[PATCH v3 02/26] block: Convert integrity to bvec_alloc_bs()

From: Kent Overstreet
Date: Mon Sep 24 2012 - 18:41:43 EST

This adds a pointer to the bvec array to struct bio_integrity_payload,
instead of the bvecs always being inline; then the bvecs are allocated
with bvec_alloc_bs().

Changed bvec_alloc_bs() and bvec_free_bs() to take a pointer to a
mempool instead of the bioset, so that bio integrity can use a different
mempool for its bvecs, and thus avoid a potential deadlock.

This is eventually for immutable bio vecs - immutable bvecs aren't
useful if we still have to copy them, hence the need for the pointer.
Less code is always nice too, though.

Signed-off-by: Kent Overstreet <koverstreet@xxxxxxxxxx>
CC: Jens Axboe <axboe@xxxxxxxxx>
CC: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
---
fs/bio-integrity.c | 132 +++++++++++++++++++---------------------------------
fs/bio.c | 34 ++++++--------
include/linux/bio.h | 13 ++++--
3 files changed, 72 insertions(+), 107 deletions(-)

diff --git a/fs/bio-integrity.c b/fs/bio-integrity.c
index c7b6b52..65b708d 100644
--- a/fs/bio-integrity.c
+++ b/fs/bio-integrity.c
@@ -27,48 +27,11 @@
#include <linux/workqueue.h>
#include <linux/slab.h>

-struct integrity_slab {
- struct kmem_cache *slab;
- unsigned short nr_vecs;
- char name[8];
-};
-
-#define IS(x) { .nr_vecs = x, .name = "bip-"__stringify(x) }
-struct integrity_slab bip_slab[BIOVEC_NR_POOLS] __read_mostly = {
- IS(1), IS(4), IS(16), IS(64), IS(128), IS(BIO_MAX_PAGES),
-};
-#undef IS
+#define BIP_INLINE_VECS 4

+static struct kmem_cache *bip_slab;
static struct workqueue_struct *kintegrityd_wq;

-static inline unsigned int vecs_to_idx(unsigned int nr)
-{
- switch (nr) {
- case 1:
- return 0;
- case 2 ... 4:
- return 1;
- case 5 ... 16:
- return 2;
- case 17 ... 64:
- return 3;
- case 65 ... 128:
- return 4;
- case 129 ... BIO_MAX_PAGES:
- return 5;
- default:
- BUG();
- }
-}
-
-static inline int use_bip_pool(unsigned int idx)
-{
- if (idx == BIOVEC_MAX_IDX)
- return 1;
-
- return 0;
-}
-
/**
* bio_integrity_alloc - Allocate integrity payload and attach it to bio
* @bio: bio to attach integrity metadata to
@@ -84,37 +47,39 @@ struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
unsigned int nr_vecs)
{
struct bio_integrity_payload *bip;
- unsigned int idx = vecs_to_idx(nr_vecs);
struct bio_set *bs = bio->bi_pool;
+ unsigned long idx = BIO_POOL_NONE;
+ unsigned inline_vecs;
+
+ if (!bs) {
+ bip = kmalloc(sizeof(struct bio_integrity_payload) +
+ sizeof(struct bio_vec) * nr_vecs, gfp_mask);
+ inline_vecs = nr_vecs;
+ } else {
+ bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);
+ inline_vecs = BIP_INLINE_VECS;
+ }

- if (!bs)
- bs = fs_bio_set;
-
- BUG_ON(bio == NULL);
- bip = NULL;
-
- /* Lower order allocations come straight from slab */
- if (!use_bip_pool(idx))
- bip = kmem_cache_alloc(bip_slab[idx].slab, gfp_mask);
+ if (unlikely(!bip))
+ return NULL;

- /* Use mempool if lower order alloc failed or max vecs were requested */
- if (bip == NULL) {
- idx = BIOVEC_MAX_IDX; /* so we free the payload properly later */
- bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);
+ memset(bip, 0, sizeof(struct bio_integrity_payload));

- if (unlikely(bip == NULL)) {
- printk(KERN_ERR "%s: could not alloc bip\n", __func__);
- return NULL;
- }
+ if (nr_vecs > inline_vecs) {
+ bip->bip_vec = bvec_alloc_bs(gfp_mask, nr_vecs, &idx,
+ bs->bvec_integrity_pool);
+ if (!bip->bip_vec)
+ goto err;
}

- memset(bip, 0, sizeof(*bip));
-
bip->bip_slab = idx;
bip->bip_bio = bio;
bio->bi_integrity = bip;

return bip;
+err:
+ mempool_free(bip, bs->bio_integrity_pool);
+ return NULL;
}
EXPORT_SYMBOL(bio_integrity_alloc);

