Merge tag 'fsverity-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt

[linux-2.6-microblaze.git] / fs / namei.c

diff --git a/fs/namei.c b/fs/namei.c
index 21fd067..de74ad2 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -630,6 +630,11 @@ static inline bool legitimize_path(struct nameidata *nd,
 static bool legitimize_links(struct nameidata *nd)
 {
        int i;
+       if (unlikely(nd->flags & LOOKUP_CACHED)) {
+               drop_links(nd);
+               nd->depth = 0;
+               return false;
+       }
        for (i = 0; i < nd->depth; i++) {
                struct saved *last = nd->stack + i;
                if (unlikely(!legitimize_path(nd, &last->link, last->seq))) {
@@ -705,19 +710,19 @@ out:
 }
 
 /**
- * unlazy_child - try to switch to ref-walk mode.
+ * try_to_unlazy_next - try to switch to ref-walk mode.
  * @nd: nameidata pathwalk data
- * @dentry: child of nd->path.dentry
- * @seq: seq number to check dentry against
- * Returns: 0 on success, -ECHILD on failure
+ * @dentry: next dentry to step into
+ * @seq: seq number to check @dentry against
+ * Returns: true on success, false on failure
  *
- * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry
- * for ref-walk mode.  @dentry must be a path found by a do_lookup call on
- * @nd.  Must be called from rcu-walk context.
- * Nothing should touch nameidata between unlazy_child() failure and
+ * Similar to to try_to_unlazy(), but here we have the next dentry already
+ * picked by rcu-walk and want to legitimize that in addition to the current
+ * nd->path and nd->root for ref-walk mode.  Must be called from rcu-walk context.
+ * Nothing should touch nameidata between try_to_unlazy_next() failure and
  * terminate_walk().
  */
-static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq)
+static bool try_to_unlazy_next(struct nameidata *nd, struct dentry *dentry, unsigned seq)
 {
        BUG_ON(!(nd->flags & LOOKUP_RCU));
 
@@ -747,7 +752,7 @@ static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned se
        if (unlikely(!legitimize_root(nd)))
                goto out_dput;
        rcu_read_unlock();
-       return 0;
+       return true;
 
 out2:
        nd->path.mnt = NULL;
@@ -755,11 +760,11 @@ out1:
        nd->path.dentry = NULL;
 out:
        rcu_read_unlock();
-       return -ECHILD;
+       return false;
 out_dput:
        rcu_read_unlock();
        dput(dentry);
-       return -ECHILD;
+       return false;
 }
 
 static inline int d_revalidate(struct dentry *dentry, unsigned int flags)
@@ -792,6 +797,7 @@ static int complete_walk(struct nameidata *nd)
                 */
                if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED)))
                        nd->root.mnt = NULL;
+               nd->flags &= ~LOOKUP_CACHED;
                if (!try_to_unlazy(nd))
                        return -ECHILD;
        }
@@ -1372,7 +1378,7 @@ static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry,
                        return -ENOENT;
                if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
                        return 0;
-               if (unlazy_child(nd, dentry, seq))
+               if (!try_to_unlazy_next(nd, dentry, seq))
                        return -ECHILD;
                // *path might've been clobbered by __follow_mount_rcu()
                path->mnt = nd->path.mnt;
@@ -1493,7 +1499,7 @@ static struct dentry *lookup_fast(struct nameidata *nd,
                status = d_revalidate(dentry, nd->flags);
                if (likely(status > 0))
                        return dentry;
-               if (unlazy_child(nd, dentry, seq))
+               if (!try_to_unlazy_next(nd, dentry, seq))
                        return ERR_PTR(-ECHILD);
                if (status == -ECHILD)
                        /* we'd been told to redo it in non-rcu mode */
@@ -2204,6 +2210,10 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
        int error;
        const char *s = nd->name->name;
 
+       /* LOOKUP_CACHED requires RCU, ask caller to retry */
+       if ((flags & (LOOKUP_RCU | LOOKUP_CACHED)) == LOOKUP_CACHED)
+               return ERR_PTR(-EAGAIN);
+
        if (!*s)
                flags &= ~LOOKUP_RCU;
        if (flags & LOOKUP_RCU)