[PATCH] autofs4: avoid panic on bind mount of autofs owned directory
While this is not a solution to bind and move mounts on autofs owned
directories it is necessary to fix the trady error handling.
At least it avoids the kernel panic I observed checking out bug #4589.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index c7b2b88..9c09641 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -185,6 +185,19 @@
int autofs4_wait_release(struct autofs_sb_info *,autofs_wqt_t,int);
void autofs4_catatonic_mode(struct autofs_sb_info *);
+static inline int autofs4_follow_mount(struct vfsmount **mnt, struct dentry **dentry)
+{
+ int res = 0;
+
+ while (d_mountpoint(*dentry)) {
+ int followed = follow_down(mnt, dentry);
+ if (!followed)
+ break;
+ res = 1;
+ }
+ return res;
+}
+
static inline int simple_positive(struct dentry *dentry)
{
return dentry->d_inode && !d_unhashed(dentry);
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 500425e..feb6ac4 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -56,12 +56,9 @@
mntget(mnt);
dget(dentry);
- if (!follow_down(&mnt, &dentry))
+ if (!autofs4_follow_mount(&mnt, &dentry))
goto done;
- while (d_mountpoint(dentry) && follow_down(&mnt, &dentry))
- ;
-
/* This is an autofs submount, we can't expire it */
if (is_autofs4_dentry(dentry))
goto done;
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 3765c04..e137acf 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -205,7 +205,11 @@
struct vfsmount *fp_mnt = mntget(mnt);
struct dentry *fp_dentry = dget(dentry);
- while (follow_down(&fp_mnt, &fp_dentry) && d_mountpoint(fp_dentry));
+ if (!autofs4_follow_mount(&fp_mnt, &fp_dentry)) {
+ dput(fp_dentry);
+ mntput(fp_mnt);
+ return -ENOENT;
+ }
fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
status = PTR_ERR(fp);