iput(inode);
}
+/*
+ * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry
+ * is in use - which includes both the "real" per-superblock
+ * LRU list _and_ the DCACHE_SHRINK_LIST use.
+ *
+ * The DCACHE_SHRINK_LIST bit is set whenever the dentry is
+ * on the shrink list (ie not on the superblock LRU list).
+ *
+ * The per-cpu "nr_dentry_unused" counters are updated with
+ * the DCACHE_LRU_LIST bit.
+ *
+ * These helper functions make sure we always follow the
+ * rules. d_lock must be held by the caller.
+ */
+#define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x))
+static void d_lru_add(struct dentry *dentry)
+{
+ D_FLAG_VERIFY(dentry, 0);
+ dentry->d_flags |= DCACHE_LRU_LIST;
+ this_cpu_inc(nr_dentry_unused);
+ WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
+}
+
+static void d_lru_del(struct dentry *dentry)
+{
+ D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
+ dentry->d_flags &= ~DCACHE_LRU_LIST;
+ this_cpu_dec(nr_dentry_unused);
+ WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
+}
+
+static void d_shrink_del(struct dentry *dentry)
+{
+ D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
+ list_del_init(&dentry->d_lru);
+ dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
+ this_cpu_dec(nr_dentry_unused);
+}
+
+static void d_shrink_add(struct dentry *dentry, struct list_head *list)
+{
+ D_FLAG_VERIFY(dentry, 0);
+ list_add(&dentry->d_lru, list);
+ dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST;
+ this_cpu_inc(nr_dentry_unused);
+}
+
+/*
+ * These can only be called under the global LRU lock, ie during the
+ * callback for freeing the LRU list. "isolate" removes it from the
+ * LRU lists entirely, while shrink_move moves it to the indicated
+ * private list.
+ */
+static void d_lru_isolate(struct dentry *dentry)
+{
+ D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
+ dentry->d_flags &= ~DCACHE_LRU_LIST;
+ this_cpu_dec(nr_dentry_unused);
+ list_del_init(&dentry->d_lru);
+}
+
+static void d_lru_shrink_move(struct dentry *dentry, struct list_head *list)
+{
+ D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
+ dentry->d_flags |= DCACHE_SHRINK_LIST;
+ list_move_tail(&dentry->d_lru, list);
+}
+
/*
* dentry_lru_(add|del)_list) must be called with d_lock held.
*/
static void dentry_lru_add(struct dentry *dentry)
{
- if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) {
- if (list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru))
- this_cpu_inc(nr_dentry_unused);
- dentry->d_flags |= DCACHE_LRU_LIST;
- }
+ if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
+ d_lru_add(dentry);
}
/*
*/
static void dentry_lru_del(struct dentry *dentry)
{
- if (dentry->d_flags & DCACHE_SHRINK_LIST) {
- list_del_init(&dentry->d_lru);
- dentry->d_flags &= ~DCACHE_SHRINK_LIST;
- return;
+ if (dentry->d_flags & DCACHE_LRU_LIST) {
+ if (dentry->d_flags & DCACHE_SHRINK_LIST)
+ return d_shrink_del(dentry);
+ d_lru_del(dentry);
}
-
- if (list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru))
- this_cpu_dec(nr_dentry_unused);
- dentry->d_flags &= ~DCACHE_LRU_LIST;
}
/**
* If ref is non-zero, then decrement the refcount too.
* Returns dentry requiring refcount drop, or NULL if we're done.
*/
-static inline struct dentry *
+static struct dentry *
dentry_kill(struct dentry *dentry, int unlock_on_failure)
__releases(dentry->d_lock)
{
goto kill_it;
}
- dentry->d_flags |= DCACHE_REFERENCED;
+ if (!(dentry->d_flags & DCACHE_REFERENCED))
+ dentry->d_flags |= DCACHE_REFERENCED;
dentry_lru_add(dentry);
dentry->d_lockref.count--;
dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
if (&dentry->d_lru == list)
break; /* empty */
+
+ /*
+ * Get the dentry lock, and re-verify that the dentry is
+ * this on the shrinking list. If it is, we know that
+ * DCACHE_SHRINK_LIST and DCACHE_LRU_LIST are set.
