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Subject[PATCH 43/73] union-mount: Process negative dentries in __lookup_union() [ver #2]
Date
From: Valerie Aurora <vaurora@redhat.com>

Whiteouts end a union lookup. So do opaque directories, unless
specific fallthru entry exists for this name.

Original-author: Valerie Aurora <vaurora@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---
fs/namei.c | 22 +++++++++++++++++++++-
1 files changed, 21 insertions(+), 1 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 8caed86..009d9b5 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1163,11 +1163,31 @@ static int __lookup_union(struct nameidata *nd, struct qstr *name,
err = PTR_ERR(lower.dentry);
goto out_err;
}
- /* XXX - do nothing, lookup rule processing in later patches */
+
+ /* A negative dentry can mean several things: a plain negative
+ * dentry is ignored and lookup continues to the next layer,
+ * but a whiteout or a non-fallthru in an opaque dir covers
+ * everything below it.
+ */
+ if (!lower.dentry->d_inode) {
+ if (d_is_whiteout(lower.dentry))
+ goto out_lookup_done;
+ if (IS_OPAQUE(nd->path.dentry->d_inode) &&
+ !d_is_fallthru(lower.dentry))
+ goto out_lookup_done;
+ path_put(&lower);
+ continue;
+ }
+
+ /* XXX - do nothing, more in later patches */
path_put(&lower);
}
return 0;

+out_lookup_done:
+ path_put(&lower);
+ return 0;
+
out_err:
d_free_unions(topmost->dentry);
path_put(&lower);


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