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dm-bufio: use kmalloc to allocate power-of-two sized buffers

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Vlastimil Babka said [1] that kmalloc will return a power-of-two-aligned
buffer if it was called with a power-of-two size. So, we can use kmalloc
instead of our own slab cache in dm-bufio. Note that the code for the
slab cache was not removed because dm-bufio supports non-power-of-two
buffer sizes.

Link: https://lore.kernel.org/linux-mm/e7fca292-7c79-4f97-a90c-d68178d8ca59@suse.cz/ [1]

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
This commit is contained in:
Mikulas Patocka 2024-11-18 16:14:27 +01:00
parent e74fa2447b
commit 61a57254a9
1 changed files with 20 additions and 5 deletions
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25
drivers/md/dm-bufio.c
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@ -318,9 +318,10 @@ static struct lru_entry *lru_evict(struct lru *lru, le_predicate pred, void *con
*/
enum data_mode {
DATA_MODE_SLAB = 0,
DATA_MODE_GET_FREE_PAGES = 1,
DATA_MODE_VMALLOC = 2,
DATA_MODE_LIMIT = 3
DATA_MODE_KMALLOC = 1,
DATA_MODE_GET_FREE_PAGES = 2,
DATA_MODE_VMALLOC = 3,
DATA_MODE_LIMIT = 4
};
struct dm_buffer {
@ -1062,6 +1063,7 @@ static unsigned long dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES;
static unsigned long dm_bufio_peak_allocated;
static unsigned long dm_bufio_allocated_kmem_cache;
static unsigned long dm_bufio_allocated_kmalloc;
static unsigned long dm_bufio_allocated_get_free_pages;
static unsigned long dm_bufio_allocated_vmalloc;
static unsigned long dm_bufio_current_allocated;
@ -1104,6 +1106,7 @@ static void adjust_total_allocated(struct dm_buffer *b, bool unlink)
static unsigned long * const class_ptr[DATA_MODE_LIMIT] = {
&dm_bufio_allocated_kmem_cache,
&dm_bufio_allocated_kmalloc,
&dm_bufio_allocated_get_free_pages,
&dm_bufio_allocated_vmalloc,
};
@ -1181,6 +1184,11 @@ static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
return kmem_cache_alloc(c->slab_cache, gfp_mask);
}
if (unlikely(c->block_size < PAGE_SIZE)) {
*data_mode = DATA_MODE_KMALLOC;
return kmalloc(c->block_size, gfp_mask | __GFP_RECLAIMABLE);
}
if (c->block_size <= KMALLOC_MAX_SIZE &&
gfp_mask & __GFP_NORETRY) {
*data_mode = DATA_MODE_GET_FREE_PAGES;
@ -1204,6 +1212,10 @@ static void free_buffer_data(struct dm_bufio_client *c,
kmem_cache_free(c->slab_cache, data);
break;
case DATA_MODE_KMALLOC:
kfree(data);
break;
case DATA_MODE_GET_FREE_PAGES:
free_pages((unsigned long)data,
c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT));
@ -2519,8 +2531,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
goto bad_dm_io;
}
if (block_size <= KMALLOC_MAX_SIZE &&
(block_size < PAGE_SIZE || !is_power_of_2(block_size))) {
if (block_size <= KMALLOC_MAX_SIZE && !is_power_of_2(block_size)) {
unsigned int align = min(1U << __ffs(block_size), (unsigned int)PAGE_SIZE);
snprintf(slab_name, sizeof(slab_name), "dm_bufio_cache-%u-%u",
@ -2902,6 +2913,7 @@ static int __init dm_bufio_init(void)
__u64 mem;
dm_bufio_allocated_kmem_cache = 0;
dm_bufio_allocated_kmalloc = 0;
dm_bufio_allocated_get_free_pages = 0;
dm_bufio_allocated_vmalloc = 0;
dm_bufio_current_allocated = 0;
@ -2990,6 +3002,9 @@ MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory");
module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, 0444);
MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc");
module_param_named(allocated_kmalloc_bytes, dm_bufio_allocated_kmalloc, ulong, 0444);
MODULE_PARM_DESC(allocated_kmalloc_bytes, "Memory allocated with kmalloc_alloc");
module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, 0444);
MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages");