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authorSasha Levin <sasha.levin@oracle.com>2014-10-21 16:43:55 -0400
committerJan Kara <jack@suse.cz>2014-10-22 10:02:04 +0200
commit3c9cafe05ff002eb84d438a02f3c8d468720463b (patch)
treecf3d905c079b6e2f8b00d97523c8b4cdacf8edc1 /fs
parent474d2605d119479e5aa050f738632e63589d4bb5 (diff)
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fs, jbd: use a more generic hash function
While the hash function used by the revoke hashtable is good somewhere else, it's not really good here. The default hash shift (8) means that one third of the hashing function gets lost (and is undefined anyways (8 - 12 = negative shift)): "(block << (hash_shift - 12))) & (table->hash_size - 1)" Instead, just use the kernel's generic hash function that gets used everywhere else. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs')
-rw-r--r--fs/jbd/revoke.c7
1 files changed, 2 insertions, 5 deletions
diff --git a/fs/jbd/revoke.c b/fs/jbd/revoke.c
index 8898bbd2b61e..dcead636c33b 100644
--- a/fs/jbd/revoke.c
+++ b/fs/jbd/revoke.c
@@ -93,6 +93,7 @@
#include <linux/bio.h>
#endif
#include <linux/log2.h>
+#include <linux/hash.h>
static struct kmem_cache *revoke_record_cache;
static struct kmem_cache *revoke_table_cache;
@@ -129,15 +130,11 @@ static void flush_descriptor(journal_t *, struct journal_head *, int, int);
/* Utility functions to maintain the revoke table */
-/* Borrowed from buffer.c: this is a tried and tested block hash function */
static inline int hash(journal_t *journal, unsigned int block)
{
struct jbd_revoke_table_s *table = journal->j_revoke;
- int hash_shift = table->hash_shift;
- return ((block << (hash_shift - 6)) ^
- (block >> 13) ^
- (block << (hash_shift - 12))) & (table->hash_size - 1);
+ return hash_32(block, table->hash_shift);
}
static int insert_revoke_hash(journal_t *journal, unsigned int blocknr,