vfs: reimplement d_rcu_to_refcount() using lockref_get_or_lock()

[mirror_ubuntu-bionic-kernel.git] / include / linux / dcache.h

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index b90337c9d468ead13e94f4c6ed110bdf75723755..9169b91ea2d289e34952400b8ca89252222690e7 100644 (file)
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -9,6 +9,7 @@
 #include <linux/seqlock.h>
 #include <linux/cache.h>
 #include <linux/rcupdate.h>
+#include <linux/lockref.h>
 
 struct nameidata;
 struct path;
@@ -100,6 +101,8 @@ extern unsigned int full_name_hash(const unsigned char *, unsigned int);
 # endif
 #endif
 
+#define d_lock d_lockref.lock
+
 struct dentry {
        /* RCU lookup touched fields */
        unsigned int d_flags;           /* protected by d_lock */
@@ -112,8 +115,7 @@ struct dentry {
        unsigned char d_iname[DNAME_INLINE_LEN];        /* small names */
 
        /* Ref lookup also touches following */
-       unsigned int d_count;           /* protected by d_lock */
-       spinlock_t d_lock;              /* per dentry lock */
+       struct lockref d_lockref;       /* per-dentry lock and refcount */
        const struct dentry_operations *d_op;
        struct super_block *d_sb;       /* The root of the dentry tree */
        unsigned long d_time;           /* used by d_revalidate */
@@ -302,31 +304,9 @@ extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
 extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
                                const struct qstr *name, unsigned *seq);
 
-/**
- * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
- * @dentry: dentry to take a ref on
- * @seq: seqcount to verify against
- * Returns: 0 on failure, else 1.
- *
- * __d_rcu_to_refcount operates on a dentry,seq pair that was returned
- * by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
- */
-static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
-{
-       int ret = 0;
-
-       assert_spin_locked(&dentry->d_lock);
-       if (!read_seqcount_retry(&dentry->d_seq, seq)) {
-               ret = 1;
-               dentry->d_count++;
-       }
-
-       return ret;
-}
-
 static inline unsigned d_count(const struct dentry *dentry)
 {
-       return dentry->d_count;
+       return dentry->d_lockref.count;
 }
 
 /* validate "insecure" dentry pointer */
@@ -336,6 +316,7 @@ extern int d_validate(struct dentry *, struct dentry *);
  * helper function for dentry_operations.d_dname() members
  */
 extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
+extern char *simple_dname(struct dentry *, char *, int);
 
 extern char *__d_path(const struct path *, const struct path *, char *, int);
 extern char *d_absolute_path(const struct path *, char *, int);
@@ -356,17 +337,14 @@ extern char *dentry_path(struct dentry *, char *, int);
 static inline struct dentry *dget_dlock(struct dentry *dentry)
 {
        if (dentry)
-               dentry->d_count++;
+               dentry->d_lockref.count++;
        return dentry;
 }
 
 static inline struct dentry *dget(struct dentry *dentry)
 {
-       if (dentry) {
-               spin_lock(&dentry->d_lock);
-               dget_dlock(dentry);
-               spin_unlock(&dentry->d_lock);
-       }
+       if (dentry)
+               lockref_get(&dentry->d_lockref);
        return dentry;
 }