linux-kernel - [PATCH -V7 5/9] vfs: Add freadlink syscall

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Date:	Wed, 12 May 2010 21:20:40 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	hch@...radead.org, viro@...iv.linux.org.uk, adilger@....com,
	corbet@....net, serue@...ibm.com, neilb@...e.de
Cc:	linux-fsdevel@...r.kernel.org, sfrench@...ibm.com,
	philippe.deniel@....FR, linux-kernel@...r.kernel.org,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: [PATCH -V7 5/9] vfs: Add freadlink syscall

This enables to use open-by-handle and then get the link target
details of a symlink using the fd returned by handle

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
---
 fs/stat.c |   27 +++++++++++++++++++++++++++
 1 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/fs/stat.c b/fs/stat.c
index c4ecd52..0fbab00 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -314,6 +314,33 @@ SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
 	return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
 }
 
+SYSCALL_DEFINE3(freadlink, int, fd, char __user *, buf,
+		int, bufsiz)
+{
+	int fput_needed;
+	struct file *file;
+	int error = -EBADF;
+	struct inode *inode;
+
+	file = fget_light(fd, &fput_needed);
+	if (!file)
+		return error;
+
+	inode = file->f_path.dentry->d_inode;
+	error = -EINVAL;
+	if (inode->i_op->readlink) {
+		error = security_inode_readlink(file->f_path.dentry);
+		if (!error) {
+			touch_atime(file->f_path.mnt, file->f_path.dentry);
+			error = inode->i_op->readlink(file->f_path.dentry,
+						buf, bufsiz);
+		}
+	}
+	fput_light(file, fput_needed);
+	return error;
+}
+
+
 
 /* ---------- LFS-64 ----------- */
 #ifdef __ARCH_WANT_STAT64
-- 
1.7.1.78.g212f0

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