From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Aneesh Kumar K.V" Subject: [PATCH -V9 5/9] vfs: Support null pathname in readlink Date: Tue, 18 May 2010 17:30:11 +0530 Message-ID: <1274184015-19207-6-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1274184015-19207-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Cc: linux-fsdevel@vger.kernel.org, sfrench@us.ibm.com, philippe.deniel@CEA.FR, linux-kernel@vger.kernel.org, "Aneesh Kumar K.V" To: hch@infradead.org, viro@zeniv.linux.org.uk, adilger@sun.com, corbet@lwn.net, serue@us.ibm.com, neilb@suse.de Return-path: In-Reply-To: <1274184015-19207-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org From: NeilBrown This enables to use readlink to get the link target name from a file descriptor point to the link. This can be used with open_by_handle syscall that returns a file descriptor for a link. We can then use this file descriptor to get the target name. Signed-off-by: NeilBrown Signed-off-by: Aneesh Kumar K.V --- fs/stat.c | 30 ++++++++++++++++++++++-------- 1 files changed, 22 insertions(+), 8 deletions(-) diff --git a/fs/stat.c b/fs/stat.c index c4ecd52..49b95a7 100644 --- a/fs/stat.c +++ b/fs/stat.c @@ -284,26 +284,40 @@ SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf) SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname, char __user *, buf, int, bufsiz) { - struct path path; - int error; + int error = 0; + struct path path, *pp; + struct file *file = NULL; if (bufsiz <= 0) return -EINVAL; - error = user_path_at(dfd, pathname, 0, &path); + if (pathname == NULL && dfd != AT_FDCWD) { + file = fget(dfd); + + if (file) + pp = &file->f_path; + else + error = -EBADF; + } else { + error = user_path_at(dfd, pathname, 0, &path); + pp = &path; + } if (!error) { - struct inode *inode = path.dentry->d_inode; + struct inode *inode = pp->dentry->d_inode; error = -EINVAL; if (inode->i_op->readlink) { - error = security_inode_readlink(path.dentry); + error = security_inode_readlink(pp->dentry); if (!error) { - touch_atime(path.mnt, path.dentry); - error = inode->i_op->readlink(path.dentry, + touch_atime(pp->mnt, pp->dentry); + error = inode->i_op->readlink(pp->dentry, buf, bufsiz); } } - path_put(&path); + if (file) + fput(file); + else + path_put(&path); } return error; } -- 1.7.1.78.g212f0