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authorLinus Torvalds <torvalds@linux-foundation.org>2016-06-10 07:51:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-06-10 20:21:46 -0700
commit8387ff2577eb9ed245df9a39947f66976c6bcd02 (patch)
tree79fafcb5777f16e520d1c39e9389039f866b4c6d /include/linux/stringhash.h
parent147d9e7bcad3b8d5465f6eea6292731e7f35dee8 (diff)
vfs: make the string hashes salt the hash
We always mixed in the parent pointer into the dentry name hash, but we did it late at lookup time. It turns out that we can simplify that lookup-time action by salting the hash with the parent pointer early instead of late. A few other users of our string hashes also wanted to mix in their own pointers into the hash, and those are updated to use the same mechanism. Hash users that don't have any particular initial salt can just use the NULL pointer as a no-salt. Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: George Spelvin <linux@sciencehorizons.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/stringhash.h')
-rw-r--r--include/linux/stringhash.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/stringhash.h b/include/linux/stringhash.h
index 451771d9b9c0..eb7debb280c0 100644
--- a/include/linux/stringhash.h
+++ b/include/linux/stringhash.h
@@ -34,7 +34,7 @@
*/
/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
-#define init_name_hash() 0
+#define init_name_hash(salt) (unsigned long)(salt)
/* partial hash update function. Assume roughly 4 bits per character */
static inline unsigned long
@@ -60,7 +60,7 @@ static inline unsigned long end_name_hash(unsigned long hash)
*
* If not set, this falls back to a wrapper around the preceding.
*/
-extern unsigned int __pure full_name_hash(const char *, unsigned int);
+extern unsigned int __pure full_name_hash(const void *salt, const char *, unsigned int);
/*
* A hash_len is a u64 with the hash of a string in the low
@@ -71,6 +71,6 @@ extern unsigned int __pure full_name_hash(const char *, unsigned int);
#define hashlen_create(hash, len) ((u64)(len)<<32 | (u32)(hash))
/* Return the "hash_len" (hash and length) of a null-terminated string */
-extern u64 __pure hashlen_string(const char *name);
+extern u64 __pure hashlen_string(const void *salt, const char *name);
#endif /* __LINUX_STRINGHASH_H */