new ->follow_link() and ->put_link() calling conventions

a) instead of storing the symlink body (via nd_set_link()) and returning
an opaque pointer later passed to ->put_link(), ->follow_link() _stores_
that opaque pointer (into void * passed by address by caller) and returns
the symlink body.  Returning ERR_PTR() on error, NULL on jump (procfs magic
symlinks) and pointer to symlink body for normal symlinks.  Stored pointer
is ignored in all cases except the last one.

Storing NULL for opaque pointer (or not storing it at all) means no call
of ->put_link().

b) the body used to be passed to ->put_link() implicitly (via nameidata).
Now only the opaque pointer is.  In the cases when we used the symlink body
to free stuff, ->follow_link() now should store it as opaque pointer in addition
to returning it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 4 insertions, 6 deletions

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index f4cd7204e236..26c4dcb1ef56 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -41,7 +41,6 @@
 
 #include <linux/capability.h>
 #include <linux/xattr.h>
-#include <linux/namei.h>
 #include <linux/posix_acl.h>
 #include <linux/security.h>
 #include <linux/fiemap.h>
@@ -414,9 +413,10 @@ xfs_vn_rename(
  * we need to be very careful about how much stack we use.
  * uio is kmalloced for this reason...
  */
-STATIC void *
+STATIC const char *
 xfs_vn_follow_link(
 	struct dentry		*dentry,
+	void			**cookie,
 	struct nameidata	*nd)
 {
 	char			*link;
@@ -430,14 +430,12 @@ xfs_vn_follow_link(
 	if (unlikely(error))
 		goto out_kfree;
 
-	nd_set_link(nd, link);
-	return NULL;
+	return *cookie = link;
 
  out_kfree:
 	kfree(link);
  out_err:
-	nd_set_link(nd, ERR_PTR(error));
-	return NULL;
+	return ERR_PTR(error);
 }
 
 STATIC int