Merge tag 'for-5.12/block-2021-02-17' of git://git.kernel.dk/linux-block

Pull core block updates from Jens Axboe:
 "Another nice round of removing more code than what is added, mostly
  due to Christoph's relentless pursuit of tech debt removal/cleanups.
  This pull request contains:

   - Two series of BFQ improvements (Paolo, Jan, Jia)

   - Block iov_iter improvements (Pavel)

   - bsg error path fix (Pan)

   - blk-mq scheduler improvements (Jan)

   - -EBUSY discard fix (Jan)

   - bvec allocation improvements (Ming, Christoph)

   - bio allocation and init improvements (Christoph)

   - Store bdev pointer in bio instead of gendisk + partno (Christoph)

   - Block trace point cleanups (Christoph)

   - hard read-only vs read-only split (Christoph)

   - Block based swap cleanups (Christoph)

   - Zoned write granularity support (Damien)

   - Various fixes/tweaks (Chunguang, Guoqing, Lei, Lukas, Huhai)"

* tag 'for-5.12/block-2021-02-17' of git://git.kernel.dk/linux-block: (104 commits)
  mm: simplify swapdev_block
  sd_zbc: clear zone resources for non-zoned case
  block: introduce blk_queue_clear_zone_settings()
  zonefs: use zone write granularity as block size
  block: introduce zone_write_granularity limit
  block: use blk_queue_set_zoned in add_partition()
  nullb: use blk_queue_set_zoned() to setup zoned devices
  nvme: cleanup zone information initialization
  block: document zone_append_max_bytes attribute
  block: use bi_max_vecs to find the bvec pool
  md/raid10: remove dead code in reshape_request
  block: mark the bio as cloned in bio_iov_bvec_set
  block: set BIO_NO_PAGE_REF in bio_iov_bvec_set
  block: remove a layer of indentation in bio_iov_iter_get_pages
  block: turn the nr_iovecs argument to bio_alloc* into an unsigned short
  block: remove the 1 and 4 vec bvec_slabs entries
  block: streamline bvec_alloc
  block: factor out a bvec_alloc_gfp helper
  block: move struct biovec_slab to bio.c
  block: reuse BIO_INLINE_VECS for integrity bvecs
  ...

1 files changed, 253 insertions, 318 deletions

diff --git a/block/bio.c b/block/bio.c
index 2f21d2958b60..a1c4d2900c7a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -19,27 +19,40 @@
 #include <linux/highmem.h>
 #include <linux/sched/sysctl.h>
 #include <linux/blk-crypto.h>
+#include <linux/xarray.h>
 
 #include <trace/events/block.h>
 #include "blk.h"
 #include "blk-rq-qos.h"
 
-/*
- * Test patch to inline a certain number of bi_io_vec's inside the bio
- * itself, to shrink a bio data allocation from two mempool calls to one
- */
-#define BIO_INLINE_VECS		4
-
-/*
- * if you change this list, also change bvec_alloc or things will
- * break badly! cannot be bigger than what you can fit into an
- * unsigned short
- */
-#define BV(x, n) { .nr_vecs = x, .name = "biovec-"#n }
-static struct biovec_slab bvec_slabs[BVEC_POOL_NR] __read_mostly = {
-	BV(1, 1), BV(4, 4), BV(16, 16), BV(64, 64), BV(128, 128), BV(BIO_MAX_PAGES, max),
+static struct biovec_slab {
+	int nr_vecs;
+	char *name;
+	struct kmem_cache *slab;
+} bvec_slabs[] __read_mostly = {
+	{ .nr_vecs = 16, .name = "biovec-16" },
+	{ .nr_vecs = 64, .name = "biovec-64" },
+	{ .nr_vecs = 128, .name = "biovec-128" },
+	{ .nr_vecs = BIO_MAX_PAGES, .name = "biovec-max" },
 };
-#undef BV
+
+static struct biovec_slab *biovec_slab(unsigned short nr_vecs)
+{
+	switch (nr_vecs) {
+	/* smaller bios use inline vecs */
+	case 5 ... 16:
+		return &bvec_slabs[0];
+	case 17 ... 64:
+		return &bvec_slabs[1];
+	case 65 ... 128:
+		return &bvec_slabs[2];
+	case 129 ... BIO_MAX_PAGES:
+		return &bvec_slabs[3];
+	default:
+		BUG();
+		return NULL;
+	}
+}
 
