bio->bi_end_io = pkt_end_io_read;
    > - bio->bi_private = pkt;
    > - bio->bi_io_vec = vec;
    > - bio->bi_destructor = pkt_bio_destructor;
    > + bio_reset(bio);
    > + bio->bi_sector = pkt->sector + f * (CD_FRAMESIZE >> 9);
    > + bio->bi_bdev = pd->bdev;
    >
    > p = (f * CD_FRAMESIZE) / PAGE_SIZE;
    > offset = (f * CD_FRAMESIZE) % PAGE_SIZE;
    > @@ -1418,14 +1386,9 @@ static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt)
    > }
    >
    > /* Start the write request */
    > - bio_init(pkt->w_bio);
    > - pkt->w_bio->bi_max_vecs = PACKET_MAX_SIZE;
    > + bio_reset(pkt->w_bio);
    > pkt->w_bio->bi_sector = pkt->sector;
    > pkt->w_bio->bi_bdev = pd->bdev;
    > - pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
    > - pkt->w_bio->bi_private = pkt;
    > - pkt->w_bio->bi_io_vec = bvec;
    > - pkt->w_bio->bi_destructor = pkt_bio_destructor;
    > for (f = 0; f < pkt->frames; f++)
    > if (!bio_add_page(pkt->w_bio, bvec[f].bv_page, CD_FRAMESIZE, bvec[f].bv_offset))
    > BUG();




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