From ff17fa561a04b5fdb25997fda98a2313bb471be6 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun, 15 Apr 2018 18:21:47 -0400
Subject: [PATCH] d_invalidate(): unhash immediately
Once that is done, we can just hunt mountpoints down one by one;
no new mountpoints can be added from now on, so we don't need
anything tricky in finish() callback, etc.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/dcache.c | 62 ++++++++++++++---------------------------------------
1 file changed, 16 insertions(+), 46 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 86d2de63461e1..449d0f895e6fb 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1542,78 +1542,48 @@ void shrink_dcache_for_umount(struct super_block *sb)
}
}
-struct detach_data {
- struct select_data select;
- struct dentry *mountpoint;
-};
-static enum d_walk_ret detach_and_collect(void *_data, struct dentry *dentry)
+static enum d_walk_ret find_submount(void *_data, struct dentry *dentry)
{
- struct detach_data *data = _data;
-
+ struct dentry **victim = _data;
if (d_mountpoint(dentry)) {
__dget_dlock(dentry);
- data->mountpoint = dentry;
+ *victim = dentry;
return D_WALK_QUIT;
}
-
- return select_collect(&data->select, dentry);
-}
-
-static void check_and_drop(void *_data)
-{
- struct detach_data *data = _data;
-
- if (!data->mountpoint && list_empty(&data->select.dispose))
- __d_drop(data->select.start);
+ return D_WALK_CONTINUE;
}
/**
* d_invalidate - detach submounts, prune dcache, and drop
* @dentry: dentry to invalidate (aka detach, prune and drop)
- *
- * no dcache lock.
- *
- * The final d_drop is done as an atomic operation relative to
- * rename_lock ensuring there are no races with d_set_mounted. This
- * ensures there are no unhashed dentries on the path to a mountpoint.
*/
void d_invalidate(struct dentry *dentry)
{
- /*
- * If it's already been dropped, return OK.
- */
+ bool had_submounts = false;
spin_lock(&dentry->d_lock);
if (d_unhashed(dentry)) {
spin_unlock(&dentry->d_lock);
return;
}
+ __d_drop(dentry);
spin_unlock(&dentry->d_lock);
/* Negative dentries can be dropped without further checks */
- if (!dentry->d_inode) {
- d_drop(dentry);
+ if (!dentry->d_inode)
return;
- }
+ shrink_dcache_parent(dentry);
for (;;) {
- struct detach_data data;
-
- data.mountpoint = NULL;
- INIT_LIST_HEAD(&data.select.dispose);
- data.select.start = dentry;
- data.select.found = 0;
-
- d_walk(dentry, &data, detach_and_collect, check_and_drop);
-
- if (!list_empty(&data.select.dispose))
- shrink_dentry_list(&data.select.dispose);
- else if (!data.mountpoint)
+ struct dentry *victim = NULL;
+ d_walk(dentry, &victim, find_submount, NULL);
+ if (!victim) {
+ if (had_submounts)
+ shrink_dcache_parent(dentry);
return;
-
- if (data.mountpoint) {
- detach_mounts(data.mountpoint);
- dput(data.mountpoint);
}
+ had_submounts = true;
+ detach_mounts(victim);
+ dput(victim);
}
}
EXPORT_SYMBOL(d_invalidate);