 /*
  * fs_bio_set is the bio_set containing bio and iovec memory pools used by
@@ -58,178 +71,133 @@ struct bio_slab {
 	char name[8];
 };
 static DEFINE_MUTEX(bio_slab_lock);
-static struct bio_slab *bio_slabs;
-static unsigned int bio_slab_nr, bio_slab_max;
+static DEFINE_XARRAY(bio_slabs);
 
-static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
+static struct bio_slab *create_bio_slab(unsigned int size)
 {
-	unsigned int sz = sizeof(struct bio) + extra_size;
-	struct kmem_cache *slab = NULL;
-	struct bio_slab *bslab, *new_bio_slabs;
-	unsigned int new_bio_slab_max;
-	unsigned int i, entry = -1;
+	struct bio_slab *bslab = kzalloc(sizeof(*bslab), GFP_KERNEL);
 
-	mutex_lock(&bio_slab_lock);
+	if (!bslab)
+		return NULL;
 
-	i = 0;
-	while (i < bio_slab_nr) {
-		bslab = &bio_slabs[i];
+	snprintf(bslab->name, sizeof(bslab->name), "bio-%d", size);
+	bslab->slab = kmem_cache_create(bslab->name, size,
+			ARCH_KMALLOC_MINALIGN, SLAB_HWCACHE_ALIGN, NULL);
+	if (!bslab->slab)
+		goto fail_alloc_slab;
 
-		if (!bslab->slab && entry == -1)
-			entry = i;
-		else if (bslab->slab_size == sz) {
-			slab = bslab->slab;
-			bslab->slab_ref++;
-			break;
-		}
-		i++;
-	}
+	bslab->slab_ref = 1;
+	bslab->slab_size = size;
 
-	if (slab)
-		goto out_unlock;
-
-	if (bio_slab_nr == bio_slab_max && entry == -1) {
-		new_bio_slab_max = bio_slab_max << 1;
-		new_bio_slabs = krealloc(bio_slabs,
-					 new_bio_slab_max * sizeof(struct bio_slab),
-					 GFP_KERNEL);
-		if (!new_bio_slabs)
-			goto out_unlock;
-		bio_slab_max = new_bio_slab_max;
-		bio_slabs = new_bio_slabs;
-	}
-	if (entry == -1)
-		entry = bio_slab_nr++;
+	if (!xa_err(xa_store(&bio_slabs, size, bslab, GFP_KERNEL)))
+		return bslab;
+
+	kmem_cache_destroy(bslab->slab);
 
-	bslab = &bio_slabs[entry];
+fail_alloc_slab:
+	kfree(bslab);
+	return NULL;
+}
+
+static inline unsigned int bs_bio_slab_size(struct bio_set *bs)
+{
+	return bs->front_pad + sizeof(struct bio) + bs->back_pad;
+}
 
-	snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry);
-	slab = kmem_cache_create(bslab->name, sz, ARCH_KMALLOC_MINALIGN,
-				 SLAB_HWCACHE_ALIGN, NULL);
-	if (!slab)
-		goto out_unlock;
+static struct kmem_cache *bio_find_or_create_slab(struct bio_set *bs)
+{
+	unsigned int size = bs_bio_slab_size(bs);
+	struct bio_slab *bslab;
 
-	bslab->slab = slab;
-	bslab->slab_ref = 1;
-	bslab->slab_size = sz;
-out_unlock:
+	mutex_lock(&bio_slab_lock);
+	bslab = xa_load(&bio_slabs, size);
+	if (bslab)
+		bslab->slab_ref++;
+	else
+		bslab = create_bio_slab(size);
 	mutex_unlock(&bio_slab_lock);
-	return slab;
+
+	if (bslab)
+		return bslab->slab;
+	return NULL;
 }
 
 static void bio_put_slab(struct bio_set *bs)
 {
 	struct bio_slab *bslab = NULL;
-	unsigned int i;
+	unsigned int slab_size = bs_bio_slab_size(bs);
 
 	mutex_lock(&bio_slab_lock);
 
-	for (i = 0; i < bio_slab_nr; i++) {
-		if (bs->bio_slab == bio_slabs[i].slab) {
-			bslab = &bio_slabs[i];
-			break;
-		}
-	}
-
+	bslab = xa_load(&bio_slabs, slab_size);
 	if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
 		goto out;
 
+	WARN_ON_ONCE(bslab->slab != bs->bio_slab);
+
 	WARN_ON(!bslab->slab_ref);
 
 	if (--bslab->slab_ref)
 		goto out;
 
