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infra: better dent hash function

This commit is contained in:
Thomas Schoebel-Theuer 2020-09-17 18:02:15 +02:00
parent 5d1484fc26
commit 423ff91956
2 changed files with 32 additions and 17 deletions
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11
kernel/sy_old/strategy.h
View File

@ -77,6 +77,15 @@ extern char *my_id(void);
struct mars_dent;
typedef void (*dent_skip_fn)(struct mars_dent *);
unsigned int dent_hash(const char *str, int len);
#define DENT_HASH_ANCHOR(global,index) \
({ \
struct list_head *table = (global)->dent_hash_table[(index) / MARS_GLOBAL_HASH_TABLE]; \
\
table + ((index) % MARS_GLOBAL_HASH_TABLE); \
})
#define MARS_DENT(TYPE) \
struct list_head dent_link; \
struct list_head dent_hash_link; \
@ -99,7 +108,7 @@ typedef void (*dent_skip_fn)(struct mars_dent *);
int d_serial; /* for pre-grouping order */ \
int d_version; /* dynamic programming per call of mars_ent_work() */ \
int d_child_count; \
int d_hash; \
unsigned int d_hash; \
int d_proto; \
char d_once_error; \
bool d_no_scan; \

38
kernel/sy_old/sy_generic.c
View File

@ -37,6 +37,7 @@
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/utsname.h>
#include <linux/crc32c.h>
#include "strategy.h"
@ -1436,6 +1437,23 @@ int get_inode(char *newpath, struct mars_dent *dent, bool get_deleted)
return status;
}
unsigned int dent_hash(const char *str, int len)
{
u32 raw_hash = crc32c(0, str, len);
u32 mask = (u32)-1;
unsigned int hash = 0;
/* catch all possible bits */
while (mask) {
hash ^= raw_hash;
raw_hash /= MARS_GLOBAL_HASH;
mask /= MARS_GLOBAL_HASH;
}
hash %= MARS_GLOBAL_HASH;
return hash;
}
static
int dent_compare(struct mars_dent *a, struct mars_dent *b)
{
@ -1492,8 +1510,7 @@ int mars_filler(void *__buf, const char *name, int namlen, loff_t offset,
// end_remove_this
struct mars_dent *dent;
char *newpath;
unsigned char digest[MARS_DIGEST_SIZE];
int hash;
unsigned int hash;
int prefix = 0;
int pathlen;
int class;
@ -1526,10 +1543,7 @@ int mars_filler(void *__buf, const char *name, int namlen, loff_t offset,
pathlen += namlen;
newpath[pathlen] = '\0';
mars_digest(MREF_CHKSUM_CRC32C,
NULL,
digest,
newpath, pathlen);
hash = dent_hash(newpath, pathlen);
dent = brick_zmem_alloc(cookie->allocsize);
@ -1538,7 +1552,6 @@ int mars_filler(void *__buf, const char *name, int namlen, loff_t offset,
dent->d_path = newpath;
newpath = NULL;
hash = *(unsigned long *)&digest % MARS_GLOBAL_HASH;
dent->d_hash = hash;
dent->d_name = brick_string_alloc(namlen + 1);
memcpy(dent->d_name, name, namlen);
@ -1581,13 +1594,6 @@ void _reconnect_dent(struct mars_cookie *cookie, struct mars_dent *dent)
fatal: ;
}
#define _HASH_ANCHOR(global,index) \
({ \
struct list_head *table = (global)->dent_hash_table[(index) / MARS_GLOBAL_HASH_TABLE]; \
\
table + ((index) % MARS_GLOBAL_HASH_TABLE); \
})
static
void _mars_order(struct mars_cookie *cookie, struct mars_dent *dent)
{
@ -1609,7 +1615,7 @@ void _mars_order(struct mars_cookie *cookie, struct mars_dent *dent)
*/
sorted_anchor = &global->dent_anchor;
CHECK_PTR(sorted_anchor, fatal);
hash_anchor = _HASH_ANCHOR(global, dent->d_hash);
hash_anchor = DENT_HASH_ANCHOR(global, dent->d_hash);
CHECK_PTR(hash_anchor, fatal);
sorted_prev = sorted_anchor;
@ -1675,7 +1681,7 @@ void _mars_order(struct mars_cookie *cookie, struct mars_dent *dent)
}
#endif
hash_try_anchor = _HASH_ANCHOR(global, hash_try_index);
hash_try_anchor = DENT_HASH_ANCHOR(global, hash_try_index);
CHECK_PTR(hash_try_anchor, fatal);
hash_try = test->dent_hash_link.next;
CHECK_PTR(hash_try, fatal);