[PATCH 44/73] union-mount: Return files found in lower layers in__lookup_union() [ver #2]

[David Howells]

From: Valerie Aurora <vaurora@xxxxxxxxxx>

If we find a file during union lookup, don't look in any lower layers
and replace the topmost path with the file's path.

Original-author: Valerie Aurora <vaurora@xxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

 fs/namei.c |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 009d9b5..f81f24e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1179,11 +1179,31 @@ static int __lookup_union(struct nameidata *nd, struct qstr *name,
 			continue;
 		}
 
+		/* Files block everything below them.  Special case: If we find
+		 * a file below a directory (which makes no sense), just ignore
+		 * the file and return the directory above it.
+		 */
+		if (!S_ISDIR(lower.dentry->d_inode->i_mode)) {
+			if (topmost->dentry->d_inode &&
+			    S_ISDIR(topmost->dentry->d_inode->i_mode))
+				goto out_lookup_done;
+			goto out_found_file;
+		}
+
 		/* XXX - do nothing, more in later patches */
 		path_put(&lower);
 	}
 	return 0;
 
+out_found_file:
+	/* Swap out the positive lower dentry with the negative upper
+	 * dentry for this file.  Note that the matching mntput() is done
+	 * in link_path_walk().
+	 */
+	dput(topmost->dentry);
+	*topmost = lower;
+	return 0;
+
 out_lookup_done:
 	path_put(&lower);
 	return 0;

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