merge handle_reval_dot and nameidata_drop_rcu_last
new helper: complete_walk(). Done on successful completion
of walk, drops out of RCU mode, does d_revalidate of final
result if that hadn't been done already.
handle_reval_dot() and nameidata_drop_rcu_last() subsumed into
that one; callers converted to use of complete_walk().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namei.c b/fs/namei.c
index 1039cba..9f59431 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -469,43 +469,6 @@
}
/**
- * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk
- * @nd: nameidata pathwalk data to drop
- * Returns: 0 on success, -ECHILD on failure
- *
- * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk.
- * nd->path should be the final element of the lookup, so nd->root is discarded.
- * Must be called from rcu-walk context.
- */
-static int nameidata_drop_rcu_last(struct nameidata *nd)
-{
- struct dentry *dentry = nd->path.dentry;
-
- BUG_ON(!(nd->flags & LOOKUP_RCU));
- nd->flags &= ~LOOKUP_RCU;
- if (!(nd->flags & LOOKUP_ROOT))
- nd->root.mnt = NULL;
- spin_lock(&dentry->d_lock);
- if (!__d_rcu_to_refcount(dentry, nd->seq))
- goto err_unlock;
- BUG_ON(nd->inode != dentry->d_inode);
- spin_unlock(&dentry->d_lock);
-
- mntget(nd->path.mnt);
-
- rcu_read_unlock();
- br_read_unlock(vfsmount_lock);
-
- return 0;
-
-err_unlock:
- spin_unlock(&dentry->d_lock);
- rcu_read_unlock();
- br_read_unlock(vfsmount_lock);
- return -ECHILD;
-}
-
-/**
* release_open_intent - free up open intent resources
* @nd: pointer to nameidata
*/
@@ -548,26 +511,39 @@
return dentry;
}
-/*
- * handle_reval_path - force revalidation of a dentry
+/**
+ * complete_walk - successful completion of path walk
+ * @nd: pointer nameidata
*
- * In some situations the path walking code will trust dentries without
- * revalidating them. This causes problems for filesystems that depend on
- * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set
- * (which indicates that it's possible for the dentry to go stale), force
- * a d_revalidate call before proceeding.
- *
- * Returns 0 if the revalidation was successful. If the revalidation fails,
- * either return the error returned by d_revalidate or -ESTALE if the
- * revalidation it just returned 0. If d_revalidate returns 0, we attempt to
- * invalidate the dentry. It's up to the caller to handle putting references
- * to the path if necessary.
+ * If we had been in RCU mode, drop out of it and legitimize nd->path.
+ * Revalidate the final result, unless we'd already done that during
+ * the path walk or the filesystem doesn't ask for it. Return 0 on
+ * success, -error on failure. In case of failure caller does not
+ * need to drop nd->path.
*/
-static inline int handle_reval_path(struct nameidata *nd)
+static int complete_walk(struct nameidata *nd)
{
struct dentry *dentry = nd->path.dentry;
int status;
+ if (nd->flags & LOOKUP_RCU) {
+ nd->flags &= ~LOOKUP_RCU;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ spin_lock(&dentry->d_lock);
+ if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ return -ECHILD;
+ }
+ BUG_ON(nd->inode != dentry->d_inode);
+ spin_unlock(&dentry->d_lock);
+ mntget(nd->path.mnt);
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ }
+
if (likely(!(nd->flags & LOOKUP_JUMPED)))
return 0;
@@ -585,6 +561,7 @@
if (!status)
status = -ESTALE;
+ path_put(&nd->path);
return status;
}
@@ -1598,18 +1575,8 @@
}
}
- if (nd->flags & LOOKUP_RCU) {
- /* went all way through without dropping RCU */
- BUG_ON(err);
- if (nameidata_drop_rcu_last(nd))
- err = -ECHILD;
- }
-
- if (!err) {
- err = handle_reval_path(nd);
- if (err)
- path_put(&nd->path);
- }
+ if (!err)
+ err = complete_walk(nd);
if (!err && nd->flags & LOOKUP_DIRECTORY) {
if (!nd->inode->i_op->lookup) {
@@ -2075,13 +2042,9 @@
return ERR_PTR(error);
/* fallthrough */
case LAST_ROOT:
- if (nd->flags & LOOKUP_RCU) {
- if (nameidata_drop_rcu_last(nd))
- return ERR_PTR(-ECHILD);
- }
- error = handle_reval_path(nd);
+ error = complete_walk(nd);
if (error)
- goto exit;
+ return ERR_PTR(error);
audit_inode(pathname, nd->path.dentry);
if (open_flag & O_CREAT) {
error = -EISDIR;
@@ -2089,10 +2052,9 @@
}
goto ok;
case LAST_BIND:
- /* can't be RCU mode here */
- error = handle_reval_path(nd);
+ error = complete_walk(nd);
if (error)
- goto exit;
+ return ERR_PTR(error);
audit_inode(pathname, dir);
goto ok;
}
@@ -2111,10 +2073,9 @@
if (error) /* symlink */
return NULL;
/* sayonara */
- if (nd->flags & LOOKUP_RCU) {
- if (nameidata_drop_rcu_last(nd))
- return ERR_PTR(-ECHILD);
- }
+ error = complete_walk(nd);
+ if (error)
+ return ERR_PTR(-ECHILD);
error = -ENOTDIR;
if (nd->flags & LOOKUP_DIRECTORY) {
@@ -2126,11 +2087,9 @@
}
/* create side of things */
-
- if (nd->flags & LOOKUP_RCU) {
- if (nameidata_drop_rcu_last(nd))
- return ERR_PTR(-ECHILD);
- }
+ error = complete_walk(nd);
+ if (error)
+ return ERR_PTR(error);
audit_inode(pathname, dir);
error = -EISDIR;