@@ -130,20 +95,20 @@ void bio_integrity_free(struct bio *bio)
struct bio_integrity_payload *bip = bio->bi_integrity;
struct bio_set *bs = bio->bi_pool;

- if (!bs)
- bs = fs_bio_set;
-
- BUG_ON(bip == NULL);
-
/* A cloned bio doesn't own the integrity metadata */
if (!bio_flagged(bio, BIO_CLONED) && !bio_flagged(bio, BIO_FS_INTEGRITY)
&& bip->bip_buf != NULL)
kfree(bip->bip_buf);

- if (use_bip_pool(bip->bip_slab))
+ if (bs) {
+ if (bip->bip_slab != BIO_POOL_NONE)
+ bvec_free_bs(bs->bvec_integrity_pool, bip->bip_vec,
+ bip->bip_slab);
+
mempool_free(bip, bs->bio_integrity_pool);
- else
- kmem_cache_free(bip_slab[bip->bip_slab].slab, bip);
+ } else {
+ kfree(bip);
+ }

bio->bi_integrity = NULL;
}
@@ -697,6 +662,9 @@ void bio_integrity_split(struct bio *bio, struct bio_pair *bp, int sectors)
bp->iv1 = bip->bip_vec[0];
bp->iv2 = bip->bip_vec[0];

+ bp->bip1.bip_vec = &bp->iv1;
+ bp->bip2.bip_vec = &bp->iv2;
+
bp->iv1.bv_len = sectors * bi->tuple_size;
bp->iv2.bv_offset += sectors * bi->tuple_size;
bp->iv2.bv_len -= sectors * bi->tuple_size;
@@ -743,13 +711,14 @@ EXPORT_SYMBOL(bio_integrity_clone);

int bioset_integrity_create(struct bio_set *bs, int pool_size)
{
- unsigned int max_slab = vecs_to_idx(BIO_MAX_PAGES);
-
if (bs->bio_integrity_pool)
return 0;

- bs->bio_integrity_pool =
- mempool_create_slab_pool(pool_size, bip_slab[max_slab].slab);
+ bs->bio_integrity_pool = mempool_create_slab_pool(pool_size, bip_slab);
+
+ bs->bvec_integrity_pool = biovec_create_pool(bs, pool_size);
+ if (!bs->bvec_integrity_pool)
+ return -1;

if (!bs->bio_integrity_pool)
return -1;
@@ -762,13 +731,14 @@ void bioset_integrity_free(struct bio_set *bs)
{
if (bs->bio_integrity_pool)
mempool_destroy(bs->bio_integrity_pool);
+
+ if (bs->bvec_integrity_pool)
+ mempool_destroy(bs->bio_integrity_pool);
}
EXPORT_SYMBOL(bioset_integrity_free);

void __init bio_integrity_init(void)
{
- unsigned int i;
-
/*
* kintegrityd won't block much but may burn a lot of CPU cycles.
* Make it highpri CPU intensive wq with max concurrency of 1.
@@ -778,14 +748,10 @@ void __init bio_integrity_init(void)
if (!kintegrityd_wq)
panic("Failed to create kintegrityd\n");

- for (i = 0 ; i < BIOVEC_NR_POOLS ; i++) {
- unsigned int size;
-
- size = sizeof(struct bio_integrity_payload)
- + bip_slab[i].nr_vecs * sizeof(struct bio_vec);
-
- bip_slab[i].slab =
- kmem_cache_create(bip_slab[i].name, size, 0,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
- }
+ bip_slab = kmem_cache_create("bio_integrity_payload",
+ sizeof(struct bio_integrity_payload) +
+ sizeof(struct bio_vec) * BIP_INLINE_VECS,
+ 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
+ if (!bip_slab)
+ panic("Failed to create slab\n");
}
diff --git a/fs/bio.c b/fs/bio.c
index 63f05a9..ac8b443 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -158,12 +158,12 @@ unsigned int bvec_nr_vecs(unsigned short idx)
return bvec_slabs[idx].nr_vecs;
}

-void bvec_free_bs(struct bio_set *bs, struct bio_vec *bv, unsigned int idx)
+void bvec_free_bs(mempool_t *pool, struct bio_vec *bv, unsigned int idx)
{
BIO_BUG_ON(idx >= BIOVEC_NR_POOLS);

if (idx == BIOVEC_MAX_IDX)
- mempool_free(bv, bs->bvec_pool);
+ mempool_free(bv, pool);
else {
struct biovec_slab *bvs = bvec_slabs + idx;

@@ -172,7 +172,7 @@ void bvec_free_bs(struct bio_set *bs, struct bio_vec *bv, unsigned int idx)
}

struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx,
- struct bio_set *bs)
+ mempool_t *pool)
{
struct bio_vec *bvl;

