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Subject[PATCH 41/73] union-mount: Temporarily disable some syscalls [ver #2]
Date
From: Valerie Aurora <vaurora@redhat.com>

After some of the following patches in this series, a few system calls
will crash the kernel if called on union-mounted file systems.
Temporarily disable rename(), unlink(), and rmdir() on unioned file
systems until they are correctly implemented by later patches.

Original-author: Valerie Aurora <vaurora@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---

fs/namei.c | 17 +++++++++++++++++
1 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 991a32c..f53c0bc 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -38,6 +38,7 @@

#include "internal.h"
#include "mount.h"
+#include "union.h"

/* [Feb-1997 T. Schoebel-Theuer]
* Fundamental changes in the pathname lookup mechanisms (namei)
@@ -2891,6 +2892,11 @@ static long do_rmdir(int dfd, const char __user *pathname)
if (error)
return error;

+ /* rmdir() on union mounts not implemented yet */
+ error = -EINVAL;
+ if (IS_DIR_UNIONED(nd.path.dentry))
+ goto exit1;
+
switch(nd.last_type) {
case LAST_DOTDOT:
error = -ENOTEMPTY;
@@ -2991,6 +2997,11 @@ static long do_unlinkat(int dfd, const char __user *pathname)
if (nd.last_type != LAST_NORM)
goto exit1;

+ /* unlink() on union mounts not implemented yet */
+ error = -EINVAL;
+ if (IS_DIR_UNIONED(nd.path.dentry))
+ goto exit1;
+
nd.flags &= ~LOOKUP_PARENT;

mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
@@ -3384,6 +3395,12 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
if (oldnd.path.mnt != newnd.path.mnt)
goto exit2;

+ /* rename() on union mounts not implemented yet */
+ error = -EXDEV;
+ if (IS_DIR_UNIONED(oldnd.path.dentry) ||
+ IS_DIR_UNIONED(newnd.path.dentry))
+ goto exit2;
+
old_dir = oldnd.path.dentry;
error = -EBUSY;
if (oldnd.last_type != LAST_NORM)


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