[PATCH 03/24] ovl: rearrange ovl_follow_link to it doesn't need to call ->put_link

Al Viro
2015-04-20T18:13:13Z

From: NeilBrown <neilb@suse.de>

ovl_follow_link current calls ->put_link on an error path.
However ->put_link is about to change in a way that it will be
impossible to call it from ovl_follow_link.

So rearrange the code to avoid the need for that error path.
Specifically: move the kmalloc() call before the ->follow_link()
call to the subordinate filesystem.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/overlayfs/inode.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 04f1248..1b4b9c5e 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -145,6 +145,7 @@ static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd)
void *ret;
struct dentry *realdentry;
struct inode *realinode;
+ struct ovl_link_data *data = NULL;

realdentry = ovl_dentry_real(dentry);
realinode = realdentry->d_inode;
@@ -152,25 +153,23 @@ static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd)
if (WARN_ON(!realinode->i_op->follow_link))
return ERR_PTR(-EPERM);

- ret = realinode->i_op->follow_link(realdentry, nd);
- if (IS_ERR(ret))
- return ret;
-
if (realinode->i_op->put_link) {
- struct ovl_link_data *data;
-
data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL);
- if (!data) {
- realinode->i_op->put_link(realdentry, nd, ret);
+ if (!data)
return ERR_PTR(-ENOMEM);
- }
data->realdentry = realdentry;
- data->cookie = ret;
+ }

- return data;
- } else {
- return NULL;
+ ret = realinode->i_op->follow_link(realdentry, nd);
+ if (IS_ERR(ret)) {
+ kfree(data);
+ return ret;
}
+
+ if (data)
+ data->cookie = ret;
+
+ return data;
}

static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c)
--
2.1.4