+	xa_erase(&bio_slabs, slab_size);
+
 	kmem_cache_destroy(bslab->slab);
-	bslab->slab = NULL;
+	kfree(bslab);
 
 out:
 	mutex_unlock(&bio_slab_lock);
 }
 
-unsigned int bvec_nr_vecs(unsigned short idx)
+void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned short nr_vecs)
 {
-	return bvec_slabs[--idx].nr_vecs;
-}
-
-void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned int idx)
-{
-	if (!idx)
-		return;
-	idx--;
+	BIO_BUG_ON(nr_vecs > BIO_MAX_PAGES);
 
-	BIO_BUG_ON(idx >= BVEC_POOL_NR);
-
-	if (idx == BVEC_POOL_MAX) {
+	if (nr_vecs == BIO_MAX_PAGES)
 		mempool_free(bv, pool);
-	} else {
-		struct biovec_slab *bvs = bvec_slabs + idx;
+	else if (nr_vecs > BIO_INLINE_VECS)
+		kmem_cache_free(biovec_slab(nr_vecs)->slab, bv);
+}
 
-		kmem_cache_free(bvs->slab, bv);
-	}
+/*
+ * Make the first allocation restricted and don't dump info on allocation
+ * failures, since we'll fall back to the mempool in case of failure.
+ */
+static inline gfp_t bvec_alloc_gfp(gfp_t gfp)
+{
+	return (gfp & ~(__GFP_DIRECT_RECLAIM | __GFP_IO)) |
+		__GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
 }
 
-struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx,
-			   mempool_t *pool)
+struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs,
+		gfp_t gfp_mask)
 {
-	struct bio_vec *bvl;
+	struct biovec_slab *bvs = biovec_slab(*nr_vecs);
 
-	/*
-	 * see comment near bvec_array define!
-	 */
-	switch (nr) {
-	case 1:
-		*idx = 0;
-		break;
-	case 2 ... 4:
-		*idx = 1;
-		break;
-	case 5 ... 16:
-		*idx = 2;
-		break;
-	case 17 ... 64:
-		*idx = 3;
-		break;
-	case 65 ... 128:
-		*idx = 4;
-		break;
-	case 129 ... BIO_MAX_PAGES:
-		*idx = 5;
-		break;
-	default:
+	if (WARN_ON_ONCE(!bvs))
 		return NULL;
-	}
 
 	/*
-	 * idx now points to the pool we want to allocate from. only the
-	 * 1-vec entry pool is mempool backed.
+	 * Upgrade the nr_vecs request to take full advantage of the allocation.
+	 * We also rely on this in the bvec_free path.
 	 */
-	if (*idx == BVEC_POOL_MAX) {
-fallback:
-		bvl = mempool_alloc(pool, gfp_mask);
-	} else {
-		struct biovec_slab *bvs = bvec_slabs + *idx;
-		gfp_t __gfp_mask = gfp_mask & ~(__GFP_DIRECT_RECLAIM | __GFP_IO);
+	*nr_vecs = bvs->nr_vecs;
 
-		/*
-		 * Make this allocation restricted and don't dump info on
-		 * allocation failures, since we'll fallback to the mempool
-		 * in case of failure.
-		 */
-		__gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
+	/*
+	 * Try a slab allocation first for all smaller allocations.  If that
+	 * fails and __GFP_DIRECT_RECLAIM is set retry with the mempool.
+	 * The mempool is sized to handle up to BIO_MAX_PAGES entries.
+	 */
+	if (*nr_vecs < BIO_MAX_PAGES) {
+		struct bio_vec *bvl;
 
-		/*
-		 * Try a slab allocation. If this fails and __GFP_DIRECT_RECLAIM
-		 * is set, retry with the 1-entry mempool
-		 */
-		bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
-		if (unlikely(!bvl && (gfp_mask & __GFP_DIRECT_RECLAIM))) {
-			*idx = BVEC_POOL_MAX;
-			goto fallback;
-		}
+		bvl = kmem_cache_alloc(bvs->slab, bvec_alloc_gfp(gfp_mask));
+		if (likely(bvl) || !(gfp_mask & __GFP_DIRECT_RECLAIM))
+			return bvl;
+		*nr_vecs = BIO_MAX_PAGES;
 	}
 
