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authorLinus Torvalds <torvalds@linux-foundation.org>2012-03-06 11:16:17 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-08 18:08:44 -0800
commitbfcfaa77bdf0f775263e906015982a608df01c76 (patch)
tree6671137d4af157b851d953b7e2809abbfa809e81 /fs/dcache.c
parent9f8050c4f99789d03ca96d4e625bd6637241828f (diff)
downloadop-kernel-dev-bfcfaa77bdf0f775263e906015982a608df01c76.zip
op-kernel-dev-bfcfaa77bdf0f775263e906015982a608df01c76.tar.gz
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 <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/dcache.c')
-rw-r--r--fs/dcache.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index bcbdb33..ffd47a1 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)
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