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Commit f51f2e0a authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm bufio: support non-power-of-two block sizes



Support block sizes that are not a power-of-two (but they must be a
multiple of 512b).  As always, a slab cache is used for allocations.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 359dbf19
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+39 −25
Original line number Diff line number Diff line
@@ -56,12 +56,6 @@
 */
#define DM_BUFIO_INLINE_VECS		16

/*
 * Don't try to use alloc_pages for blocks larger than this.
 * For explanation, see alloc_buffer_data below.
 */
#define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT	(PAGE_SIZE << (MAX_ORDER - 1))

/*
 * Align buffer writes to this boundary.
 * Tests show that SSDs have the highest IOPS when using 4k writes.
@@ -98,8 +92,7 @@ struct dm_bufio_client {

	struct block_device *bdev;
	unsigned block_size;
	unsigned char sectors_per_block_bits;
	unsigned char pages_per_block_bits;
	s8 sectors_per_block_bits;
	void (*alloc_callback)(struct dm_buffer *);
	void (*write_callback)(struct dm_buffer *);

@@ -375,11 +368,11 @@ static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
		return kmem_cache_alloc(c->slab_cache, gfp_mask);
	}

	if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT &&
	if (c->block_size <= KMALLOC_MAX_SIZE &&
	    gfp_mask & __GFP_NORETRY) {
		*data_mode = DATA_MODE_GET_FREE_PAGES;
		return (void *)__get_free_pages(gfp_mask,
						c->pages_per_block_bits);
						c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT));
	}

	*data_mode = DATA_MODE_VMALLOC;
@@ -416,7 +409,8 @@ static void free_buffer_data(struct dm_bufio_client *c,
		break;

	case DATA_MODE_GET_FREE_PAGES:
		free_pages((unsigned long)data, c->pages_per_block_bits);
		free_pages((unsigned long)data,
			   c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT));
		break;

	case DATA_MODE_VMALLOC:
@@ -634,10 +628,14 @@ static void submit_io(struct dm_buffer *b, int rw, bio_end_io_t *end_io)
	sector_t sector;
	unsigned offset, end;

	sector = (b->block << b->c->sectors_per_block_bits) + b->c->start;
	if (likely(b->c->sectors_per_block_bits >= 0))
		sector = b->block << b->c->sectors_per_block_bits;
	else
		sector = b->block * (b->c->block_size >> SECTOR_SHIFT);
	sector += b->c->start;

	if (rw != REQ_OP_WRITE) {
		n_sectors = 1 << b->c->sectors_per_block_bits;
		n_sectors = b->c->block_size >> SECTOR_SHIFT;
		offset = 0;
	} else {
		if (b->c->write_callback)
@@ -941,8 +939,11 @@ static void __get_memory_limit(struct dm_bufio_client *c,
		}
	}

	buffers = dm_bufio_cache_size_per_client >>
		  (c->sectors_per_block_bits + SECTOR_SHIFT);
	buffers = dm_bufio_cache_size_per_client;
	if (likely(c->sectors_per_block_bits >= 0))
		buffers >>= c->sectors_per_block_bits + SECTOR_SHIFT;
	else
		buffers /= c->block_size;

	if (buffers < c->minimum_buffers)
		buffers = c->minimum_buffers;
@@ -1476,8 +1477,12 @@ EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);

sector_t dm_bufio_get_device_size(struct dm_bufio_client *c)
{
	return i_size_read(c->bdev->bd_inode) >>
			   (SECTOR_SHIFT + c->sectors_per_block_bits);
	sector_t s = i_size_read(c->bdev->bd_inode) >> SECTOR_SHIFT;
	if (likely(c->sectors_per_block_bits >= 0))
		s >>= c->sectors_per_block_bits;
	else
		sector_div(s, c->block_size >> SECTOR_SHIFT);
	return s;
}
EXPORT_SYMBOL_GPL(dm_bufio_get_device_size);

@@ -1576,7 +1581,11 @@ static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp)
static unsigned long get_retain_buffers(struct dm_bufio_client *c)
{
	unsigned long retain_bytes = READ_ONCE(dm_bufio_retain_bytes);
        return retain_bytes >> (c->sectors_per_block_bits + SECTOR_SHIFT);
	if (likely(c->sectors_per_block_bits >= 0))
		retain_bytes >>= c->sectors_per_block_bits + SECTOR_SHIFT;
	else
		retain_bytes /= c->block_size;
	return retain_bytes;
}

static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan,
@@ -1642,8 +1651,11 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
	unsigned i;
	char slab_name[27];

	BUG_ON(block_size < 1 << SECTOR_SHIFT ||
	       (block_size & (block_size - 1)));
	if (!block_size || block_size & ((1 << SECTOR_SHIFT) - 1)) {
		DMERR("%s: block size not specified or is not multiple of 512b", __func__);
		r = -EINVAL;
		goto bad_client;
	}

	c = kzalloc(sizeof(*c), GFP_KERNEL);
	if (!c) {
@@ -1654,9 +1666,10 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign

	c->bdev = bdev;
	c->block_size = block_size;
	if (is_power_of_2(block_size))
		c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT;
	c->pages_per_block_bits = (__ffs(block_size) >= PAGE_SHIFT) ?
				  __ffs(block_size) - PAGE_SHIFT : 0;
	else
		c->sectors_per_block_bits = -1;

	c->alloc_callback = alloc_callback;
	c->write_callback = write_callback;
@@ -1681,7 +1694,8 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
		goto bad_dm_io;
	}

	if (block_size < PAGE_SIZE) {
	if (block_size <= KMALLOC_MAX_SIZE &&
	    (block_size < PAGE_SIZE || !is_power_of_2(block_size))) {
		snprintf(slab_name, sizeof slab_name, "dm_bufio_cache-%u", c->block_size);
		c->slab_cache = kmem_cache_create(slab_name, c->block_size, ARCH_KMALLOC_MINALIGN,
						  SLAB_RECLAIM_ACCOUNT, NULL);