lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 22 Oct 2014 10:02:18 +0200 From: Jan Kara <jack@...e.cz> To: Sasha Levin <sasha.levin@...cle.com> Cc: akpm@...ux-foundation.org, jack@...e.cz, linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, a.ryabinin@...sung.com Subject: Re: [PATCH] fs, jbd: use a more generic hash function On Tue 21-10-14 16:43:55, Sasha Levin wrote: > 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. Thanks. Merged to my tree. Honza > > Signed-off-by: Sasha Levin <sasha.levin@...cle.com> > --- > fs/jbd/revoke.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/fs/jbd/revoke.c b/fs/jbd/revoke.c > index 8898bbd..dcead63 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, > -- > 1.7.10.4 > -- Jan Kara <jack@...e.cz> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists