fs/9p: Always ask new inode in lookup for cache mode disabled

This make sure we don't end up reusing the unlinked inode object.
The ideal way is to use inode i_generation. But i_generation is
not available in userspace always.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 9e3ea6c..e3c03db 100644 (file)
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -825,6 +825,7 @@ static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
                                      struct nameidata *nameidata)
 {
+       struct dentry *res;
        struct super_block *sb;
        struct v9fs_session_info *v9ses;
        struct p9_fid *dfid, *fid;
@@ -856,22 +857,35 @@ struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
 
                return ERR_PTR(result);
        }
-
-       inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
+       /*
+        * Make sure we don't use a wrong inode due to parallel
+        * unlink. For cached mode create calls request for new
+        * inode. But with cache disabled, lookup should do this.
+        */
+       if (v9ses->cache)
+               inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
+       else
+               inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
        if (IS_ERR(inode)) {
                result = PTR_ERR(inode);
                inode = NULL;
                goto error;
        }
-
        result = v9fs_fid_add(dentry, fid);
        if (result < 0)
                goto error_iput;
-
 inst_out:
-       d_add(dentry, inode);
-       return NULL;
-
+       /*
+        * If we had a rename on the server and a parallel lookup
+        * for the new name, then make sure we instantiate with
+        * the new name. ie look up for a/b, while on server somebody
+        * moved b under k and client parallely did a lookup for
+        * k/b.
+        */
+       res = d_materialise_unique(dentry, inode);
+       if (!IS_ERR(res))
+               return res;
+       result = PTR_ERR(res);
 error_iput:
        iput(inode);
 error: