From 949a852e46dda07caaa0ff02e181f55d24e3ebf8 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun, 6 Mar 2016 14:20:52 -0500
Subject: [PATCH] namei: teach lookup_slow() to skip revalidate
... and make mountpoint_last() use it. That makes all
candidates for lookup with parent locked shared go
through lookup_slow().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/namei.c | 58 ++++++++++++++++++++++++++-----------------
include/linux/namei.h | 1 +
2 files changed, 36 insertions(+), 23 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index cb70a817d439..dbb8ec1a2006 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1605,7 +1605,29 @@ static struct dentry *lookup_slow(const struct qstr *name,
{
struct dentry *dentry;
inode_lock(dir->d_inode);
- dentry = __lookup_hash(name, dir, flags);
+ dentry = d_lookup(dir, name);
+ if (unlikely(dentry)) {
+ if ((dentry->d_flags & DCACHE_OP_REVALIDATE) &&
+ !(flags & LOOKUP_NO_REVAL)) {
+ int error = d_revalidate(dentry, flags);
+ if (unlikely(error <= 0)) {
+ if (!error)
+ d_invalidate(dentry);
+ dput(dentry);
+ dentry = ERR_PTR(error);
+ }
+ }
+ if (dentry) {
+ inode_unlock(dir->d_inode);
+ return dentry;
+ }
+ }
+ dentry = d_alloc(dir, name);
+ if (unlikely(!dentry)) {
+ inode_unlock(dir->d_inode);
+ return ERR_PTR(-ENOMEM);
+ }
+ dentry = lookup_real(dir->d_inode, dentry, flags);
inode_unlock(dir->d_inode);
return dentry;
}
@@ -2425,31 +2447,21 @@ mountpoint_last(struct nameidata *nd, struct path *path)
if (error)
return error;
dentry = dget(nd->path.dentry);
- goto done;
- }
-
- inode_lock(dir->d_inode);
- dentry = d_lookup(dir, &nd->last);
- if (!dentry) {
- /*
- * No cached dentry. Mounted dentries are pinned in the cache,
- * so that means that this dentry is probably a symlink or the
- * path doesn't actually point to a mounted dentry.
- */
- dentry = d_alloc(dir, &nd->last);
+ } else {
+ dentry = d_lookup(dir, &nd->last);
if (!dentry) {
- inode_unlock(dir->d_inode);
- return -ENOMEM;
- }
- dentry = lookup_real(dir->d_inode, dentry, nd->flags);
- if (IS_ERR(dentry)) {
- inode_unlock(dir->d_inode);
- return PTR_ERR(dentry);
+ /*
+ * No cached dentry. Mounted dentries are pinned in the
+ * cache, so that means that this dentry is probably
+ * a symlink or the path doesn't actually point
+ * to a mounted dentry.
+ */
+ dentry = lookup_slow(&nd->last, dir,
+ nd->flags | LOOKUP_NO_REVAL);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
}
}
- inode_unlock(dir->d_inode);
-
-done:
if (d_is_negative(dentry)) {
dput(dentry);
return -ENOENT;
diff --git a/include/linux/namei.h b/include/linux/namei.h
index d0f25d81b46a..77d01700daf7 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -31,6 +31,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
#define LOOKUP_PARENT 0x0010
#define LOOKUP_REVAL 0x0020
#define LOOKUP_RCU 0x0040
+#define LOOKUP_NO_REVAL 0x0080
/*
* Intent data