[patch 06/12] fuse: fix dereferencing dentry parent

[Miklos Szeredi]

There's no locking for ->d_revalidate, so fuse_dentry_revalidate()
should use dget_parent() instead of simply dereferencing ->d_parent.

Due to topology changes in the directory tree the parent could become
negative or be destroyed while being used.  There hasn't been any
reports about this yet.

Signed-off-by: Miklos Szeredi <miklos@xxxxxxxxxx>

---
Index: linux/fs/fuse/dir.c
===================================================================
--- linux.orig/fs/fuse/dir.c	2006-10-16 16:21:11.000000000 +0200
+++ linux/fs/fuse/dir.c	2006-10-16 16:21:20.000000000 +0200
@@ -138,6 +138,7 @@ static int fuse_dentry_revalidate(struct
 		struct fuse_entry_out outarg;
 		struct fuse_conn *fc;
 		struct fuse_req *req;
+		struct dentry *parent;
 
 		/* Doesn't hurt to "reset" the validity timeout */
 		fuse_invalidate_entry_cache(entry);
@@ -151,8 +152,10 @@ static int fuse_dentry_revalidate(struct
 		if (IS_ERR(req))
 			return 0;
 
-		fuse_lookup_init(req, entry->d_parent->d_inode, entry, &outarg);
+		parent = dget_parent(entry);
+		fuse_lookup_init(req, parent->d_inode, entry, &outarg);
 		request_send(fc, req);
+		dput(parent);
 		err = req->out.h.error;
 		/* Zero nodeid is same as -ENOENT */
 		if (!err && !outarg.nodeid)

--
-
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