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zram: switch to 64-bit hash for dedup

Browse source 
The original dedup code does not handle collision from the observation
that it practically does not happen.

For additional peace of mind, use a bigger hash size for reducing the
possibility of collision even further.

Signed-off-by: Juhyung Park <qkrwngud825@gmail.com>
Signed-off-by: Marco Zanin <mrczn.bb@gmail.com>
Signed-off-by: snnbyyds <snnbyyds@gmail.com>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
This commit is contained in:
Juhyung Park 2021-10-03 17:38:24 +09:00 • committed by Sorayukii
commit df412d7834
4 changed files with 12 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

12
drivers/block/zram/zram_dedup.c
View file

@ -28,13 +28,13 @@ u64 zram_dedup_meta_size(struct zram *zram)
return (u64)atomic64_read(&zram->stats.meta_data_size);
}
static u32 zram_dedup_checksum(unsigned char *mem)
static u64 zram_dedup_checksum(unsigned char *mem)
{
return xxhash(mem, PAGE_SIZE, 0);
return xxh64(mem, PAGE_SIZE, 0);
}
void zram_dedup_insert(struct zram *zram, struct zram_entry *new,
u32 checksum)
u64 checksum)
{
struct zram_hash *hash;
struct rb_root *rb_root;
@ -91,7 +91,7 @@ static unsigned long zram_dedup_put(struct zram *zram,
struct zram_entry *entry)
{
struct zram_hash *hash;
u32 checksum;
u64 checksum;
unsigned long val;
checksum = entry->checksum;
@ -156,7 +156,7 @@ again:
}
static struct zram_entry *zram_dedup_get(struct zram *zram,
unsigned char *mem, u32 checksum)
unsigned char *mem, u64 checksum)
{
struct zram_hash *hash;
struct zram_entry *entry;
@ -182,7 +182,7 @@ static struct zram_entry *zram_dedup_get(struct zram *zram,
}
struct zram_entry *zram_dedup_find(struct zram *zram, struct page *page,
u32 *checksum)
u64 *checksum)
{
void *mem;
struct zram_entry *entry;

8
drivers/block/zram/zram_dedup.h
View file

@ -10,9 +10,9 @@ u64 zram_dedup_dup_size(struct zram *zram);
u64 zram_dedup_meta_size(struct zram *zram);
void zram_dedup_insert(struct zram *zram, struct zram_entry *new,
u32 checksum);
u64 checksum);
struct zram_entry *zram_dedup_find(struct zram *zram, struct page *page,
u32 *checksum);
u64 *checksum);
void zram_dedup_init_entry(struct zram *zram, struct zram_entry *entry,
unsigned long handle, unsigned int len);
@ -26,9 +26,9 @@ static inline u64 zram_dedup_dup_size(struct zram *zram) { return 0; }
static inline u64 zram_dedup_meta_size(struct zram *zram) { return 0; }
static inline void zram_dedup_insert(struct zram *zram, struct zram_entry *new,
u32 checksum) { }
u64 checksum) { }
static inline struct zram_entry *zram_dedup_find(struct zram *zram,
struct page *page, u32 *checksum) { return NULL; }
struct page *page, u64 *checksum) { return NULL; }
static inline void zram_dedup_init_entry(struct zram *zram,
struct zram_entry *entry, unsigned long handle,

2
drivers/block/zram/zram_drv.c
View file

@ -1430,7 +1430,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
void *src, *dst, *mem;
struct zcomp_strm *zstrm;
struct page *page = bvec->bv_page;
u32 checksum;
u64 checksum;
unsigned long element = 0;
enum zram_pageflags flags = 0;

2
drivers/block/zram/zram_drv.h
View file

@ -61,7 +61,7 @@ enum zram_pageflags {
struct zram_entry {
struct rb_node rb_node;
u32 len;
u32 checksum;
u64 checksum;
unsigned long refcount;
unsigned long handle;
};