-	(*idx)++;
-	return bvl;
+	return mempool_alloc(pool, gfp_mask);
 }
 
 void bio_uninit(struct bio *bio)
@@ -255,7 +223,7 @@ static void bio_free(struct bio *bio)
 	bio_uninit(bio);
 
 	if (bs) {
-		bvec_free(&bs->bvec_pool, bio->bi_io_vec, BVEC_POOL_IDX(bio));
+		bvec_free(&bs->bvec_pool, bio->bi_io_vec, bio->bi_max_vecs);
 
 		/*
 		 * If we have front padding, adjust the bio pointer before freeing
@@ -299,12 +267,8 @@ EXPORT_SYMBOL(bio_init);
  */
 void bio_reset(struct bio *bio)
 {
-	unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
-
 	bio_uninit(bio);
-
 	memset(bio, 0, BIO_RESET_BYTES);
-	bio->bi_flags = flags;
 	atomic_set(&bio->__bi_remaining, 1);
 }
 EXPORT_SYMBOL(bio_reset);
@@ -405,122 +369,97 @@ static void punt_bios_to_rescuer(struct bio_set *bs)
  * @nr_iovecs:	number of iovecs to pre-allocate
  * @bs:		the bio_set to allocate from.
  *
- * Description:
- *   If @bs is NULL, uses kmalloc() to allocate the bio; else the allocation is
- *   backed by the @bs's mempool.
+ * Allocate a bio from the mempools in @bs.
  *
- *   When @bs is not NULL, if %__GFP_DIRECT_RECLAIM is set then bio_alloc will
- *   always be able to allocate a bio. This is due to the mempool guarantees.
- *   To make this work, callers must never allocate more than 1 bio at a time
- *   from this pool. Callers that need to allocate more than 1 bio must always
- *   submit the previously allocated bio for IO before attempting to allocate
- *   a new one. Failure to do so can cause deadlocks under memory pressure.
+ * If %__GFP_DIRECT_RECLAIM is set then bio_alloc will always be able to
+ * allocate a bio.  This is due to the mempool guarantees.  To make this work,
+ * callers must never allocate more than 1 bio at a time from the general pool.
+ * Callers that need to allocate more than 1 bio must always submit the
+ * previously allocated bio for IO before attempting to allocate a new one.
+ * Failure to do so can cause deadlocks under memory pressure.
  *
- *   Note that when running under submit_bio_noacct() (i.e. any block
- *   driver), bios are not submitted until after you return - see the code in
- *   submit_bio_noacct() that converts recursion into iteration, to prevent
- *   stack overflows.
+ * Note that when running under submit_bio_noacct() (i.e. any block driver),
+ * bios are not submitted until after you return - see the code in
+ * submit_bio_noacct() that converts recursion into iteration, to prevent
+ * stack overflows.
  *
- *   This would normally mean allocating multiple bios under
- *   submit_bio_noacct() would be susceptible to deadlocks, but we have
- *   deadlock avoidance code that resubmits any blocked bios from a rescuer
- *   thread.
+ * This would normally mean allocating multiple bios under submit_bio_noacct()
+ * would be susceptible to deadlocks, but we have
+ * deadlock avoidance code that resubmits any blocked bios from a rescuer
+ * thread.
  *
- *   However, we do not guarantee forward progress for allocations from other
- *   mempools. Doing multiple allocations from the same mempool under
- *   submit_bio_noacct() should be avoided - instead, use bio_set's front_pad
- *   for per bio allocations.
+ * However, we do not guarantee forward progress for allocations from other
+ * mempools. Doing multiple allocations from the same mempool under
+ * submit_bio_noacct() should be avoided - instead, use bio_set's front_pad
+ * for per bio allocations.
  *
- *   RETURNS:
- *   Pointer to new bio on success, NULL on failure.
+ * Returns: Pointer to new bio on success, NULL on failure.
  */
-struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs,
+struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned short nr_iovecs,
 			     struct bio_set *bs)
 {
 	gfp_t saved_gfp = gfp_mask;
-	unsigned front_pad;
-	unsigned inline_vecs;
-	struct bio_vec *bvl = NULL;
 	struct bio *bio;
 	void *p;
 
-	if (!bs) {
-		if (nr_iovecs > UIO_MAXIOV)
-			return NULL;
-
-		p = kmalloc(struct_size(bio, bi_inline_vecs, nr_iovecs), gfp_mask);
-		front_pad = 0;
-		inline_vecs = nr_iovecs;
-	} else {
-		/* should not use nobvec bioset for nr_iovecs > 0 */
-		if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) &&
-				 nr_iovecs > 0))
-			return NULL;
-		/*
-		 * submit_bio_noacct() converts recursion to iteration; this
-		 * means if we're running beneath it, any bios we allocate and
-		 * submit will not be submitted (and thus freed) until after we
-		 * return.
-		 *
-		 * This exposes us to a potential deadlock if we allocate
-		 * multiple bios from the same bio_set() while running
-		 * underneath submit_bio_noacct(). If we were to allocate
-		 * multiple bios (say a stacking block driver that was splitting
-		 * bios), we would deadlock if we exhausted the mempool's
-		 * reserve.
-		 *
-		 * We solve this, and guarantee forward progress, with a rescuer
-		 * workqueue per bio_set. If we go to allocate and there are
-		 * bios on current->bio_list, we first try the allocation
-		 * without __GFP_DIRECT_RECLAIM; if that fails, we punt those
-		 * bios we would be blocking to the rescuer workqueue before
-		 * we retry with the original gfp_flags.
-		 */
-
-		if (current->bio_list &&
-		    (!bio_list_empty(&current->bio_list[0]) ||
-		     !bio_list_empty(&current->bio_list[1])) &&
-		    bs->rescue_workqueue)
-			gfp_mask &= ~__GFP_DIRECT_RECLAIM;
+	/* should not use nobvec bioset for nr_iovecs > 0 */
+	if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) && nr_iovecs > 0))
+		return NULL;
 
+	/*
+	 * submit_bio_noacct() converts recursion to iteration; this means if
+	 * we're running beneath it, any bios we allocate and submit will not be
+	 * submitted (and thus freed) until after we return.
+	 *
+	 * This exposes us to a potential deadlock if we allocate multiple bios
+	 * from the same bio_set() while running underneath submit_bio_noacct().
+	 * If we were to allocate multiple bios (say a stacking block driver
+	 * that was splitting bios), we would deadlock if we exhausted the
+	 * mempool's reserve.
+	 *
+	 * We solve this, and guarantee forward progress, with a rescuer
+	 * workqueue per bio_set. If we go to allocate and there are bios on
+	 * current->bio_list, we first try the allocation without
+	 * __GFP_DIRECT_RECLAIM; if that fails, we punt those bios we would be
+	 * blocking to the rescuer workqueue before we retry with the original
+	 * gfp_flags.
+	 */
+	if (current->bio_list &&
+	    (!bio_list_empty(&current->bio_list[0]) ||
+	     !bio_list_empty(&current->bio_list[1])) &&
+	    bs->rescue_workqueue)
+		gfp_mask &= ~__GFP_DIRECT_RECLAIM;
+
+	p = mempool_alloc(&bs->bio_pool, gfp_mask);
+	if (!p && gfp_mask != saved_gfp) {
+		punt_bios_to_rescuer(bs);
+		gfp_mask = saved_gfp;
 		p = mempool_alloc(&bs->bio_pool, gfp_mask);
-		if (!p && gfp_mask != saved_gfp) {
-			punt_bios_to_rescuer(bs);
-			gfp_mask = saved_gfp;
-			p = mempool_alloc(&bs->bio_pool, gfp_mask);
-		}
-
-		front_pad = bs->front_pad;
-		inline_vecs = BIO_INLINE_VECS;
 	}
-
 	if (unlikely(!p))
 		return NULL;
 
-	bio = p + front_pad;
-	bio_init(bio, NULL, 0);
+	bio = p + bs->front_pad;
+	if (nr_iovecs > BIO_INLINE_VECS) {
+		struct bio_vec *bvl = NULL;
 
-	if (nr_iovecs > inline_vecs) {
-		unsigned long idx = 0;
-
-		bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, &bs->bvec_pool);
+		bvl = bvec_alloc(&bs->bvec_pool, &nr_iovecs, gfp_mask);
 		if (!bvl && gfp_mask != saved_gfp) {
 			punt_bios_to_rescuer(bs);
 			gfp_mask = saved_gfp;
-			bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, &bs->bvec_pool);
+			bvl = bvec_alloc(&bs->bvec_pool, &nr_iovecs, gfp_mask);
 		}
-
 		if (unlikely(!bvl))
 			goto err_free;
 
