linux-kernel - [PATCH 3.2 28/77] fix sysvfs symlinks

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Date:	Thu, 24 Dec 2015 15:37:42 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Al Viro" <viro@...iv.linux.org.uk>
Subject: [PATCH 3.2 28/77] fix sysvfs symlinks

3.2.75-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@...iv.linux.org.uk>

commit 0ebf7f10d67a70e120f365018f1c5fce9ddc567d upstream.

The thing got broken back in 2002 - sysvfs does *not* have inline
symlinks; even short ones have bodies stored in the first block
of file.  sysv_symlink() handles that correctly; unfortunately,
attempting to look an existing symlink up will end up confusing
them for inline symlinks, and interpret the block number containing
the body as the body itself.

Nobody has noticed until now, which says something about the level
of testing sysvfs gets ;-/

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
[bwh: Backported to 3.2:
 - Adjust context
 - Also delete unused sysv_fast_symlink_inode_operations]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/sysv/inode.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

--- a/fs/sysv/inode.c
+++ b/fs/sysv/inode.c
@@ -176,14 +176,8 @@ void sysv_set_inode(struct inode *inode,
 		inode->i_fop = &sysv_dir_operations;
 		inode->i_mapping->a_ops = &sysv_aops;
 	} else if (S_ISLNK(inode->i_mode)) {
-		if (inode->i_blocks) {
-			inode->i_op = &sysv_symlink_inode_operations;
-			inode->i_mapping->a_ops = &sysv_aops;
-		} else {
-			inode->i_op = &sysv_fast_symlink_inode_operations;
-			nd_terminate_link(SYSV_I(inode)->i_data, inode->i_size,
-				sizeof(SYSV_I(inode)->i_data) - 1);
-		}
+		inode->i_op = &sysv_symlink_inode_operations;
+		inode->i_mapping->a_ops = &sysv_aops;
 	} else
 		init_special_inode(inode, inode->i_mode, rdev);
 }
--- a/fs/sysv/Makefile
+++ b/fs/sysv/Makefile
@@ -5,4 +5,4 @@
 obj-$(CONFIG_SYSV_FS) += sysv.o
 
 sysv-objs := ialloc.o balloc.o inode.o itree.o file.o dir.o \
-	     namei.o super.o symlink.o
+	     namei.o super.o
--- a/fs/sysv/symlink.c
+++ /dev/null
@@ -1,20 +0,0 @@
-/*
- *  linux/fs/sysv/symlink.c
- *
- *  Handling of System V filesystem fast symlinks extensions.
- *  Aug 2001, Christoph Hellwig (hch@...radead.org)
- */
-
-#include "sysv.h"
-#include <linux/namei.h>
-
-static void *sysv_follow_link(struct dentry *dentry, struct nameidata *nd)
-{
-	nd_set_link(nd, (char *)SYSV_I(dentry->d_inode)->i_data);
-	return NULL;
-}
-
-const struct inode_operations sysv_fast_symlink_inode_operations = {
-	.readlink	= generic_readlink,
-	.follow_link	= sysv_follow_link,
-};

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