1 files changed, 28 insertions, 5 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index fe19ac13f75f..bcbdb33fcc20 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -104,7 +104,7 @@ static unsigned int d_hash_shift __read_mostly;
 
 static struct hlist_bl_head *dentry_hashtable __read_mostly;
 
-static inline struct hlist_bl_head *d_hash(struct dentry *parent,
+static inline struct hlist_bl_head *d_hash(const struct dentry *parent,
                                         unsigned long hash)
 {
         hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
@@ -137,6 +137,26 @@ int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
 }
 #endif
 
+/*
+ * Compare 2 name strings, return 0 if they match, otherwise non-zero.
+ * The strings are both count bytes long, and count is non-zero.
+ */
+static inline int dentry_cmp(const unsigned char *cs, size_t scount,
+                                const unsigned char *ct, size_t tcount)
+{
+        if (scount != tcount)
+                return 1;
+
+        do {
+                if (*cs != *ct)
+                        return 1;
+                cs++;
+                ct++;
+                tcount--;
+        } while (tcount);
+        return 0;
+}
+
 static void __d_free(struct rcu_head *head)
 {
         struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
@@ -1717,8 +1737,9 @@ EXPORT_SYMBOL(d_add_ci);
  * child is looked up. Thus, an interlocking stepping of sequence lock checks
  * is formed, giving integrity down the path walk.
  */
-struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
-                                unsigned *seq, struct inode **inode)
+struct dentry *__d_lookup_rcu(const struct dentry *parent,
+                                const struct qstr *name,
+                                unsigned *seqp, struct inode **inode)
 {
         unsigned int len = name->len;
         unsigned int hash = name->hash;
@@ -1748,6 +1769,7 @@ struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
          * See Documentation/filesystems/path-lookup.txt for more details.
          */
         hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
+                unsigned seq;
                 struct inode *i;
                 const char *tname;
                 int tlen;
@@ -1756,7 +1778,7 @@ struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
                         continue;
 
 seqretry:
-                *seq = read_seqcount_begin(&dentry->d_seq);
+                seq = read_seqcount_begin(&dentry->d_seq);
                 if (dentry->d_parent != parent)
                         continue;
                 if (d_unhashed(dentry))
@@ -1771,7 +1793,7 @@ seqretry:
                  * edge of memory when walking. If we could load this
                  * atomically some other way, we could drop this check.
                  */
-                if (read_seqcount_retry(&dentry->d_seq, *seq))
+                if (read_seqcount_retry(&dentry->d_seq, seq))
                         goto seqretry;
                 if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
                         if (parent->d_op->d_compare(parent, *inode,
@@ -1788,6 +1810,7 @@ seqretry:
                  * order to do anything useful with the returned dentry
                  * anyway.
                  */
+                *seqp = seq;
                 *inode = i;
                 return dentry;
         }