[PATCH] switch all filesystems over to d_obtain_alias

[linux-2.6-omap-h63xx.git] / fs / nfs / getroot.c

diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index 0ee43843f4ec40c79f1516fb869a5eb720cb355c..b7c9b2df1f299dd15d30b81d533b602d8ae09572 100644 (file)
--- a/fs/nfs/getroot.c
+++ b/fs/nfs/getroot.c
@@ -57,6 +57,17 @@ static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *i
                }
                /* Circumvent igrab(): we know the inode is not being freed */
                atomic_inc(&inode->i_count);
+               /*
+                * Ensure that this dentry is invisible to d_find_alias().
+                * Otherwise, it may be spliced into the tree by
+                * d_materialise_unique if a parent directory from the same
+                * filesystem gets mounted at a later time.
+                * This again causes shrink_dcache_for_umount_subtree() to
+                * Oops, since the test for IS_ROOT() will fail.
+                */
+               spin_lock(&dcache_lock);
+               list_del_init(&sb->s_root->d_alias);
+               spin_unlock(&dcache_lock);
        }
        return 0;
 }
@@ -85,7 +96,7 @@ struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh)
        inode = nfs_fhget(sb, mntfh, fsinfo.fattr);
        if (IS_ERR(inode)) {
                dprintk("nfs_get_root: get root inode failed\n");
-               return ERR_PTR(PTR_ERR(inode));
+               return ERR_CAST(inode);
        }
 
        error = nfs_superblock_set_dummy_root(sb, inode);
@@ -96,11 +107,10 @@ struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh)
         * if the dentry tree reaches them; however if the dentry already
         * exists, we'll pick it up at this point and use it as the root
         */
-       mntroot = d_alloc_anon(inode);
-       if (!mntroot) {
-               iput(inode);
+       mntroot = d_obtain_alias(inode);
+       if (IS_ERR(mntroot)) {
                dprintk("nfs_get_root: get root dentry failed\n");
-               return ERR_PTR(-ENOMEM);
+               return mntroot;
        }
 
        security_d_instantiate(mntroot, inode);
@@ -255,7 +265,7 @@ struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh)
        inode = nfs_fhget(sb, mntfh, &fattr);
        if (IS_ERR(inode)) {
                dprintk("nfs_get_root: get root inode failed\n");
-               return ERR_PTR(PTR_ERR(inode));
+               return ERR_CAST(inode);
        }
 
        error = nfs_superblock_set_dummy_root(sb, inode);
@@ -266,11 +276,10 @@ struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh)
         * if the dentry tree reaches them; however if the dentry already
         * exists, we'll pick it up at this point and use it as the root
         */
-       mntroot = d_alloc_anon(inode);
-       if (!mntroot) {
-               iput(inode);
+       mntroot = d_obtain_alias(inode);
+       if (IS_ERR(mntroot)) {
                dprintk("nfs_get_root: get root dentry failed\n");
-               return ERR_PTR(-ENOMEM);
+               return mntroot;
        }
 
        security_d_instantiate(mntroot, inode);