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: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 39 insertions, 25 deletions

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 4a216926ee19..e88797e04fcc 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -57,12 +57,6 @@
 #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);
 
@@ -1575,8 +1580,12 @@ 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);
+        unsigned long retain_bytes = READ_ONCE(dm_bufio_retain_bytes);
+        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;
-        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;
+        if (is_power_of_2(block_size))
+                c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT;
+        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);