diff options
Diffstat (limited to 'include/linux/dcache.h')
| -rw-r--r-- | include/linux/dcache.h | 32 |
1 files changed, 29 insertions, 3 deletions
diff --git a/include/linux/dcache.h b/include/linux/dcache.h index ca648685f0cc..c2e7390289cc 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -5,6 +5,7 @@ #include <linux/list.h> #include <linux/rculist.h> #include <linux/spinlock.h> +#include <linux/seqlock.h> #include <linux/cache.h> #include <linux/rcupdate.h> @@ -90,6 +91,7 @@ struct dentry { unsigned int d_count; /* protected by d_lock */ unsigned int d_flags; /* protected by d_lock */ spinlock_t d_lock; /* per dentry lock */ + seqcount_t d_seq; /* per dentry seqlock */ int d_mounted; struct inode *d_inode; /* Where the name belongs to - NULL is * negative */ @@ -266,9 +268,33 @@ extern void d_move(struct dentry *, struct dentry *); extern struct dentry *d_ancestor(struct dentry *, struct dentry *); /* appendix may either be NULL or be used for transname suffixes */ -extern struct dentry * d_lookup(struct dentry *, struct qstr *); -extern struct dentry * __d_lookup(struct dentry *, struct qstr *); -extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *); +extern struct dentry *d_lookup(struct dentry *, struct qstr *); +extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *); +extern struct dentry *__d_lookup(struct dentry *, struct qstr *); +extern struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name, + unsigned *seq, struct inode **inode); + +/** + * __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; +} /* validate "insecure" dentry pointer */ extern int d_validate(struct dentry *, struct dentry *); |