-		bio->bi_flags |= idx << BVEC_POOL_OFFSET;
+		bio_init(bio, bvl, nr_iovecs);
 	} else if (nr_iovecs) {
-		bvl = bio->bi_inline_vecs;
+		bio_init(bio, bio->bi_inline_vecs, BIO_INLINE_VECS);
+	} else {
+		bio_init(bio, NULL, 0);
 	}
 
 	bio->bi_pool = bs;
-	bio->bi_max_vecs = nr_iovecs;
-	bio->bi_io_vec = bvl;
 	return bio;
 
 err_free:
@@ -529,6 +468,31 @@ err_free:
 }
 EXPORT_SYMBOL(bio_alloc_bioset);
 
+/**
+ * bio_kmalloc - kmalloc a bio for I/O
+ * @gfp_mask:   the GFP_* mask given to the slab allocator
+ * @nr_iovecs:	number of iovecs to pre-allocate
+ *
+ * Use kmalloc to allocate and initialize a bio.
+ *
+ * Returns: Pointer to new bio on success, NULL on failure.
+ */
+struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned short nr_iovecs)
+{
+	struct bio *bio;
+
+	if (nr_iovecs > UIO_MAXIOV)
+		return NULL;
+
+	bio = kmalloc(struct_size(bio, bi_inline_vecs, nr_iovecs), gfp_mask);
+	if (unlikely(!bio))
+		return NULL;
+	bio_init(bio, nr_iovecs ? bio->bi_inline_vecs : NULL, nr_iovecs);
+	bio->bi_pool = NULL;
+	return bio;
+}
+EXPORT_SYMBOL(bio_kmalloc);
+
 void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start)
 {
 	unsigned long flags;
@@ -607,16 +571,7 @@ void bio_truncate(struct bio *bio, unsigned new_size)
  */
 void guard_bio_eod(struct bio *bio)
 {
-	sector_t maxsector;
-	struct block_device *part;
-
-	rcu_read_lock();
-	part = __disk_get_part(bio->bi_disk, bio->bi_partno);
-	if (part)
-		maxsector = bdev_nr_sectors(part);
-	else	
-		maxsector = get_capacity(bio->bi_disk);
-	rcu_read_unlock();
+	sector_t maxsector = bdev_nr_sectors(bio->bi_bdev);
 
 	if (!maxsector)
 		return;
@@ -673,17 +628,18 @@ EXPORT_SYMBOL(bio_put);
  */
 void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
 {
-	BUG_ON(bio->bi_pool && BVEC_POOL_IDX(bio));
+	WARN_ON_ONCE(bio->bi_pool && bio->bi_max_vecs);
 
 	/*
-	 * most users will be overriding ->bi_disk with a new target,
+	 * most users will be overriding ->bi_bdev with a new target,
 	 * so we don't set nor calculate new physical/hw segment counts here
 	 */
-	bio->bi_disk = bio_src->bi_disk;
-	bio->bi_partno = bio_src->bi_partno;
+	bio->bi_bdev = bio_src->bi_bdev;
 	bio_set_flag(bio, BIO_CLONED);
 	if (bio_flagged(bio_src, BIO_THROTTLED))
 		bio_set_flag(bio, BIO_THROTTLED);
+	if (bio_flagged(bio_src, BIO_REMAPPED))
+		bio_set_flag(bio, BIO_REMAPPED);
 	bio->bi_opf = bio_src->bi_opf;
 	bio->bi_ioprio = bio_src->bi_ioprio;
 	bio->bi_write_hint = bio_src->bi_write_hint;
@@ -730,7 +686,7 @@ EXPORT_SYMBOL(bio_clone_fast);
 
 const char *bio_devname(struct bio *bio, char *buf)
 {
-	return disk_name(bio->bi_disk, bio->bi_partno, buf);
+	return bdevname(bio->bi_bdev, buf);
 }
 EXPORT_SYMBOL(bio_devname);
 
@@ -870,7 +826,7 @@ EXPORT_SYMBOL(bio_add_pc_page);
 int bio_add_zone_append_page(struct bio *bio, struct page *page,
 			     unsigned int len, unsigned int offset)
 {
-	struct request_queue *q = bio->bi_disk->queue;
+	struct request_queue *q = bio->bi_bdev->bd_disk->queue;
 	bool same_page = false;
 
 	if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_ZONE_APPEND))
@@ -993,21 +949,18 @@ void bio_release_pages(struct bio *bio, bool mark_dirty)
 }
 EXPORT_SYMBOL_GPL(bio_release_pages);
 
-static int __bio_iov_bvec_add_pages(struct bio *bio, struct iov_iter *iter)
+static int bio_iov_bvec_set(struct bio *bio, struct iov_iter *iter)
 {
-	const struct bio_vec *bv = iter->bvec;
-	unsigned int len;
-	size_t size;
-
-	if (WARN_ON_ONCE(iter->iov_offset > bv->bv_len))
-		return -EINVAL;
-
-	len = min_t(size_t, bv->bv_len - iter->iov_offset, iter->count);
-	size = bio_add_page(bio, bv->bv_page, len,
-				bv->bv_offset + iter->iov_offset);
-	if (unlikely(size != len))
-		return -EINVAL;
-	iov_iter_advance(iter, size);
+	WARN_ON_ONCE(bio->bi_max_vecs);
+
+	bio->bi_vcnt = iter->nr_segs;
+	bio->bi_io_vec = (struct bio_vec *)iter->bvec;
+	bio->bi_iter.bi_bvec_done = iter->iov_offset;
+	bio->bi_iter.bi_size = iter->count;
+	bio_set_flag(bio, BIO_NO_PAGE_REF);
+	bio_set_flag(bio, BIO_CLONED);
+
+	iov_iter_advance(iter, iter->count);
 	return 0;
 }
 
@@ -1070,7 +1023,7 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
 {
 	unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
 	unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
-	struct request_queue *q = bio->bi_disk->queue;
+	struct request_queue *q = bio->bi_bdev->bd_disk->queue;
 	unsigned int max_append_sectors = queue_max_zone_append_sectors(q);
 	struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
 	struct page **pages = (struct page **)bv;
@@ -1121,41 +1074,40 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
  * This takes either an iterator pointing to user memory, or one pointing to
  * kernel pages (BVEC iterator). If we're adding user pages, we pin them and
  * map them into the kernel. On IO completion, the caller should put those
- * pages. If we're adding kernel pages, and the caller told us it's safe to
- * do so, we just have to add the pages to the bio directly. We don't grab an
- * extra reference to those pages (the user should already have that), and we
- * don't put the page on IO completion. The caller needs to check if the bio is
- * flagged BIO_NO_PAGE_REF on IO completion. If it isn't, then pages should be
- * released.
+ * pages. For bvec based iterators bio_iov_iter_get_pages() uses the provided
+ * bvecs rather than copying them. Hence anyone issuing kiocb based IO needs
+ * to ensure the bvecs and pages stay referenced until the submitted I/O is
+ * completed by a call to ->ki_complete() or returns with an error other than
+ * -EIOCBQUEUED. The caller needs to check if the bio is flagged BIO_NO_PAGE_REF
+ * on IO completion. If it isn't, then pages should be released.
  *
  * The function tries, but does not guarantee, to pin as many pages as
  * fit into the bio, or are requested in @iter, whatever is smaller. If
  * MM encounters an error pinning the requested pages, it stops. Error
  * is returned only if 0 pages could be pinned.
+ *
+ * It's intended for direct IO, so doesn't do PSI tracking, the caller is
+ * responsible for setting BIO_WORKINGSET if necessary.
  */
 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 {
-	const bool is_bvec = iov_iter_is_bvec(iter);
-	int ret;
+	int ret = 0;
 
-	if (WARN_ON_ONCE(bio->bi_vcnt))
-		return -EINVAL;
+	if (iov_iter_is_bvec(iter)) {
+		if (WARN_ON_ONCE(bio_op(bio) == REQ_OP_ZONE_APPEND))
+			return -EINVAL;
+		return bio_iov_bvec_set(bio, iter);
+	}
 
 	do {
-		if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
-			if (WARN_ON_ONCE(is_bvec))
-				return -EINVAL;
+		if (bio_op(bio) == REQ_OP_ZONE_APPEND)
 			ret = __bio_iov_append_get_pages(bio, iter);
-		} else {
-			if (is_bvec)
-				ret = __bio_iov_bvec_add_pages(bio, iter);
-			else
-				ret = __bio_iov_iter_get_pages(bio, iter);
-		}
+		else
+			ret = __bio_iov_iter_get_pages(bio, iter);
 	} while (!ret && iov_iter_count(iter) && !bio_full(bio, 0));
 
