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, 8 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index 72e4e01..0c83fde 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1024,12 +1024,9 @@ int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 }
 EXPORT_SYMBOL(noop_fsync);
 
-void kfree_put_link(struct dentry *dentry, struct nameidata *nd,
-				void *cookie)
+void kfree_put_link(struct dentry *dentry, void *cookie)
 {
-	char *s = nd_get_link(nd);
-	if (!IS_ERR(s))
-		kfree(s);
+	kfree(cookie);
 }
 EXPORT_SYMBOL(kfree_put_link);
 
@@ -1094,10 +1091,9 @@ simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
 }
 EXPORT_SYMBOL(simple_nosetlease);
 
-void *simple_follow_link(struct dentry *dentry, struct nameidata *nd)
+const char *simple_follow_link(struct dentry *dentry, void **cookie, struct nameidata *nd)
 {
-	nd_set_link(nd, d_inode(dentry)->i_link);
-	return NULL;
+	return d_inode(dentry)->i_link;
 }
 EXPORT_SYMBOL(simple_follow_link);