+ */
spin_lock(&dentry->d_lock);
if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
spin_unlock(&dentry->d_lock);
* to the LRU here, so we can simply remove it from the list
* here regardless of whether it is referenced or not.
*/
- list_del_init(&dentry->d_lru);
- dentry->d_flags &= ~DCACHE_SHRINK_LIST;
+ d_shrink_del(dentry);
/*
* We found an inuse dentry which was not removed from
}
rcu_read_unlock();
+ /*
+ * If 'try_to_prune()' returns a dentry, it will
+ * be the same one we passed in, and d_lock will
+ * have been held the whole time, so it will not
+ * have been added to any other lists. We failed
+ * to get the inode lock.
+ *
+ * We just add it back to the shrink list.
+ */
dentry = try_prune_one_dentry(dentry);
rcu_read_lock();
if (dentry) {
- dentry->d_flags |= DCACHE_SHRINK_LIST;
- list_add(&dentry->d_lru, list);
+ d_shrink_add(dentry, list);
spin_unlock(&dentry->d_lock);
}
}
* another pass through the LRU.
*/
if (dentry->d_lockref.count) {
- list_del_init(&dentry->d_lru);
+ d_lru_isolate(dentry);
spin_unlock(&dentry->d_lock);
return LRU_REMOVED;
}
return LRU_ROTATE;
}
- dentry->d_flags |= DCACHE_SHRINK_LIST;
- list_move_tail(&dentry->d_lru, freeable);
- this_cpu_dec(nr_dentry_unused);
+ d_lru_shrink_move(dentry, freeable);
spin_unlock(&dentry->d_lock);
return LRU_REMOVED;
if (!spin_trylock(&dentry->d_lock))
return LRU_SKIP;
- dentry->d_flags |= DCACHE_SHRINK_LIST;
- list_move_tail(&dentry->d_lru, freeable);
- this_cpu_dec(nr_dentry_unused);
+ d_lru_shrink_move(dentry, freeable);
spin_unlock(&dentry->d_lock);
return LRU_REMOVED;
* list is non-empty and continue searching.
*/
-/**
- * have_submounts - check for mounts over a dentry
- * @parent: dentry to check.
- *
- * Return true if the parent or its subdirectories contain
- * a mount point
- */
-
static enum d_walk_ret check_mount(void *data, struct dentry *dentry)
{
int *ret = data;
return D_WALK_CONTINUE;
}
+/**
+ * have_submounts - check for mounts over a dentry
+ * @parent: dentry to check.
+ *
+ * Return true if the parent or its subdirectories contain
+ * a mount point
+ */
int have_submounts(struct dentry *parent)
{
int ret = 0;
if (dentry->d_lockref.count) {
dentry_lru_del(dentry);
} else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
- dentry_lru_del(dentry);
- list_add_tail(&dentry->d_lru, &data->dispose);
- dentry->d_flags |= DCACHE_SHRINK_LIST;
+ /*
+ * We can't use d_lru_shrink_move() because we
+ * need to get the global LRU lock and do the
+ * LRU accounting.
+ */
+ d_lru_del(dentry);
+ d_shrink_add(dentry, &data->dispose);
data->found++;
ret = D_WALK_NORETRY;
}
dentry_lock_for_move(dentry, target);
write_seqcount_begin(&dentry->d_seq);
- write_seqcount_begin(&target->d_seq);
+ write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
/* __d_drop does write_seqcount_barrier, but they're OK to nest. */
dentry_lock_for_move(anon, dentry);
write_seqcount_begin(&dentry->d_seq);
- write_seqcount_begin(&anon->d_seq);
+ write_seqcount_begin_nested(&anon->d_seq, DENTRY_D_LOCK_NESTED);
dparent = dentry->d_parent;
projects / ~andy / linux / blobdiff