From 76fca90e9f3abc82114d9d02d8e14e0324a18ca2 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Fri, 9 Dec 2016 16:45:04 +0100 Subject: vfs: default to generic_readlink() If i_op->readlink is NULL, but i_op->get_link is set then vfs_readlink() defaults to calling generic_readlink(). The IOP_DEFAULT_READLINK flag indicates that the above conditions are met and the default action can be taken. Signed-off-by: Miklos Szeredi --- fs/namei.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'fs') diff --git a/fs/namei.c b/fs/namei.c index 12a4159de72a..b87465d67c60 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -4682,10 +4682,19 @@ int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) { struct inode *inode = d_inode(dentry); - if (!inode->i_op->readlink) - return -EINVAL; + if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { + if (unlikely(inode->i_op->readlink)) + return inode->i_op->readlink(dentry, buffer, buflen); + + if (!d_is_symlink(dentry)) + return -EINVAL; + + spin_lock(&inode->i_lock); + inode->i_opflags |= IOP_DEFAULT_READLINK; + spin_unlock(&inode->i_lock); + } - return inode->i_op->readlink(dentry, buffer, buflen); + return generic_readlink(dentry, buffer, buflen); } EXPORT_SYMBOL(vfs_readlink); -- cgit v1.2.3