fs: rcu-walk aware d_revalidate method

Require filesystems be aware of .d_revalidate being called in rcu-walk
mode (nd->flags & LOOKUP_RCU). For now do a simple push down, returning
-ECHILD from all implementations.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

1 files changed, 6 insertions, 1 deletions

diff --git a/fs/coda/dir.c b/fs/coda/dir.c
index aa40c811f8d2..619a8303766e 100644
--- a/fs/coda/dir.c
+++ b/fs/coda/dir.c
@@ -18,6 +18,7 @@
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <linux/spinlock.h>
+#include <linux/namei.h>
 
 #include <asm/uaccess.h>
 
@@ -541,9 +542,13 @@ out:
 /* called when a cache lookup succeeds */
 static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd)
 {
-        struct inode *inode = de->d_inode;
+        struct inode *inode;
         struct coda_inode_info *cii;
 
+        if (nd->flags & LOOKUP_RCU)
+                return -ECHILD;
+
+        inode = de->d_inode;
         if (!inode || coda_isroot(inode))
                 goto out;
         if (is_bad_inode(inode))