Messages in this thread Patch in this message | | | Date | 25 May 2016 03:22:50 -0400 | From | "George Spelvin" <> | Subject | [PATCH 02/10] fs/namei.c: Add hash_string() function |
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It's not actually used in that file, but goes with hash_name() and full_name_hash(), so it's simplest to keep it there.
Also simplify the prototype of full_name_hash to be take a "char *" rather than "unsigned char *". That's consistent with hash_name().
Signed-off-by: George Spelvin <linux@sciencehorizons.net> --- fs/namei.c | 47 +++++++++++++++++++++++++++++++++++++++++++--- include/linux/stringhash.h | 8 ++++++-- 2 files changed, 50 insertions(+), 5 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c index 42f8ca03..ce640d65 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1822,7 +1822,8 @@ static inline unsigned long mix_hash(unsigned long hash) #endif -unsigned int full_name_hash(const unsigned char *name, unsigned int len) +/* Return the hash of a string of known length */ +unsigned int full_name_hash(const char *name, unsigned int len) { unsigned long a, hash = 0; @@ -1842,6 +1843,29 @@ done: } EXPORT_SYMBOL(full_name_hash); +/* Return the "hash_len" (hash and length) of a null-terminated string */ +u64 hash_string(const char *name) +{ + unsigned long a, adata, mask, hash, len; + const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; + + hash = a = 0; + len = -sizeof(unsigned long); + do { + hash = mix_hash(hash + a); + len += sizeof(unsigned long); + a = load_unaligned_zeropad(name+len); + } while (!has_zero(a, &adata, &constants)); + + adata = prep_zero_mask(a, adata, &constants); + mask = create_zero_mask(adata); + hash += a & zero_bytemask(mask); + len += find_zero(mask); + + return hashlen_create(fold_hash(hash), len); +} +EXPORT_SYMBOL(hash_string); + /* * Calculate the length and hash of the path component, and * return the "hash_len" as the result. @@ -1872,15 +1896,32 @@ static inline u64 hash_name(const char *name) #else -unsigned int full_name_hash(const unsigned char *name, unsigned int len) +/* Return the hash of a string of known length */ +unsigned int full_name_hash(const char *name, unsigned int len) { unsigned long hash = init_name_hash(); while (len--) - hash = partial_name_hash(*name++, hash); + hash = partial_name_hash((unsigned char)*name++, hash); return end_name_hash(hash); } EXPORT_SYMBOL(full_name_hash); +/* Return the "hash_len" (hash and length) of a null-terminated string */ +u64 hash_string(const char *name) +{ + unsigned long hash = init_name_hash(); + unsigned long len = 0, c; + + c = (unsigned char)*name; + do { + len++; + hash = partial_name_hash(c, hash); + c = (unsigned char)name[len]; + } while (c); + return hashlen_create(end_name_hash(hash), len); +} +EXPORT_SYMBOL(hash_string); + /* * We know there's a real path component here of at least * one character. diff --git a/include/linux/stringhash.h b/include/linux/stringhash.h index 144d8c0f..d1c80ba2 100644 --- a/include/linux/stringhash.h +++ b/include/linux/stringhash.h @@ -1,7 +1,8 @@ #ifndef __LINUX_STRINGHASH_H #define __LINUX_STRINGHASH_H -#include <linux/types.h> +#include <linux/compiler.h> /* For __pure */ +#include <linux/types.h> /* For u32, u64 */ /* * Routines for hashing strings of bytes to a 32-bit hash value. @@ -59,7 +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 full_name_hash(const unsigned char *, unsigned int); +extern unsigned int __pure full_name_hash(const char *, unsigned int); /* * A hash_len is a u64 with the hash of a string in the low @@ -69,4 +70,7 @@ extern unsigned int full_name_hash(const unsigned char *, unsigned int); #define hashlen_len(hashlen) ((u32)((hashlen) >> 32)) #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 hash_string(const char *name); + #endif /* __LINUX_STRINGHASH_H */ -- 2.8.1
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