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Diffstat (limited to 'fs')
-rw-r--r--fs/dcache.c88
1 files changed, 37 insertions, 51 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 611ffe928c03..361882a14ccb 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1012,6 +1012,34 @@ void shrink_dcache_for_umount(struct super_block *sb)
}
/*
+ * This tries to ascend one level of parenthood, but
+ * we can race with renaming, so we need to re-check
+ * the parenthood after dropping the lock and check
+ * that the sequence number still matches.
+ */
+static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq)
+{
+ struct dentry *new = old->d_parent;
+
+ rcu_read_lock();
+ spin_unlock(&old->d_lock);
+ spin_lock(&new->d_lock);
+
+ /*
+ * might go back up the wrong parent if we have had a rename
+ * or deletion
+ */
+ if (new != old->d_parent ||
+ (!locked && read_seqretry(&rename_lock, seq))) {
+ spin_unlock(&new->d_lock);
+ new = NULL;
+ }
+ rcu_read_unlock();
+ return new;
+}
+
+
+/*
* Search for at least 1 mount point in the dentry's subdirs.
* We descend to the next level whenever the d_subdirs
* list is non-empty and continue searching.
@@ -1066,24 +1094,10 @@ resume:
* All done at this level ... ascend and resume the search.
*/
if (this_parent != parent) {
- struct dentry *tmp;
- struct dentry *child;
-
- tmp = this_parent->d_parent;
- rcu_read_lock();
- spin_unlock(&this_parent->d_lock);
- child = this_parent;
- this_parent = tmp;
- spin_lock(&this_parent->d_lock);
- /* might go back up the wrong parent if we have had a rename
- * or deletion */
- if (this_parent != child->d_parent ||
- (!locked && read_seqretry(&rename_lock, seq))) {
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
+ struct dentry *child = this_parent;
+ this_parent = try_to_ascend(this_parent, locked, seq);
+ if (!this_parent)
goto rename_retry;
- }
- rcu_read_unlock();
next = child->d_u.d_child.next;
goto resume;
}
@@ -1181,24 +1195,10 @@ resume:
* All done at this level ... ascend and resume the search.
*/
if (this_parent != parent) {
- struct dentry *tmp;
- struct dentry *child;
-
- tmp = this_parent->d_parent;
- rcu_read_lock();
- spin_unlock(&this_parent->d_lock);
- child = this_parent;
- this_parent = tmp;
- spin_lock(&this_parent->d_lock);
- /* might go back up the wrong parent if we have had a rename
- * or deletion */
- if (this_parent != child->d_parent ||
- (!locked && read_seqretry(&rename_lock, seq))) {
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
+ struct dentry *child = this_parent;
+ this_parent = try_to_ascend(this_parent, locked, seq);
+ if (!this_parent)
goto rename_retry;
- }
- rcu_read_unlock();
next = child->d_u.d_child.next;
goto resume;
}
@@ -2942,28 +2942,14 @@ resume:
spin_unlock(&dentry->d_lock);
}
if (this_parent != root) {
- struct dentry *tmp;
- struct dentry *child;
-
- tmp = this_parent->d_parent;
+ struct dentry *child = this_parent;
if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
this_parent->d_flags |= DCACHE_GENOCIDE;
this_parent->d_count--;
}
- rcu_read_lock();
- spin_unlock(&this_parent->d_lock);
- child = this_parent;
- this_parent = tmp;
- spin_lock(&this_parent->d_lock);
- /* might go back up the wrong parent if we have had a rename
- * or deletion */
- if (this_parent != child->d_parent ||
- (!locked && read_seqretry(&rename_lock, seq))) {
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
+ this_parent = try_to_ascend(this_parent, locked, seq);
+ if (!this_parent)
goto rename_retry;
- }
- rcu_read_unlock();
next = child->d_u.d_child.next;
goto resume;
}