@@ -208,7 +208,7 @@ struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx,
*/
if (*idx == BIOVEC_MAX_IDX) {
fallback:
- bvl = mempool_alloc(bs->bvec_pool, gfp_mask);
+ bvl = mempool_alloc(pool, gfp_mask);
} else {
struct biovec_slab *bvs = bvec_slabs + *idx;
gfp_t __gfp_mask = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
@@ -251,7 +251,7 @@ static void bio_free(struct bio *bio)

if (bs) {
if (bio_has_allocated_vec(bio))
- bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
+ bvec_free_bs(bs->bvec_pool, bio->bi_io_vec, BIO_POOL_IDX(bio));

/*
* If we have front padding, adjust the bio pointer before freeing
@@ -440,11 +440,11 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
bio_init(bio);

if (nr_iovecs > inline_vecs) {
- bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
+ bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs->bvec_pool);
if (!bvl && gfp_mask != saved_gfp) {
punt_bios_to_rescuer(bs);
gfp_mask = saved_gfp;
- bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
+ bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs->bvec_pool);
}

if (unlikely(!bvl))
@@ -1655,20 +1655,11 @@ EXPORT_SYMBOL(bio_sector_offset);
* create memory pools for biovec's in a bio_set.
* use the global biovec slabs created for general use.
*/
-static int biovec_create_pools(struct bio_set *bs, int pool_entries)
+mempool_t *biovec_create_pool(struct bio_set *bs, int pool_entries)
{
struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;

- bs->bvec_pool = mempool_create_slab_pool(pool_entries, bp->slab);
- if (!bs->bvec_pool)
- return -ENOMEM;
-
- return 0;
-}
-
-static void biovec_free_pools(struct bio_set *bs)
-{
- mempool_destroy(bs->bvec_pool);
+ return mempool_create_slab_pool(pool_entries, bp->slab);
}

void bioset_free(struct bio_set *bs)
@@ -1679,8 +1670,10 @@ void bioset_free(struct bio_set *bs)
if (bs->bio_pool)
mempool_destroy(bs->bio_pool);

+ if (bs->bvec_pool)
+ mempool_destroy(bs->bvec_pool);
+
bioset_integrity_free(bs);
- biovec_free_pools(bs);
bio_put_slab(bs);

kfree(bs);
@@ -1725,7 +1718,8 @@ struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
if (!bs->bio_pool)
goto bad;

- if (biovec_create_pools(bs, pool_size))
+ bs->bvec_pool = biovec_create_pool(bs, pool_size);
+ if (!bs->bvec_pool)
goto bad;

bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 8e2d108..a7c021d 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -182,7 +182,10 @@ struct bio_integrity_payload {
unsigned short bip_idx; /* current bip_vec index */

struct work_struct bip_work; /* I/O completion */
- struct bio_vec bip_vec[0]; /* embedded bvec array */
+
+ struct bio_vec *bip_vec;
+ struct bio_vec bip_inline_vecs[0];/* embedded bvec array */
+
};
#endif /* CONFIG_BLK_DEV_INTEGRITY */

@@ -213,6 +216,7 @@ extern void bio_pair_release(struct bio_pair *dbio);

extern struct bio_set *bioset_create(unsigned int, unsigned int);
extern void bioset_free(struct bio_set *);
+mempool_t *biovec_create_pool(struct bio_set *bs, int pool_entries);

extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
extern void bio_put(struct bio *);
@@ -288,8 +292,8 @@ extern struct bio *bio_copy_user_iov(struct request_queue *,
int, int, gfp_t);
extern int bio_uncopy_user(struct bio *);
void zero_fill_bio(struct bio *bio);
-extern struct bio_vec *bvec_alloc_bs(gfp_t, int, unsigned long *, struct bio_set *);
-extern void bvec_free_bs(struct bio_set *, struct bio_vec *, unsigned int);
+extern struct bio_vec *bvec_alloc_bs(gfp_t, int, unsigned long *, mempool_t *);
+extern void bvec_free_bs(mempool_t *, struct bio_vec *, unsigned int);
extern unsigned int bvec_nr_vecs(unsigned short idx);

#ifdef CONFIG_BLK_CGROUP
@@ -511,10 +515,11 @@ struct bio_set {
unsigned int front_pad;

mempool_t *bio_pool;
+ mempool_t *bvec_pool;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
mempool_t *bio_integrity_pool;
+ mempool_t *bvec_integrity_pool;
#endif
- mempool_t *bvec_pool;

/*
* Deadlock avoidance for stacking block drivers: see comments in
--
1.7.12

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/