From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.
===============
commit 31dec1327e377b6d91a8a6c92b5cd8513939a233 upstream.
There used to be a bunch of tree-walkers in dcache.c, all alike.
try_to_ascend() had been introduced to abstract a piece of logics
duplicated in all of them. These days all these tree-walkers are
implemented via the same iterator (d_walk()), which is the only
remaining caller of try_to_ascend(), so let's fold it back...
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
fs/dcache.c | 49 ++++++++++++++++++-------------------------------
1 file changed, 18 insertions(+), 31 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 7839720ce9f2..116af43494e6 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -465,7 +465,7 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
{
list_del(&dentry->d_u.d_child);
/*
- * Inform try_to_ascend() that we are no longer attached to the
+ * Inform d_walk() that we are no longer attached to the
* dentry tree
*/
dentry->d_flags |= DCACHE_DENTRY_KILLED;
@@ -1060,34 +1060,6 @@ void shrink_dcache_sb(struct super_block *sb)
}
EXPORT_SYMBOL(shrink_dcache_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, 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 ||
- (old->d_flags & DCACHE_DENTRY_KILLED) ||
- need_seqretry(&rename_lock, seq)) {
- spin_unlock(&new->d_lock);
- new = NULL;
- }
- rcu_read_unlock();
- return new;
-}
-
/**
* enum d_walk_ret - action to talke during tree walk
* @D_WALK_CONTINUE: contrinue walk
@@ -1176,9 +1148,24 @@ resume:
*/
if (this_parent != parent) {
struct dentry *child = this_parent;
- this_parent = try_to_ascend(this_parent, seq);
- if (!this_parent)
+ this_parent = child->d_parent;
+
+ rcu_read_lock();
+ spin_unlock(&child->d_lock);
+ 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 ||
+ (child->d_flags & DCACHE_DENTRY_KILLED) ||
+ need_seqretry(&rename_lock, seq)) {
+ spin_unlock(&this_parent->d_lock);
+ rcu_read_unlock();
goto rename_retry;
+ }
+ rcu_read_unlock();
next = child->d_u.d_child.next;
goto resume;
}
--
2.1.2
--
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