1 files changed, 22 insertions, 2 deletions

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index e3869098163e..bc4b06b3160a 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -900,6 +900,7 @@ defined:
 
 struct dentry_operations {
         int (*d_revalidate)(struct dentry *, unsigned int);
+        int (*d_weak_revalidate)(struct dentry *, unsigned int);
         int (*d_hash)(const struct dentry *, const struct inode *,
                         struct qstr *);
         int (*d_compare)(const struct dentry *, const struct inode *,
@@ -915,8 +916,13 @@ struct dentry_operations {
 
   d_revalidate: called when the VFS needs to revalidate a dentry. This
         is called whenever a name look-up finds a dentry in the
-        dcache. Most filesystems leave this as NULL, because all their
-        dentries in the dcache are valid
+        dcache. Most local filesystems leave this as NULL, because all their
+        dentries in the dcache are valid. Network filesystems are different
+        since things can change on the server without the client necessarily
+        being aware of it.
+
+        This function should return a positive value if the dentry is still
+        valid, and zero or a negative error code if it isn't.
 
         d_revalidate may be called in rcu-walk mode (flags & LOOKUP_RCU).
         If in rcu-walk mode, the filesystem must revalidate the dentry without
@@ -927,6 +933,20 @@ struct dentry_operations {
         If a situation is encountered that rcu-walk cannot handle, return
         -ECHILD and it will be called again in ref-walk mode.
 
+ d_weak_revalidate: called when the VFS needs to revalidate a "jumped" dentry.
+        This is called when a path-walk ends at dentry that was not acquired by
+        doing a lookup in the parent directory. This includes "/", "." and "..",
+        as well as procfs-style symlinks and mountpoint traversal.
+
+        In this case, we are less concerned with whether the dentry is still
+        fully correct, but rather that the inode is still valid. As with
+        d_revalidate, most local filesystems will set this to NULL since their
+        dcache entries are always valid.
+
+        This function has the same return code semantics as d_revalidate.
+
+        d_weak_revalidate is only called after leaving rcu-walk mode.
+
   d_hash: called when the VFS adds a dentry to the hash table. The first
         dentry passed to d_hash is the parent directory that the name is
         to be hashed into. The inode is the dentry's inode.