From bfcfaa77bdf0f775263e906015982a608df01c76 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 6 Mar 2012 11:16:17 -0800 Subject: vfs: use 'unsigned long' accesses for dcache name comparison and hashing Ok, this is hacky, and only works on little-endian machines with goo unaligned handling. And even then only with CONFIG_DEBUG_PAGEALLOC disabled, since it can access up to 7 bytes after the pathname. But it runs like a bat out of hell. Signed-off-by: Linus Torvalds --- fs/dcache.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index bcbdb33fcc20..ffd47a16d870 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -144,6 +144,28 @@ int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, static inline int dentry_cmp(const unsigned char *cs, size_t scount, const unsigned char *ct, size_t tcount) { +#ifdef CONFIG_DCACHE_WORD_ACCESS + unsigned long a,b,mask; + + if (unlikely(scount != tcount)) + return 1; + + for (;;) { + a = *(unsigned long *)cs; + b = *(unsigned long *)ct; + if (tcount < sizeof(unsigned long)) + break; + if (unlikely(a != b)) + return 1; + cs += sizeof(unsigned long); + ct += sizeof(unsigned long); + tcount -= sizeof(unsigned long); + if (!tcount) + return 0; + } + mask = ~(~0ul << tcount*8); + return unlikely(!!((a ^ b) & mask)); +#else if (scount != tcount) return 1; @@ -155,6 +177,7 @@ static inline int dentry_cmp(const unsigned char *cs, size_t scount, tcount--; } while (tcount); return 0; +#endif } static void __d_free(struct rcu_head *head) -- cgit v1.2.3