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lightnvm: pblk: remove unnecessary bio_get/put
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In the read path, pblk gets a reference to the incoming bio and puts it
after ending the bio. Though this behavior is correct, it is unnecessary
since pblk is the one putting the bio, therefore, it cannot disappear
underneath it.

Removing this reference, allows to clean up rqd->bio and avoids pointer
bouncing for the different read paths. Now, the incoming bio always
resides in the read context and pblk's internal bios (if any) reside in
rqd->bio.

Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Javier González authored and Jens Axboe committed Jun 1, 2018
1 parent 4a82888 commit 87cc40b
Showing 1 changed file with 28 additions and 37 deletions.
65 changes: 28 additions & 37 deletions drivers/lightnvm/pblk-read.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -39,10 +39,10 @@ static int pblk_read_from_cache(struct pblk *pblk, struct bio *bio,
}

static void pblk_read_ppalist_rq(struct pblk *pblk, struct nvm_rq *rqd,
sector_t blba, unsigned long *read_bitmap)
struct bio *bio, sector_t blba,
unsigned long *read_bitmap)
{
struct pblk_sec_meta *meta_list = rqd->meta_list;
struct bio *bio = rqd->bio;
struct ppa_addr ppas[PBLK_MAX_REQ_ADDRS];
int nr_secs = rqd->nr_ppas;
bool advanced_bio = false;
Expand Down Expand Up @@ -189,31 +189,25 @@ static void pblk_end_user_read(struct bio *bio)
WARN_ONCE(bio->bi_status, "pblk: corrupted read bio\n");
#endif
bio_endio(bio);
bio_put(bio);
}

static void __pblk_end_io_read(struct pblk *pblk, struct nvm_rq *rqd,
bool put_line)
{
struct nvm_tgt_dev *dev = pblk->dev;
struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
struct bio *bio = rqd->bio;
struct bio *int_bio = rqd->bio;
unsigned long start_time = r_ctx->start_time;

generic_end_io_acct(dev->q, READ, &pblk->disk->part0, start_time);

if (rqd->error)
pblk_log_read_err(pblk, rqd);
#ifdef CONFIG_NVM_DEBUG
else
WARN_ONCE(bio->bi_status, "pblk: corrupted read error\n");
#endif

pblk_read_check_seq(pblk, rqd, r_ctx->lba);

bio_put(bio);
if (r_ctx->private)
pblk_end_user_read((struct bio *)r_ctx->private);
if (int_bio)
bio_put(int_bio);

if (put_line)
pblk_read_put_rqd_kref(pblk, rqd);
Expand All @@ -230,16 +224,19 @@ static void __pblk_end_io_read(struct pblk *pblk, struct nvm_rq *rqd,
static void pblk_end_io_read(struct nvm_rq *rqd)
{
struct pblk *pblk = rqd->private;
struct pblk_g_ctx *r_ctx = nvm_rq_to_pdu(rqd);
struct bio *bio = (struct bio *)r_ctx->private;

pblk_end_user_read(bio);
__pblk_end_io_read(pblk, rqd, true);
}

static int pblk_partial_read_bio(struct pblk *pblk, struct nvm_rq *rqd,
unsigned int bio_init_idx,
unsigned long *read_bitmap)
static int pblk_partial_read(struct pblk *pblk, struct nvm_rq *rqd,
struct bio *orig_bio, unsigned int bio_init_idx,
unsigned long *read_bitmap)
{
struct bio *new_bio, *bio = rqd->bio;
struct pblk_sec_meta *meta_list = rqd->meta_list;
struct bio *new_bio;
struct bio_vec src_bv, dst_bv;
void *ppa_ptr = NULL;
void *src_p, *dst_p;
Expand All @@ -256,11 +253,11 @@ static int pblk_partial_read_bio(struct pblk *pblk, struct nvm_rq *rqd,
new_bio = bio_alloc(GFP_KERNEL, nr_holes);

if (pblk_bio_add_pages(pblk, new_bio, GFP_KERNEL, nr_holes))
goto err_add_pages;
goto fail_add_pages;

if (nr_holes != new_bio->bi_vcnt) {
pr_err("pblk: malformed bio\n");
goto err;
goto fail;
}

for (i = 0; i < nr_secs; i++)
Expand All @@ -283,7 +280,7 @@ static int pblk_partial_read_bio(struct pblk *pblk, struct nvm_rq *rqd,
if (ret) {
bio_put(rqd->bio);
pr_err("pblk: sync read IO submission failed\n");
goto err;
goto fail;
}

if (rqd->error) {
Expand Down Expand Up @@ -319,7 +316,7 @@ static int pblk_partial_read_bio(struct pblk *pblk, struct nvm_rq *rqd,
meta_list[hole].lba = lba_list_media[i];

src_bv = new_bio->bi_io_vec[i++];
dst_bv = bio->bi_io_vec[bio_init_idx + hole];
dst_bv = orig_bio->bi_io_vec[bio_init_idx + hole];

src_p = kmap_atomic(src_bv.bv_page);
dst_p = kmap_atomic(dst_bv.bv_page);
Expand All @@ -338,28 +335,26 @@ static int pblk_partial_read_bio(struct pblk *pblk, struct nvm_rq *rqd,

bio_put(new_bio);

/* Complete the original bio and associated request */
bio_endio(bio);
rqd->bio = bio;
/* restore original request */
rqd->bio = NULL;
rqd->nr_ppas = nr_secs;

__pblk_end_io_read(pblk, rqd, false);
return NVM_IO_OK;
return NVM_IO_DONE;

err:
fail:
/* Free allocated pages in new bio */
pblk_bio_free_pages(pblk, new_bio, 0, new_bio->bi_vcnt);
err_add_pages:
fail_add_pages:
pr_err("pblk: failed to perform partial read\n");
__pblk_end_io_read(pblk, rqd, false);
return NVM_IO_ERR;
}

static void pblk_read_rq(struct pblk *pblk, struct nvm_rq *rqd,
static void pblk_read_rq(struct pblk *pblk, struct nvm_rq *rqd, struct bio *bio,
sector_t lba, unsigned long *read_bitmap)
{
struct pblk_sec_meta *meta_list = rqd->meta_list;
struct bio *bio = rqd->bio;
struct ppa_addr ppa;

pblk_lookup_l2p_seq(pblk, &ppa, lba, 1);
Expand Down Expand Up @@ -423,14 +418,15 @@ int pblk_submit_read(struct pblk *pblk, struct bio *bio)
rqd = pblk_alloc_rqd(pblk, PBLK_READ);

rqd->opcode = NVM_OP_PREAD;
rqd->bio = bio;
rqd->nr_ppas = nr_secs;
rqd->bio = NULL; /* cloned bio if needed */
rqd->private = pblk;
rqd->end_io = pblk_end_io_read;

r_ctx = nvm_rq_to_pdu(rqd);
r_ctx->start_time = jiffies;
r_ctx->lba = blba;
r_ctx->private = bio; /* original bio */

/* Save the index for this bio's start. This is needed in case
* we need to fill a partial read.
Expand All @@ -448,17 +444,15 @@ int pblk_submit_read(struct pblk *pblk, struct bio *bio)
rqd->ppa_list = rqd->meta_list + pblk_dma_meta_size;
rqd->dma_ppa_list = rqd->dma_meta_list + pblk_dma_meta_size;

pblk_read_ppalist_rq(pblk, rqd, blba, &read_bitmap);
pblk_read_ppalist_rq(pblk, rqd, bio, blba, &read_bitmap);
} else {
pblk_read_rq(pblk, rqd, blba, &read_bitmap);
pblk_read_rq(pblk, rqd, bio, blba, &read_bitmap);
}

bio_get(bio);
if (bitmap_full(&read_bitmap, nr_secs)) {
bio_endio(bio);
atomic_inc(&pblk->inflight_io);
__pblk_end_io_read(pblk, rqd, false);
return NVM_IO_OK;
return NVM_IO_DONE;
}

/* All sectors are to be read from the device */
Expand All @@ -473,13 +467,10 @@ int pblk_submit_read(struct pblk *pblk, struct bio *bio)
}

rqd->bio = int_bio;
r_ctx->private = bio;

if (pblk_submit_io(pblk, rqd)) {
pr_err("pblk: read IO submission failed\n");
ret = NVM_IO_ERR;
if (int_bio)
bio_put(int_bio);
goto fail_end_io;
}

Expand All @@ -489,7 +480,7 @@ int pblk_submit_read(struct pblk *pblk, struct bio *bio)
/* The read bio request could be partially filled by the write buffer,
* but there are some holes that need to be read from the drive.
*/
return pblk_partial_read_bio(pblk, rqd, bio_init_idx, &read_bitmap);
return pblk_partial_read(pblk, rqd, bio, bio_init_idx, &read_bitmap);

fail_rqd_free:
pblk_free_rqd(pblk, rqd, PBLK_READ);
Expand Down

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