diff options
| -rw-r--r-- | fs/dcache.c | 75 |
1 files changed, 59 insertions, 16 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index e7484f9c73b4..4858d2e5cf2e 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -235,18 +235,44 @@ static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *c return dentry_string_cmp(cs, ct, tcount); } +struct external_name { + union { + atomic_t count; + struct rcu_head head; + } u; + unsigned char name[]; +}; + +static inline struct external_name *external_name(struct dentry *dentry) +{ + return container_of(dentry->d_name.name, struct external_name, name[0]); +} + static void __d_free(struct rcu_head *head) { struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); WARN_ON(!hlist_unhashed(&dentry->d_alias)); - if (dname_external(dentry)) - kfree(dentry->d_name.name); + kmem_cache_free(dentry_cache, dentry); +} + +static void __d_free_external(struct rcu_head *head) +{ + struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); + WARN_ON(!hlist_unhashed(&dentry->d_alias)); + kfree(external_name(dentry)); kmem_cache_free(dentry_cache, dentry); } static void dentry_free(struct dentry *dentry) { + if (unlikely(dname_external(dentry))) { + struct external_name *p = external_name(dentry); + if (likely(atomic_dec_and_test(&p->u.count))) { + call_rcu(&dentry->d_u.d_rcu, __d_free_external); + return; + } + } /* if dentry was never visible to RCU, immediate free is OK */ if (!(dentry->d_flags & DCACHE_RCUACCESS)) __d_free(&dentry->d_u.d_rcu); @@ -1438,11 +1464,14 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) */ dentry->d_iname[DNAME_INLINE_LEN-1] = 0; if (name->len > DNAME_INLINE_LEN-1) { - dname = kmalloc(name->len + 1, GFP_KERNEL); - if (!dname) { + size_t size = offsetof(struct external_name, name[1]); + struct external_name *p = kmalloc(size + name->len, GFP_KERNEL); + if (!p) { kmem_cache_free(dentry_cache, dentry); return NULL; } + atomic_set(&p->u.count, 1); + dname = p->name; } else { dname = dentry->d_iname; } @@ -2372,11 +2401,10 @@ void dentry_update_name_case(struct dentry *dentry, struct qstr *name) } EXPORT_SYMBOL(dentry_update_name_case); -static void switch_names(struct dentry *dentry, struct dentry *target, - bool exchange) +static void swap_names(struct dentry *dentry, struct dentry *target) { - if (dname_external(target)) { - if (dname_external(dentry)) { + if (unlikely(dname_external(target))) { + if (unlikely(dname_external(dentry))) { /* * Both external: swap the pointers */ @@ -2392,7 +2420,7 @@ static void switch_names(struct dentry *dentry, struct dentry *target, target->d_name.name = target->d_iname; } } else { - if (dname_external(dentry)) { + if (unlikely(dname_external(dentry))) { /* * dentry:external, target:internal. Give dentry's * storage to target and make dentry internal @@ -2407,12 +2435,6 @@ static void switch_names(struct dentry *dentry, struct dentry *target, */ unsigned int i; BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long))); - if (!exchange) { - memcpy(dentry->d_iname, target->d_name.name, - target->d_name.len + 1); - dentry->d_name.hash_len = target->d_name.hash_len; - return; - } for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) { swap(((long *) &dentry->d_iname)[i], ((long *) &target->d_iname)[i]); @@ -2422,6 +2444,24 @@ static void switch_names(struct dentry *dentry, struct dentry *target, swap(dentry->d_name.hash_len, target->d_name.hash_len); } +static void copy_name(struct dentry *dentry, struct dentry *target) +{ + struct external_name *old_name = NULL; + if (unlikely(dname_external(dentry))) + old_name = external_name(dentry); + if (unlikely(dname_external(target))) { + atomic_inc(&external_name(target)->u.count); + dentry->d_name = target->d_name; + } else { + memcpy(dentry->d_iname, target->d_name.name, + target->d_name.len + 1); + dentry->d_name.name = dentry->d_iname; + dentry->d_name.hash_len = target->d_name.hash_len; + } + if (old_name && likely(atomic_dec_and_test(&old_name->u.count))) + kfree_rcu(old_name, u.head); +} + static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) { /* @@ -2518,7 +2558,10 @@ static void __d_move(struct dentry *dentry, struct dentry *target, } /* Switch the names.. */ - switch_names(dentry, target, exchange); + if (exchange) + swap_names(dentry, target); + else + copy_name(dentry, target); /* ... and switch them in the tree */ if (IS_ROOT(dentry)) { |