-	if (is_bvec)
-		bio_set_flag(bio, BIO_NO_PAGE_REF);
+	/* don't account direct I/O as memory stall */
+	bio_clear_flag(bio, BIO_WORKINGSET);
 	return bio->bi_vcnt ? 0 : ret;
 }
 EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages);
@@ -1178,7 +1130,8 @@ static void submit_bio_wait_endio(struct bio *bio)
  */
 int submit_bio_wait(struct bio *bio)
 {
-	DECLARE_COMPLETION_ONSTACK_MAP(done, bio->bi_disk->lockdep_map);
+	DECLARE_COMPLETION_ONSTACK_MAP(done,
+			bio->bi_bdev->bd_disk->lockdep_map);
 	unsigned long hang_check;
 
 	bio->bi_private = &done;
@@ -1455,8 +1408,8 @@ again:
 	if (!bio_integrity_endio(bio))
 		return;
 
-	if (bio->bi_disk)
-		rq_qos_done_bio(bio->bi_disk->queue, bio);
+	if (bio->bi_bdev)
+		rq_qos_done_bio(bio->bi_bdev->bd_disk->queue, bio);
 
 	/*
 	 * Need to have a real endio function for chained bios, otherwise
@@ -1471,8 +1424,8 @@ again:
 		goto again;
 	}
 
-	if (bio->bi_disk && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
-		trace_block_bio_complete(bio->bi_disk->queue, bio);
+	if (bio->bi_bdev && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
+		trace_block_bio_complete(bio->bi_bdev->bd_disk->queue, bio);
 		bio_clear_flag(bio, BIO_TRACE_COMPLETION);
 	}
 
@@ -1559,7 +1512,7 @@ EXPORT_SYMBOL_GPL(bio_trim);
  */
 int biovec_init_pool(mempool_t *pool, int pool_entries)
 {
-	struct biovec_slab *bp = bvec_slabs + BVEC_POOL_MAX;
+	struct biovec_slab *bp = bvec_slabs + ARRAY_SIZE(bvec_slabs) - 1;
 
 	return mempool_init_slab_pool(pool, pool_entries, bp->slab);
 }
@@ -1612,15 +1565,17 @@ int bioset_init(struct bio_set *bs,
 		unsigned int front_pad,
 		int flags)
 {
-	unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
-
 	bs->front_pad = front_pad;
+	if (flags & BIOSET_NEED_BVECS)
+		bs->back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
+	else
+		bs->back_pad = 0;
 
 	spin_lock_init(&bs->rescue_lock);
 	bio_list_init(&bs->rescue_list);
 	INIT_WORK(&bs->rescue_work, bio_alloc_rescue);
 
-	bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
+	bs->bio_slab = bio_find_or_create_slab(bs);
 	if (!bs->bio_slab)
 		return -ENOMEM;
 
@@ -1663,39 +1618,19 @@ int bioset_init_from_src(struct bio_set *bs, struct bio_set *src)
 }
 EXPORT_SYMBOL(bioset_init_from_src);
 
-static void __init biovec_init_slabs(void)
+static int __init init_bio(void)
 {
 	int i;
 
-	for (i = 0; i < BVEC_POOL_NR; i++) {
-		int size;
-		struct biovec_slab *bvs = bvec_slabs + i;
+	bio_integrity_init();
 
-		if (bvs->nr_vecs <= BIO_INLINE_VECS) {
-			bvs->slab = NULL;
-			continue;
-		}
+	for (i = 0; i < ARRAY_SIZE(bvec_slabs); i++) {
+		struct biovec_slab *bvs = bvec_slabs + i;
 
-		size = bvs->nr_vecs * sizeof(struct bio_vec);
-		bvs->slab = kmem_cache_create(bvs->name, size, 0,
-                                SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
+		bvs->slab = kmem_cache_create(bvs->name,
+				bvs->nr_vecs * sizeof(struct bio_vec), 0,
+				SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
 	}
-}
-
-static int __init init_bio(void)
-{
-	bio_slab_max = 2;
-	bio_slab_nr = 0;
-	bio_slabs = kcalloc(bio_slab_max, sizeof(struct bio_slab),
-			    GFP_KERNEL);
-
-	BUILD_BUG_ON(BIO_FLAG_LAST > BVEC_POOL_OFFSET);
-
-	if (!bio_slabs)
-		panic("bio: can't allocate bios\n");
-
-	bio_integrity_init();
-	biovec_init_slabs();
 
 	if (bioset_init(&fs_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS))
 		panic("bio: can't allocate bios\n");