vfs: avoid non-forwarding large load after small store in path lookup

[deliverable/linux.git] / fs / namei.c

diff --git a/fs/namei.c b/fs/namei.c
index a996bb48dfabf4f645dced56f527ed3d5568bb2c..2be5120b81b3c06512c032fd4f20ed4a0c57cc36 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -34,6 +34,7 @@
 #include <linux/device_cgroup.h>
 #include <linux/fs_struct.h>
 #include <linux/posix_acl.h>
+#include <linux/hash.h>
 #include <asm/uaccess.h>
 
 #include "internal.h"
@@ -1634,8 +1635,7 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd)
 
 static inline unsigned int fold_hash(unsigned long hash)
 {
-       hash += hash >> (8*sizeof(int));
-       return hash;
+       return hash_64(hash, 32);
 }
 
 #else  /* 32-bit case */
@@ -1669,13 +1669,14 @@ EXPORT_SYMBOL(full_name_hash);
 
 /*
  * Calculate the length and hash of the path component, and
- * return the length of the component;
+ * fill in the qstr. return the "len" as the result.
  */
-static inline unsigned long hash_name(const char *name, unsigned int *hashp)
+static inline unsigned long hash_name(const char *name, struct qstr *res)
 {
        unsigned long a, b, adata, bdata, mask, hash, len;
        const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
 
+       res->name = name;
        hash = a = 0;
        len = -sizeof(unsigned long);
        do {
@@ -1691,9 +1692,10 @@ static inline unsigned long hash_name(const char *name, unsigned int *hashp)
        mask = create_zero_mask(adata | bdata);
 
        hash += a & zero_bytemask(mask);
-       *hashp = fold_hash(hash);
+       len += find_zero(mask);
+       res->hash_len = hashlen_create(fold_hash(hash), len);
 
-       return len + find_zero(mask);
+       return len;
 }
 
 #else
@@ -1711,18 +1713,19 @@ EXPORT_SYMBOL(full_name_hash);
  * We know there's a real path component here of at least
  * one character.
  */
-static inline unsigned long hash_name(const char *name, unsigned int *hashp)
+static inline long hash_name(const char *name, struct qstr *res)
 {
        unsigned long hash = init_name_hash();
        unsigned long len = 0, c;
 
+       res->name = name;
        c = (unsigned char)*name;
        do {
                len++;
                hash = partial_name_hash(c, hash);
                c = (unsigned char)name[len];
        } while (c && c != '/');
-       *hashp = end_name_hash(hash);
+       res->hash_len = hashlen_create(end_name_hash(hash), len);
        return len;
 }
 
@@ -1756,9 +1759,7 @@ static int link_path_walk(const char *name, struct nameidata *nd)
                if (err)
                        break;
 
-               len = hash_name(name, &this.hash);
-               this.name = name;
-               this.len = len;
+               len = hash_name(name, &this);
 
                type = LAST_NORM;
                if (name[0] == '.') switch (len) {