fs: fix do_lookup false negative
fs: fix do_lookup false negative
In do_lookup, if we initially find no dentry, we take the directory i_mutex and
re-check the lookup. If we find a dentry there, then we revalidate it if
needed. However if that revalidate asks for the dentry to be invalidated, we
return -ENOENT from do_lookup. What should happen instead is an attempt to
allocate and lookup a new dentry.
This is probably not noticed because it is rare. It is only reached if a
concurrent create races in first (in which case, the dentry probably won't be
invalidated anyway), or if the racy __d_lookup has failed due to a
false-negative (which is very rare).
Fix this by removing code and have it use the normal reval path.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namei.c b/fs/namei.c
index 17ea76b..c2742b7 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -709,6 +709,7 @@
dentry = __d_lookup(nd->path.dentry, name);
if (!dentry)
goto need_lookup;
+found:
if (dentry->d_op && dentry->d_op->d_revalidate)
goto need_revalidate;
done:
@@ -766,14 +767,7 @@
* we waited on the semaphore. Need to revalidate.
*/
mutex_unlock(&dir->i_mutex);
- if (dentry->d_op && dentry->d_op->d_revalidate) {
- dentry = do_revalidate(dentry, nd);
- if (!dentry)
- dentry = ERR_PTR(-ENOENT);
- }
- if (IS_ERR(dentry))
- goto fail;
- goto done;
+ goto found;
need_revalidate:
dentry = do_revalidate(dentry, nd);