split __follow_mount_rcu() into normal and .. cases
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namei.c b/fs/namei.c
index 2358b32..da9c265 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -919,12 +919,11 @@
}
/*
- * Skip to top of mountpoint pile in rcuwalk mode. We abort the rcu-walk if we
- * meet a managed dentry and we're not walking to "..". True is returned to
- * continue, false to abort.
+ * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
+ * we meet a managed dentry that would need blocking.
*/
static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
- struct inode **inode, bool reverse_transit)
+ struct inode **inode)
{
for (;;) {
struct vfsmount *mounted;
@@ -933,8 +932,7 @@
* that wants to block transit.
*/
*inode = path->dentry->d_inode;
- if (!reverse_transit &&
- unlikely(managed_dentry_might_block(path->dentry)))
+ if (unlikely(managed_dentry_might_block(path->dentry)))
return false;
if (!d_mountpoint(path->dentry))
@@ -949,10 +947,29 @@
}
if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
- return reverse_transit;
+ return false;
return true;
}
+static void follow_mount_rcu(struct nameidata *nd, struct path *path,
+ struct inode **inode)
+{
+ for (;;) {
+ struct vfsmount *mounted;
+ *inode = path->dentry->d_inode;
+
+ if (!d_mountpoint(path->dentry))
+ break;
+
+ mounted = __lookup_mnt(path->mnt, path->dentry, 1);
+ if (!mounted)
+ break;
+ path->mnt = mounted;
+ path->dentry = mounted->mnt_root;
+ nd->seq = read_seqcount_begin(&path->dentry->d_seq);
+ }
+}
+
static int follow_dotdot_rcu(struct nameidata *nd)
{
struct inode *inode = nd->inode;
@@ -982,7 +999,7 @@
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
inode = nd->path.dentry->d_inode;
}
- __follow_mount_rcu(nd, &nd->path, &inode, true);
+ follow_mount_rcu(nd, &nd->path, &inode);
nd->inode = inode;
return 0;
@@ -1157,7 +1174,7 @@
}
path->mnt = mnt;
path->dentry = dentry;
- if (likely(__follow_mount_rcu(nd, path, inode, false)))
+ if (likely(__follow_mount_rcu(nd, path, inode)))
return 0;
unlazy:
if (unlazy_walk(nd, dentry))